gdb/exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2014 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef EXCEPTIONS_H
  21 #define EXCEPTIONS_H
  22
  23 #include "ui-out.h"
  24 #include "gdb_setjmp.h"
  25
  26 /* Reasons for calling throw_exceptions().  NOTE: all reason values
  27    must be less than zero.  enum value 0 is reserved for internal use
  28    as the return value from an initial setjmp().  The function
  29    catch_exceptions() reserves values >= 0 as legal results from its
  30    wrapped function.  */
  31
  32 enum return_reason
  33   {
  34     /* User interrupt.  */
  35     RETURN_QUIT = -2,
  36     /* Any other error.  */
  37     RETURN_ERROR
  38   };
  39
  40 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  41
  42 typedef enum
  43 {
  44   RETURN_MASK_QUIT = RETURN_MASK (RETURN_QUIT),
  45   RETURN_MASK_ERROR = RETURN_MASK (RETURN_ERROR),
  46   RETURN_MASK_ALL = (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  47 } return_mask;
  48
  49 /* Describe all exceptions.  */
  50
  51 enum errors {
  52   GDB_NO_ERROR,
  53
  54   /* Any generic error, the corresponding text is in
  55      exception.message.  */
  56   GENERIC_ERROR,
  57
  58   /* Something requested was not found.  */
  59   NOT_FOUND_ERROR,
  60
  61   /* Thread library lacks support necessary for finding thread local
  62      storage.  */
  63   TLS_NO_LIBRARY_SUPPORT_ERROR,
  64
  65   /* Load module not found while attempting to find thread local storage.  */
  66   TLS_LOAD_MODULE_NOT_FOUND_ERROR,
  67
  68   /* Thread local storage has not been allocated yet.  */
  69   TLS_NOT_ALLOCATED_YET_ERROR,
  70
  71   /* Something else went wrong while attempting to find thread local
  72      storage.  The ``struct gdb_exception'' message field provides
  73      more detail.  */
  74   TLS_GENERIC_ERROR,
  75
  76   /* Problem parsing an XML document.  */
  77   XML_PARSE_ERROR,
  78
  79   /* Error accessing memory.  */
  80   MEMORY_ERROR,
  81
  82   /* Value not available.  E.g., a register was not collected in a
  83      traceframe.  */
  84   NOT_AVAILABLE_ERROR,
  85
  86   /* Value was optimized out.  Note: if the value was a register, this
  87      means the register was not saved in the frame.  */
  88   OPTIMIZED_OUT_ERROR,
  89
  90   /* DW_OP_GNU_entry_value resolving failed.  */
  91   NO_ENTRY_VALUE_ERROR,
  92
  93   /* Target throwing an error has been closed.  Current command should be
  94      aborted as the inferior state is no longer valid.  */
  95   TARGET_CLOSE_ERROR,
  96
  97   /* An undefined command was executed.  */
  98   UNDEFINED_COMMAND_ERROR,
  99
 100   /* Requested feature, method, mechanism, etc. is not supported.  */
 101   NOT_SUPPORTED_ERROR,
 102
 103   /* Add more errors here.  */
 104   NR_ERRORS
 105 };
 106
 107 struct gdb_exception
 108 {
 109   enum return_reason reason;
 110   enum errors error;
 111   const char *message;
 112 };
 113
 114 /* A pre-defined non-exception.  */
 115 extern const struct gdb_exception exception_none;
 116
 117 /* Functions to drive the exceptions state m/c (internal to
 118    exceptions).  */
 119 SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 120                                       gdb_exception *exception,
 121                                       return_mask mask);
 122 int exceptions_state_mc_action_iter (void);
 123 int exceptions_state_mc_action_iter_1 (void);
 124
 125 /* Macro to wrap up standard try/catch behavior.
 126
 127    The double loop lets us correctly handle code "break"ing out of the
 128    try catch block.  (It works as the "break" only exits the inner
 129    "while" loop, the outer for loop detects this handling it
 130    correctly.)  Of course "return" and "goto" are not so lucky.
 131
 132    For instance:
 133
 134    *INDENT-OFF*
 135
 136    volatile struct gdb_exception e;
 137    TRY_CATCH (e, RETURN_MASK_ERROR)
 138      {
 139      }
 140    switch (e.reason)
 141      {
 142      case RETURN_ERROR: ...
 143      }
 144
 145   */
 146
 147 #define TRY_CATCH(EXCEPTION,MASK) \
 148      { \
 149        SIGJMP_BUF *buf = \
 150          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 151        SIGSETJMP (*buf); \
 152      } \
 153      while (exceptions_state_mc_action_iter ()) \
 154        while (exceptions_state_mc_action_iter_1 ())
 155
 156 /* *INDENT-ON* */
 157
 158
 159 /* If E is an exception, print it's error message on the specified
 160    stream.  For _fprintf, prefix the message with PREFIX...  */
 161 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 162 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 163                                const char *prefix,
 164                                ...) ATTRIBUTE_PRINTF (3, 4);
 165
 166 /* Throw an exception (as described by "struct gdb_exception").  Will
 167    execute a LONG JUMP to the inner most containing exception handler
 168    established using catch_exceptions() (or similar).
 169
 170    Code normally throws an exception using error() et.al.  For various
 171    reaons, GDB also contains code that throws an exception directly.
 172    For instance, the remote*.c targets contain CNTRL-C signal handlers
 173    that propogate the QUIT event up the exception chain.  ``This could
 174    be a good thing or a dangerous thing.'' -- the Existential
 175    Wombat.  */
 176
 177 extern void throw_exception (struct gdb_exception exception)
 178      ATTRIBUTE_NORETURN;
 179 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 180      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 181 extern void throw_vquit (const char *fmt, va_list ap)
 182      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 183 extern void throw_error (enum errors error, const char *fmt, ...)
 184      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 185 extern void throw_quit (const char *fmt, ...)
 186      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2);
 187
 188 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 189    handler.  If an exception (enum return_reason) is thrown using
 190    throw_exception() than all cleanups installed since
 191    catch_exceptions() was entered are invoked, the (-ve) exception
 192    value is then returned by catch_exceptions.  If FUNC() returns
 193    normally (with a positive or zero return value) then that value is
 194    returned by catch_exceptions().  It is an internal_error() for
 195    FUNC() to return a negative value.
 196
 197    For the period of the FUNC() call: UIOUT is installed as the output
 198    builder; ERRSTRING is installed as the error/quit message; and a
 199    new cleanup_chain is established.  The old values are restored
 200    before catch_exceptions() returns.
 201
 202    The variant catch_exceptions_with_msg() is the same as
 203    catch_exceptions() but adds the ability to return an allocated
 204    copy of the gdb error message.  This is used when a silent error is
 205    issued and the caller wants to manually issue the error message.
 206
 207    MASK specifies what to catch; it is normally set to
 208    RETURN_MASK_ALL, if for no other reason than that the code which
 209    calls catch_errors might not be set up to deal with a quit which
 210    isn't caught.  But if the code can deal with it, it generally
 211    should be RETURN_MASK_ERROR, unless for some reason it is more
 212    useful to abort only the portion of the operation inside the
 213    catch_errors.  Note that quit should return to the command line
 214    fairly quickly, even if some further processing is being done.
 215
 216    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 217    builder variable should just go away.
 218
 219    This function supersedes catch_errors().
 220
 221    This function uses SETJMP() and LONGJUMP().  */
 222
 223 struct ui_out;
 224 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 225 extern int catch_exceptions (struct ui_out *uiout,
 226                              catch_exceptions_ftype *func, void *func_args,
 227                              return_mask mask);
 228 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 229 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 230                                       catch_exceptions_ftype *func,
 231                                       void *func_args,
 232                                       char **gdberrmsg,
 233                                       return_mask mask);
 234
 235 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 236    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 237    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 238    value.  It's unfortunate that, catch_errors() does not return an
 239    indication of the exact exception that it caught - quit_flag might
 240    help.
 241
 242    This function is superseded by catch_exceptions().  */
 243
 244 typedef int (catch_errors_ftype) (void *);
 245 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 246
 247 #endif