gdb/extension-priv.h

   1 /* Private implementation details of interface between gdb and its
   2    extension languages.
   3
   4    Copyright (C) 2014-2015 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef EXTENSION_PRIV_H
  22 #define EXTENSION_PRIV_H
  23
  24 #include "extension.h"
  25
  26 /* The return code for some API calls.  */
  27
  28 enum ext_lang_rc
  29   {
  30     /* The operation completed successfully.  */
  31     EXT_LANG_RC_OK,
  32
  33     /* The operation was not performed (e.g., no pretty-printer).  */
  34     EXT_LANG_RC_NOP,
  35
  36     /* There was an error (e.g., Python error while printing a value).
  37        When an error occurs no further extension languages are tried.
  38        This is to preserve existing behaviour, and because it's convenient
  39        for Python developers.
  40        Note: This is different than encountering a memory error trying to read
  41        a value for pretty-printing.  Here we're referring to, e.g., programming
  42        errors that trigger an exception in the extension language.  */
  43     EXT_LANG_RC_ERROR
  44   };
  45
  46 /* High level description of an extension/scripting language.
  47    An entry for each is compiled into GDB regardless of whether the support
  48    is present.  This is done so that we can issue meaningful errors if the
  49    support is not compiled in.  */
  50
  51 struct extension_language_defn
  52 {
  53   /* Enum of the extension language.  */
  54   enum extension_language language;
  55
  56   /* The name of the extension language, lowercase.  E.g., python.  */
  57   const char *name;
  58
  59   /* The capitalized name of the extension language.
  60      For python this is "Python".  For gdb this is "GDB".  */
  61   const char *capitalized_name;
  62
  63   /* The file suffix of this extension language.  E.g., ".py".  */
  64   const char *suffix;
  65
  66   /* The suffix of per-objfile scripts to auto-load.
  67      E.g., When the program loads libfoo.so, look for libfoo.so-gdb.py.  */
  68   const char *auto_load_suffix;
  69
  70   /* We support embedding external extension language code in GDB's own
  71      scripting language.  We do this by having a special command that begins
  72      the extension language snippet, and terminate it with "end".
  73      This specifies the control type used to implement this.  */
  74   enum command_control_type cli_control_type;
  75
  76   /* A pointer to the "methods" to load scripts in this language,
  77      or NULL if the support is not compiled into GDB.  */
  78   const struct extension_language_script_ops *script_ops;
  79
  80   /* Either a pointer to the "methods" of the extension language interface
  81      or NULL if the support is not compiled into GDB.
  82      This is also NULL for GDB's own scripting language which is relatively
  83      primitive, and doesn't provide these features.  */
  84   const struct extension_language_ops *ops;
  85 };
  86
  87 /* The interface for loading scripts from external extension languages,
  88    as well as GDB's own scripting language.
  89    All of these methods are required to be implemented.
  90
  91    By convention all of these functions take a pseudo-this parameter
  92    as the first argument.  */
  93
  94 struct extension_language_script_ops
  95 {
  96   /* Load a script.  This is called, e.g., via the "source" command.
  97      If there's an error while processing the script this function may,
  98      but is not required to, throw an error.  */
  99   script_sourcer_func *script_sourcer;
 100
 101   /* Load a script attached to an objfile.
 102      If there's an error while processing the script this function may,
 103      but is not required to, throw an error.  */
 104   objfile_script_sourcer_func *objfile_script_sourcer;
 105
 106   /* Return non-zero if auto-loading scripts in this extension language
 107      is enabled.  */
 108   int (*auto_load_enabled) (const struct extension_language_defn *);
 109 };
 110
 111 /* The interface for making calls from GDB to an external extension
 112    language.  This is for non-script-loading related functionality, like
 113    pretty-printing, etc.  The reason these are separated out is GDB's own
 114    scripting language makes use of extension_language_script_opts, but it
 115    makes no use of these.  There is no (current) intention to split
 116    extension_language_ops up any further.
 117    All of these methods are optional and may be NULL, except where
 118    otherwise indicated.
 119
 120    By convention all of these functions take a pseudo-this parameter
 121    as the first argument.  */
 122
 123 struct extension_language_ops
 124 {
 125   /* Called at the end of gdb initialization to give the extension language
 126      an opportunity to finish up.  This is useful for things like adding
 127      new commands where one has to wait until gdb itself is initialized.  */
 128   void (*finish_initialization) (const struct extension_language_defn *);
 129
 130   /* Return non-zero if the extension language successfully initialized.
 131      This method is required.  */
 132   int (*initialized) (const struct extension_language_defn *);
 133
 134   /* Process a sequence of commands embedded in GDB's own scripting language.
 135      E.g.,
 136      python
 137      print 42
 138      end  */
 139   void (*eval_from_control_command) (const struct extension_language_defn *,
 140                                      struct command_line *);
 141
 142   /* Type-printing support:
 143      start_type_printers, apply_type_printers, free_type_printers.
 144      These methods are optional and may be NULL, but if one of them is
 145      implemented then they all must be.  */
 146
 147   /* Called before printing a type.  */
 148   void (*start_type_printers) (const struct extension_language_defn *,
 149                                struct ext_lang_type_printers *);
 150
 151   /* Try to pretty-print TYPE.  If successful the pretty-printed type is
 152      stored in *PRETTIED_TYPE, and the caller must free it.
 153      Returns EXT_LANG_RC_OK upon success, EXT_LANG_RC_NOP if the type
 154      is not recognized, and EXT_LANG_RC_ERROR if an error was encountered.
 155      This function has a bit of a funny name, since it actually applies
 156      recognizers, but this seemed clearer given the start_type_printers
 157      and free_type_printers functions.  */
 158   enum ext_lang_rc (*apply_type_printers)
 159     (const struct extension_language_defn *,
 160      const struct ext_lang_type_printers *,
 161      struct type *, char **prettied_type);
 162
 163   /* Called after a type has been printed to give the type pretty-printer
 164      mechanism an opportunity to clean up.  */
 165   void (*free_type_printers) (const struct extension_language_defn *,
 166                               struct ext_lang_type_printers *);
 167
 168   /* Try to pretty-print a value of type TYPE located at VALADDR
 169      + EMBEDDED_OFFSET, which came from the inferior at address ADDRESS
 170      + EMBEDDED_OFFSET, onto stdio stream STREAM according to OPTIONS.
 171      VAL is the whole object that came from ADDRESS.  VALADDR must point to
 172      the head of VAL's contents buffer.
 173      Returns EXT_LANG_RC_OK upon success, EXT_LANG_RC_NOP if the value
 174      is not recognized, and EXT_LANG_RC_ERROR if an error was encountered.  */
 175   enum ext_lang_rc (*apply_val_pretty_printer)
 176     (const struct extension_language_defn *,
 177      struct type *type, const gdb_byte *valaddr,
 178      int embedded_offset, CORE_ADDR address,
 179      struct ui_file *stream, int recurse,
 180      const struct value *val, const struct value_print_options *options,
 181      const struct language_defn *language);
 182
 183   /* GDB access to the "frame filter" feature.
 184      FRAME is the source frame to start frame-filter invocation.  FLAGS is an
 185      integer holding the flags for printing.  The following elements of
 186      the FRAME_FILTER_FLAGS enum denotes the make-up of FLAGS:
 187      PRINT_LEVEL is a flag indicating whether to print the frame's
 188      relative level in the output.  PRINT_FRAME_INFO is a flag that
 189      indicates whether this function should print the frame
 190      information, PRINT_ARGS is a flag that indicates whether to print
 191      frame arguments, and PRINT_LOCALS, likewise, with frame local
 192      variables.  ARGS_TYPE is an enumerator describing the argument
 193      format, OUT is the output stream to print.  FRAME_LOW is the
 194      beginning of the slice of frames to print, and FRAME_HIGH is the
 195      upper limit of the frames to count.  Returns SCR_BT_ERROR on error,
 196      or SCR_BT_COMPLETED on success.  */
 197   enum ext_lang_bt_status (*apply_frame_filter)
 198     (const struct extension_language_defn *,
 199      struct frame_info *frame, int flags, enum ext_lang_frame_args args_type,
 200      struct ui_out *out, int frame_low, int frame_high);
 201
 202   /* Update values held by the extension language when OBJFILE is discarded.
 203      New global types must be created for every such value, which must then be
 204      updated to use the new types.
 205      This function typically just iterates over all appropriate values and
 206      calls preserve_one_value for each one.
 207      COPIED_TYPES is used to prevent cycles / duplicates and is passed to
 208      preserve_one_value.  */
 209   void (*preserve_values) (const struct extension_language_defn *,
 210                            struct objfile *objfile, htab_t copied_types);
 211
 212   /* Return non-zero if there is a stop condition for the breakpoint.
 213      This is used to implement the restriction that a breakpoint may have
 214      at most one condition.  */
 215   int (*breakpoint_has_cond) (const struct extension_language_defn *,
 216                               struct breakpoint *);
 217
 218   /* Return a value of enum ext_lang_bp_stop indicating if there is a stop
 219      condition for the breakpoint, and if so whether the program should
 220      stop.  This is called when the program has stopped at the specified
 221      breakpoint.
 222      While breakpoints can have at most one condition, this is called for
 223      every extension language, even if another extension language has a
 224      "stop" method: other kinds of breakpoints may be implemented using
 225      this method, e.g., "finish breakpoints" in Python.  */
 226   enum ext_lang_bp_stop (*breakpoint_cond_says_stop)
 227     (const struct extension_language_defn *, struct breakpoint *);
 228
 229   /* The next three are used to connect GDB's SIGINT handling with the
 230      extension language's.
 231
 232      Terminology: If an extension language can use GDB's SIGINT handling then
 233      we say the extension language has "cooperative SIGINT handling".
 234      Python is an example of this.
 235
 236      These need not be implemented, but if one of them is implemented
 237      then they all must be.  */
 238
 239   /* Clear the SIGINT indicator.  */
 240   void (*clear_quit_flag) (const struct extension_language_defn *);
 241
 242   /* Set the SIGINT indicator.
 243      This is called by GDB's SIGINT handler and must be async-safe.  */
 244   void (*set_quit_flag) (const struct extension_language_defn *);
 245
 246   /* Return non-zero if a SIGINT has occurred.
 247      This is expected to also clear the indicator.  */
 248   int (*check_quit_flag) (const struct extension_language_defn *);
 249
 250   /* Called before gdb prints its prompt, giving extension languages an
 251      opportunity to change it with set_prompt.
 252      Returns EXT_LANG_RC_OK if the prompt was changed, EXT_LANG_RC_NOP if
 253      the prompt was not changed, and EXT_LANG_RC_ERROR if an error was
 254      encountered.
 255      Extension languages are called in order, and once the prompt is
 256      changed or an error occurs no further languages are called.  */
 257   enum ext_lang_rc (*before_prompt) (const struct extension_language_defn *,
 258                                      const char *current_gdb_prompt);
 259
 260   /* xmethod support:
 261      clone_xmethod_worker_data, free_xmethod_worker_data,
 262      get_matching_xmethod_workers, get_xmethod_arg_types,
 263      invoke_xmethod.
 264      These methods are optional and may be NULL, but if one of them is
 265      implemented then they all must be.  */
 266
 267   /* Clone DATA and return a new but identical xmethod worker data
 268      object for this extension language.  */
 269   void * (*clone_xmethod_worker_data)
 270     (const struct extension_language_defn *extlang, void *data);
 271
 272   /* Free the DATA object of this extension language.  */
 273   void (*free_xmethod_worker_data)
 274     (const struct extension_language_defn *extlang, void *data);
 275
 276   /* Return a vector of matching xmethod workers defined in this
 277      extension language.  The workers service methods with name
 278      METHOD_NAME on objects of type OBJ_TYPE.  The vector is returned
 279      in DM_VEC.  */
 280   enum ext_lang_rc (*get_matching_xmethod_workers)
 281     (const struct extension_language_defn *extlang,
 282      struct type *obj_type,
 283      const char *method_name,
 284      xmethod_worker_vec **dm_vec);
 285
 286   /* Given a WORKER servicing a particular method, return the types
 287      of the arguments the method takes.  The number of arguments is
 288      returned in NARGS, and their types are returned in the array
 289      ARGTYPES.  */
 290   enum ext_lang_rc (*get_xmethod_arg_types)
 291     (const struct extension_language_defn *extlang,
 292      struct xmethod_worker *worker,
 293      int *nargs,
 294      struct type ***arg_types);
 295
 296   /* Invoke the xmethod serviced by WORKER.  The xmethod is invoked
 297      on OBJECT with arguments in the array ARGS.  NARGS is the length of
 298      this array.  Returns the value returned by the xmethod.  */
 299   struct value * (*invoke_xmethod)
 300     (const struct extension_language_defn *extlang,
 301      struct xmethod_worker *worker,
 302      struct value *object,
 303      struct value **args,
 304      int nargs);
 305 };
 306
 307 /* State necessary to restore a signal handler to its previous value.  */
 308
 309 struct signal_handler
 310 {
 311   /* Non-zero if "handler" has been set.  */
 312   int handler_saved;
 313
 314   /* The signal handler.  */
 315   RETSIGTYPE (*handler) ();
 316 };
 317
 318 /* State necessary to restore the currently active extension language
 319    to its previous value.  */
 320
 321 struct active_ext_lang_state
 322 {
 323   /* The previously active extension language.  */
 324   const struct extension_language_defn *ext_lang;
 325
 326   /* Its SIGINT handler.  */
 327   struct signal_handler sigint_handler;
 328 };
 329
 330 extern const struct extension_language_defn *get_active_ext_lang (void);
 331
 332 extern struct active_ext_lang_state *set_active_ext_lang
 333   (const struct extension_language_defn *);
 334
 335 extern void restore_active_ext_lang (struct active_ext_lang_state *previous);
 336
 337 #endif /* EXTENSION_PRIV_H */