1 @c Copyright (C) 2008--2021 Free Software Foundation, Inc.
2 @c Permission is granted to copy, distribute and/or modify this document
3 @c under the terms of the GNU Free Documentation License, Version 1.3 or
4 @c any later version published by the Free Software Foundation; with the
5 @c Invariant Sections being ``Free Software'' and ``Free Software Needs
6 @c Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
7 @c and with the Back-Cover Texts as in (a) below.
9 @c (a) The FSF's Back-Cover Text is: ``You are free to copy and modify
10 @c this GNU Manual. Buying copies from GNU Press supports the FSF in
11 @c developing GNU and promoting software freedom.''
14 @section Extending @value{GDBN} using Guile
15 @cindex guile scripting
16 @cindex scripting with guile
18 You can extend @value{GDBN} using the @uref{http://www.gnu.org/software/guile/,
19 Guile implementation of the Scheme programming language}.
20 This feature is available only if @value{GDBN} was configured using
21 @option{--with-guile}.
24 * Guile Introduction:: Introduction to Guile scripting in @value{GDBN}
25 * Guile Commands:: Accessing Guile from @value{GDBN}
26 * Guile API:: Accessing @value{GDBN} from Guile
27 * Guile Auto-loading:: Automatically loading Guile code
28 * Guile Modules:: Guile modules provided by @value{GDBN}
31 @node Guile Introduction
32 @subsection Guile Introduction
34 Guile is an implementation of the Scheme programming language
35 and is the GNU project's official extension language.
37 Guile support in @value{GDBN} follows the Python support in @value{GDBN}
38 reasonably closely, so concepts there should carry over.
39 However, some things are done differently where it makes sense.
41 @value{GDBN} requires Guile version 3.0, 2.2, or 2.0.
43 @cindex guile scripts directory
44 Guile scripts used by @value{GDBN} should be installed in
45 @file{@var{data-directory}/guile}, where @var{data-directory} is
46 the data directory as determined at @value{GDBN} startup (@pxref{Data Files}).
47 This directory, known as the @dfn{guile directory},
48 is automatically added to the Guile Search Path in order to allow
49 the Guile interpreter to locate all scripts installed at this location.
52 @subsection Guile Commands
53 @cindex guile commands
54 @cindex commands to access guile
56 @value{GDBN} provides two commands for accessing the Guile interpreter:
63 The @code{guile-repl} command can be used to start an interactive
64 Guile prompt or @dfn{repl}. To return to @value{GDBN},
65 type @kbd{,q} or the @code{EOF} character (e.g., @kbd{Ctrl-D} on
66 an empty prompt). These commands do not take any arguments.
70 @item guile @r{[}@var{scheme-expression}@r{]}
71 @itemx gu @r{[}@var{scheme-expression}@r{]}
72 The @code{guile} command can be used to evaluate a Scheme expression.
74 If given an argument, @value{GDBN} will pass the argument to the Guile
75 interpreter for evaluation.
78 (@value{GDBP}) guile (display (+ 20 3)) (newline)
82 The result of the Scheme expression is displayed using normal Guile rules.
85 (@value{GDBP}) guile (+ 20 3)
89 If you do not provide an argument to @code{guile}, it will act as a
90 multi-line command, like @code{define}. In this case, the Guile
91 script is made up of subsequent command lines, given after the
92 @code{guile} command. This command list is terminated using a line
93 containing @code{end}. For example:
104 It is also possible to execute a Guile script from the @value{GDBN}
108 @item source @file{script-name}
109 The script name must end with @samp{.scm} and @value{GDBN} must be configured
110 to recognize the script language based on filename extension using
111 the @code{script-extension} setting. @xref{Extending GDB, ,Extending GDB}.
113 @item guile (load "script-name")
114 This method uses the @code{load} Guile function.
115 It takes a string argument that is the name of the script to load.
116 See the Guile documentation for a description of this function.
117 (@pxref{Loading,,, guile, GNU Guile Reference Manual}).
121 @subsection Guile API
123 @cindex programming in guile
125 You can get quick online help for @value{GDBN}'s Guile API by issuing
126 the command @w{@kbd{help guile}}, or by issuing the command @kbd{,help}
127 from an interactive Guile session. Furthermore, most Guile procedures
128 provided by @value{GDBN} have doc strings which can be obtained with
129 @kbd{,describe @var{procedure-name}} or @kbd{,d @var{procedure-name}}
130 from the Guile interactive prompt.
133 * Basic Guile:: Basic Guile Functions
134 * Guile Configuration:: Guile configuration variables
135 * GDB Scheme Data Types:: Scheme representations of GDB objects
136 * Guile Exception Handling:: How Guile exceptions are translated
137 * Values From Inferior In Guile:: Guile representation of values
138 * Arithmetic In Guile:: Arithmetic in Guile
139 * Types In Guile:: Guile representation of types
140 * Guile Pretty Printing API:: Pretty-printing values with Guile
141 * Selecting Guile Pretty-Printers:: How GDB chooses a pretty-printer
142 * Writing a Guile Pretty-Printer:: Writing a pretty-printer
143 * Commands In Guile:: Implementing new commands in Guile
144 * Parameters In Guile:: Adding new @value{GDBN} parameters
145 * Progspaces In Guile:: Program spaces
146 * Objfiles In Guile:: Object files in Guile
147 * Frames In Guile:: Accessing inferior stack frames from Guile
148 * Blocks In Guile:: Accessing blocks from Guile
149 * Symbols In Guile:: Guile representation of symbols
150 * Symbol Tables In Guile:: Guile representation of symbol tables
151 * Breakpoints In Guile:: Manipulating breakpoints using Guile
152 * Lazy Strings In Guile:: Guile representation of lazy strings
153 * Architectures In Guile:: Guile representation of architectures
154 * Disassembly In Guile:: Disassembling instructions from Guile
155 * I/O Ports in Guile:: GDB I/O ports
156 * Memory Ports in Guile:: Accessing memory through ports and bytevectors
157 * Iterators In Guile:: Basic iterator support
161 @subsubsection Basic Guile
164 @cindex guile pagination
165 At startup, @value{GDBN} overrides Guile's @code{current-output-port} and
166 @code{current-error-port} to print using @value{GDBN}'s output-paging streams.
167 A Guile program which outputs to one of these streams may have its
168 output interrupted by the user (@pxref{Screen Size}). In this
169 situation, a Guile @code{signal} exception is thrown with value @code{SIGINT}.
171 Guile's history mechanism uses the same naming as @value{GDBN}'s,
172 namely the user of dollar-variables (e.g., $1, $2, etc.).
173 The results of evaluations in Guile and in GDB are counted separately,
174 @code{$1} in Guile is not the same value as @code{$1} in @value{GDBN}.
176 @value{GDBN} is not thread-safe. If your Guile program uses multiple
177 threads, you must be careful to only call @value{GDBN}-specific
178 functions in the @value{GDBN} thread.
180 Some care must be taken when writing Guile code to run in
181 @value{GDBN}. Two things are worth noting in particular:
185 @value{GDBN} installs handlers for @code{SIGCHLD} and @code{SIGINT}.
186 Guile code must not override these, or even change the options using
187 @code{sigaction}. If your program changes the handling of these
188 signals, @value{GDBN} will most likely stop working correctly. Note
189 that it is unfortunately common for GUI toolkits to install a
190 @code{SIGCHLD} handler.
193 @value{GDBN} takes care to mark its internal file descriptors as
194 close-on-exec. However, this cannot be done in a thread-safe way on
195 all platforms. Your Guile programs should be aware of this and
196 should both create new file descriptors with the close-on-exec flag
197 set and arrange to close unneeded file descriptors before starting a
201 @cindex guile gdb module
202 @value{GDBN} introduces a new Guile module, named @code{gdb}. All
203 methods and classes added by @value{GDBN} are placed in this module.
204 @value{GDBN} does not automatically @code{import} the @code{gdb} module,
205 scripts must do this themselves. There are various options for how to
206 import a module, so @value{GDBN} leaves the choice of how the @code{gdb}
207 module is imported to the user.
208 To simplify interactive use, it is recommended to add one of the following
212 guile (use-modules (gdb))
216 guile (use-modules ((gdb) #:renamer (symbol-prefix-proc 'gdb:)))
219 Which one to choose depends on your preference.
220 The second one adds @code{gdb:} as a prefix to all module functions
223 The rest of this manual assumes the @code{gdb} module has been imported
224 without any prefix. See the Guile documentation for @code{use-modules}
226 (@pxref{Using Guile Modules,,, guile, GNU Guile Reference Manual}).
231 (gdb) guile (value-type (make-value 1))
232 ERROR: Unbound variable: value-type
233 Error while executing Scheme code.
234 (gdb) guile (use-modules (gdb))
235 (gdb) guile (value-type (make-value 1))
240 The @code{(gdb)} module provides these basic Guile functions.
243 @deffn {Scheme Procedure} execute command @r{[}#:from-tty boolean@r{]} @r{[}#:to-string boolean@r{]}
244 Evaluate @var{command}, a string, as a @value{GDBN} CLI command.
245 If a @value{GDBN} exception happens while @var{command} runs, it is
246 translated as described in
247 @ref{Guile Exception Handling,,Guile Exception Handling}.
249 @var{from-tty} specifies whether @value{GDBN} ought to consider this
250 command as having originated from the user invoking it interactively.
251 It must be a boolean value. If omitted, it defaults to @code{#f}.
253 By default, any output produced by @var{command} is sent to
254 @value{GDBN}'s standard output (and to the log output if logging is
255 turned on). If the @var{to-string} parameter is
256 @code{#t}, then output will be collected by @code{execute} and
257 returned as a string. The default is @code{#f}, in which case the
258 return value is unspecified. If @var{to-string} is @code{#t}, the
259 @value{GDBN} virtual terminal will be temporarily set to unlimited width
260 and height, and its pagination will be disabled; @pxref{Screen Size}.
263 @deffn {Scheme Procedure} history-ref number
264 Return a value from @value{GDBN}'s value history (@pxref{Value
265 History}). The @var{number} argument indicates which history element to return.
266 If @var{number} is negative, then @value{GDBN} will take its absolute value
267 and count backward from the last element (i.e., the most recent element) to
268 find the value to return. If @var{number} is zero, then @value{GDBN} will
269 return the most recent element. If the element specified by @var{number}
270 doesn't exist in the value history, a @code{gdb:error} exception will be
273 If no exception is raised, the return value is always an instance of
274 @code{<gdb:value>} (@pxref{Values From Inferior In Guile}).
276 @emph{Note:} @value{GDBN}'s value history is independent of Guile's.
277 @code{$1} in @value{GDBN}'s value history contains the result of evaluating
278 an expression from @value{GDBN}'s command line and @code{$1} from Guile's
279 history contains the result of evaluating an expression from Guile's
283 @deffn {Scheme Procedure} history-append! value
284 Append @var{value}, an instance of @code{<gdb:value>}, to @value{GDBN}'s
285 value history. Return its index in the history.
287 Putting into history values returned by Guile extensions will allow
288 the user convenient access to those values via CLI history
292 @deffn {Scheme Procedure} parse-and-eval expression
293 Parse @var{expression} as an expression in the current language,
294 evaluate it, and return the result as a @code{<gdb:value>}.
295 The @var{expression} must be a string.
297 This function can be useful when implementing a new command
298 (@pxref{Commands In Guile}), as it provides a way to parse the
299 command's arguments as an expression.
300 It is also is useful when computing values.
301 For example, it is the only way to get the value of a
302 convenience variable (@pxref{Convenience Vars}) as a @code{<gdb:value>}.
305 @node Guile Configuration
306 @subsubsection Guile Configuration
307 @cindex guile configuration
309 @value{GDBN} provides these Scheme functions to access various configuration
312 @deffn {Scheme Procedure} data-directory
313 Return a string containing @value{GDBN}'s data directory.
314 This directory contains @value{GDBN}'s ancillary files.
317 @deffn {Scheme Procedure} guile-data-directory
318 Return a string containing @value{GDBN}'s Guile data directory.
319 This directory contains the Guile modules provided by @value{GDBN}.
322 @deffn {Scheme Procedure} gdb-version
323 Return a string containing the @value{GDBN} version.
326 @deffn {Scheme Procedure} host-config
327 Return a string containing the host configuration.
328 This is the string passed to @code{--host} when @value{GDBN} was configured.
331 @deffn {Scheme Procedure} target-config
332 Return a string containing the target configuration.
333 This is the string passed to @code{--target} when @value{GDBN} was configured.
336 @node GDB Scheme Data Types
337 @subsubsection GDB Scheme Data Types
340 The values exposed by @value{GDBN} to Guile are known as
341 @dfn{@value{GDBN} objects}. There are several kinds of @value{GDBN}
342 object, and each is disjoint from all other types known to Guile.
344 @deffn {Scheme Procedure} gdb-object-kind object
345 Return the kind of the @value{GDBN} object, e.g., @code{<gdb:breakpoint>},
349 @value{GDBN} defines the following object types:
353 @xref{Architectures In Guile}.
356 @xref{Blocks In Guile}.
358 @item <gdb:block-symbols-iterator>
359 @xref{Blocks In Guile}.
361 @item <gdb:breakpoint>
362 @xref{Breakpoints In Guile}.
365 @xref{Commands In Guile}.
367 @item <gdb:exception>
368 @xref{Guile Exception Handling}.
371 @xref{Frames In Guile}.
374 @xref{Iterators In Guile}.
376 @item <gdb:lazy-string>
377 @xref{Lazy Strings In Guile}.
380 @xref{Objfiles In Guile}.
382 @item <gdb:parameter>
383 @xref{Parameters In Guile}.
385 @item <gdb:pretty-printer>
386 @xref{Guile Pretty Printing API}.
388 @item <gdb:pretty-printer-worker>
389 @xref{Guile Pretty Printing API}.
391 @item <gdb:progspace>
392 @xref{Progspaces In Guile}.
395 @xref{Symbols In Guile}.
398 @xref{Symbol Tables In Guile}.
401 @xref{Symbol Tables In Guile}.
404 @xref{Types In Guile}.
407 @xref{Types In Guile}.
410 @xref{Values From Inferior In Guile}.
413 The following @value{GDBN} objects are managed internally so that the
414 Scheme function @code{eq?} may be applied to them.
419 @item <gdb:breakpoint>
422 @item <gdb:progspace>
428 @node Guile Exception Handling
429 @subsubsection Guile Exception Handling
430 @cindex guile exceptions
431 @cindex exceptions, guile
432 @kindex set guile print-stack
434 When executing the @code{guile} command, Guile exceptions
435 uncaught within the Guile code are translated to calls to the
436 @value{GDBN} error-reporting mechanism. If the command that called
437 @code{guile} does not handle the error, @value{GDBN} will
438 terminate it and report the error according to the setting of
439 the @code{guile print-stack} parameter.
441 The @code{guile print-stack} parameter has three settings:
448 An error message is printed containing the Guile exception name,
449 the associated value, and the Guile call stack backtrace at the
450 point where the exception was raised. Example:
453 (@value{GDBP}) guile (display foo)
454 ERROR: In procedure memoize-variable-access!:
455 ERROR: Unbound variable: foo
456 Error while executing Scheme code.
460 In addition to an error message a full backtrace is printed.
463 (@value{GDBP}) set guile print-stack full
464 (@value{GDBP}) guile (display foo)
467 157: 10 [catch #t #<catch-closure 2c76e20> ...]
469 ?: 9 [apply-smob/1 #<catch-closure 2c76e20>]
471 157: 8 [catch #t #<catch-closure 2c76d20> ...]
473 ?: 7 [apply-smob/1 #<catch-closure 2c76d20>]
474 ?: 6 [call-with-input-string "(display foo)" ...]
476 2320: 5 [save-module-excursion #<procedure 2c2dc30 ... ()>]
477 In ice-9/eval-string.scm:
478 44: 4 [read-and-eval #<input: string 27cb410> #:lang ...]
479 37: 3 [lp (display foo)]
482 393: 1 [eval #<memoized foo> ()]
484 ?: 0 [memoize-variable-access! #<memoized foo> ...]
486 ERROR: In procedure memoize-variable-access!:
487 ERROR: Unbound variable: foo
488 Error while executing Scheme code.
492 @value{GDBN} errors that happen in @value{GDBN} commands invoked by
493 Guile code are converted to Guile exceptions. The type of the
494 Guile exception depends on the error.
496 Guile procedures provided by @value{GDBN} can throw the standard
497 Guile exceptions like @code{wrong-type-arg} and @code{out-of-range}.
499 User interrupt (via @kbd{C-c} or by typing @kbd{q} at a pagination
500 prompt) is translated to a Guile @code{signal} exception with value
503 @value{GDBN} Guile procedures can also throw these exceptions:
507 This exception is a catch-all for errors generated from within @value{GDBN}.
509 @item gdb:invalid-object
510 This exception is thrown when accessing Guile objects that wrap underlying
511 @value{GDBN} objects have become invalid. For example, a
512 @code{<gdb:breakpoint>} object becomes invalid if the user deletes it
513 from the command line. The object still exists in Guile, but the
514 object it represents is gone. Further operations on this breakpoint
515 will throw this exception.
517 @item gdb:memory-error
518 This exception is thrown when an operation tried to access invalid
519 memory in the inferior.
521 @item gdb:pp-type-error
522 This exception is thrown when a Guile pretty-printer passes a bad object
526 The following exception-related procedures are provided by the
529 @deffn {Scheme Procedure} make-exception key args
530 Return a @code{<gdb:exception>} object given by its @var{key} and
531 @var{args}, which are the standard Guile parameters of an exception.
532 See the Guile documentation for more information (@pxref{Exceptions,,,
533 guile, GNU Guile Reference Manual}).
536 @deffn {Scheme Procedure} exception? object
537 Return @code{#t} if @var{object} is a @code{<gdb:exception>} object.
538 Otherwise return @code{#f}.
541 @deffn {Scheme Procedure} exception-key exception
542 Return the @var{args} field of a @code{<gdb:exception>} object.
545 @deffn {Scheme Procedure} exception-args exception
546 Return the @var{args} field of a @code{<gdb:exception>} object.
549 @node Values From Inferior In Guile
550 @subsubsection Values From Inferior In Guile
551 @cindex values from inferior, in guile
552 @cindex guile, working with values from inferior
554 @tindex @code{<gdb:value>}
555 @value{GDBN} provides values it obtains from the inferior program in
556 an object of type @code{<gdb:value>}. @value{GDBN} uses this object
557 for its internal bookkeeping of the inferior's values, and for
558 fetching values when necessary.
560 @value{GDBN} does not memoize @code{<gdb:value>} objects.
561 @code{make-value} always returns a fresh object.
564 (gdb) guile (eq? (make-value 1) (make-value 1))
566 (gdb) guile (equal? (make-value 1) (make-value 1))
570 A @code{<gdb:value>} that represents a function can be executed via
571 inferior function call with @code{value-call}.
572 Any arguments provided to the call must match the function's prototype,
573 and must be provided in the order specified by that prototype.
575 For example, @code{some-val} is a @code{<gdb:value>} instance
576 representing a function that takes two integers as arguments. To
577 execute this function, call it like so:
580 (define result (value-call some-val 10 20))
583 Any values returned from a function call are @code{<gdb:value>} objects.
585 Note: Unlike Python scripting in @value{GDBN},
586 inferior values that are simple scalars cannot be used directly in
587 Scheme expressions that are valid for the value's data type.
588 For example, @code{(+ (parse-and-eval "int_variable") 2)} does not work.
589 And inferior values that are structures or instances of some class cannot
590 be accessed using any special syntax, instead @code{value-field} must be used.
592 The following value-related procedures are provided by the
595 @deffn {Scheme Procedure} value? object
596 Return @code{#t} if @var{object} is a @code{<gdb:value>} object.
597 Otherwise return @code{#f}.
600 @deffn {Scheme Procedure} make-value value @r{[}#:type type@r{]}
601 Many Scheme values can be converted directly to a @code{<gdb:value>}
602 with this procedure. If @var{type} is specified, the result is a value
603 of this type, and if @var{value} can't be represented with this type
604 an exception is thrown. Otherwise the type of the result is determined from
605 @var{value} as described below.
607 @xref{Architectures In Guile}, for a list of the builtin
608 types for an architecture.
610 Here's how Scheme values are converted when @var{type} argument to
611 @code{make-value} is not specified:
615 A Scheme boolean is converted the boolean type for the current language.
618 A Scheme integer is converted to the first of a C @code{int},
619 @code{unsigned int}, @code{long}, @code{unsigned long},
620 @code{long long} or @code{unsigned long long} type
621 for the current architecture that can represent the value.
623 If the Scheme integer cannot be represented as a target integer
624 an @code{out-of-range} exception is thrown.
627 A Scheme real is converted to the C @code{double} type for the
628 current architecture.
631 A Scheme string is converted to a string in the current target
632 language using the current target encoding.
633 Characters that cannot be represented in the current target encoding
634 are replaced with the corresponding escape sequence. This is Guile's
635 @code{SCM_FAILED_CONVERSION_ESCAPE_SEQUENCE} conversion strategy
636 (@pxref{Strings,,, guile, GNU Guile Reference Manual}).
638 Passing @var{type} is not supported in this case,
639 if it is provided a @code{wrong-type-arg} exception is thrown.
641 @item @code{<gdb:lazy-string>}
642 If @var{value} is a @code{<gdb:lazy-string>} object (@pxref{Lazy Strings In
643 Guile}), then the @code{lazy-string->value} procedure is called, and
646 Passing @var{type} is not supported in this case,
647 if it is provided a @code{wrong-type-arg} exception is thrown.
649 @item Scheme bytevector
650 If @var{value} is a Scheme bytevector and @var{type} is provided,
651 @var{value} must be the same size, in bytes, of values of type @var{type},
652 and the result is essentially created by using @code{memcpy}.
654 If @var{value} is a Scheme bytevector and @var{type} is not provided,
655 the result is an array of type @code{uint8} of the same length.
659 @cindex optimized out value in guile
660 @deffn {Scheme Procedure} value-optimized-out? value
661 Return @code{#t} if the compiler optimized out @var{value},
662 thus it is not available for fetching from the inferior.
663 Otherwise return @code{#f}.
666 @deffn {Scheme Procedure} value-address value
667 If @var{value} is addressable, returns a
668 @code{<gdb:value>} object representing the address.
669 Otherwise, @code{#f} is returned.
672 @deffn {Scheme Procedure} value-type value
673 Return the type of @var{value} as a @code{<gdb:type>} object
674 (@pxref{Types In Guile}).
677 @deffn {Scheme Procedure} value-dynamic-type value
678 Return the dynamic type of @var{value}. This uses C@t{++} run-time
679 type information (@acronym{RTTI}) to determine the dynamic type of the
680 value. If the value is of class type, it will return the class in
681 which the value is embedded, if any. If the value is of pointer or
682 reference to a class type, it will compute the dynamic type of the
683 referenced object, and return a pointer or reference to that type,
684 respectively. In all other cases, it will return the value's static
687 Note that this feature will only work when debugging a C@t{++} program
688 that includes @acronym{RTTI} for the object in question. Otherwise,
689 it will just return the static type of the value as in @kbd{ptype foo}.
690 @xref{Symbols, ptype}.
693 @deffn {Scheme Procedure} value-cast value type
694 Return a new instance of @code{<gdb:value>} that is the result of
695 casting @var{value} to the type described by @var{type}, which must
696 be a @code{<gdb:type>} object. If the cast cannot be performed for some
697 reason, this method throws an exception.
700 @deffn {Scheme Procedure} value-dynamic-cast value type
701 Like @code{value-cast}, but works as if the C@t{++} @code{dynamic_cast}
702 operator were used. Consult a C@t{++} reference for details.
705 @deffn {Scheme Procedure} value-reinterpret-cast value type
706 Like @code{value-cast}, but works as if the C@t{++} @code{reinterpret_cast}
707 operator were used. Consult a C@t{++} reference for details.
710 @deffn {Scheme Procedure} value-dereference value
711 For pointer data types, this method returns a new @code{<gdb:value>} object
712 whose contents is the object pointed to by @var{value}. For example, if
713 @code{foo} is a C pointer to an @code{int}, declared in your C program as
720 then you can use the corresponding @code{<gdb:value>} to access what
721 @code{foo} points to like this:
724 (define bar (value-dereference foo))
727 The result @code{bar} will be a @code{<gdb:value>} object holding the
728 value pointed to by @code{foo}.
730 A similar function @code{value-referenced-value} exists which also
731 returns @code{<gdb:value>} objects corresponding to the values pointed to
732 by pointer values (and additionally, values referenced by reference
733 values). However, the behavior of @code{value-dereference}
734 differs from @code{value-referenced-value} by the fact that the
735 behavior of @code{value-dereference} is identical to applying the C
736 unary operator @code{*} on a given value. For example, consider a
737 reference to a pointer @code{ptrref}, declared in your C@t{++} program
745 intptr &ptrref = ptr;
748 Though @code{ptrref} is a reference value, one can apply the method
749 @code{value-dereference} to the @code{<gdb:value>} object corresponding
750 to it and obtain a @code{<gdb:value>} which is identical to that
751 corresponding to @code{val}. However, if you apply the method
752 @code{value-referenced-value}, the result would be a @code{<gdb:value>}
753 object identical to that corresponding to @code{ptr}.
756 (define scm-ptrref (parse-and-eval "ptrref"))
757 (define scm-val (value-dereference scm-ptrref))
758 (define scm-ptr (value-referenced-value scm-ptrref))
761 The @code{<gdb:value>} object @code{scm-val} is identical to that
762 corresponding to @code{val}, and @code{scm-ptr} is identical to that
763 corresponding to @code{ptr}. In general, @code{value-dereference} can
764 be applied whenever the C unary operator @code{*} can be applied
765 to the corresponding C value. For those cases where applying both
766 @code{value-dereference} and @code{value-referenced-value} is allowed,
767 the results obtained need not be identical (as we have seen in the above
768 example). The results are however identical when applied on
769 @code{<gdb:value>} objects corresponding to pointers (@code{<gdb:value>}
770 objects with type code @code{TYPE_CODE_PTR}) in a C/C@t{++} program.
773 @deffn {Scheme Procedure} value-referenced-value value
774 For pointer or reference data types, this method returns a new
775 @code{<gdb:value>} object corresponding to the value referenced by the
776 pointer/reference value. For pointer data types,
777 @code{value-dereference} and @code{value-referenced-value} produce
778 identical results. The difference between these methods is that
779 @code{value-dereference} cannot get the values referenced by reference
780 values. For example, consider a reference to an @code{int}, declared
781 in your C@t{++} program as
789 then applying @code{value-dereference} to the @code{<gdb:value>} object
790 corresponding to @code{ref} will result in an error, while applying
791 @code{value-referenced-value} will result in a @code{<gdb:value>} object
792 identical to that corresponding to @code{val}.
795 (define scm-ref (parse-and-eval "ref"))
796 (define err-ref (value-dereference scm-ref)) ;; error
797 (define scm-val (value-referenced-value scm-ref)) ;; ok
800 The @code{<gdb:value>} object @code{scm-val} is identical to that
801 corresponding to @code{val}.
804 @deffn {Scheme Procedure} value-field value field-name
805 Return field @var{field-name} from @code{<gdb:value>} object @var{value}.
808 @deffn {Scheme Procedure} value-subscript value index
809 Return the value of array @var{value} at index @var{index}.
810 The @var{value} argument must be a subscriptable @code{<gdb:value>} object.
813 @deffn {Scheme Procedure} value-call value arg-list
814 Perform an inferior function call, taking @var{value} as a pointer
815 to the function to call.
816 Each element of list @var{arg-list} must be a <gdb:value> object or an object
817 that can be converted to a value.
818 The result is the value returned by the function.
821 @deffn {Scheme Procedure} value->bool value
822 Return the Scheme boolean representing @code{<gdb:value>} @var{value}.
823 The value must be ``integer like''. Pointers are ok.
826 @deffn {Scheme Procedure} value->integer
827 Return the Scheme integer representing @code{<gdb:value>} @var{value}.
828 The value must be ``integer like''. Pointers are ok.
831 @deffn {Scheme Procedure} value->real
832 Return the Scheme real number representing @code{<gdb:value>} @var{value}.
833 The value must be a number.
836 @deffn {Scheme Procedure} value->bytevector
837 Return a Scheme bytevector with the raw contents of @code{<gdb:value>}
838 @var{value}. No transformation, endian or otherwise, is performed.
842 @deffn {Scheme Procedure} value->string value @r{[}#:encoding encoding@r{]} @r{[}#:errors errors@r{]} @r{[}#:length length@r{]}
843 If @var{value>} represents a string, then this method
844 converts the contents to a Guile string. Otherwise, this method will
847 Values are interpreted as strings according to the rules of the
848 current language. If the optional length argument is given, the
849 string will be converted to that length, and will include any embedded
850 zeroes that the string may contain. Otherwise, for languages
851 where the string is zero-terminated, the entire string will be
854 For example, in C-like languages, a value is a string if it is a pointer
855 to or an array of characters or ints of type @code{wchar_t}, @code{char16_t},
858 If the optional @var{encoding} argument is given, it must be a string
859 naming the encoding of the string in the @code{<gdb:value>}, such as
860 @code{"ascii"}, @code{"iso-8859-6"} or @code{"utf-8"}. It accepts
861 the same encodings as the corresponding argument to Guile's
862 @code{scm_from_stringn} function, and the Guile codec machinery will be used
863 to convert the string. If @var{encoding} is not given, or if
864 @var{encoding} is the empty string, then either the @code{target-charset}
865 (@pxref{Character Sets}) will be used, or a language-specific encoding
866 will be used, if the current language is able to supply one.
868 The optional @var{errors} argument is one of @code{#f}, @code{error} or
869 @code{substitute}. @code{error} and @code{substitute} must be symbols.
870 If @var{errors} is not specified, or if its value is @code{#f}, then the
871 default conversion strategy is used, which is set with the Scheme function
872 @code{set-port-conversion-strategy!}.
873 If the value is @code{'error} then an exception is thrown if there is any
874 conversion error. If the value is @code{'substitute} then any conversion
875 error is replaced with question marks.
876 @xref{Strings,,, guile, GNU Guile Reference Manual}.
878 If the optional @var{length} argument is given, the string will be
879 fetched and converted to the given length.
880 The length must be a Scheme integer and not a @code{<gdb:value>} integer.
884 @deffn {Scheme Procedure} value->lazy-string value @r{[}#:encoding encoding@r{]} @r{[}#:length length@r{]}
885 If this @code{<gdb:value>} represents a string, then this method
886 converts @var{value} to a @code{<gdb:lazy-string} (@pxref{Lazy Strings
887 In Guile}). Otherwise, this method will throw an exception.
889 If the optional @var{encoding} argument is given, it must be a string
890 naming the encoding of the @code{<gdb:lazy-string}. Some examples are:
891 @code{"ascii"}, @code{"iso-8859-6"} or @code{"utf-8"}. If the
892 @var{encoding} argument is an encoding that @value{GDBN} does not
893 recognize, @value{GDBN} will raise an error.
895 When a lazy string is printed, the @value{GDBN} encoding machinery is
896 used to convert the string during printing. If the optional
897 @var{encoding} argument is not provided, or is an empty string,
898 @value{GDBN} will automatically select the encoding most suitable for
899 the string type. For further information on encoding in @value{GDBN}
900 please see @ref{Character Sets}.
902 If the optional @var{length} argument is given, the string will be
903 fetched and encoded to the length of characters specified. If
904 the @var{length} argument is not provided, the string will be fetched
905 and encoded until a null of appropriate width is found.
906 The length must be a Scheme integer and not a @code{<gdb:value>} integer.
909 @deffn {Scheme Procedure} value-lazy? value
910 Return @code{#t} if @var{value} has not yet been fetched
912 Otherwise return @code{#f}.
913 @value{GDBN} does not fetch values until necessary, for efficiency.
917 (define myval (parse-and-eval "somevar"))
920 The value of @code{somevar} is not fetched at this time. It will be
921 fetched when the value is needed, or when the @code{fetch-lazy}
922 procedure is invoked.
925 @deffn {Scheme Procedure} make-lazy-value type address
926 Return a @code{<gdb:value>} that will be lazily fetched from the
927 target. The object of type @code{<gdb:type>} whose value to fetch is
928 specified by its @var{type} and its target memory @var{address}, which
932 @deffn {Scheme Procedure} value-fetch-lazy! value
933 If @var{value} is a lazy value (@code{(value-lazy? value)} is @code{#t}),
934 then the value is fetched from the inferior.
935 Any errors that occur in the process will produce a Guile exception.
937 If @var{value} is not a lazy value, this method has no effect.
939 The result of this function is unspecified.
942 @deffn {Scheme Procedure} value-print value
943 Return the string representation (print form) of @code{<gdb:value>}
947 @node Arithmetic In Guile
948 @subsubsection Arithmetic In Guile
950 The @code{(gdb)} module provides several functions for performing
951 arithmetic on @code{<gdb:value>} objects.
952 The arithmetic is performed as if it were done by the target,
953 and therefore has target semantics which are not necessarily
954 those of Scheme. For example operations work with a fixed precision,
955 not the arbitrary precision of Scheme.
957 Wherever a function takes an integer or pointer as an operand,
958 @value{GDBN} will convert appropriate Scheme values to perform
961 @deffn {Scheme Procedure} value-add a b
964 @deffn {Scheme Procedure} value-sub a b
967 @deffn {Scheme Procedure} value-mul a b
970 @deffn {Scheme Procedure} value-div a b
973 @deffn {Scheme Procedure} value-rem a b
976 @deffn {Scheme Procedure} value-mod a b
979 @deffn {Scheme Procedure} value-pow a b
982 @deffn {Scheme Procedure} value-not a
985 @deffn {Scheme Procedure} value-neg a
988 @deffn {Scheme Procedure} value-pos a
991 @deffn {Scheme Procedure} value-abs a
994 @deffn {Scheme Procedure} value-lsh a b
997 @deffn {Scheme Procedure} value-rsh a b
1000 @deffn {Scheme Procedure} value-min a b
1003 @deffn {Scheme Procedure} value-max a b
1006 @deffn {Scheme Procedure} value-lognot a
1009 @deffn {Scheme Procedure} value-logand a b
1012 @deffn {Scheme Procedure} value-logior a b
1015 @deffn {Scheme Procedure} value-logxor a b
1018 @deffn {Scheme Procedure} value=? a b
1021 @deffn {Scheme Procedure} value<? a b
1024 @deffn {Scheme Procedure} value<=? a b
1027 @deffn {Scheme Procedure} value>? a b
1030 @deffn {Scheme Procedure} value>=? a b
1033 Scheme does not provide a @code{not-equal} function,
1034 and thus Guile support in @value{GDBN} does not either.
1036 @node Types In Guile
1037 @subsubsection Types In Guile
1038 @cindex types in guile
1039 @cindex guile, working with types
1042 @value{GDBN} represents types from the inferior in objects of type
1045 The following type-related procedures are provided by the
1046 @code{(gdb)} module.
1048 @deffn {Scheme Procedure} type? object
1049 Return @code{#t} if @var{object} is an object of type @code{<gdb:type>}.
1050 Otherwise return @code{#f}.
1053 @deffn {Scheme Procedure} lookup-type name @r{[}#:block block@r{]}
1054 This function looks up a type by its @var{name}, which must be a string.
1056 If @var{block} is given, it is an object of type @code{<gdb:block>},
1057 and @var{name} is looked up in that scope.
1058 Otherwise, it is searched for globally.
1060 Ordinarily, this function will return an instance of @code{<gdb:type>}.
1061 If the named type cannot be found, it will throw an exception.
1064 @deffn {Scheme Procedure} type-code type
1065 Return the type code of @var{type}. The type code will be one of the
1066 @code{TYPE_CODE_} constants defined below.
1069 @deffn {Scheme Procedure} type-tag type
1070 Return the tag name of @var{type}. The tag name is the name after
1071 @code{struct}, @code{union}, or @code{enum} in C and C@t{++}; not all
1072 languages have this concept. If this type has no tag name, then
1073 @code{#f} is returned.
1076 @deffn {Scheme Procedure} type-name type
1077 Return the name of @var{type}.
1078 If this type has no name, then @code{#f} is returned.
1081 @deffn {Scheme Procedure} type-print-name type
1082 Return the print name of @var{type}.
1083 This returns something even for anonymous types.
1084 For example, for an anonymous C struct @code{"struct @{...@}"} is returned.
1087 @deffn {Scheme Procedure} type-sizeof type
1088 Return the size of this type, in target @code{char} units. Usually, a
1089 target's @code{char} type will be an 8-bit byte. However, on some
1090 unusual platforms, this type may have a different size.
1093 @deffn {Scheme Procedure} type-strip-typedefs type
1094 Return a new @code{<gdb:type>} that represents the real type of @var{type},
1095 after removing all layers of typedefs.
1098 @deffn {Scheme Procedure} type-array type n1 @r{[}n2@r{]}
1099 Return a new @code{<gdb:type>} object which represents an array of this
1100 type. If one argument is given, it is the inclusive upper bound of
1101 the array; in this case the lower bound is zero. If two arguments are
1102 given, the first argument is the lower bound of the array, and the
1103 second argument is the upper bound of the array. An array's length
1104 must not be negative, but the bounds can be.
1107 @deffn {Scheme Procedure} type-vector type n1 @r{[}n2@r{]}
1108 Return a new @code{<gdb:type>} object which represents a vector of this
1109 type. If one argument is given, it is the inclusive upper bound of
1110 the vector; in this case the lower bound is zero. If two arguments are
1111 given, the first argument is the lower bound of the vector, and the
1112 second argument is the upper bound of the vector. A vector's length
1113 must not be negative, but the bounds can be.
1115 The difference between an @code{array} and a @code{vector} is that
1116 arrays behave like in C: when used in expressions they decay to a pointer
1117 to the first element whereas vectors are treated as first class values.
1120 @deffn {Scheme Procedure} type-pointer type
1121 Return a new @code{<gdb:type>} object which represents a pointer to
1125 @deffn {Scheme Procedure} type-range type
1126 Return a list of two elements: the low bound and high bound of @var{type}.
1127 If @var{type} does not have a range, an exception is thrown.
1130 @deffn {Scheme Procedure} type-reference type
1131 Return a new @code{<gdb:type>} object which represents a reference to
1135 @deffn {Scheme Procedure} type-target type
1136 Return a new @code{<gdb:type>} object which represents the target type
1139 For a pointer type, the target type is the type of the pointed-to
1140 object. For an array type (meaning C-like arrays), the target type is
1141 the type of the elements of the array. For a function or method type,
1142 the target type is the type of the return value. For a complex type,
1143 the target type is the type of the elements. For a typedef, the
1144 target type is the aliased type.
1146 If the type does not have a target, this method will throw an
1150 @deffn {Scheme Procedure} type-const type
1151 Return a new @code{<gdb:type>} object which represents a
1152 @code{const}-qualified variant of @var{type}.
1155 @deffn {Scheme Procedure} type-volatile type
1156 Return a new @code{<gdb:type>} object which represents a
1157 @code{volatile}-qualified variant of @var{type}.
1160 @deffn {Scheme Procedure} type-unqualified type
1161 Return a new @code{<gdb:type>} object which represents an unqualified
1162 variant of @var{type}. That is, the result is neither @code{const} nor
1166 @deffn {Scheme Procedure} type-num-fields
1167 Return the number of fields of @code{<gdb:type>} @var{type}.
1170 @deffn {Scheme Procedure} type-fields type
1171 Return the fields of @var{type} as a list.
1172 For structure and union types, @code{fields} has the usual meaning.
1173 Range types have two fields, the minimum and maximum values. Enum types
1174 have one field per enum constant. Function and method types have one
1175 field per parameter. The base types of C@t{++} classes are also
1176 represented as fields. If the type has no fields, or does not fit
1177 into one of these categories, an empty list will be returned.
1178 @xref{Fields of a type in Guile}.
1181 @deffn {Scheme Procedure} make-field-iterator type
1182 Return the fields of @var{type} as a <gdb:iterator> object.
1183 @xref{Iterators In Guile}.
1186 @deffn {Scheme Procedure} type-field type field-name
1187 Return field named @var{field-name} in @var{type}.
1188 The result is an object of type @code{<gdb:field>}.
1189 @xref{Fields of a type in Guile}.
1190 If the type does not have fields, or @var{field-name} is not a field
1191 of @var{type}, an exception is thrown.
1193 For example, if @code{some-type} is a @code{<gdb:type>} instance holding
1194 a structure type, you can access its @code{foo} field with:
1197 (define bar (type-field some-type "foo"))
1200 @code{bar} will be a @code{<gdb:field>} object.
1203 @deffn {Scheme Procedure} type-has-field? type name
1204 Return @code{#t} if @code{<gdb:type>} @var{type} has field named @var{name}.
1205 Otherwise return @code{#f}.
1208 Each type has a code, which indicates what category this type falls
1209 into. The available type categories are represented by constants
1210 defined in the @code{(gdb)} module:
1214 The type is a pointer.
1216 @item TYPE_CODE_ARRAY
1217 The type is an array.
1219 @item TYPE_CODE_STRUCT
1220 The type is a structure.
1222 @item TYPE_CODE_UNION
1223 The type is a union.
1225 @item TYPE_CODE_ENUM
1226 The type is an enum.
1228 @item TYPE_CODE_FLAGS
1229 A bit flags type, used for things such as status registers.
1231 @item TYPE_CODE_FUNC
1232 The type is a function.
1235 The type is an integer type.
1238 A floating point type.
1240 @item TYPE_CODE_VOID
1241 The special type @code{void}.
1246 @item TYPE_CODE_RANGE
1247 A range type, that is, an integer type with bounds.
1249 @item TYPE_CODE_STRING
1250 A string type. Note that this is only used for certain languages with
1251 language-defined string types; C strings are not represented this way.
1253 @item TYPE_CODE_BITSTRING
1254 A string of bits. It is deprecated.
1256 @item TYPE_CODE_ERROR
1257 An unknown or erroneous type.
1259 @item TYPE_CODE_METHOD
1260 A method type, as found in C@t{++}.
1262 @item TYPE_CODE_METHODPTR
1263 A pointer-to-member-function.
1265 @item TYPE_CODE_MEMBERPTR
1266 A pointer-to-member.
1271 @item TYPE_CODE_CHAR
1274 @item TYPE_CODE_BOOL
1277 @item TYPE_CODE_COMPLEX
1278 A complex float type.
1280 @item TYPE_CODE_TYPEDEF
1281 A typedef to some other type.
1283 @item TYPE_CODE_NAMESPACE
1284 A C@t{++} namespace.
1286 @item TYPE_CODE_DECFLOAT
1287 A decimal floating point type.
1289 @item TYPE_CODE_INTERNAL_FUNCTION
1290 A function internal to @value{GDBN}. This is the type used to represent
1291 convenience functions (@pxref{Convenience Funs}).
1294 Further support for types is provided in the @code{(gdb types)}
1295 Guile module (@pxref{Guile Types Module}).
1297 @anchor{Fields of a type in Guile}
1298 Each field is represented as an object of type @code{<gdb:field>}.
1300 The following field-related procedures are provided by the
1301 @code{(gdb)} module:
1303 @deffn {Scheme Procedure} field? object
1304 Return @code{#t} if @var{object} is an object of type @code{<gdb:field>}.
1305 Otherwise return @code{#f}.
1308 @deffn {Scheme Procedure} field-name field
1309 Return the name of the field, or @code{#f} for anonymous fields.
1312 @deffn {Scheme Procedure} field-type field
1313 Return the type of the field. This is usually an instance of
1314 @code{<gdb:type>}, but it can be @code{#f} in some situations.
1317 @deffn {Scheme Procedure} field-enumval field
1318 Return the enum value represented by @code{<gdb:field>} @var{field}.
1321 @deffn {Scheme Procedure} field-bitpos field
1322 Return the bit position of @code{<gdb:field>} @var{field}.
1323 This attribute is not available for @code{static} fields (as in
1327 @deffn {Scheme Procedure} field-bitsize field
1328 If the field is packed, or is a bitfield, return the size of
1329 @code{<gdb:field>} @var{field} in bits. Otherwise, zero is returned;
1330 in which case the field's size is given by its type.
1333 @deffn {Scheme Procedure} field-artificial? field
1334 Return @code{#t} if the field is artificial, usually meaning that
1335 it was provided by the compiler and not the user.
1336 Otherwise return @code{#f}.
1339 @deffn {Scheme Procedure} field-base-class? field
1340 Return @code{#t} if the field represents a base class of a C@t{++}
1342 Otherwise return @code{#f}.
1345 @node Guile Pretty Printing API
1346 @subsubsection Guile Pretty Printing API
1347 @cindex guile pretty printing api
1349 An example output is provided (@pxref{Pretty Printing}).
1351 A pretty-printer is represented by an object of type <gdb:pretty-printer>.
1352 Pretty-printer objects are created with @code{make-pretty-printer}.
1354 The following pretty-printer-related procedures are provided by the
1355 @code{(gdb)} module:
1357 @deffn {Scheme Procedure} make-pretty-printer name lookup-function
1358 Return a @code{<gdb:pretty-printer>} object named @var{name}.
1360 @var{lookup-function} is a function of one parameter: the value to
1361 be printed. If the value is handled by this pretty-printer, then
1362 @var{lookup-function} returns an object of type
1363 <gdb:pretty-printer-worker> to perform the actual pretty-printing.
1364 Otherwise @var{lookup-function} returns @code{#f}.
1367 @deffn {Scheme Procedure} pretty-printer? object
1368 Return @code{#t} if @var{object} is a @code{<gdb:pretty-printer>} object.
1369 Otherwise return @code{#f}.
1372 @deffn {Scheme Procedure} pretty-printer-enabled? pretty-printer
1373 Return @code{#t} if @var{pretty-printer} is enabled.
1374 Otherwise return @code{#f}.
1377 @deffn {Scheme Procedure} set-pretty-printer-enabled! pretty-printer flag
1378 Set the enabled flag of @var{pretty-printer} to @var{flag}.
1379 The value returned is unspecified.
1382 @deffn {Scheme Procedure} pretty-printers
1383 Return the list of global pretty-printers.
1386 @deffn {Scheme Procedure} set-pretty-printers! pretty-printers
1387 Set the list of global pretty-printers to @var{pretty-printers}.
1388 The value returned is unspecified.
1391 @deffn {Scheme Procedure} make-pretty-printer-worker display-hint to-string children
1392 Return an object of type @code{<gdb:pretty-printer-worker>}.
1394 This function takes three parameters:
1398 @var{display-hint} provides a hint to @value{GDBN} or @value{GDBN}
1399 front end via MI to change the formatting of the value being printed.
1400 The value must be a string or @code{#f} (meaning there is no hint).
1401 Several values for @var{display-hint}
1402 are predefined by @value{GDBN}:
1406 Indicate that the object being printed is ``array-like''. The CLI
1407 uses this to respect parameters such as @code{set print elements} and
1408 @code{set print array}.
1411 Indicate that the object being printed is ``map-like'', and that the
1412 children of this value can be assumed to alternate between keys and
1416 Indicate that the object being printed is ``string-like''. If the
1417 printer's @code{to-string} function returns a Guile string of some
1418 kind, then @value{GDBN} will call its internal language-specific
1419 string-printing function to format the string. For the CLI this means
1420 adding quotation marks, possibly escaping some characters, respecting
1421 @code{set print elements}, and the like.
1425 @var{to-string} is either a function of one parameter, the
1426 @code{<gdb:pretty-printer-worker>} object, or @code{#f}.
1428 When printing from the CLI, if the @code{to-string} method exists,
1429 then @value{GDBN} will prepend its result to the values returned by
1430 @code{children}. Exactly how this formatting is done is dependent on
1431 the display hint, and may change as more hints are added. Also,
1432 depending on the print settings (@pxref{Print Settings}), the CLI may
1433 print just the result of @code{to-string} in a stack trace, omitting
1434 the result of @code{children}.
1436 If this method returns a string, it is printed verbatim.
1438 Otherwise, if this method returns an instance of @code{<gdb:value>},
1439 then @value{GDBN} prints this value. This may result in a call to
1440 another pretty-printer.
1442 If instead the method returns a Guile value which is convertible to a
1443 @code{<gdb:value>}, then @value{GDBN} performs the conversion and prints
1444 the resulting value. Again, this may result in a call to another
1445 pretty-printer. Guile scalars (integers, floats, and booleans) and
1446 strings are convertible to @code{<gdb:value>}; other types are not.
1448 Finally, if this method returns @code{#f} then no further operations
1449 are peformed in this method and nothing is printed.
1451 If the result is not one of these types, an exception is raised.
1453 @var{to-string} may also be @code{#f} in which case it is left to
1454 @var{children} to print the value.
1457 @var{children} is either a function of one parameter, the
1458 @code{<gdb:pretty-printer-worker>} object, or @code{#f}.
1460 @value{GDBN} will call this function on a pretty-printer to compute the
1461 children of the pretty-printer's value.
1463 This function must return a <gdb:iterator> object.
1464 Each item returned by the iterator must be a tuple holding
1465 two elements. The first element is the ``name'' of the child; the
1466 second element is the child's value. The value can be any Guile
1467 object which is convertible to a @value{GDBN} value.
1469 If @var{children} is @code{#f}, @value{GDBN} will act
1470 as though the value has no children.
1472 Children may be hidden from display based on the value of @samp{set
1473 print max-depth} (@pxref{Print Settings}).
1477 @value{GDBN} provides a function which can be used to look up the
1478 default pretty-printer for a @code{<gdb:value>}:
1480 @deffn {Scheme Procedure} default-visualizer value
1481 This function takes a @code{<gdb:value>} object as an argument. If a
1482 pretty-printer for this value exists, then it is returned. If no such
1483 printer exists, then this returns @code{#f}.
1486 @node Selecting Guile Pretty-Printers
1487 @subsubsection Selecting Guile Pretty-Printers
1488 @cindex selecting guile pretty-printers
1490 There are three sets of pretty-printers that @value{GDBN} searches:
1494 Per-objfile list of pretty-printers (@pxref{Objfiles In Guile}).
1496 Per-progspace list of pretty-printers (@pxref{Progspaces In Guile}).
1498 The global list of pretty-printers (@pxref{Guile Pretty Printing API}).
1499 These printers are available when debugging any inferior.
1502 Pretty-printer lookup is done by passing the value to be printed to the
1503 lookup function of each enabled object in turn.
1504 Lookup stops when a lookup function returns a non-@code{#f} value
1505 or when the list is exhausted.
1506 Lookup functions must return either a @code{<gdb:pretty-printer-worker>}
1507 object or @code{#f}. Otherwise an exception is thrown.
1509 @value{GDBN} first checks the result of @code{objfile-pretty-printers}
1510 of each @code{<gdb:objfile>} in the current program space and iteratively
1511 calls each enabled lookup function in the list for that @code{<gdb:objfile>}
1512 until a non-@code{#f} object is returned.
1513 If no pretty-printer is found in the objfile lists, @value{GDBN} then
1514 searches the result of @code{progspace-pretty-printers} of the current
1515 program space, calling each enabled function until a non-@code{#f} object
1517 After these lists have been exhausted, it tries the global pretty-printers
1518 list, obtained with @code{pretty-printers}, again calling each enabled
1519 function until a non-@code{#f} object is returned.
1521 The order in which the objfiles are searched is not specified. For a
1522 given list, functions are always invoked from the head of the list,
1523 and iterated over sequentially until the end of the list, or a
1524 @code{<gdb:pretty-printer-worker>} object is returned.
1526 For various reasons a pretty-printer may not work.
1527 For example, the underlying data structure may have changed and
1528 the pretty-printer is out of date.
1530 The consequences of a broken pretty-printer are severe enough that
1531 @value{GDBN} provides support for enabling and disabling individual
1532 printers. For example, if @code{print frame-arguments} is on,
1533 a backtrace can become highly illegible if any argument is printed
1534 with a broken printer.
1536 Pretty-printers are enabled and disabled from Scheme by calling
1537 @code{set-pretty-printer-enabled!}.
1538 @xref{Guile Pretty Printing API}.
1540 @node Writing a Guile Pretty-Printer
1541 @subsubsection Writing a Guile Pretty-Printer
1542 @cindex writing a Guile pretty-printer
1544 A pretty-printer consists of two basic parts: a lookup function to determine
1545 if the type is supported, and the printer itself.
1547 Here is an example showing how a @code{std::string} printer might be
1548 written. @xref{Guile Pretty Printing API}, for details.
1551 (define (make-my-string-printer value)
1552 "Print a my::string string"
1553 (make-pretty-printer-worker
1556 (value-field value "_data"))
1560 And here is an example showing how a lookup function for the printer
1561 example above might be written.
1564 (define (str-lookup-function pretty-printer value)
1565 (let ((tag (type-tag (value-type value))))
1567 (string-prefix? "std::string<" tag)
1568 (make-my-string-printer value))))
1571 Then to register this printer in the global printer list:
1574 (append-pretty-printer!
1575 (make-pretty-printer "my-string" str-lookup-function))
1578 The example lookup function extracts the value's type, and attempts to
1579 match it to a type that it can pretty-print. If it is a type the
1580 printer can pretty-print, it will return a <gdb:pretty-printer-worker> object.
1581 If not, it returns @code{#f}.
1583 We recommend that you put your core pretty-printers into a Guile
1584 package. If your pretty-printers are for use with a library, we
1585 further recommend embedding a version number into the package name.
1586 This practice will enable @value{GDBN} to load multiple versions of
1587 your pretty-printers at the same time, because they will have
1590 You should write auto-loaded code (@pxref{Guile Auto-loading}) such that it
1591 can be evaluated multiple times without changing its meaning. An
1592 ideal auto-load file will consist solely of @code{import}s of your
1593 printer modules, followed by a call to a register pretty-printers with
1594 the current objfile.
1596 Taken as a whole, this approach will scale nicely to multiple
1597 inferiors, each potentially using a different library version.
1598 Embedding a version number in the Guile package name will ensure that
1599 @value{GDBN} is able to load both sets of printers simultaneously.
1600 Then, because the search for pretty-printers is done by objfile, and
1601 because your auto-loaded code took care to register your library's
1602 printers with a specific objfile, @value{GDBN} will find the correct
1603 printers for the specific version of the library used by each
1606 To continue the @code{my::string} example,
1607 this code might appear in @code{(my-project my-library v1)}:
1611 (define (register-printers objfile)
1612 (append-objfile-pretty-printer!
1613 (make-pretty-printer "my-string" str-lookup-function)))
1617 And then the corresponding contents of the auto-load file would be:
1620 (use-modules (gdb) (my-project my-library v1))
1621 (register-printers (current-objfile))
1624 The previous example illustrates a basic pretty-printer.
1625 There are a few things that can be improved on.
1626 The printer only handles one type, whereas a library typically has
1627 several types. One could install a lookup function for each desired type
1628 in the library, but one could also have a single lookup function recognize
1629 several types. The latter is the conventional way this is handled.
1630 If a pretty-printer can handle multiple data types, then its
1631 @dfn{subprinters} are the printers for the individual data types.
1633 The @code{(gdb printing)} module provides a formal way of solving this
1634 problem (@pxref{Guile Printing Module}).
1635 Here is another example that handles multiple types.
1637 These are the types we are going to pretty-print:
1640 struct foo @{ int a, b; @};
1641 struct bar @{ struct foo x, y; @};
1644 Here are the printers:
1647 (define (make-foo-printer value)
1648 "Print a foo object"
1649 (make-pretty-printer-worker
1652 (format #f "a=<~a> b=<~a>"
1653 (value-field value "a") (value-field value "a")))
1656 (define (make-bar-printer value)
1657 "Print a bar object"
1658 (make-pretty-printer-worker
1661 (format #f "x=<~a> y=<~a>"
1662 (value-field value "x") (value-field value "y")))
1666 This example doesn't need a lookup function, that is handled by the
1667 @code{(gdb printing)} module. Instead a function is provided to build up
1668 the object that handles the lookup.
1671 (use-modules (gdb printing))
1673 (define (build-pretty-printer)
1674 (let ((pp (make-pretty-printer-collection "my-library")))
1675 (pp-collection-add-tag-printer "foo" make-foo-printer)
1676 (pp-collection-add-tag-printer "bar" make-bar-printer)
1680 And here is the autoload support:
1683 (use-modules (gdb) (my-library))
1684 (append-objfile-pretty-printer! (current-objfile) (build-pretty-printer))
1687 Finally, when this printer is loaded into @value{GDBN}, here is the
1688 corresponding output of @samp{info pretty-printer}:
1691 (gdb) info pretty-printer
1698 @node Commands In Guile
1699 @subsubsection Commands In Guile
1701 @cindex commands in guile
1702 @cindex guile commands
1703 You can implement new @value{GDBN} CLI commands in Guile. A CLI
1704 command object is created with the @code{make-command} Guile function,
1705 and added to @value{GDBN} with the @code{register-command!} Guile function.
1706 This two-step approach is taken to separate out the side-effect of adding
1707 the command to @value{GDBN} from @code{make-command}.
1709 There is no support for multi-line commands, that is commands that
1710 consist of multiple lines and are terminated with @code{end}.
1712 @c TODO: line length
1713 @deffn {Scheme Procedure} (make-command name @r{[}#:invoke invoke{]} @r{[}#:command-class command-class@r{]} @r{[}#:completer-class completer{]} @r{[}#:prefix? prefix@r{]} @r{[}#:doc doc-string{]})
1715 The argument @var{name} is the name of the command. If @var{name} consists of
1716 multiple words, then the initial words are looked for as prefix
1717 commands. In this case, if one of the prefix commands does not exist,
1718 an exception is raised.
1720 The result is the @code{<gdb:command>} object representing the command.
1721 The command is not usable until it has been registered with @value{GDBN}
1722 with @code{register-command!}.
1724 The rest of the arguments are optional.
1726 The argument @var{invoke} is a procedure of three arguments: @var{self},
1727 @var{args} and @var{from-tty}. The argument @var{self} is the
1728 @code{<gdb:command>} object representing the command.
1729 The argument @var{args} is a string representing the arguments passed to
1730 the command, after leading and trailing whitespace has been stripped.
1731 The argument @var{from-tty} is a boolean flag and specifies whether the
1732 command should consider itself to have been originated from the user
1733 invoking it interactively. If this function throws an exception,
1734 it is turned into a @value{GDBN} @code{error} call.
1735 Otherwise, the return value is ignored.
1737 The argument @var{command-class} is one of the @samp{COMMAND_} constants
1738 defined below. This argument tells @value{GDBN} how to categorize the
1739 new command in the help system. The default is @code{COMMAND_NONE}.
1741 The argument @var{completer} is either @code{#f}, one of the @samp{COMPLETE_}
1742 constants defined below, or a procedure, also defined below.
1743 This argument tells @value{GDBN} how to perform completion
1744 for this command. If not provided or if the value is @code{#f},
1745 then no completion is performed on the command.
1747 The argument @var{prefix} is a boolean flag indicating whether the new
1748 command is a prefix command; sub-commands of this command may be
1751 The argument @var{doc-string} is help text for the new command.
1752 If no documentation string is provided, the default value ``This command is
1753 not documented.'' is used.
1756 @deffn {Scheme Procedure} register-command! command
1757 Add @var{command}, a @code{<gdb:command>} object, to @value{GDBN}'s
1759 It is an error to register a command more than once.
1760 The result is unspecified.
1763 @deffn {Scheme Procedure} command? object
1764 Return @code{#t} if @var{object} is a @code{<gdb:command>} object.
1765 Otherwise return @code{#f}.
1768 @cindex don't repeat Guile command
1769 @deffn {Scheme Procedure} dont-repeat
1770 By default, a @value{GDBN} command is repeated when the user enters a
1771 blank line at the command prompt. A command can suppress this
1772 behavior by invoking the @code{dont-repeat} function. This is similar
1773 to the user command @code{dont-repeat}, see @ref{Define, dont-repeat}.
1776 @deffn {Scheme Procedure} string->argv string
1777 Convert a string to a list of strings split up according to
1778 @value{GDBN}'s argv parsing rules.
1779 It is recommended to use this for consistency.
1780 Arguments are separated by spaces and may be quoted.
1784 scheme@@(guile-user)> (string->argv "1 2\\ \\\"3 '4 \"5' \"6 '7\"")
1785 $1 = ("1" "2 \"3" "4 \"5" "6 '7")
1789 @deffn {Scheme Procedure} throw-user-error message . args
1790 Throw a @code{gdb:user-error} exception.
1791 The argument @var{message} is the error message as a format string, like the
1792 @var{fmt} argument to the @code{format} Scheme function.
1793 @xref{Formatted Output,,, guile, GNU Guile Reference Manual}.
1794 The argument @var{args} is a list of the optional arguments of @var{message}.
1796 This is used when the command detects a user error of some kind,
1797 say a bad command argument.
1800 (gdb) guile (use-modules (gdb))
1802 (register-command! (make-command "test-user-error"
1803 #:command-class COMMAND_OBSCURE
1804 #:invoke (lambda (self arg from-tty)
1805 (throw-user-error "Bad argument ~a" arg))))
1807 (gdb) test-user-error ugh
1808 ERROR: Bad argument ugh
1812 @cindex completion of Guile commands
1813 @deffn completer self text word
1814 If the @var{completer} option to @code{make-command} is a procedure,
1815 it takes three arguments: @var{self} which is the @code{<gdb:command>}
1816 object, and @var{text} and @var{word} which are both strings.
1817 The argument @var{text} holds the complete command line up to the cursor's
1818 location. The argument @var{word} holds the last word of the command line;
1819 this is computed using a word-breaking heuristic.
1821 All forms of completion are handled by this function, that is,
1822 the @key{TAB} and @key{M-?} key bindings (@pxref{Completion}),
1823 and the @code{complete} command (@pxref{Help, complete}).
1825 This procedure can return several kinds of values:
1829 If the return value is a list, the contents of the list are used as the
1830 completions. It is up to @var{completer} to ensure that the
1831 contents actually do complete the word. An empty list is
1832 allowed, it means that there were no completions available. Only
1833 string elements of the list are used; other elements in the
1837 If the return value is a @code{<gdb:iterator>} object, it is iterated over to
1838 obtain the completions. It is up to @code{completer-procedure} to ensure
1839 that the results actually do complete the word. Only
1840 string elements of the result are used; other elements in the
1841 sequence are ignored.
1844 All other results are treated as though there were no available
1849 When a new command is registered, it will have been declared as a member of
1850 some general class of commands. This is used to classify top-level
1851 commands in the on-line help system; note that prefix commands are not
1852 listed under their own category but rather that of their top-level
1853 command. The available classifications are represented by constants
1854 defined in the @code{gdb} module:
1858 The command does not belong to any particular class. A command in
1859 this category will not be displayed in any of the help categories.
1860 This is the default.
1862 @item COMMAND_RUNNING
1863 The command is related to running the inferior. For example,
1864 @code{start}, @code{step}, and @code{continue} are in this category.
1865 Type @kbd{help running} at the @value{GDBN} prompt to see a list of
1866 commands in this category.
1869 The command is related to data or variables. For example,
1870 @code{call}, @code{find}, and @code{print} are in this category. Type
1871 @kbd{help data} at the @value{GDBN} prompt to see a list of commands
1875 The command has to do with manipulation of the stack. For example,
1876 @code{backtrace}, @code{frame}, and @code{return} are in this
1877 category. Type @kbd{help stack} at the @value{GDBN} prompt to see a
1878 list of commands in this category.
1881 This class is used for file-related commands. For example,
1882 @code{file}, @code{list} and @code{section} are in this category.
1883 Type @kbd{help files} at the @value{GDBN} prompt to see a list of
1884 commands in this category.
1886 @item COMMAND_SUPPORT
1887 This should be used for ``support facilities'', generally meaning
1888 things that are useful to the user when interacting with @value{GDBN},
1889 but not related to the state of the inferior. For example,
1890 @code{help}, @code{make}, and @code{shell} are in this category. Type
1891 @kbd{help support} at the @value{GDBN} prompt to see a list of
1892 commands in this category.
1894 @item COMMAND_STATUS
1895 The command is an @samp{info}-related command, that is, related to the
1896 state of @value{GDBN} itself. For example, @code{info}, @code{macro},
1897 and @code{show} are in this category. Type @kbd{help status} at the
1898 @value{GDBN} prompt to see a list of commands in this category.
1900 @item COMMAND_BREAKPOINTS
1901 The command has to do with breakpoints. For example, @code{break},
1902 @code{clear}, and @code{delete} are in this category. Type @kbd{help
1903 breakpoints} at the @value{GDBN} prompt to see a list of commands in
1906 @item COMMAND_TRACEPOINTS
1907 The command has to do with tracepoints. For example, @code{trace},
1908 @code{actions}, and @code{tfind} are in this category. Type
1909 @kbd{help tracepoints} at the @value{GDBN} prompt to see a list of
1910 commands in this category.
1913 The command is a general purpose command for the user, and typically
1914 does not fit in one of the other categories.
1915 Type @kbd{help user-defined} at the @value{GDBN} prompt to see
1916 a list of commands in this category, as well as the list of gdb macros
1917 (@pxref{Sequences}).
1919 @item COMMAND_OBSCURE
1920 The command is only used in unusual circumstances, or is not of
1921 general interest to users. For example, @code{checkpoint},
1922 @code{fork}, and @code{stop} are in this category. Type @kbd{help
1923 obscure} at the @value{GDBN} prompt to see a list of commands in this
1926 @item COMMAND_MAINTENANCE
1927 The command is only useful to @value{GDBN} maintainers. The
1928 @code{maintenance} and @code{flushregs} commands are in this category.
1929 Type @kbd{help internals} at the @value{GDBN} prompt to see a list of
1930 commands in this category.
1933 A new command can use a predefined completion function, either by
1934 specifying it via an argument at initialization, or by returning it
1935 from the @code{completer} procedure. These predefined completion
1936 constants are all defined in the @code{gdb} module:
1940 This constant means that no completion should be done.
1942 @item COMPLETE_FILENAME
1943 This constant means that filename completion should be performed.
1945 @item COMPLETE_LOCATION
1946 This constant means that location completion should be done.
1947 @xref{Specify Location}.
1949 @item COMPLETE_COMMAND
1950 This constant means that completion should examine @value{GDBN}
1953 @item COMPLETE_SYMBOL
1954 This constant means that completion should be done using symbol names
1957 @item COMPLETE_EXPRESSION
1958 This constant means that completion should be done on expressions.
1959 Often this means completing on symbol names, but some language
1960 parsers also have support for completing on field names.
1963 The following code snippet shows how a trivial CLI command can be
1964 implemented in Guile:
1968 (register-command! (make-command "hello-world"
1969 #:command-class COMMAND_USER
1970 #:doc "Greet the whole world."
1971 #:invoke (lambda (self args from-tty) (display "Hello, World!\n"))))
1977 @node Parameters In Guile
1978 @subsubsection Parameters In Guile
1980 @cindex parameters in guile
1981 @cindex guile parameters
1983 You can implement new @value{GDBN} @dfn{parameters} using Guile
1984 @footnote{Note that @value{GDBN} parameters must not be confused with
1985 Guile’s parameter objects (@pxref{Parameters,,, guile, GNU Guile
1986 Reference Manual}).}.
1988 There are many parameters that already exist and can be set in
1989 @value{GDBN}. Two examples are: @code{set follow-fork} and
1990 @code{set charset}. Setting these parameters influences certain
1991 behavior in @value{GDBN}. Similarly, you can define parameters that
1992 can be used to influence behavior in custom Guile scripts and commands.
1994 A new parameter is defined with the @code{make-parameter} Guile function,
1995 and added to @value{GDBN} with the @code{register-parameter!} Guile function.
1996 This two-step approach is taken to separate out the side-effect of adding
1997 the parameter to @value{GDBN} from @code{make-parameter}.
1999 Parameters are exposed to the user via the @code{set} and
2000 @code{show} commands. @xref{Help}.
2003 @deffn {Scheme Procedure} (make-parameter name @r{[}#:command-class command-class@r{]} @r{[}#:parameter-type parameter-type{]} @r{[}#:enum-list enum-list@r{]} @r{[}#:set-func set-func{]} @r{[}#:show-func show-func{]} @r{[}#:doc doc{]} @r{[}#:set-doc set-doc{]} @r{[}#:show-doc show-doc{]} @r{[}#:initial-value initial-value{]})
2005 The argument @var{name} is the name of the new parameter. If @var{name}
2006 consists of multiple words, then the initial words are looked for as prefix
2007 parameters. An example of this can be illustrated with the
2008 @code{set print} set of parameters. If @var{name} is
2009 @code{print foo}, then @code{print} will be searched as the prefix
2010 parameter. In this case the parameter can subsequently be accessed in
2011 @value{GDBN} as @code{set print foo}.
2012 If @var{name} consists of multiple words, and no prefix parameter group
2013 can be found, an exception is raised.
2015 The result is the @code{<gdb:parameter>} object representing the parameter.
2016 The parameter is not usable until it has been registered with @value{GDBN}
2017 with @code{register-parameter!}.
2019 The rest of the arguments are optional.
2021 The argument @var{command-class} should be one of the @samp{COMMAND_} constants
2022 (@pxref{Commands In Guile}). This argument tells @value{GDBN} how to
2023 categorize the new parameter in the help system.
2024 The default is @code{COMMAND_NONE}.
2026 The argument @var{parameter-type} should be one of the @samp{PARAM_} constants
2027 defined below. This argument tells @value{GDBN} the type of the new
2028 parameter; this information is used for input validation and
2029 completion. The default is @code{PARAM_BOOLEAN}.
2031 If @var{parameter-type} is @code{PARAM_ENUM}, then
2032 @var{enum-list} must be a list of strings. These strings
2033 represent the possible values for the parameter.
2035 If @var{parameter-type} is not @code{PARAM_ENUM}, then the presence
2036 of @var{enum-list} will cause an exception to be thrown.
2038 The argument @var{set-func} is a function of one argument: @var{self} which
2039 is the @code{<gdb:parameter>} object representing the parameter.
2040 @value{GDBN} will call this function when a @var{parameter}'s value has
2041 been changed via the @code{set} API (for example, @kbd{set foo off}).
2042 The value of the parameter has already been set to the new value.
2043 This function must return a string to be displayed to the user.
2044 @value{GDBN} will add a trailing newline if the string is non-empty.
2045 @value{GDBN} generally doesn't print anything when a parameter is set,
2046 thus typically this function should return @samp{""}.
2047 A non-empty string result should typically be used for displaying warnings
2050 The argument @var{show-func} is a function of two arguments: @var{self} which
2051 is the @code{<gdb:parameter>} object representing the parameter, and
2052 @var{svalue} which is the string representation of the current value.
2053 @value{GDBN} will call this function when a @var{parameter}'s
2054 @code{show} API has been invoked (for example, @kbd{show foo}).
2055 This function must return a string, and will be displayed to the user.
2056 @value{GDBN} will add a trailing newline.
2058 The argument @var{doc} is the help text for the new parameter.
2059 If there is no documentation string, a default value is used.
2061 The argument @var{set-doc} is the help text for this parameter's
2064 The argument @var{show-doc} is the help text for this parameter's
2065 @code{show} command.
2067 The argument @var{initial-value} specifies the initial value of the parameter.
2068 If it is a function, it takes one parameter, the @code{<gdb:parameter>}
2069 object and its result is used as the initial value of the parameter.
2070 The initial value must be valid for the parameter type,
2071 otherwise an exception is thrown.
2074 @deffn {Scheme Procedure} register-parameter! parameter
2075 Add @var{parameter}, a @code{<gdb:parameter>} object, to @value{GDBN}'s
2077 It is an error to register a parameter more than once.
2078 The result is unspecified.
2081 @deffn {Scheme Procedure} parameter? object
2082 Return @code{#t} if @var{object} is a @code{<gdb:parameter>} object.
2083 Otherwise return @code{#f}.
2086 @deffn {Scheme Procedure} parameter-value parameter
2087 Return the value of @var{parameter} which may either be
2088 a @code{<gdb:parameter>} object or a string naming the parameter.
2091 @deffn {Scheme Procedure} set-parameter-value! parameter new-value
2092 Assign @var{parameter} the value of @var{new-value}.
2093 The argument @var{parameter} must be an object of type @code{<gdb:parameter>}.
2094 @value{GDBN} does validation when assignments are made.
2097 When a new parameter is defined, its type must be specified. The
2098 available types are represented by constants defined in the @code{gdb}
2103 The value is a plain boolean. The Guile boolean values, @code{#t}
2104 and @code{#f} are the only valid values.
2106 @item PARAM_AUTO_BOOLEAN
2107 The value has three possible states: true, false, and @samp{auto}. In
2108 Guile, true and false are represented using boolean constants, and
2109 @samp{auto} is represented using @code{#:auto}.
2111 @item PARAM_UINTEGER
2112 The value is an unsigned integer. The value of 0 should be
2113 interpreted to mean ``unlimited''.
2115 @item PARAM_ZINTEGER
2116 The value is an integer.
2118 @item PARAM_ZUINTEGER
2119 The value is an unsigned integer.
2121 @item PARAM_ZUINTEGER_UNLIMITED
2122 The value is an integer in the range @samp{[0, INT_MAX]}.
2123 A value of @samp{-1} means ``unlimited'', and other negative
2124 numbers are not allowed.
2127 The value is a string. When the user modifies the string, any escape
2128 sequences, such as @samp{\t}, @samp{\f}, and octal escapes, are
2129 translated into corresponding characters and encoded into the current
2132 @item PARAM_STRING_NOESCAPE
2133 The value is a string. When the user modifies the string, escapes are
2134 passed through untranslated.
2136 @item PARAM_OPTIONAL_FILENAME
2137 The value is a either a filename (a string), or @code{#f}.
2139 @item PARAM_FILENAME
2140 The value is a filename. This is just like
2141 @code{PARAM_STRING_NOESCAPE}, but uses file names for completion.
2144 The value is a string, which must be one of a collection of string
2145 constants provided when the parameter is created.
2148 @node Progspaces In Guile
2149 @subsubsection Program Spaces In Guile
2151 @cindex progspaces in guile
2152 @tindex <gdb:progspace>
2153 A program space, or @dfn{progspace}, represents a symbolic view
2154 of an address space.
2155 It consists of all of the objfiles of the program.
2156 @xref{Objfiles In Guile}.
2157 @xref{Inferiors Connections and Programs, program spaces}, for more details
2158 about program spaces.
2160 Each progspace is represented by an instance of the @code{<gdb:progspace>}
2161 smob. @xref{GDB Scheme Data Types}.
2163 The following progspace-related functions are available in the
2164 @code{(gdb)} module:
2166 @deffn {Scheme Procedure} progspace? object
2167 Return @code{#t} if @var{object} is a @code{<gdb:progspace>} object.
2168 Otherwise return @code{#f}.
2171 @deffn {Scheme Procedure} progspace-valid? progspace
2172 Return @code{#t} if @var{progspace} is valid, @code{#f} if not.
2173 A @code{<gdb:progspace>} object can become invalid
2174 if the program it refers to is not loaded in @value{GDBN} any longer.
2177 @deffn {Scheme Procedure} current-progspace
2178 This function returns the program space of the currently selected inferior.
2179 There is always a current progspace, this never returns @code{#f}.
2180 @xref{Inferiors Connections and Programs}.
2183 @deffn {Scheme Procedure} progspaces
2184 Return a list of all the progspaces currently known to @value{GDBN}.
2187 @deffn {Scheme Procedure} progspace-filename progspace
2188 Return the absolute file name of @var{progspace} as a string.
2189 This is the name of the file passed as the argument to the @code{file}
2190 or @code{symbol-file} commands.
2191 If the program space does not have an associated file name,
2192 then @code{#f} is returned. This occurs, for example, when @value{GDBN}
2193 is started without a program to debug.
2195 A @code{gdb:invalid-object-error} exception is thrown if @var{progspace}
2199 @deffn {Scheme Procedure} progspace-objfiles progspace
2200 Return the list of objfiles of @var{progspace}.
2201 The order of objfiles in the result is arbitrary.
2202 Each element is an object of type @code{<gdb:objfile>}.
2203 @xref{Objfiles In Guile}.
2205 A @code{gdb:invalid-object-error} exception is thrown if @var{progspace}
2209 @deffn {Scheme Procedure} progspace-pretty-printers progspace
2210 Return the list of pretty-printers of @var{progspace}.
2211 Each element is an object of type @code{<gdb:pretty-printer>}.
2212 @xref{Guile Pretty Printing API}, for more information.
2215 @deffn {Scheme Procedure} set-progspace-pretty-printers! progspace printer-list
2216 Set the list of registered @code{<gdb:pretty-printer>} objects for
2217 @var{progspace} to @var{printer-list}.
2218 @xref{Guile Pretty Printing API}, for more information.
2221 @node Objfiles In Guile
2222 @subsubsection Objfiles In Guile
2224 @cindex objfiles in guile
2225 @tindex <gdb:objfile>
2226 @value{GDBN} loads symbols for an inferior from various
2227 symbol-containing files (@pxref{Files}). These include the primary
2228 executable file, any shared libraries used by the inferior, and any
2229 separate debug info files (@pxref{Separate Debug Files}).
2230 @value{GDBN} calls these symbol-containing files @dfn{objfiles}.
2232 Each objfile is represented as an object of type @code{<gdb:objfile>}.
2234 The following objfile-related procedures are provided by the
2235 @code{(gdb)} module:
2237 @deffn {Scheme Procedure} objfile? object
2238 Return @code{#t} if @var{object} is a @code{<gdb:objfile>} object.
2239 Otherwise return @code{#f}.
2242 @deffn {Scheme Procedure} objfile-valid? objfile
2243 Return @code{#t} if @var{objfile} is valid, @code{#f} if not.
2244 A @code{<gdb:objfile>} object can become invalid
2245 if the object file it refers to is not loaded in @value{GDBN} any
2246 longer. All other @code{<gdb:objfile>} procedures will throw an exception
2247 if it is invalid at the time the procedure is called.
2250 @deffn {Scheme Procedure} objfile-filename objfile
2251 Return the file name of @var{objfile} as a string,
2252 with symbolic links resolved.
2255 @deffn {Scheme Procedure} objfile-progspace objfile
2256 Return the @code{<gdb:progspace>} that this object file lives in.
2257 @xref{Progspaces In Guile}, for more on progspaces.
2260 @deffn {Scheme Procedure} objfile-pretty-printers objfile
2261 Return the list of registered @code{<gdb:pretty-printer>} objects for
2262 @var{objfile}. @xref{Guile Pretty Printing API}, for more information.
2265 @deffn {Scheme Procedure} set-objfile-pretty-printers! objfile printer-list
2266 Set the list of registered @code{<gdb:pretty-printer>} objects for
2267 @var{objfile} to @var{printer-list}. The
2268 @var{printer-list} must be a list of @code{<gdb:pretty-printer>} objects.
2269 @xref{Guile Pretty Printing API}, for more information.
2272 @deffn {Scheme Procedure} current-objfile
2273 When auto-loading a Guile script (@pxref{Guile Auto-loading}), @value{GDBN}
2274 sets the ``current objfile'' to the corresponding objfile. This
2275 function returns the current objfile. If there is no current objfile,
2276 this function returns @code{#f}.
2279 @deffn {Scheme Procedure} objfiles
2280 Return a list of all the objfiles in the current program space.
2283 @node Frames In Guile
2284 @subsubsection Accessing inferior stack frames from Guile.
2286 @cindex frames in guile
2287 When the debugged program stops, @value{GDBN} is able to analyze its call
2288 stack (@pxref{Frames,,Stack frames}). The @code{<gdb:frame>} class
2289 represents a frame in the stack. A @code{<gdb:frame>} object is only valid
2290 while its corresponding frame exists in the inferior's stack. If you try
2291 to use an invalid frame object, @value{GDBN} will throw a
2292 @code{gdb:invalid-object} exception (@pxref{Guile Exception Handling}).
2294 Two @code{<gdb:frame>} objects can be compared for equality with the
2295 @code{equal?} function, like:
2298 (@value{GDBP}) guile (equal? (newest-frame) (selected-frame))
2302 The following frame-related procedures are provided by the
2303 @code{(gdb)} module:
2305 @deffn {Scheme Procedure} frame? object
2306 Return @code{#t} if @var{object} is a @code{<gdb:frame>} object.
2307 Otherwise return @code{#f}.
2310 @deffn {Scheme Procedure} frame-valid? frame
2311 Returns @code{#t} if @var{frame} is valid, @code{#f} if not.
2312 A frame object can become invalid if the frame it refers to doesn't
2313 exist anymore in the inferior. All @code{<gdb:frame>} procedures will throw
2314 an exception if the frame is invalid at the time the procedure is called.
2317 @deffn {Scheme Procedure} frame-name frame
2318 Return the function name of @var{frame}, or @code{#f} if it can't be
2322 @deffn {Scheme Procedure} frame-arch frame
2323 Return the @code{<gdb:architecture>} object corresponding to @var{frame}'s
2324 architecture. @xref{Architectures In Guile}.
2327 @deffn {Scheme Procedure} frame-type frame
2328 Return the type of @var{frame}. The value can be one of:
2332 An ordinary stack frame.
2335 A fake stack frame that was created by @value{GDBN} when performing an
2336 inferior function call.
2339 A frame representing an inlined function. The function was inlined
2340 into a @code{NORMAL_FRAME} that is older than this one.
2342 @item TAILCALL_FRAME
2343 A frame representing a tail call. @xref{Tail Call Frames}.
2345 @item SIGTRAMP_FRAME
2346 A signal trampoline frame. This is the frame created by the OS when
2347 it calls into a signal handler.
2350 A fake stack frame representing a cross-architecture call.
2352 @item SENTINEL_FRAME
2353 This is like @code{NORMAL_FRAME}, but it is only used for the
2358 @deffn {Scheme Procedure} frame-unwind-stop-reason frame
2359 Return an integer representing the reason why it's not possible to find
2360 more frames toward the outermost frame. Use
2361 @code{unwind-stop-reason-string} to convert the value returned by this
2362 function to a string. The value can be one of:
2365 @item FRAME_UNWIND_NO_REASON
2366 No particular reason (older frames should be available).
2368 @item FRAME_UNWIND_NULL_ID
2369 The previous frame's analyzer returns an invalid result.
2371 @item FRAME_UNWIND_OUTERMOST
2372 This frame is the outermost.
2374 @item FRAME_UNWIND_UNAVAILABLE
2375 Cannot unwind further, because that would require knowing the
2376 values of registers or memory that have not been collected.
2378 @item FRAME_UNWIND_INNER_ID
2379 This frame ID looks like it ought to belong to a NEXT frame,
2380 but we got it for a PREV frame. Normally, this is a sign of
2381 unwinder failure. It could also indicate stack corruption.
2383 @item FRAME_UNWIND_SAME_ID
2384 This frame has the same ID as the previous one. That means
2385 that unwinding further would almost certainly give us another
2386 frame with exactly the same ID, so break the chain. Normally,
2387 this is a sign of unwinder failure. It could also indicate
2390 @item FRAME_UNWIND_NO_SAVED_PC
2391 The frame unwinder did not find any saved PC, but we needed
2392 one to unwind further.
2394 @item FRAME_UNWIND_MEMORY_ERROR
2395 The frame unwinder caused an error while trying to access memory.
2397 @item FRAME_UNWIND_FIRST_ERROR
2398 Any stop reason greater or equal to this value indicates some kind
2399 of error. This special value facilitates writing code that tests
2400 for errors in unwinding in a way that will work correctly even if
2401 the list of the other values is modified in future @value{GDBN}
2402 versions. Using it, you could write:
2405 (define reason (frame-unwind-stop-readon (selected-frame)))
2406 (define reason-str (unwind-stop-reason-string reason))
2407 (if (>= reason FRAME_UNWIND_FIRST_ERROR)
2408 (format #t "An error occured: ~s\n" reason-str))
2413 @deffn {Scheme Procedure} frame-pc frame
2414 Return the frame's resume address.
2417 @deffn {Scheme Procedure} frame-block frame
2418 Return the frame's code block as a @code{<gdb:block>} object.
2419 @xref{Blocks In Guile}.
2422 @deffn {Scheme Procedure} frame-function frame
2423 Return the symbol for the function corresponding to this frame
2424 as a @code{<gdb:symbol>} object, or @code{#f} if there isn't one.
2425 @xref{Symbols In Guile}.
2428 @deffn {Scheme Procedure} frame-older frame
2429 Return the frame that called @var{frame}.
2432 @deffn {Scheme Procedure} frame-newer frame
2433 Return the frame called by @var{frame}.
2436 @deffn {Scheme Procedure} frame-sal frame
2437 Return the frame's @code{<gdb:sal>} (symtab and line) object.
2438 @xref{Symbol Tables In Guile}.
2441 @deffn {Scheme Procedure} frame-read-register frame register
2442 Return the value of @var{register} in @var{frame}. @var{register}
2443 should be a string, like @samp{pc}.
2446 @deffn {Scheme Procedure} frame-read-var frame variable @r{[}#:block block@r{]}
2447 Return the value of @var{variable} in @var{frame}. If the optional
2448 argument @var{block} is provided, search for the variable from that
2449 block; otherwise start at the frame's current block (which is
2450 determined by the frame's current program counter). The
2451 @var{variable} must be given as a string or a @code{<gdb:symbol>}
2452 object, and @var{block} must be a @code{<gdb:block>} object.
2455 @deffn {Scheme Procedure} frame-select frame
2456 Set @var{frame} to be the selected frame. @xref{Stack, ,Examining the
2460 @deffn {Scheme Procedure} selected-frame
2461 Return the selected frame object. @xref{Selection,,Selecting a Frame}.
2464 @deffn {Scheme Procedure} newest-frame
2465 Return the newest frame object for the selected thread.
2468 @deffn {Scheme Procedure} unwind-stop-reason-string reason
2469 Return a string explaining the reason why @value{GDBN} stopped unwinding
2470 frames, as expressed by the given @var{reason} code (an integer, see the
2471 @code{frame-unwind-stop-reason} procedure above in this section).
2474 @node Blocks In Guile
2475 @subsubsection Accessing blocks from Guile.
2477 @cindex blocks in guile
2480 In @value{GDBN}, symbols are stored in blocks. A block corresponds
2481 roughly to a scope in the source code. Blocks are organized
2482 hierarchically, and are represented individually in Guile as an object
2483 of type @code{<gdb:block>}. Blocks rely on debugging information being
2486 A frame has a block. Please see @ref{Frames In Guile}, for a more
2487 in-depth discussion of frames.
2489 The outermost block is known as the @dfn{global block}. The global
2490 block typically holds public global variables and functions.
2492 The block nested just inside the global block is the @dfn{static
2493 block}. The static block typically holds file-scoped variables and
2496 @value{GDBN} provides a method to get a block's superblock, but there
2497 is currently no way to examine the sub-blocks of a block, or to
2498 iterate over all the blocks in a symbol table (@pxref{Symbol Tables In
2501 Here is a short example that should help explain blocks:
2504 /* This is in the global block. */
2507 /* This is in the static block. */
2508 static int file_scope;
2510 /* 'function' is in the global block, and 'argument' is
2511 in a block nested inside of 'function'. */
2512 int function (int argument)
2514 /* 'local' is in a block inside 'function'. It may or may
2515 not be in the same block as 'argument'. */
2519 /* 'inner' is in a block whose superblock is the one holding
2523 /* If this call is expanded by the compiler, you may see
2524 a nested block here whose function is 'inline_function'
2525 and whose superblock is the one holding 'inner'. */
2531 The following block-related procedures are provided by the
2532 @code{(gdb)} module:
2534 @deffn {Scheme Procedure} block? object
2535 Return @code{#t} if @var{object} is a @code{<gdb:block>} object.
2536 Otherwise return @code{#f}.
2539 @deffn {Scheme Procedure} block-valid? block
2540 Returns @code{#t} if @code{<gdb:block>} @var{block} is valid,
2541 @code{#f} if not. A block object can become invalid if the block it
2542 refers to doesn't exist anymore in the inferior. All other
2543 @code{<gdb:block>} methods will throw an exception if it is invalid at
2544 the time the procedure is called. The block's validity is also checked
2545 during iteration over symbols of the block.
2548 @deffn {Scheme Procedure} block-start block
2549 Return the start address of @code{<gdb:block>} @var{block}.
2552 @deffn {Scheme Procedure} block-end block
2553 Return the end address of @code{<gdb:block>} @var{block}.
2556 @deffn {Scheme Procedure} block-function block
2557 Return the name of @code{<gdb:block>} @var{block} represented as a
2558 @code{<gdb:symbol>} object.
2559 If the block is not named, then @code{#f} is returned.
2561 For ordinary function blocks, the superblock is the static block.
2562 However, you should note that it is possible for a function block to
2563 have a superblock that is not the static block -- for instance this
2564 happens for an inlined function.
2567 @deffn {Scheme Procedure} block-superblock block
2568 Return the block containing @code{<gdb:block>} @var{block}.
2569 If the parent block does not exist, then @code{#f} is returned.
2572 @deffn {Scheme Procedure} block-global-block block
2573 Return the global block associated with @code{<gdb:block>} @var{block}.
2576 @deffn {Scheme Procedure} block-static-block block
2577 Return the static block associated with @code{<gdb:block>} @var{block}.
2580 @deffn {Scheme Procedure} block-global? block
2581 Return @code{#t} if @code{<gdb:block>} @var{block} is a global block.
2582 Otherwise return @code{#f}.
2585 @deffn {Scheme Procedure} block-static? block
2586 Return @code{#t} if @code{<gdb:block>} @var{block} is a static block.
2587 Otherwise return @code{#f}.
2590 @deffn {Scheme Procedure} block-symbols
2591 Return a list of all symbols (as <gdb:symbol> objects) in
2592 @code{<gdb:block>} @var{block}.
2595 @deffn {Scheme Procedure} make-block-symbols-iterator block
2596 Return an object of type @code{<gdb:iterator>} that will iterate
2597 over all symbols of the block.
2598 Guile programs should not assume that a specific block object will
2599 always contain a given symbol, since changes in @value{GDBN} features and
2600 infrastructure may cause symbols move across blocks in a symbol table.
2601 @xref{Iterators In Guile}.
2604 @deffn {Scheme Procedure} block-symbols-progress?
2605 Return #t if the object is a <gdb:block-symbols-progress> object.
2606 This object would be obtained from the @code{progress} element of the
2607 @code{<gdb:iterator>} object returned by @code{make-block-symbols-iterator}.
2610 @deffn {Scheme Procedure} lookup-block pc
2611 Return the innermost @code{<gdb:block>} containing the given @var{pc}
2612 value. If the block cannot be found for the @var{pc} value specified,
2613 the function will return @code{#f}.
2616 @node Symbols In Guile
2617 @subsubsection Guile representation of Symbols.
2619 @cindex symbols in guile
2620 @tindex <gdb:symbol>
2622 @value{GDBN} represents every variable, function and type as an
2623 entry in a symbol table. @xref{Symbols, ,Examining the Symbol Table}.
2624 Guile represents these symbols in @value{GDBN} with the
2625 @code{<gdb:symbol>} object.
2627 The following symbol-related procedures are provided by the
2628 @code{(gdb)} module:
2630 @deffn {Scheme Procedure} symbol? object
2631 Return @code{#t} if @var{object} is an object of type @code{<gdb:symbol>}.
2632 Otherwise return @code{#f}.
2635 @deffn {Scheme Procedure} symbol-valid? symbol
2636 Return @code{#t} if the @code{<gdb:symbol>} object is valid,
2637 @code{#f} if not. A @code{<gdb:symbol>} object can become invalid if
2638 the symbol it refers to does not exist in @value{GDBN} any longer.
2639 All other @code{<gdb:symbol>} procedures will throw an exception if it is
2640 invalid at the time the procedure is called.
2643 @deffn {Scheme Procedure} symbol-type symbol
2644 Return the type of @var{symbol} or @code{#f} if no type is recorded.
2645 The result is an object of type @code{<gdb:type>}.
2646 @xref{Types In Guile}.
2649 @deffn {Scheme Procedure} symbol-symtab symbol
2650 Return the symbol table in which @var{symbol} appears.
2651 The result is an object of type @code{<gdb:symtab>}.
2652 @xref{Symbol Tables In Guile}.
2655 @deffn {Scheme Procedure} symbol-line symbol
2656 Return the line number in the source code at which @var{symbol} was defined.
2660 @deffn {Scheme Procedure} symbol-name symbol
2661 Return the name of @var{symbol} as a string.
2664 @deffn {Scheme Procedure} symbol-linkage-name symbol
2665 Return the name of @var{symbol}, as used by the linker (i.e., may be mangled).
2668 @deffn {Scheme Procedure} symbol-print-name symbol
2669 Return the name of @var{symbol} in a form suitable for output. This is either
2670 @code{name} or @code{linkage_name}, depending on whether the user
2671 asked @value{GDBN} to display demangled or mangled names.
2674 @deffn {Scheme Procedure} symbol-addr-class symbol
2675 Return the address class of the symbol. This classifies how to find the value
2676 of a symbol. Each address class is a constant defined in the
2677 @code{(gdb)} module and described later in this chapter.
2680 @deffn {Scheme Procedure} symbol-needs-frame? symbol
2681 Return @code{#t} if evaluating @var{symbol}'s value requires a frame
2682 (@pxref{Frames In Guile}) and @code{#f} otherwise. Typically,
2683 local variables will require a frame, but other symbols will not.
2686 @deffn {Scheme Procedure} symbol-argument? symbol
2687 Return @code{#t} if @var{symbol} is an argument of a function.
2688 Otherwise return @code{#f}.
2691 @deffn {Scheme Procedure} symbol-constant? symbol
2692 Return @code{#t} if @var{symbol} is a constant.
2693 Otherwise return @code{#f}.
2696 @deffn {Scheme Procedure} symbol-function? symbol
2697 Return @code{#t} if @var{symbol} is a function or a method.
2698 Otherwise return @code{#f}.
2701 @deffn {Scheme Procedure} symbol-variable? symbol
2702 Return @code{#t} if @var{symbol} is a variable.
2703 Otherwise return @code{#f}.
2706 @deffn {Scheme Procedure} symbol-value symbol @r{[}#:frame frame@r{]}
2707 Compute the value of @var{symbol}, as a @code{<gdb:value>}. For
2708 functions, this computes the address of the function, cast to the
2709 appropriate type. If the symbol requires a frame in order to compute
2710 its value, then @var{frame} must be given. If @var{frame} is not
2711 given, or if @var{frame} is invalid, then an exception is thrown.
2714 @c TODO: line length
2715 @deffn {Scheme Procedure} lookup-symbol name @r{[}#:block block@r{]} @r{[}#:domain domain@r{]}
2716 This function searches for a symbol by name. The search scope can be
2717 restricted to the parameters defined in the optional domain and block
2720 @var{name} is the name of the symbol. It must be a string. The
2721 optional @var{block} argument restricts the search to symbols visible
2722 in that @var{block}. The @var{block} argument must be a
2723 @code{<gdb:block>} object. If omitted, the block for the current frame
2724 is used. The optional @var{domain} argument restricts
2725 the search to the domain type. The @var{domain} argument must be a
2726 domain constant defined in the @code{(gdb)} module and described later
2729 The result is a list of two elements.
2730 The first element is a @code{<gdb:symbol>} object or @code{#f} if the symbol
2732 If the symbol is found, the second element is @code{#t} if the symbol
2733 is a field of a method's object (e.g., @code{this} in C@t{++}),
2734 otherwise it is @code{#f}.
2735 If the symbol is not found, the second element is @code{#f}.
2738 @deffn {Scheme Procedure} lookup-global-symbol name @r{[}#:domain domain@r{]}
2739 This function searches for a global symbol by name.
2740 The search scope can be restricted by the domain argument.
2742 @var{name} is the name of the symbol. It must be a string.
2743 The optional @var{domain} argument restricts the search to the domain type.
2744 The @var{domain} argument must be a domain constant defined in the @code{(gdb)}
2745 module and described later in this chapter.
2747 The result is a @code{<gdb:symbol>} object or @code{#f} if the symbol
2751 The available domain categories in @code{<gdb:symbol>} are represented
2752 as constants in the @code{(gdb)} module:
2755 @item SYMBOL_UNDEF_DOMAIN
2756 This is used when a domain has not been discovered or none of the
2757 following domains apply. This usually indicates an error either
2758 in the symbol information or in @value{GDBN}'s handling of symbols.
2760 @item SYMBOL_VAR_DOMAIN
2761 This domain contains variables, function names, typedef names and enum
2764 @item SYMBOL_STRUCT_DOMAIN
2765 This domain holds struct, union and enum type names.
2767 @item SYMBOL_LABEL_DOMAIN
2768 This domain contains names of labels (for gotos).
2770 @item SYMBOL_VARIABLES_DOMAIN
2771 This domain holds a subset of the @code{SYMBOLS_VAR_DOMAIN}; it
2772 contains everything minus functions and types.
2774 @item SYMBOL_FUNCTIONS_DOMAIN
2775 This domain contains all functions.
2777 @item SYMBOL_TYPES_DOMAIN
2778 This domain contains all types.
2781 The available address class categories in @code{<gdb:symbol>} are represented
2782 as constants in the @code{gdb} module:
2785 @item SYMBOL_LOC_UNDEF
2786 If this is returned by address class, it indicates an error either in
2787 the symbol information or in @value{GDBN}'s handling of symbols.
2789 @item SYMBOL_LOC_CONST
2790 Value is constant int.
2792 @item SYMBOL_LOC_STATIC
2793 Value is at a fixed address.
2795 @item SYMBOL_LOC_REGISTER
2796 Value is in a register.
2798 @item SYMBOL_LOC_ARG
2799 Value is an argument. This value is at the offset stored within the
2800 symbol inside the frame's argument list.
2802 @item SYMBOL_LOC_REF_ARG
2803 Value address is stored in the frame's argument list. Just like
2804 @code{LOC_ARG} except that the value's address is stored at the
2805 offset, not the value itself.
2807 @item SYMBOL_LOC_REGPARM_ADDR
2808 Value is a specified register. Just like @code{LOC_REGISTER} except
2809 the register holds the address of the argument instead of the argument
2812 @item SYMBOL_LOC_LOCAL
2813 Value is a local variable.
2815 @item SYMBOL_LOC_TYPEDEF
2816 Value not used. Symbols in the domain @code{SYMBOL_STRUCT_DOMAIN} all
2819 @item SYMBOL_LOC_BLOCK
2822 @item SYMBOL_LOC_CONST_BYTES
2823 Value is a byte-sequence.
2825 @item SYMBOL_LOC_UNRESOLVED
2826 Value is at a fixed address, but the address of the variable has to be
2827 determined from the minimal symbol table whenever the variable is
2830 @item SYMBOL_LOC_OPTIMIZED_OUT
2831 The value does not actually exist in the program.
2833 @item SYMBOL_LOC_COMPUTED
2834 The value's address is a computed location.
2837 @node Symbol Tables In Guile
2838 @subsubsection Symbol table representation in Guile.
2840 @cindex symbol tables in guile
2841 @tindex <gdb:symtab>
2844 Access to symbol table data maintained by @value{GDBN} on the inferior
2845 is exposed to Guile via two objects: @code{<gdb:sal>} (symtab-and-line) and
2846 @code{<gdb:symtab>}. Symbol table and line data for a frame is returned
2847 from the @code{frame-find-sal} @code{<gdb:frame>} procedure.
2848 @xref{Frames In Guile}.
2850 For more information on @value{GDBN}'s symbol table management, see
2851 @ref{Symbols, ,Examining the Symbol Table}.
2853 The following symtab-related procedures are provided by the
2854 @code{(gdb)} module:
2856 @deffn {Scheme Procedure} symtab? object
2857 Return @code{#t} if @var{object} is an object of type @code{<gdb:symtab>}.
2858 Otherwise return @code{#f}.
2861 @deffn {Scheme Procedure} symtab-valid? symtab
2862 Return @code{#t} if the @code{<gdb:symtab>} object is valid,
2863 @code{#f} if not. A @code{<gdb:symtab>} object becomes invalid when
2864 the symbol table it refers to no longer exists in @value{GDBN}.
2865 All other @code{<gdb:symtab>} procedures will throw an exception
2866 if it is invalid at the time the procedure is called.
2869 @deffn {Scheme Procedure} symtab-filename symtab
2870 Return the symbol table's source filename.
2873 @deffn {Scheme Procedure} symtab-fullname symtab
2874 Return the symbol table's source absolute file name.
2877 @deffn {Scheme Procedure} symtab-objfile symtab
2878 Return the symbol table's backing object file. @xref{Objfiles In Guile}.
2881 @deffn {Scheme Procedure} symtab-global-block symtab
2882 Return the global block of the underlying symbol table.
2883 @xref{Blocks In Guile}.
2886 @deffn {Scheme Procedure} symtab-static-block symtab
2887 Return the static block of the underlying symbol table.
2888 @xref{Blocks In Guile}.
2891 The following symtab-and-line-related procedures are provided by the
2892 @code{(gdb)} module:
2894 @deffn {Scheme Procedure} sal? object
2895 Return @code{#t} if @var{object} is an object of type @code{<gdb:sal>}.
2896 Otherwise return @code{#f}.
2899 @deffn {Scheme Procedure} sal-valid? sal
2900 Return @code{#t} if @var{sal} is valid, @code{#f} if not.
2901 A @code{<gdb:sal>} object becomes invalid when the Symbol table object
2902 it refers to no longer exists in @value{GDBN}. All other
2903 @code{<gdb:sal>} procedures will throw an exception if it is
2904 invalid at the time the procedure is called.
2907 @deffn {Scheme Procedure} sal-symtab sal
2908 Return the symbol table object (@code{<gdb:symtab>}) for @var{sal}.
2911 @deffn {Scheme Procedure} sal-line sal
2912 Return the line number for @var{sal}.
2915 @deffn {Scheme Procedure} sal-pc sal
2916 Return the start of the address range occupied by code for @var{sal}.
2919 @deffn {Scheme Procedure} sal-last sal
2920 Return the end of the address range occupied by code for @var{sal}.
2923 @deffn {Scheme Procedure} find-pc-line pc
2924 Return the @code{<gdb:sal>} object corresponding to the @var{pc} value.
2925 If an invalid value of @var{pc} is passed as an argument, then the
2926 @code{symtab} and @code{line} attributes of the returned @code{<gdb:sal>}
2927 object will be @code{#f} and 0 respectively.
2930 @node Breakpoints In Guile
2931 @subsubsection Manipulating breakpoints using Guile
2933 @cindex breakpoints in guile
2934 @tindex <gdb:breakpoint>
2936 Breakpoints in Guile are represented by objects of type
2937 @code{<gdb:breakpoint>}. New breakpoints can be created with the
2938 @code{make-breakpoint} Guile function, and then added to @value{GDBN} with the
2939 @code{register-breakpoint!} Guile function.
2940 This two-step approach is taken to separate out the side-effect of adding
2941 the breakpoint to @value{GDBN} from @code{make-breakpoint}.
2943 Support is also provided to view and manipulate breakpoints created
2946 The following breakpoint-related procedures are provided by the
2947 @code{(gdb)} module:
2949 @c TODO: line length
2950 @deffn {Scheme Procedure} make-breakpoint location @r{[}#:type type@r{]} @r{[}#:wp-class wp-class@r{]} @r{[}#:internal internal@r{]}
2951 Create a new breakpoint at @var{location}, a string naming the
2952 location of the breakpoint, or an expression that defines a watchpoint.
2953 The contents can be any location recognized by the @code{break} command,
2954 or in the case of a watchpoint, by the @code{watch} command.
2956 The breakpoint is initially marked as @samp{invalid}.
2957 The breakpoint is not usable until it has been registered with @value{GDBN}
2958 with @code{register-breakpoint!}, at which point it becomes @samp{valid}.
2959 The result is the @code{<gdb:breakpoint>} object representing the breakpoint.
2961 The optional @var{type} denotes the breakpoint to create.
2962 This argument can be either @code{BP_BREAKPOINT} or @code{BP_WATCHPOINT},
2963 and defaults to @code{BP_BREAKPOINT}.
2965 The optional @var{wp-class} argument defines the class of watchpoint to
2966 create, if @var{type} is @code{BP_WATCHPOINT}. If a watchpoint class is
2967 not provided, it is assumed to be a @code{WP_WRITE} class.
2969 The optional @var{internal} argument allows the breakpoint to become
2970 invisible to the user. The breakpoint will neither be reported when
2971 registered, nor will it be listed in the output from @code{info breakpoints}
2972 (but will be listed with the @code{maint info breakpoints} command).
2973 If an internal flag is not provided, the breakpoint is visible
2976 When a watchpoint is created, @value{GDBN} will try to create a
2977 hardware assisted watchpoint. If successful, the type of the watchpoint
2978 is changed from @code{BP_WATCHPOINT} to @code{BP_HARDWARE_WATCHPOINT}
2979 for @code{WP_WRITE}, @code{BP_READ_WATCHPOINT} for @code{WP_READ},
2980 and @code{BP_ACCESS_WATCHPOINT} for @code{WP_ACCESS}.
2981 If not successful, the type of the watchpoint is left as @code{WP_WATCHPOINT}.
2983 The available types are represented by constants defined in the @code{gdb}
2988 Normal code breakpoint.
2991 Watchpoint breakpoint.
2993 @item BP_HARDWARE_WATCHPOINT
2994 Hardware assisted watchpoint.
2995 This value cannot be specified when creating the breakpoint.
2997 @item BP_READ_WATCHPOINT
2998 Hardware assisted read watchpoint.
2999 This value cannot be specified when creating the breakpoint.
3001 @item BP_ACCESS_WATCHPOINT
3002 Hardware assisted access watchpoint.
3003 This value cannot be specified when creating the breakpoint.
3006 The available watchpoint types represented by constants are defined in the
3007 @code{(gdb)} module:
3011 Read only watchpoint.
3014 Write only watchpoint.
3017 Read/Write watchpoint.
3022 @deffn {Scheme Procedure} register-breakpoint! breakpoint
3023 Add @var{breakpoint}, a @code{<gdb:breakpoint>} object, to @value{GDBN}'s
3024 list of breakpoints. The breakpoint must have been created with
3025 @code{make-breakpoint}. One cannot register breakpoints that have been
3026 created outside of Guile. Once a breakpoint is registered it becomes
3028 It is an error to register an already registered breakpoint.
3029 The result is unspecified.
3032 @deffn {Scheme Procedure} delete-breakpoint! breakpoint
3033 Remove @var{breakpoint} from @value{GDBN}'s list of breakpoints.
3034 This also invalidates the Guile @var{breakpoint} object.
3035 Any further attempt to access the object will throw an exception.
3037 If @var{breakpoint} was created from Guile with @code{make-breakpoint}
3038 it may be re-registered with @value{GDBN}, in which case the breakpoint
3039 becomes valid again.
3042 @deffn {Scheme Procedure} breakpoints
3043 Return a list of all breakpoints.
3044 Each element of the list is a @code{<gdb:breakpoint>} object.
3047 @deffn {Scheme Procedure} breakpoint? object
3048 Return @code{#t} if @var{object} is a @code{<gdb:breakpoint>} object,
3049 and @code{#f} otherwise.
3052 @deffn {Scheme Procedure} breakpoint-valid? breakpoint
3053 Return @code{#t} if @var{breakpoint} is valid, @code{#f} otherwise.
3054 Breakpoints created with @code{make-breakpoint} are marked as invalid
3055 until they are registered with @value{GDBN} with @code{register-breakpoint!}.
3056 A @code{<gdb:breakpoint>} object can become invalid
3057 if the user deletes the breakpoint. In this case, the object still
3058 exists, but the underlying breakpoint does not. In the cases of
3059 watchpoint scope, the watchpoint remains valid even if execution of the
3060 inferior leaves the scope of that watchpoint.
3063 @deffn {Scheme Procedure} breakpoint-number breakpoint
3064 Return the breakpoint's number --- the identifier used by
3065 the user to manipulate the breakpoint.
3068 @deffn {Scheme Procedure} breakpoint-type breakpoint
3069 Return the breakpoint's type --- the identifier used to
3070 determine the actual breakpoint type or use-case.
3073 @deffn {Scheme Procedure} breakpoint-visible? breakpoint
3074 Return @code{#t} if the breakpoint is visible to the user
3075 when hit, or when the @samp{info breakpoints} command is run.
3076 Otherwise return @code{#f}.
3079 @deffn {Scheme Procedure} breakpoint-location breakpoint
3080 Return the location of the breakpoint, as specified by
3081 the user. It is a string. If the breakpoint does not have a location
3082 (that is, it is a watchpoint) return @code{#f}.
3085 @deffn {Scheme Procedure} breakpoint-expression breakpoint
3086 Return the breakpoint expression, as specified by the user. It is a string.
3087 If the breakpoint does not have an expression (the breakpoint is not a
3088 watchpoint) return @code{#f}.
3091 @deffn {Scheme Procedure} breakpoint-enabled? breakpoint
3092 Return @code{#t} if the breakpoint is enabled, and @code{#f} otherwise.
3095 @deffn {Scheme Procedure} set-breakpoint-enabled! breakpoint flag
3096 Set the enabled state of @var{breakpoint} to @var{flag}.
3097 If flag is @code{#f} it is disabled, otherwise it is enabled.
3100 @deffn {Scheme Procedure} breakpoint-silent? breakpoint
3101 Return @code{#t} if the breakpoint is silent, and @code{#f} otherwise.
3103 Note that a breakpoint can also be silent if it has commands and the
3104 first command is @code{silent}. This is not reported by the
3105 @code{silent} attribute.
3108 @deffn {Scheme Procedure} set-breakpoint-silent! breakpoint flag
3109 Set the silent state of @var{breakpoint} to @var{flag}.
3110 If flag is @code{#f} the breakpoint is made silent,
3111 otherwise it is made non-silent (or noisy).
3114 @deffn {Scheme Procedure} breakpoint-ignore-count breakpoint
3115 Return the ignore count for @var{breakpoint}.
3118 @deffn {Scheme Procedure} set-breakpoint-ignore-count! breakpoint count
3119 Set the ignore count for @var{breakpoint} to @var{count}.
3122 @deffn {Scheme Procedure} breakpoint-hit-count breakpoint
3123 Return hit count of @var{breakpoint}.
3126 @deffn {Scheme Procedure} set-breakpoint-hit-count! breakpoint count
3127 Set the hit count of @var{breakpoint} to @var{count}.
3128 At present, @var{count} must be zero.
3131 @deffn {Scheme Procedure} breakpoint-thread breakpoint
3132 Return the global-thread-id for thread-specific breakpoint
3133 @var{breakpoint}. Return #f if @var{breakpoint} is not
3137 @deffn {Scheme Procedure} set-breakpoint-thread! breakpoint global-thread-id|#f
3138 Set the thread-id for @var{breakpoint} to @var{global-thread-id} If
3139 set to @code{#f}, the breakpoint is no longer thread-specific.
3142 @deffn {Scheme Procedure} breakpoint-task breakpoint
3143 If the breakpoint is Ada task-specific, return the Ada task id.
3144 If the breakpoint is not task-specific (or the underlying
3145 language is not Ada), return @code{#f}.
3148 @deffn {Scheme Procedure} set-breakpoint-task! breakpoint task
3149 Set the Ada task of @var{breakpoint} to @var{task}.
3150 If set to @code{#f}, the breakpoint is no longer task-specific.
3153 @deffn {Scheme Procedure} breakpoint-condition breakpoint
3154 Return the condition of @var{breakpoint}, as specified by the user.
3155 It is a string. If there is no condition, return @code{#f}.
3158 @deffn {Scheme Procedure} set-breakpoint-condition! breakpoint condition
3159 Set the condition of @var{breakpoint} to @var{condition},
3160 which must be a string. If set to @code{#f} then the breakpoint
3161 becomes unconditional.
3164 @deffn {Scheme Procedure} breakpoint-stop breakpoint
3165 Return the stop predicate of @var{breakpoint}.
3166 See @code{set-breakpoint-stop!} below in this section.
3169 @deffn {Scheme Procedure} set-breakpoint-stop! breakpoint procedure|#f
3170 Set the stop predicate of @var{breakpoint}. The predicate
3171 @var{procedure} takes one argument: the <gdb:breakpoint> object.
3172 If this predicate is set to a procedure then it is invoked whenever
3173 the inferior reaches this breakpoint. If it returns @code{#t},
3174 or any non-@code{#f} value, then the inferior is stopped,
3175 otherwise the inferior will continue.
3177 If there are multiple breakpoints at the same location with a
3178 @code{stop} predicate, each one will be called regardless of the
3179 return status of the previous. This ensures that all @code{stop}
3180 predicates have a chance to execute at that location. In this scenario
3181 if one of the methods returns @code{#t} but the others return
3182 @code{#f}, the inferior will still be stopped.
3184 You should not alter the execution state of the inferior (i.e.@:, step,
3185 next, etc.), alter the current frame context (i.e.@:, change the current
3186 active frame), or alter, add or delete any breakpoint. As a general
3187 rule, you should not alter any data within @value{GDBN} or the inferior
3190 Example @code{stop} implementation:
3193 (define (my-stop? bkpt)
3194 (let ((int-val (parse-and-eval "foo")))
3195 (value=? int-val 3)))
3196 (define bkpt (make-breakpoint "main.c:42"))
3197 (register-breakpoint! bkpt)
3198 (set-breakpoint-stop! bkpt my-stop?)
3202 @deffn {Scheme Procedure} breakpoint-commands breakpoint
3203 Return the commands attached to @var{breakpoint} as a string,
3204 or @code{#f} if there are none.
3207 @node Lazy Strings In Guile
3208 @subsubsection Guile representation of lazy strings.
3210 @cindex lazy strings in guile
3211 @tindex <gdb:lazy-string>
3213 A @dfn{lazy string} is a string whose contents is not retrieved or
3214 encoded until it is needed.
3216 A @code{<gdb:lazy-string>} is represented in @value{GDBN} as an
3217 @code{address} that points to a region of memory, an @code{encoding}
3218 that will be used to encode that region of memory, and a @code{length}
3219 to delimit the region of memory that represents the string. The
3220 difference between a @code{<gdb:lazy-string>} and a string wrapped within
3221 a @code{<gdb:value>} is that a @code{<gdb:lazy-string>} will be treated
3222 differently by @value{GDBN} when printing. A @code{<gdb:lazy-string>} is
3223 retrieved and encoded during printing, while a @code{<gdb:value>}
3224 wrapping a string is immediately retrieved and encoded on creation.
3226 The following lazy-string-related procedures are provided by the
3227 @code{(gdb)} module:
3229 @deffn {Scheme Procedure} lazy-string? object
3230 Return @code{#t} if @var{object} is an object of type @code{<gdb:lazy-string>}.
3231 Otherwise return @code{#f}.
3234 @deffn {Scheme Procedure} lazy-string-address lazy-sring
3235 Return the address of @var{lazy-string}.
3238 @deffn {Scheme Procedure} lazy-string-length lazy-string
3239 Return the length of @var{lazy-string} in characters. If the
3240 length is -1, then the string will be fetched and encoded up to the
3241 first null of appropriate width.
3244 @deffn {Scheme Procedure} lazy-string-encoding lazy-string
3245 Return the encoding that will be applied to @var{lazy-string}
3246 when the string is printed by @value{GDBN}. If the encoding is not
3247 set, or contains an empty string, then @value{GDBN} will select the
3248 most appropriate encoding when the string is printed.
3251 @deffn {Scheme Procedure} lazy-string-type lazy-string
3252 Return the type that is represented by @var{lazy-string}'s type.
3253 For a lazy string this is a pointer or array type. To
3254 resolve this to the lazy string's character type, use @code{type-target-type}.
3255 @xref{Types In Guile}.
3258 @deffn {Scheme Procedure} lazy-string->value lazy-string
3259 Convert the @code{<gdb:lazy-string>} to a @code{<gdb:value>}. This value
3260 will point to the string in memory, but will lose all the delayed
3261 retrieval, encoding and handling that @value{GDBN} applies to a
3262 @code{<gdb:lazy-string>}.
3265 @node Architectures In Guile
3266 @subsubsection Guile representation of architectures
3268 @cindex guile architectures
3271 @value{GDBN} uses architecture specific parameters and artifacts in a
3272 number of its various computations. An architecture is represented
3273 by an instance of the @code{<gdb:arch>} class.
3275 The following architecture-related procedures are provided by the
3276 @code{(gdb)} module:
3278 @deffn {Scheme Procedure} arch? object
3279 Return @code{#t} if @var{object} is an object of type @code{<gdb:arch>}.
3280 Otherwise return @code{#f}.
3283 @deffn {Scheme Procedure} current-arch
3284 Return the current architecture as a @code{<gdb:arch>} object.
3287 @deffn {Scheme Procedure} arch-name arch
3288 Return the name (string value) of @code{<gdb:arch>} @var{arch}.
3291 @deffn {Scheme Procedure} arch-charset arch
3292 Return name of target character set of @code{<gdb:arch>} @var{arch}.
3295 @deffn {Scheme Procedure} arch-wide-charset
3296 Return name of target wide character set of @code{<gdb:arch>} @var{arch}.
3299 Each architecture provides a set of predefined types, obtained by
3300 the following functions.
3302 @deffn {Scheme Procedure} arch-void-type arch
3303 Return the @code{<gdb:type>} object for a @code{void} type
3304 of architecture @var{arch}.
3307 @deffn {Scheme Procedure} arch-char-type arch
3308 Return the @code{<gdb:type>} object for a @code{char} type
3309 of architecture @var{arch}.
3312 @deffn {Scheme Procedure} arch-short-type arch
3313 Return the @code{<gdb:type>} object for a @code{short} type
3314 of architecture @var{arch}.
3317 @deffn {Scheme Procedure} arch-int-type arch
3318 Return the @code{<gdb:type>} object for an @code{int} type
3319 of architecture @var{arch}.
3322 @deffn {Scheme Procedure} arch-long-type arch
3323 Return the @code{<gdb:type>} object for a @code{long} type
3324 of architecture @var{arch}.
3327 @deffn {Scheme Procedure} arch-schar-type arch
3328 Return the @code{<gdb:type>} object for a @code{signed char} type
3329 of architecture @var{arch}.
3332 @deffn {Scheme Procedure} arch-uchar-type arch
3333 Return the @code{<gdb:type>} object for an @code{unsigned char} type
3334 of architecture @var{arch}.
3337 @deffn {Scheme Procedure} arch-ushort-type arch
3338 Return the @code{<gdb:type>} object for an @code{unsigned short} type
3339 of architecture @var{arch}.
3342 @deffn {Scheme Procedure} arch-uint-type arch
3343 Return the @code{<gdb:type>} object for an @code{unsigned int} type
3344 of architecture @var{arch}.
3347 @deffn {Scheme Procedure} arch-ulong-type arch
3348 Return the @code{<gdb:type>} object for an @code{unsigned long} type
3349 of architecture @var{arch}.
3352 @deffn {Scheme Procedure} arch-float-type arch
3353 Return the @code{<gdb:type>} object for a @code{float} type
3354 of architecture @var{arch}.
3357 @deffn {Scheme Procedure} arch-double-type arch
3358 Return the @code{<gdb:type>} object for a @code{double} type
3359 of architecture @var{arch}.
3362 @deffn {Scheme Procedure} arch-longdouble-type arch
3363 Return the @code{<gdb:type>} object for a @code{long double} type
3364 of architecture @var{arch}.
3367 @deffn {Scheme Procedure} arch-bool-type arch
3368 Return the @code{<gdb:type>} object for a @code{bool} type
3369 of architecture @var{arch}.
3372 @deffn {Scheme Procedure} arch-longlong-type arch
3373 Return the @code{<gdb:type>} object for a @code{long long} type
3374 of architecture @var{arch}.
3377 @deffn {Scheme Procedure} arch-ulonglong-type arch
3378 Return the @code{<gdb:type>} object for an @code{unsigned long long} type
3379 of architecture @var{arch}.
3382 @deffn {Scheme Procedure} arch-int8-type arch
3383 Return the @code{<gdb:type>} object for an @code{int8} type
3384 of architecture @var{arch}.
3387 @deffn {Scheme Procedure} arch-uint8-type arch
3388 Return the @code{<gdb:type>} object for a @code{uint8} type
3389 of architecture @var{arch}.
3392 @deffn {Scheme Procedure} arch-int16-type arch
3393 Return the @code{<gdb:type>} object for an @code{int16} type
3394 of architecture @var{arch}.
3397 @deffn {Scheme Procedure} arch-uint16-type arch
3398 Return the @code{<gdb:type>} object for a @code{uint16} type
3399 of architecture @var{arch}.
3402 @deffn {Scheme Procedure} arch-int32-type arch
3403 Return the @code{<gdb:type>} object for an @code{int32} type
3404 of architecture @var{arch}.
3407 @deffn {Scheme Procedure} arch-uint32-type arch
3408 Return the @code{<gdb:type>} object for a @code{uint32} type
3409 of architecture @var{arch}.
3412 @deffn {Scheme Procedure} arch-int64-type arch
3413 Return the @code{<gdb:type>} object for an @code{int64} type
3414 of architecture @var{arch}.
3417 @deffn {Scheme Procedure} arch-uint64-type arch
3418 Return the @code{<gdb:type>} object for a @code{uint64} type
3419 of architecture @var{arch}.
3425 (gdb) guile (type-name (arch-uchar-type (current-arch)))
3429 @node Disassembly In Guile
3430 @subsubsection Disassembly In Guile
3432 The disassembler can be invoked from Scheme code.
3433 Furthermore, the disassembler can take a Guile port as input,
3434 allowing one to disassemble from any source, and not just target memory.
3436 @c TODO: line length
3437 @deffn {Scheme Procedure} arch-disassemble arch start-pc @r{[}#:port port@r{]} @r{[}#:offset offset@r{]} @r{[}#:size size@r{]} @r{[}#:count count@r{]}
3438 Return a list of disassembled instructions starting from the memory
3439 address @var{start-pc}.
3441 The optional argument @var{port} specifies the input port to read bytes from.
3442 If @var{port} is @code{#f} then bytes are read from target memory.
3444 The optional argument @var{offset} specifies the address offset of the
3445 first byte in @var{port}. This is useful, for example, when @var{port}
3446 specifies a @samp{bytevector} and you want the bytevector to be disassembled
3447 as if it came from that address. The @var{start-pc} passed to the reader
3448 for @var{port} is offset by the same amount.
3452 (gdb) guile (use-modules (rnrs io ports))
3453 (gdb) guile (define pc (value->integer (parse-and-eval "$pc")))
3454 (gdb) guile (define mem (open-memory #:start pc))
3455 (gdb) guile (define bv (get-bytevector-n mem 10))
3456 (gdb) guile (define bv-port (open-bytevector-input-port bv))
3457 (gdb) guile (define arch (current-arch))
3458 (gdb) guile (arch-disassemble arch pc #:port bv-port #:offset pc)
3459 (((address . 4195516) (asm . "mov $0x4005c8,%edi") (length . 5)))
3462 The optional arguments @var{size} and
3463 @var{count} determine the number of instructions in the returned list.
3464 If either @var{size} or @var{count} is specified as zero, then
3465 no instructions are disassembled and an empty list is returned.
3466 If both the optional arguments @var{size} and @var{count} are
3467 specified, then a list of at most @var{count} disassembled instructions
3468 whose start address falls in the closed memory address interval from
3469 @var{start-pc} to (@var{start-pc} + @var{size} - 1) are returned.
3470 If @var{size} is not specified, but @var{count} is specified,
3471 then @var{count} number of instructions starting from the address
3472 @var{start-pc} are returned. If @var{count} is not specified but
3473 @var{size} is specified, then all instructions whose start address
3474 falls in the closed memory address interval from @var{start-pc} to
3475 (@var{start-pc} + @var{size} - 1) are returned.
3476 If neither @var{size} nor @var{count} are specified, then a single
3477 instruction at @var{start-pc} is returned.
3479 Each element of the returned list is an alist (associative list)
3480 with the following keys:
3485 The value corresponding to this key is a Guile integer of
3486 the memory address of the instruction.
3489 The value corresponding to this key is a string value which represents
3490 the instruction with assembly language mnemonics. The assembly
3491 language flavor used is the same as that specified by the current CLI
3492 variable @code{disassembly-flavor}. @xref{Machine Code}.
3495 The value corresponding to this key is the length of the instruction in bytes.
3500 @node I/O Ports in Guile
3501 @subsubsection I/O Ports in Guile
3503 @deffn {Scheme Procedure} input-port
3504 Return @value{GDBN}'s input port as a Guile port object.
3507 @deffn {Scheme Procedure} output-port
3508 Return @value{GDBN}'s output port as a Guile port object.
3511 @deffn {Scheme Procedure} error-port
3512 Return @value{GDBN}'s error port as a Guile port object.
3515 @deffn {Scheme Procedure} stdio-port? object
3516 Return @code{#t} if @var{object} is a @value{GDBN} stdio port.
3517 Otherwise return @code{#f}.
3520 @node Memory Ports in Guile
3521 @subsubsection Memory Ports in Guile
3523 @value{GDBN} provides a @code{port} interface to target memory.
3524 This allows Guile code to read/write target memory using Guile's port and
3525 bytevector functionality. The main routine is @code{open-memory} which
3526 returns a port object. One can then read/write memory using that object.
3528 @deffn {Scheme Procedure} open-memory @r{[}#:mode mode{]} @r{[}#:start address{]} @r{[}#:size size{]}
3529 Return a port object that can be used for reading and writing memory.
3530 The port will be open according to @var{mode}, which is the standard
3531 mode argument to Guile port open routines, except that the @samp{"a"}
3532 and @samp{"l"} modes are not supported.
3533 @xref{File Ports,,, guile, GNU Guile Reference Manual}.
3534 The @samp{"b"} (binary) character may be present, but is ignored:
3535 memory ports are binary only. If @samp{"0"} is appended then
3536 the port is marked as unbuffered.
3537 The default is @samp{"r"}, read-only and buffered.
3539 The chunk of memory that can be accessed can be bounded.
3540 If both @var{start} and @var{size} are unspecified, all of memory can be
3541 accessed. If only @var{start} is specified, all of memory from that point
3542 on can be accessed. If only @var{size} if specified, all memory in the
3543 range [0,@var{size}) can be accessed. If both are specified, all memory
3544 in the rane [@var{start},@var{start}+@var{size}) can be accessed.
3547 @deffn {Scheme Procedure} memory-port?
3548 Return @code{#t} if @var{object} is an object of type @code{<gdb:memory-port>}.
3549 Otherwise return @code{#f}.
3552 @deffn {Scheme Procedure} memory-port-range memory-port
3553 Return the range of @code{<gdb:memory-port>} @var{memory-port} as a list
3554 of two elements: @code{(start end)}. The range is @var{start} to @var{end}
3558 @deffn {Scheme Procedure} memory-port-read-buffer-size memory-port
3559 Return the size of the read buffer of @code{<gdb:memory-port>}
3562 This procedure is deprecated and will be removed in @value{GDBN} 11.
3563 It returns 0 when using Guile 2.2 or later.
3566 @deffn {Scheme Procedure} set-memory-port-read-buffer-size! memory-port size
3567 Set the size of the read buffer of @code{<gdb:memory-port>}
3568 @var{memory-port} to @var{size}. The result is unspecified.
3570 This procedure is deprecated and will be removed in @value{GDBN} 11.
3571 When @value{GDBN} is built with Guile 2.2 or later, you can call
3572 @code{setvbuf} instead (@pxref{Buffering, @code{setvbuf},, guile, GNU
3573 Guile Reference Manual}).
3576 @deffn {Scheme Procedure} memory-port-write-buffer-size memory-port
3577 Return the size of the write buffer of @code{<gdb:memory-port>}
3580 This procedure is deprecated and will be removed in @value{GDBN} 11.
3581 It returns 0 when @value{GDBN} is built with Guile 2.2 or later.
3584 @deffn {Scheme Procedure} set-memory-port-write-buffer-size! memory-port size
3585 Set the size of the write buffer of @code{<gdb:memory-port>}
3586 @var{memory-port} to @var{size}. The result is unspecified.
3588 This procedure is deprecated and will be removed in @value{GDBN} 11.
3589 When @value{GDBN} is built with Guile 2.2 or later, you can call
3590 @code{setvbuf} instead.
3593 A memory port is closed like any other port, with @code{close-port}.
3595 Combined with Guile's @code{bytevectors}, memory ports provide a lot
3596 of utility. For example, to fill a buffer of 10 integers in memory,
3597 one can do something like the following.
3600 ;; In the program: int buffer[10];
3601 (use-modules (rnrs bytevectors))
3602 (use-modules (rnrs io ports))
3603 (define addr (parse-and-eval "buffer"))
3605 (define byte-size (* n 4))
3606 (define mem-port (open-memory #:mode "r+" #:start
3607 (value->integer addr) #:size byte-size))
3608 (define byte-vec (make-bytevector byte-size))
3611 (bytevector-s32-native-set! byte-vec (* i 4) (* i 42)))
3612 (put-bytevector mem-port byte-vec)
3613 (close-port mem-port)
3616 @node Iterators In Guile
3617 @subsubsection Iterators In Guile
3619 @cindex guile iterators
3620 @tindex <gdb:iterator>
3622 A simple iterator facility is provided to allow, for example,
3623 iterating over the set of program symbols without having to first
3624 construct a list of all of them. A useful contribution would be
3625 to add support for SRFI 41 and SRFI 45.
3627 @deffn {Scheme Procedure} make-iterator object progress next!
3628 A @code{<gdb:iterator>} object is constructed with the @code{make-iterator}
3629 procedure. It takes three arguments: the object to be iterated over,
3630 an object to record the progress of the iteration, and a procedure to
3631 return the next element in the iteration, or an implementation chosen value
3632 to denote the end of iteration.
3634 By convention, end of iteration is marked with @code{(end-of-iteration)},
3635 and may be tested with the @code{end-of-iteration?} predicate.
3636 The result of @code{(end-of-iteration)} is chosen so that it is not
3637 otherwise used by the @code{(gdb)} module. If you are using
3638 @code{<gdb:iterator>} in your own code it is your responsibility to
3639 maintain this invariant.
3641 A trivial example for illustration's sake:
3644 (use-modules (gdb iterator))
3645 (define my-list (list 1 2 3))
3647 (make-iterator my-list my-list
3649 (let ((l (iterator-progress iter)))
3653 (set-iterator-progress! iter (cdr l))
3657 Here is a slightly more realistic example, which computes a list of all the
3658 functions in @code{my-global-block}.
3661 (use-modules (gdb iterator))
3662 (define this-sal (find-pc-line (frame-pc (selected-frame))))
3663 (define this-symtab (sal-symtab this-sal))
3664 (define this-global-block (symtab-global-block this-symtab))
3665 (define syms-iter (make-block-symbols-iterator this-global-block))
3666 (define functions (iterator-filter symbol-function? syms-iter))
3670 @deffn {Scheme Procedure} iterator? object
3671 Return @code{#t} if @var{object} is a @code{<gdb:iterator>} object.
3672 Otherwise return @code{#f}.
3675 @deffn {Scheme Procedure} iterator-object iterator
3676 Return the first argument that was passed to @code{make-iterator}.
3677 This is the object being iterated over.
3680 @deffn {Scheme Procedure} iterator-progress iterator
3681 Return the object tracking iteration progress.
3684 @deffn {Scheme Procedure} set-iterator-progress! iterator new-value
3685 Set the object tracking iteration progress.
3688 @deffn {Scheme Procedure} iterator-next! iterator
3689 Invoke the procedure that was the third argument to @code{make-iterator},
3690 passing it one argument, the @code{<gdb:iterator>} object.
3691 The result is either the next element in the iteration, or an end
3692 marker as implemented by the @code{next!} procedure.
3693 By convention the end marker is the result of @code{(end-of-iteration)}.
3696 @deffn {Scheme Procedure} end-of-iteration
3697 Return the Scheme object that denotes end of iteration.
3700 @deffn {Scheme Procedure} end-of-iteration? object
3701 Return @code{#t} if @var{object} is the end of iteration marker.
3702 Otherwise return @code{#f}.
3705 These functions are provided by the @code{(gdb iterator)} module to
3706 assist in using iterators.
3708 @deffn {Scheme Procedure} make-list-iterator list
3709 Return a @code{<gdb:iterator>} object that will iterate over @var{list}.
3712 @deffn {Scheme Procedure} iterator->list iterator
3713 Return the elements pointed to by @var{iterator} as a list.
3716 @deffn {Scheme Procedure} iterator-map proc iterator
3717 Return the list of objects obtained by applying @var{proc} to the object
3718 pointed to by @var{iterator} and to each subsequent object.
3721 @deffn {Scheme Procedure} iterator-for-each proc iterator
3722 Apply @var{proc} to each element pointed to by @var{iterator}.
3723 The result is unspecified.
3726 @deffn {Scheme Procedure} iterator-filter pred iterator
3727 Return the list of elements pointed to by @var{iterator} that satisfy
3731 @deffn {Scheme Procedure} iterator-until pred iterator
3732 Run @var{iterator} until the result of @code{(pred element)} is true
3733 and return that as the result. Otherwise return @code{#f}.
3736 @node Guile Auto-loading
3737 @subsection Guile Auto-loading
3738 @cindex guile auto-loading
3740 When a new object file is read (for example, due to the @code{file}
3741 command, or because the inferior has loaded a shared library),
3742 @value{GDBN} will look for Guile support scripts in two ways:
3743 @file{@var{objfile}-gdb.scm} and the @code{.debug_gdb_scripts} section.
3744 @xref{Auto-loading extensions}.
3746 The auto-loading feature is useful for supplying application-specific
3747 debugging commands and scripts.
3749 Auto-loading can be enabled or disabled,
3750 and the list of auto-loaded scripts can be printed.
3753 @anchor{set auto-load guile-scripts}
3754 @kindex set auto-load guile-scripts
3755 @item set auto-load guile-scripts [on|off]
3756 Enable or disable the auto-loading of Guile scripts.
3758 @anchor{show auto-load guile-scripts}
3759 @kindex show auto-load guile-scripts
3760 @item show auto-load guile-scripts
3761 Show whether auto-loading of Guile scripts is enabled or disabled.
3763 @anchor{info auto-load guile-scripts}
3764 @kindex info auto-load guile-scripts
3765 @cindex print list of auto-loaded Guile scripts
3766 @item info auto-load guile-scripts [@var{regexp}]
3767 Print the list of all Guile scripts that @value{GDBN} auto-loaded.
3769 Also printed is the list of Guile scripts that were mentioned in
3770 the @code{.debug_gdb_scripts} section and were not found.
3771 This is useful because their names are not printed when @value{GDBN}
3772 tries to load them and fails. There may be many of them, and printing
3773 an error message for each one is problematic.
3775 If @var{regexp} is supplied only Guile scripts with matching names are printed.
3780 (gdb) info auto-load guile-scripts
3782 Yes scm-section-script.scm
3783 full name: /tmp/scm-section-script.scm
3784 No my-foo-pretty-printers.scm
3788 When reading an auto-loaded file, @value{GDBN} sets the
3789 @dfn{current objfile}. This is available via the @code{current-objfile}
3790 procedure (@pxref{Objfiles In Guile}). This can be useful for
3791 registering objfile-specific pretty-printers.
3794 @subsection Guile Modules
3795 @cindex guile modules
3797 @value{GDBN} comes with several modules to assist writing Guile code.
3800 * Guile Printing Module:: Building and registering pretty-printers
3801 * Guile Types Module:: Utilities for working with types
3804 @node Guile Printing Module
3805 @subsubsection Guile Printing Module
3807 This module provides a collection of utilities for working with
3813 (use-modules (gdb printing))
3816 @deffn {Scheme Procedure} prepend-pretty-printer! object printer
3817 Add @var{printer} to the front of the list of pretty-printers for
3818 @var{object}. The @var{object} must either be a @code{<gdb:objfile>} object,
3819 or @code{#f} in which case @var{printer} is added to the global list of
3823 @deffn {Scheme Procecure} append-pretty-printer! object printer
3824 Add @var{printer} to the end of the list of pretty-printers for
3825 @var{object}. The @var{object} must either be a @code{<gdb:objfile>} object,
3826 or @code{#f} in which case @var{printer} is added to the global list of
3830 @node Guile Types Module
3831 @subsubsection Guile Types Module
3833 This module provides a collection of utilities for working with
3834 @code{<gdb:type>} objects.
3839 (use-modules (gdb types))
3842 @deffn {Scheme Procedure} get-basic-type type
3843 Return @var{type} with const and volatile qualifiers stripped,
3844 and with typedefs and C@t{++} references converted to the underlying type.
3849 typedef const int const_int;
3851 const_int& foo_ref (foo);
3852 int main () @{ return 0; @}
3859 (gdb) guile (use-modules (gdb) (gdb types))
3860 (gdb) guile (define foo-ref (parse-and-eval "foo_ref"))
3861 (gdb) guile (get-basic-type (value-type foo-ref))
3866 @deffn {Scheme Procedure} type-has-field-deep? type field
3867 Return @code{#t} if @var{type}, assumed to be a type with fields
3868 (e.g., a structure or union), has field @var{field}.
3869 Otherwise return @code{#f}.
3870 This searches baseclasses, whereas @code{type-has-field?} does not.
3873 @deffn {Scheme Procedure} make-enum-hashtable enum-type
3874 Return a Guile hash table produced from @var{enum-type}.
3875 Elements in the hash table are referenced with @code{hashq-ref}.