gdb/extension-priv.h

   1 /* Private implementation details of interface between gdb and its
   2    extension languages.
   3
   4    Copyright (C) 2014-2023 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 #include <signal.h>
  26 #include "cli/cli-script.h"
  27
  28 /* High level description of an extension/scripting language.
  29    An entry for each is compiled into GDB regardless of whether the support
  30    is present.  This is done so that we can issue meaningful errors if the
  31    support is not compiled in.  */
  32
  33 struct extension_language_defn
  34 {
  35   /* Enum of the extension language.  */
  36   enum extension_language language;
  37
  38   /* The name of the extension language, lowercase.  E.g., python.  */
  39   const char *name;
  40
  41   /* The capitalized name of the extension language.
  42      For python this is "Python".  For gdb this is "GDB".  */
  43   const char *capitalized_name;
  44
  45   /* The file suffix of this extension language.  E.g., ".py".  */
  46   const char *suffix;
  47
  48   /* The suffix of per-objfile scripts to auto-load.
  49      E.g., When the program loads libfoo.so, look for libfoo.so-gdb.py.  */
  50   const char *auto_load_suffix;
  51
  52   /* We support embedding external extension language code in GDB's own
  53      scripting language.  We do this by having a special command that begins
  54      the extension language snippet, and terminate it with "end".
  55      This specifies the control type used to implement this.  */
  56   enum command_control_type cli_control_type;
  57
  58   /* A pointer to the "methods" to load scripts in this language,
  59      or NULL if the support is not compiled into GDB.  */
  60   const struct extension_language_script_ops *script_ops;
  61
  62   /* Either a pointer to the "methods" of the extension language interface
  63      or NULL if the support is not compiled into GDB.
  64      This is also NULL for GDB's own scripting language which is relatively
  65      primitive, and doesn't provide these features.  */
  66   const struct extension_language_ops *ops;
  67 };
  68
  69 /* The interface for loading scripts from external extension languages,
  70    as well as GDB's own scripting language.
  71    All of these methods are required to be implemented.
  72
  73    By convention all of these functions take a pseudo-this parameter
  74    as the first argument.  */
  75
  76 struct extension_language_script_ops
  77 {
  78   /* Load a script.  This is called, e.g., via the "source" command.
  79      If there's an error while processing the script this function may,
  80      but is not required to, throw an error.  */
  81   script_sourcer_func *script_sourcer;
  82
  83   /* Load a script attached to an objfile.
  84      If there's an error while processing the script this function may,
  85      but is not required to, throw an error.  */
  86   objfile_script_sourcer_func *objfile_script_sourcer;
  87
  88   /* Execute a script attached to an objfile.
  89      If there's an error while processing the script this function may,
  90      but is not required to, throw an error.  */
  91   objfile_script_executor_func *objfile_script_executor;
  92
  93   /* Return non-zero if auto-loading scripts in this extension language
  94      is enabled.  */
  95   bool (*auto_load_enabled) (const struct extension_language_defn *);
  96 };
  97
  98 /* The interface for making calls from GDB to an external extension
  99    language.  This is for non-script-loading related functionality, like
 100    pretty-printing, etc.  The reason these are separated out is GDB's own
 101    scripting language makes use of extension_language_script_opts, but it
 102    makes no use of these.  There is no (current) intention to split
 103    extension_language_ops up any further.
 104    All of these methods are optional and may be NULL, except where
 105    otherwise indicated.
 106
 107    By convention all of these functions take a pseudo-this parameter
 108    as the first argument.  */
 109
 110 struct extension_language_ops
 111 {
 112   /* Called after GDB has processed the early initialization settings
 113      files.  This is when the extension language should be initialized.  By
 114      the time this is called all of the earlier initialization functions
 115      have already been called.  */
 116   void (*initialize) (const struct extension_language_defn *);
 117
 118   /* Return non-zero if the extension language successfully initialized.
 119      This method is required.  */
 120   int (*initialized) (const struct extension_language_defn *);
 121
 122   /* Process a sequence of commands embedded in GDB's own scripting language.
 123      E.g.,
 124      python
 125      print 42
 126      end  */
 127   void (*eval_from_control_command) (const struct extension_language_defn *,
 128                                      struct command_line *);
 129
 130   /* Type-printing support:
 131      start_type_printers, apply_type_printers, free_type_printers.
 132      These methods are optional and may be NULL, but if one of them is
 133      implemented then they all must be.  */
 134
 135   /* Called before printing a type.  */
 136   void (*start_type_printers) (const struct extension_language_defn *,
 137                                struct ext_lang_type_printers *);
 138
 139   /* Try to pretty-print TYPE.  If successful the pretty-printed type is
 140      stored in *PRETTIED_TYPE.
 141      Returns EXT_LANG_RC_OK upon success, EXT_LANG_RC_NOP if the type
 142      is not recognized, and EXT_LANG_RC_ERROR if an error was encountered.
 143      This function has a bit of a funny name, since it actually applies
 144      recognizers, but this seemed clearer given the start_type_printers
 145      and free_type_printers functions.  */
 146   enum ext_lang_rc (*apply_type_printers)
 147     (const struct extension_language_defn *,
 148      const struct ext_lang_type_printers *,
 149      struct type *,
 150      gdb::unique_xmalloc_ptr<char> *prettied_type);
 151
 152   /* Called after a type has been printed to give the type pretty-printer
 153      mechanism an opportunity to clean up.  */
 154   void (*free_type_printers) (const struct extension_language_defn *,
 155                               struct ext_lang_type_printers *);
 156
 157   /* Try to pretty-print a value, onto stdio stream STREAM according
 158      to OPTIONS.  VAL is the object to print.  Returns EXT_LANG_RC_OK
 159      upon success, EXT_LANG_RC_NOP if the value is not recognized, and
 160      EXT_LANG_RC_ERROR if an error was encountered.  */
 161   enum ext_lang_rc (*apply_val_pretty_printer)
 162     (const struct extension_language_defn *,
 163      struct value *val, struct ui_file *stream, int recurse,
 164      const struct value_print_options *options,
 165      const struct language_defn *language);
 166
 167   /* GDB access to the "frame filter" feature.
 168      FRAME is the source frame to start frame-filter invocation.  FLAGS is an
 169      integer holding the flags for printing.  The following elements of
 170      the FRAME_FILTER_FLAGS enum denotes the make-up of FLAGS:
 171      PRINT_LEVEL is a flag indicating whether to print the frame's
 172      relative level in the output.  PRINT_FRAME_INFO is a flag that
 173      indicates whether this function should print the frame
 174      information, PRINT_ARGS is a flag that indicates whether to print
 175      frame arguments, and PRINT_LOCALS, likewise, with frame local
 176      variables.  ARGS_TYPE is an enumerator describing the argument
 177      format, OUT is the output stream to print.  FRAME_LOW is the
 178      beginning of the slice of frames to print, and FRAME_HIGH is the
 179      upper limit of the frames to count.  Returns SCR_BT_ERROR on error,
 180      or SCR_BT_COMPLETED on success.  */
 181   enum ext_lang_bt_status (*apply_frame_filter)
 182     (const struct extension_language_defn *,
 183      frame_info_ptr frame, frame_filter_flags flags,
 184      enum ext_lang_frame_args args_type,
 185      struct ui_out *out, int frame_low, int frame_high);
 186
 187   /* Update values held by the extension language when OBJFILE is discarded.
 188      New global types must be created for every such value, which must then be
 189      updated to use the new types.
 190      This function typically just iterates over all appropriate values and
 191      calls preserve_one_value for each one.
 192      COPIED_TYPES is used to prevent cycles / duplicates and is passed to
 193      preserve_one_value.  */
 194   void (*preserve_values) (const struct extension_language_defn *,
 195                            struct objfile *objfile, htab_t copied_types);
 196
 197   /* Return non-zero if there is a stop condition for the breakpoint.
 198      This is used to implement the restriction that a breakpoint may have
 199      at most one condition.  */
 200   int (*breakpoint_has_cond) (const struct extension_language_defn *,
 201                               struct breakpoint *);
 202
 203   /* Return a value of enum ext_lang_bp_stop indicating if there is a stop
 204      condition for the breakpoint, and if so whether the program should
 205      stop.  This is called when the program has stopped at the specified
 206      breakpoint.
 207      While breakpoints can have at most one condition, this is called for
 208      every extension language, even if another extension language has a
 209      "stop" method: other kinds of breakpoints may be implemented using
 210      this method, e.g., "finish breakpoints" in Python.  */
 211   enum ext_lang_bp_stop (*breakpoint_cond_says_stop)
 212     (const struct extension_language_defn *, struct breakpoint *);
 213
 214   /* The next two are used to connect GDB's SIGINT handling with the
 215      extension language's.
 216
 217      Terminology: If an extension language can use GDB's SIGINT handling then
 218      we say the extension language has "cooperative SIGINT handling".
 219      Python is an example of this.
 220
 221      These need not be implemented, but if one of them is implemented
 222      then they all must be.  */
 223
 224   /* Set the SIGINT indicator.
 225      This is called by GDB's SIGINT handler and must be async-safe.  */
 226   void (*set_quit_flag) (const struct extension_language_defn *);
 227
 228   /* Return non-zero if a SIGINT has occurred.
 229      This is expected to also clear the indicator.  */
 230   int (*check_quit_flag) (const struct extension_language_defn *);
 231
 232   /* Called before gdb prints its prompt, giving extension languages an
 233      opportunity to change it with set_prompt.
 234      Returns EXT_LANG_RC_OK if the prompt was changed, EXT_LANG_RC_NOP if
 235      the prompt was not changed, and EXT_LANG_RC_ERROR if an error was
 236      encountered.
 237      Extension languages are called in order, and once the prompt is
 238      changed or an error occurs no further languages are called.  */
 239   enum ext_lang_rc (*before_prompt) (const struct extension_language_defn *,
 240                                      const char *current_gdb_prompt);
 241
 242   /* Return a vector of matching xmethod workers defined in this
 243      extension language.  The workers service methods with name
 244      METHOD_NAME on objects of type OBJ_TYPE.  The vector is returned
 245      in DM_VEC.
 246
 247      This field may be NULL if the extension language does not support
 248      xmethods.  */
 249   enum ext_lang_rc (*get_matching_xmethod_workers)
 250     (const struct extension_language_defn *extlang,
 251      struct type *obj_type,
 252      const char *method_name,
 253      std::vector<xmethod_worker_up> *dm_vec);
 254
 255   /* Colorize a source file.  NAME is the source file's name, and
 256      CONTENTS is the contents of the file.  This should either return
 257      colorized (using ANSI terminal escapes) version of the contents,
 258      or an empty option.  */
 259   gdb::optional<std::string> (*colorize) (const std::string &name,
 260                                           const std::string &contents);
 261
 262   /* Colorize a single line of disassembler output, CONTENT.  This should
 263      either return colorized (using ANSI terminal escapes) version of the
 264      contents, or an empty optional.  */
 265   gdb::optional<std::string> (*colorize_disasm) (const std::string &content,
 266                                                  gdbarch *gdbarch);
 267
 268   /* Print a single instruction from ADDRESS in architecture GDBARCH.  INFO
 269      is the standard libopcodes disassembler_info structure.  Bytes for the
 270      instruction being printed should be read using INFO->read_memory_func
 271      as the actual instruction bytes might be in a buffer.
 272
 273      Use INFO->fprintf_func to print the results of the disassembly, and
 274      return the length of the instruction.
 275
 276      If no instruction can be disassembled then return an empty value and
 277      other extension languages will get a chance to perform the
 278      disassembly.  */
 279   gdb::optional<int> (*print_insn) (struct gdbarch *gdbarch,
 280                                     CORE_ADDR address,
 281                                     struct disassemble_info *info);
 282
 283   /* Give extension languages a chance to deal with missing debug
 284      information.  OBJFILE is the file for which GDB was unable to find
 285      any debug information.  */
 286   ext_lang_missing_debuginfo_result
 287     (*handle_missing_debuginfo) (const struct extension_language_defn *,
 288                                  struct objfile *objfile);
 289 };
 290
 291 /* State necessary to restore a signal handler to its previous value.  */
 292
 293 struct signal_handler
 294 {
 295   /* Non-zero if "handler" has been set.  */
 296   int handler_saved;
 297
 298   /* The signal handler.  */
 299   sighandler_t handler;
 300 };
 301
 302 /* State necessary to restore the currently active extension language
 303    to its previous value.  */
 304
 305 struct active_ext_lang_state
 306 {
 307   /* The previously active extension language.  */
 308   const struct extension_language_defn *ext_lang;
 309
 310   /* Its SIGINT handler.  */
 311   struct signal_handler sigint_handler;
 312 };
 313
 314 extern struct active_ext_lang_state *set_active_ext_lang
 315   (const struct extension_language_defn *);
 316
 317 extern void restore_active_ext_lang (struct active_ext_lang_state *previous);
 318
 319 #endif /* EXTENSION_PRIV_H */