gdb/extension.c - gdb

Global variables defined

Functions defined

Macros defined

Source code

  1. /* Interface between gdb and its extension languages.

  3.    Copyright (C) 2014-2015 Free Software Foundation, Inc.

  5.    This file is part of GDB.

  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.

  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.

  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/>.  */

  20. /* Note: With few exceptions, external functions and variables in this file
  21.    have "ext_lang" in the name, and no other symbol in gdb does.  */

  23. #include "defs.h"
  24. #include <signal.h>
  25. #include "auto-load.h"
  26. #include "breakpoint.h"
  27. #include "event-top.h"
  28. #include "extension.h"
  29. #include "extension-priv.h"
  30. #include "observer.h"
  31. #include "cli/cli-script.h"
  32. #include "python/python.h"
  33. #include "guile/guile.h"

  35. /* Iterate over all external extension languages, regardless of whether the
  36.    support has been compiled in or not.
  37.    This does not include GDB's own scripting language.  */

  39. ‌#define ALL_EXTENSION_LANGUAGES(i, extlang) \
  40.   for (/*int*/ i = 0, extlang = extension_languages[0]; \
  41.        extlang != NULL; \
  42.        extlang = extension_languages[++i])

  44. /* Iterate over all external extension languages that are supported.
  45.    This does not include GDB's own scripting language.  */

  47. ‌#define ALL_ENABLED_EXTENSION_LANGUAGES(i, extlang) \
  48.   for (/*int*/ i = 0, extlang = extension_languages[0]; \
  49.        extlang != NULL; \
  50.        extlang = extension_languages[++i]) \
  51.     if (extlang->ops != NULL)

  53. ‌static script_sourcer_func source_gdb_script;
  54. ‌static objfile_script_sourcer_func source_gdb_objfile_script;

  56. /* GDB's own scripting language.
  57.    This exists, in part, to support auto-loading ${prog}-gdb.gdb scripts.  */

  59. static const struct extension_language_script_ops
  60. ‌  extension_language_gdb_script_ops =
  61. {
  62.   source_gdb_script,
  63.   source_gdb_objfile_script,
  64.   auto_load_gdb_scripts_enabled
  65. };

  67. ‌const struct extension_language_defn extension_language_gdb =
  68. {
  69.   EXT_LANG_GDB,
  70.   "gdb",
  71.   "GDB",

  73.   /* We fall back to interpreting a script as a GDB script if it doesn't
  74.      match the other scripting languages, but for consistency's sake
  75.      give it a formal suffix.  */
  76.   ".gdb",
  77.   "-gdb.gdb",

  79.   /* cli_control_type: This is never used: GDB's own scripting language
  80.      has a variety of control types (if, while, etc.).  */
  81.   commands_control,

  83.   &extension_language_gdb_script_ops,

  85.   /* The rest of the extension language interface isn't supported by GDB's own
  86.      extension/scripting language.  */
  87.   NULL
  88. };

  90. /* NULL-terminated table of all external (non-native) extension languages.

  92.    The order of appearance in the table is important.
  93.    When multiple extension languages provide the same feature, for example
  94.    a pretty-printer for a particular type, which one gets used?
  95.    The algorithm employed here is "the first one wins".  For example, in
  96.    the case of pretty-printers this means the first one to provide a
  97.    pretty-printed value is the one that is used.  This algorithm is employed
  98.    throughout.  */

  100. ‌static const struct extension_language_defn * const extension_languages[] =
  101. {
  102.   /* To preserve existing behaviour, python should always appear first.  */
  103.   &extension_language_python,
  104.   &extension_language_guile,
  105.   NULL
  106. };

  108. /* Return a pointer to the struct extension_language_defn object of
  109.    extension language LANG.
  110.    This always returns a non-NULL pointer, even if support for the language
  111.    is not compiled into this copy of GDB.  */

  113. const struct extension_language_defn *
  114. ‌get_ext_lang_defn (enum extension_language lang)
  115. {
  116.   int i;
  117.   const struct extension_language_defn *extlang;

  119.   gdb_assert (lang != EXT_LANG_NONE);

  121.   if (lang == EXT_LANG_GDB)
  122.     return &extension_language_gdb;

  124.   ALL_EXTENSION_LANGUAGES (i, extlang)
  125.     {
  126.       if (extlang->language == lang)
  127.         return extlang;
  128.     }

  130.   gdb_assert_not_reached ("unable to find extension_language_defn");
  131. }

  133. /* Return TRUE if FILE has extension EXTENSION.  */

  135. static int
  136. ‌has_extension (const char *file, const char *extension)
  137. {
  138.   int file_len = strlen (file);
  139.   int extension_len = strlen (extension);

  141.   return (file_len > extension_len
  142.           && strcmp (&file[file_len - extension_len], extension) == 0);
  143. }

  145. /* Return the extension language of FILE, or NULL if
  146.    the extension language of FILE is not recognized.
  147.    This is done by looking at the file's suffix.  */

  149. const struct extension_language_defn *
  150. ‌get_ext_lang_of_file (const char *file)
  151. {
  152.   int i;
  153.   const struct extension_language_defn *extlang;

  155.   ALL_EXTENSION_LANGUAGES (i, extlang)
  156.     {
  157.       if (has_extension (file, extlang->suffix))
  158.         return extlang;
  159.     }

  161.   return NULL;
  162. }

  164. /* Return non-zero if support for the specified extension language
  165.    is compiled in.  */

  167. int
  168. ‌ext_lang_present_p (const struct extension_language_defn *extlang)
  169. {
  170.   return extlang->script_ops != NULL;
  171. }

  173. /* Return non-zero if the specified extension language has successfully
  174.    initialized.  */

  176. int
  177. ‌ext_lang_initialized_p (const struct extension_language_defn *extlang)
  178. {
  179.   if (extlang->ops != NULL)
  180.     {
  181.       /* This method is required.  */
  182.       gdb_assert (extlang->ops->initialized != NULL);
  183.       return extlang->ops->initialized (extlang);
  184.     }

  186.   return 0;
  187. }

  189. /* Throw an error indicating EXTLANG is not supported in this copy of GDB.  */

  191. void
  192. ‌throw_ext_lang_unsupported (const struct extension_language_defn *extlang)
  193. {
  194.   error (_("Scripting in the \"%s\" language is not supported"
  195.            " in this copy of GDB."),
  196.          ext_lang_capitalized_name (extlang));
  197. }

  199. /* Methods for GDB's own extension/scripting language.  */

  201. /* The extension_language_script_ops.script_sourcer "method".  */

  203. static void
  204. ‌source_gdb_script (const struct extension_language_defn *extlang,
  205.                    FILE *stream, const char *file)
  206. {
  207.   script_from_file (stream, file);
  208. }

  210. /* The extension_language_script_ops.objfile_script_sourcer "method".  */

  212. static void
  213. ‌source_gdb_objfile_script (const struct extension_language_defn *extlang,
  214.                            struct objfile *objfile,
  215.                            FILE *stream, const char *file)
  216. {
  217.   script_from_file (stream, file);
  218. }

  220. /* Accessors for "public" attributes of struct extension_language.  */

  222. /* Return the "name" field of EXTLANG.  */

  224. const char *
  225. ‌ext_lang_name (const struct extension_language_defn *extlang)
  226. {
  227.   return extlang->name;
  228. }

  230. /* Return the "capitalized_name" field of EXTLANG.  */

  232. const char *
  233. ‌ext_lang_capitalized_name (const struct extension_language_defn *extlang)
  234. {
  235.   return extlang->capitalized_name;
  236. }

  238. /* Return the "suffix" field of EXTLANG.  */

  240. const char *
  241. ‌ext_lang_suffix (const struct extension_language_defn *extlang)
  242. {
  243.   return extlang->suffix;
  244. }

  246. /* Return the "auto_load_suffix" field of EXTLANG.  */

  248. const char *
  249. ‌ext_lang_auto_load_suffix (const struct extension_language_defn *extlang)
  250. {
  251.   return extlang->auto_load_suffix;
  252. }

  254. /* extension_language_script_ops wrappers.  */

  256. /* Return the script "sourcer" function for EXTLANG.
  257.    This is the function that loads and processes a script.
  258.    If support for this language isn't compiled in, NULL is returned.  */

  260. script_sourcer_func *
  261. ‌ext_lang_script_sourcer (const struct extension_language_defn *extlang)
  262. {
  263.   if (extlang->script_ops == NULL)
  264.     return NULL;

  266.   /* The extension language is required to implement this function.  */
  267.   gdb_assert (extlang->script_ops->script_sourcer != NULL);

  269.   return extlang->script_ops->script_sourcer;
  270. }

  272. /* Return the objfile script "sourcer" function for EXTLANG.
  273.    This is the function that loads and processes a script for a particular
  274.    objfile.
  275.    If support for this language isn't compiled in, NULL is returned.  */

  277. objfile_script_sourcer_func *
  278. ‌ext_lang_objfile_script_sourcer (const struct extension_language_defn *extlang)
  279. {
  280.   if (extlang->script_ops == NULL)
  281.     return NULL;

  283.   /* The extension language is required to implement this function.  */
  284.   gdb_assert (extlang->script_ops->objfile_script_sourcer != NULL);

  286.   return extlang->script_ops->objfile_script_sourcer;
  287. }

  289. /* Return non-zero if auto-loading of EXTLANG scripts is enabled.
  290.    Zero is returned if support for this language isn't compiled in.  */

  292. int
  293. ‌ext_lang_auto_load_enabled (const struct extension_language_defn *extlang)
  294. {
  295.   if (extlang->script_ops == NULL)
  296.     return 0;

  298.   /* The extension language is required to implement this function.  */
  299.   gdb_assert (extlang->script_ops->auto_load_enabled != NULL);

  301.   return extlang->script_ops->auto_load_enabled (extlang);
  302. }

  304. /* Functions that iterate over all extension languages.
  305.    These only iterate over external extension languages, not including
  306.    GDB's own extension/scripting language, unless otherwise indicated.  */

  308. /* Wrapper to call the extension_language_ops.finish_initialization "method"
  309.    for each compiled-in extension language.  */

  311. void
  312. ‌finish_ext_lang_initialization (void)
  313. {
  314.   int i;
  315.   const struct extension_language_defn *extlang;

  317.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  318.     {
  319.       if (extlang->ops->finish_initialization != NULL)
  320.         extlang->ops->finish_initialization (extlang);
  321.     }
  322. }

  324. /* Invoke the appropriate extension_language_ops.eval_from_control_command
  325.    method to perform CMD, which is a list of commands in an extension language.

  327.    This function is what implements, for example:

  329.    python
  330.    print 42
  331.    end

  333.    in a GDB script.  */

  335. void
  336. ‌eval_ext_lang_from_control_command (struct command_line *cmd)
  337. {
  338.   int i;
  339.   const struct extension_language_defn *extlang;

  341.   ALL_EXTENSION_LANGUAGES (i, extlang)
  342.     {
  343.       if (extlang->cli_control_type == cmd->control_type)
  344.         {
  345.           if (extlang->ops != NULL
  346.               && extlang->ops->eval_from_control_command != NULL)
  347.             {
  348.               extlang->ops->eval_from_control_command (extlang, cmd);
  349.               return;
  350.             }
  351.           /* The requested extension language is not supported in this GDB.  */
  352.           throw_ext_lang_unsupported (extlang);
  353.         }
  354.     }

  356.   gdb_assert_not_reached ("unknown extension language in command_line");
  357. }

  359. /* Search for and load scripts for OBJFILE written in extension languages.
  360.    This includes GDB's own scripting language.

  362.    This function is what implements the loading of OBJFILE-gdb.py and
  363.    OBJFILE-gdb.gdb.  */

  365. void
  366. ‌auto_load_ext_lang_scripts_for_objfile (struct objfile *objfile)
  367. {
  368.   int i;
  369.   const struct extension_language_defn *extlang;

  371.   extlang = &extension_language_gdb;
  372.   if (ext_lang_auto_load_enabled (extlang))
  373.     auto_load_objfile_script (objfile, extlang);

  375.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  376.     {
  377.       if (ext_lang_auto_load_enabled (extlang))
  378.         auto_load_objfile_script (objfile, extlang);
  379.     }
  380. }

  382. /* Interface to type pretty-printers implemented in an extension language.  */

  384. /* Call this at the start when preparing to pretty-print a type.
  385.    The result is a pointer to an opaque object (to the caller) to be passed
  386.    to apply_ext_lang_type_printers and free_ext_lang_type_printers.

  388.    We don't know in advance which extension language will provide a
  389.    pretty-printer for the type, so all are initialized.  */

  391. struct ext_lang_type_printers *
  392. ‌start_ext_lang_type_printers (void)
  393. {
  394.   struct ext_lang_type_printers *printers
  395.     = XCNEW (struct ext_lang_type_printers);
  396.   int i;
  397.   const struct extension_language_defn *extlang;

  399.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  400.     {
  401.       if (extlang->ops->start_type_printers != NULL)
  402.         extlang->ops->start_type_printers (extlang, printers);
  403.     }

  405.   return printers;
  406. }

  408. /* Iteratively try the type pretty-printers specified by PRINTERS
  409.    according to the standard search order (specified by extension_languages),
  410.    returning the result of the first one that succeeds.
  411.    If there was an error, or if no printer succeeds, then NULL is returned.  */

  413. char *
  414. ‌apply_ext_lang_type_printers (struct ext_lang_type_printers *printers,
  415.                               struct type *type)
  416. {
  417.   int i;
  418.   const struct extension_language_defn *extlang;

  420.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  421.     {
  422.       char *result = NULL;
  423.       enum ext_lang_rc rc;

  425.       if (extlang->ops->apply_type_printers == NULL)
  426.         continue;
  427.       rc = extlang->ops->apply_type_printers (extlang, printers, type,
  428.                                               &result);
  429.       switch (rc)
  430.         {
  431.         case EXT_LANG_RC_OK:
  432.           gdb_assert (result != NULL);
  433.           return result;
  434.         case EXT_LANG_RC_ERROR:
  435.           return NULL;
  436.         case EXT_LANG_RC_NOP:
  437.           break;
  438.         default:
  439.           gdb_assert_not_reached ("bad return from apply_type_printers");
  440.         }
  441.     }

  443.   return NULL;
  444. }

  446. /* Call this after pretty-printing a type to release all memory held
  447.    by PRINTERS.  */

  449. void
  450. ‌free_ext_lang_type_printers (struct ext_lang_type_printers *printers)
  451. {
  452.   int i;
  453.   const struct extension_language_defn *extlang;

  455.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  456.     {
  457.       if (extlang->ops->free_type_printers != NULL)
  458.         extlang->ops->free_type_printers (extlang, printers);
  459.     }

  461.   xfree (printers);
  462. }

  464. /* Try to pretty-print a value of type TYPE located at VALADDR
  465.    + EMBEDDED_OFFSET, which came from the inferior at address ADDRESS
  466.    + EMBEDDED_OFFSET, onto stdio stream STREAM according to OPTIONS.
  467.    VAL is the whole object that came from ADDRESS.  VALADDR must point to
  468.    the head of VAL's contents buffer.
  469.    Returns non-zero if the value was successfully pretty-printed.

  471.    Extension languages are tried in the order specified by
  472.    extension_languages.  The first one to provide a pretty-printed
  473.    value "wins".

  475.    If an error is encountered in a pretty-printer, no further extension
  476.    languages are tried.
  477.    Note: This is different than encountering a memory error trying to read a
  478.    value for pretty-printing.  Here we're referring to, e.g., programming
  479.    errors that trigger an exception in the extension language.  */

  481. int
  482. ‌apply_ext_lang_val_pretty_printer (struct type *type, const gdb_byte *valaddr,
  483.                                    int embedded_offset, CORE_ADDR address,
  484.                                    struct ui_file *stream, int recurse,
  485.                                    const struct value *val,
  486.                                    const struct value_print_options *options,
  487.                                    const struct language_defn *language)
  488. {
  489.   int i;
  490.   const struct extension_language_defn *extlang;

  492.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  493.     {
  494.       enum ext_lang_rc rc;

  496.       if (extlang->ops->apply_val_pretty_printer == NULL)
  497.         continue;
  498.       rc = extlang->ops->apply_val_pretty_printer (extlang, type, valaddr,
  499.                                                    embedded_offset, address,
  500.                                                    stream, recurse, val,
  501.                                                    options, language);
  502.       switch (rc)
  503.         {
  504.         case EXT_LANG_RC_OK:
  505.           return 1;
  506.         case EXT_LANG_RC_ERROR:
  507.           return 0;
  508.         case EXT_LANG_RC_NOP:
  509.           break;
  510.         default:
  511.           gdb_assert_not_reached ("bad return from apply_val_pretty_printer");
  512.         }
  513.     }

  515.   return 0;
  516. }

  518. /* GDB access to the "frame filter" feature.
  519.    FRAME is the source frame to start frame-filter invocation.  FLAGS is an
  520.    integer holding the flags for printing.  The following elements of
  521.    the FRAME_FILTER_FLAGS enum denotes the make-up of FLAGS:
  522.    PRINT_LEVEL is a flag indicating whether to print the frame's
  523.    relative level in the output.  PRINT_FRAME_INFO is a flag that
  524.    indicates whether this function should print the frame
  525.    information, PRINT_ARGS is a flag that indicates whether to print
  526.    frame arguments, and PRINT_LOCALS, likewise, with frame local
  527.    variables.  ARGS_TYPE is an enumerator describing the argument
  528.    format, OUT is the output stream to print.  FRAME_LOW is the
  529.    beginning of the slice of frames to print, and FRAME_HIGH is the
  530.    upper limit of the frames to count.  Returns EXT_LANG_BT_ERROR on error,
  531.    or EXT_LANG_BT_COMPLETED on success.

  533.    Extension languages are tried in the order specified by
  534.    extension_languages.  The first one to provide a filter "wins".
  535.    If there is an error (EXT_LANG_BT_ERROR) it is reported immediately
  536.    rather than trying filters in other extension languages.  */

  538. enum ext_lang_bt_status
  539. ‌apply_ext_lang_frame_filter (struct frame_info *frame, int flags,
  540.                              enum ext_lang_frame_args args_type,
  541.                              struct ui_out *out,
  542.                              int frame_low, int frame_high)
  543. {
  544.   int i;
  545.   const struct extension_language_defn *extlang;

  547.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  548.     {
  549.       enum ext_lang_bt_status status;

  551.       if (extlang->ops->apply_frame_filter == NULL)
  552.         continue;
  553.       status = extlang->ops->apply_frame_filter (extlang, frame, flags,
  554.                                                args_type, out,
  555.                                                frame_low, frame_high);
  556.       /* We use the filters from the first extension language that has
  557.          applicable filters.  Also, an error is reported immediately
  558.          rather than continue trying.  */
  559.       if (status != EXT_LANG_BT_NO_FILTERS)
  560.         return status;
  561.     }

  563.   return EXT_LANG_BT_NO_FILTERS;
  564. }

  566. /* Update values held by the extension language when OBJFILE is discarded.
  567.    New global types must be created for every such value, which must then be
  568.    updated to use the new types.
  569.    The function typically just iterates over all appropriate values and
  570.    calls preserve_one_value for each one.
  571.    COPIED_TYPES is used to prevent cycles / duplicates and is passed to
  572.    preserve_one_value.  */

  574. void
  575. ‌preserve_ext_lang_values (struct objfile *objfile, htab_t copied_types)
  576. {
  577.   int i;
  578.   const struct extension_language_defn *extlang;

  580.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  581.     {
  582.       if (extlang->ops->preserve_values != NULL)
  583.         extlang->ops->preserve_values (extlang, objfile, copied_types);
  584.     }
  585. }

  587. /* If there is a stop condition implemented in an extension language for
  588.    breakpoint B, return a pointer to the extension language's definition.
  589.    Otherwise return NULL.
  590.    If SKIP_LANG is not EXT_LANG_NONE, skip checking this language.
  591.    This is for the case where we're setting a new condition: Only one
  592.    condition is allowed, so when setting a condition for any particular
  593.    extension language, we need to check if any other extension language
  594.    already has a condition set.  */

  596. const struct extension_language_defn *
  597. ‌get_breakpoint_cond_ext_lang (struct breakpoint *b,
  598.                               enum extension_language skip_lang)
  599. {
  600.   int i;
  601.   const struct extension_language_defn *extlang;

  603.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  604.     {
  605.       if (extlang->language != skip_lang
  606.           && extlang->ops->breakpoint_has_cond != NULL
  607.           && extlang->ops->breakpoint_has_cond (extlang, b))
  608.         return extlang;
  609.     }

  611.   return NULL;
  612. }

  614. /* Return whether a stop condition for breakpoint B says to stop.
  615.    True is also returned if there is no stop condition for B.  */

  617. int
  618. ‌breakpoint_ext_lang_cond_says_stop (struct breakpoint *b)
  619. {
  620.   int i;
  621.   const struct extension_language_defn *extlang;
  622.   enum ext_lang_bp_stop stop = EXT_LANG_BP_STOP_UNSET;

  624.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  625.     {
  626.       /* There is a rule that a breakpoint can have at most one of any of a
  627.          CLI or extension language condition.  However, Python hacks in "finish
  628.          breakpoints" on top of the "stop" check, so we have to call this for
  629.          every language, even if we could first determine whether a "stop"
  630.          method exists.  */
  631.       if (extlang->ops->breakpoint_cond_says_stop != NULL)
  632.         {
  633.           enum ext_lang_bp_stop this_stop
  634.             = extlang->ops->breakpoint_cond_says_stop (extlang, b);

  636.           if (this_stop != EXT_LANG_BP_STOP_UNSET)
  637.             {
  638.               /* Even though we have to check every extension language, only
  639.                  one of them can return yes/no (because only one of them
  640.                  can have a "stop" condition).  */
  641.               gdb_assert (stop == EXT_LANG_BP_STOP_UNSET);
  642.               stop = this_stop;
  643.             }
  644.         }
  645.     }

  647.   return stop == EXT_LANG_BP_STOP_NO ? 0 : 1;
  648. }

  650. /* ^C/SIGINT support.
  651.    This requires cooperation with the extension languages so the support
  652.    is defined here.  */

  654. /* This flag tracks quit requests when we haven't called out to an
  655.    extension language.  it also holds quit requests when we transition to
  656.    an extension language that doesn't have cooperative SIGINT handling.  */
  657. ‌static int quit_flag;

  659. /* The current extension language we've called out to, or
  660.    extension_language_gdb if there isn't one.
  661.    This must be set everytime we call out to an extension language, and reset
  662.    to the previous value when it returns.  Note that the previous value may
  663.    be a different (or the same) extension language.  */
  664. ‌static const struct extension_language_defn *active_ext_lang
  665.   = &extension_language_gdb;

  667. /* Return the currently active extension language.  */

  669. const struct extension_language_defn *
  670. ‌get_active_ext_lang (void)
  671. {
  672.   return active_ext_lang;
  673. }

  675. /* Install a SIGINT handler.  */

  677. static void
  678. ‌install_sigint_handler (const struct signal_handler *handler_state)
  679. {
  680.   gdb_assert (handler_state->handler_saved);

  682.   signal (SIGINT, handler_state->handler);
  683. }

  685. /* Install GDB's SIGINT handler, storing the previous version in *PREVIOUS.
  686.    As a simple optimization, if the previous version was GDB's SIGINT handler
  687.    then mark the previous handler as not having been saved, and thus it won't
  688.    be restored.  */

  690. static void
  691. ‌install_gdb_sigint_handler (struct signal_handler *previous)
  692. {
  693.   /* Save here to simplify comparison.  */
  694.   RETSIGTYPE (*handle_sigint_for_compare) () = handle_sigint;

  696.   previous->handler = signal (SIGINT, handle_sigint);
  697.   if (previous->handler != handle_sigint_for_compare)
  698.     previous->handler_saved = 1;
  699.   else
  700.     previous->handler_saved = 0;
  701. }

  703. /* Set the currently active extension language to NOW_ACTIVE.
  704.    The result is a pointer to a malloc'd block of memory to pass to
  705.    restore_active_ext_lang.

  707.    N.B. This function must be called every time we call out to an extension
  708.    language, and the result must be passed to restore_active_ext_lang
  709.    afterwards.

  711.    If there is a pending SIGINT it is "moved" to the now active extension
  712.    language, if it supports cooperative SIGINT handling (i.e., it provides
  713.    {clear,set,check}_quit_flag methods).  If the extension language does not
  714.    support cooperative SIGINT handling, then the SIGINT is left queued and
  715.    we require the non-cooperative extension language to call check_quit_flag
  716.    at appropriate times.
  717.    It is important for the extension language to call check_quit_flag if it
  718.    installs its own SIGINT handler to prevent the situation where a SIGINT
  719.    is queued on entry, extension language code runs for a "long" time possibly
  720.    serving one or more SIGINTs, and then returns.  Upon return, if
  721.    check_quit_flag is not called, the original SIGINT will be thrown.
  722.    Non-cooperative extension languages are free to install their own SIGINT
  723.    handler but the original must be restored upon return, either itself
  724.    or via restore_active_ext_lang.  */

  726. struct active_ext_lang_state *
  727. ‌set_active_ext_lang (const struct extension_language_defn *now_active)
  728. {
  729.   struct active_ext_lang_state *previous
  730.     = XCNEW (struct active_ext_lang_state);

  732.   previous->ext_lang = active_ext_lang;
  733.   active_ext_lang = now_active;

  735.   /* If the newly active extension language uses cooperative SIGINT handling
  736.      then ensure GDB's SIGINT handler is installed.  */
  737.   if (now_active->language == EXT_LANG_GDB
  738.       || now_active->ops->check_quit_flag != NULL)
  739.     install_gdb_sigint_handler (&previous->sigint_handler);

  741.   /* If there's a SIGINT recorded in the cooperative extension languages,
  742.      move it to the new language, or save it in GDB's global flag if the newly
  743.      active extension language doesn't use cooperative SIGINT handling.  */
  744.   if (check_quit_flag ())
  745.     set_quit_flag ();

  747.   return previous;
  748. }

  750. /* Restore active extension language from PREVIOUS.  */

  752. void
  753. ‌restore_active_ext_lang (struct active_ext_lang_state *previous)
  754. {
  755.   const struct extension_language_defn *current = active_ext_lang;

  757.   active_ext_lang = previous->ext_lang;

  759.   /* Restore the previous SIGINT handler if one was saved.  */
  760.   if (previous->sigint_handler.handler_saved)
  761.     install_sigint_handler (&previous->sigint_handler);

  763.   /* If there's a SIGINT recorded in the cooperative extension languages,
  764.      move it to the new language, or save it in GDB's global flag if the newly
  765.      active extension language doesn't use cooperative SIGINT handling.  */
  766.   if (check_quit_flag ())
  767.     set_quit_flag ();

  769.   xfree (previous);
  770. }

  772. /* Clear the quit flag.
  773.    The flag is cleared in all extension languages,
  774.    not just the currently active one.  */

  776. void
  777. ‌clear_quit_flag (void)
  778. {
  779.   int i;
  780.   const struct extension_language_defn *extlang;

  782.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  783.     {
  784.       if (extlang->ops->clear_quit_flag != NULL)
  785.         extlang->ops->clear_quit_flag (extlang);
  786.     }

  788.   quit_flag = 0;
  789. }

  791. /* Set the quit flag.
  792.    This only sets the flag in the currently active extension language.
  793.    If the currently active extension language does not have cooperative
  794.    SIGINT handling, then GDB's global flag is set, and it is up to the
  795.    extension language to call check_quit_flag.  The extension language
  796.    is free to install its own SIGINT handler, but we still need to handle
  797.    the transition.  */

  799. void
  800. ‌set_quit_flag (void)
  801. {
  802.   if (active_ext_lang->ops != NULL
  803.       && active_ext_lang->ops->set_quit_flag != NULL)
  804.     active_ext_lang->ops->set_quit_flag (active_ext_lang);
  805.   else
  806.     quit_flag = 1;
  807. }

  809. /* Return true if the quit flag has been set, false otherwise.
  810.    Note: The flag is cleared as a side-effect.
  811.    The flag is checked in all extension languages that support cooperative
  812.    SIGINT handling, not just the current one.  This simplifies transitions.  */

  814. int
  815. ‌check_quit_flag (void)
  816. {
  817.   int i, result = 0;
  818.   const struct extension_language_defn *extlang;

  820.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  821.     {
  822.       if (extlang->ops->check_quit_flag != NULL)
  823.         if (extlang->ops->check_quit_flag (extlang) != 0)
  824.           result = 1;
  825.     }

  827.   /* This is written in a particular way to avoid races.  */
  828.   if (quit_flag)
  829.     {
  830.       quit_flag = 0;
  831.       result = 1;
  832.     }

  834.   return result;
  835. }

  837. /* xmethod support.  */

  839. /* The xmethod API routines do not have "ext_lang" in the name because
  840.    the name "xmethod" implies that this routine deals with extension
  841.    languages.  Plus some of the methods take a xmethod_foo * "self/this"
  842.    arg, not an extension_language_defn * arg.  */

  844. /* Returns a new xmethod_worker with EXTLANG and DATA.  Space for the
  845.    result must be freed with free_xmethod_worker.  */

  847. struct xmethod_worker *
  848. ‌new_xmethod_worker (const struct extension_language_defn *extlang, void *data)
  849. {
  850.   struct xmethod_worker *worker = XCNEW (struct xmethod_worker);

  852.   worker->extlang = extlang;
  853.   worker->data = data;
  854.   worker->value = NULL;

  856.   return worker;
  857. }

  859. /* Clones WORKER and returns a new but identical worker.
  860.    The function get_matching_xmethod_workers (see below), returns a
  861.    vector of matching workers.  If a particular worker is selected by GDB
  862.    to invoke a method, then this function can help in cloning the
  863.    selected worker and freeing up the vector via a cleanup.

  865.    Space for the result must be freed with free_xmethod_worker.  */

  867. struct xmethod_worker *
  868. ‌clone_xmethod_worker (struct xmethod_worker *worker)
  869. {
  870.   struct xmethod_worker *new_worker;
  871.   const struct extension_language_defn *extlang = worker->extlang;

  873.   gdb_assert (extlang->ops->clone_xmethod_worker_data != NULL);

  875.   new_worker = new_xmethod_worker
  876.     (extlang,
  877.      extlang->ops->clone_xmethod_worker_data (extlang, worker->data));

  879.   return new_worker;
  880. }

  882. /* If a method with name METHOD_NAME is to be invoked on an object of type
  883.    TYPE, then all entension languages are searched for implementations of
  884.    methods with name METHOD.  All matches found are returned as a vector
  885.    of 'xmethod_worker_ptr' objects.  If no matching methods are
  886.    found, NULL is returned.  */

  888. ‌VEC (xmethod_worker_ptr) *
  889. get_matching_xmethod_workers (struct type *type, const char *method_name)
  890. {
  891.   VEC (xmethod_worker_ptr) *workers = NULL;
  892.   int i;
  893.   const struct extension_language_defn *extlang;

  895.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  896.     {
  897.       VEC (xmethod_worker_ptr) *lang_workers, *new_vec;
  898.       enum ext_lang_rc rc;

  900.       /* If an extension language does not support xmethods, ignore
  901.          it.  */
  902.       if (extlang->ops->get_matching_xmethod_workers == NULL)
  903.         continue;

  905.       rc = extlang->ops->get_matching_xmethod_workers (extlang,
  906.                                                        type, method_name,
  907.                                                        &lang_workers);
  908.       if (rc == EXT_LANG_RC_ERROR)
  909.         {
  910.           free_xmethod_worker_vec (workers);
  911.           error (_("Error while looking for matching xmethod workers "
  912.                    "defined in %s."), extlang->capitalized_name);
  913.         }

  915.       new_vec = VEC_merge (xmethod_worker_ptr, workers, lang_workers);
  916.       /* Free only the vectors and not the elements as NEW_VEC still
  917.          contains them.  */
  918.       VEC_free (xmethod_worker_ptr, workers);
  919.       VEC_free (xmethod_worker_ptr, lang_workers);
  920.       workers = new_vec;
  921.     }

  923.   return workers;
  924. }

  926. /* Return the arg types of the xmethod encapsulated in WORKER.
  927.    An array of arg types is returned.  The length of the array is returned in
  928.    NARGS.  The type of the 'this' object is returned as the first element of
  929.    array.  */

  931. struct type **
  932. ‌get_xmethod_arg_types (struct xmethod_worker *worker, int *nargs)
  933. {
  934.   enum ext_lang_rc rc;
  935.   struct type **type_array = NULL;
  936.   const struct extension_language_defn *extlang = worker->extlang;

  938.   gdb_assert (extlang->ops->get_xmethod_arg_types != NULL);

  940.   rc = extlang->ops->get_xmethod_arg_types (extlang, worker, nargs,
  941.                                             &type_array);
  942.   if (rc == EXT_LANG_RC_ERROR)
  943.     {
  944.       error (_("Error while looking for arg types of a xmethod worker "
  945.                "defined in %s."), extlang->capitalized_name);
  946.     }

  948.   return type_array;
  949. }

  951. /* Invokes the xmethod encapsulated in WORKER and returns the result.
  952.    The method is invoked on OBJ with arguments in the ARGS array.  NARGS is
  953.    the length of the this array.  */

  955. struct value *
  956. ‌invoke_xmethod (struct xmethod_worker *worker, struct value *obj,
  957.                      struct value **args, int nargs)
  958. {
  959.   gdb_assert (worker->extlang->ops->invoke_xmethod != NULL);

  961.   return worker->extlang->ops->invoke_xmethod (worker->extlang, worker,
  962.                                                obj, args, nargs);
  963. }

  965. /* Frees the xmethod worker WORKER.  */

  967. void
  968. ‌free_xmethod_worker (struct xmethod_worker *worker)
  969. {
  970.   gdb_assert (worker->extlang->ops->free_xmethod_worker_data != NULL);
  971.   worker->extlang->ops->free_xmethod_worker_data (worker->extlang,
  972.                                                   worker->data);
  973.   xfree (worker);
  974. }

  976. /* Frees a vector of xmethod_workers VEC.  */

  978. void
  979. ‌free_xmethod_worker_vec (void *vec)
  980. {
  981.   int i;
  982.   struct xmethod_worker *worker;
  983.   VEC (xmethod_worker_ptr) *v = (VEC (xmethod_worker_ptr) *) vec;

  985.   for (i = 0; VEC_iterate (xmethod_worker_ptr, v, i, worker); i++)
  986.     free_xmethod_worker (worker);

  988.   VEC_free (xmethod_worker_ptr, v);
  989. }

  991. /* Called via an observer before gdb prints its prompt.
  992.    Iterate over the extension languages giving them a chance to
  993.    change the prompt.  The first one to change the prompt wins,
  994.    and no further languages are tried.  */

  996. static void
  997. ‌ext_lang_before_prompt (const char *current_gdb_prompt)
  998. {
  999.   int i;
  1000.   const struct extension_language_defn *extlang;

  1002.   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
  1003.     {
  1004.       enum ext_lang_rc rc;

  1006.       if (extlang->ops->before_prompt == NULL)
  1007.         continue;
  1008.       rc = extlang->ops->before_prompt (extlang, current_gdb_prompt);
  1009.       switch (rc)
  1010.         {
  1011.         case EXT_LANG_RC_OK:
  1012.         case EXT_LANG_RC_ERROR:
  1013.           return;
  1014.         case EXT_LANG_RC_NOP:
  1015.           break;
  1016.         default:
  1017.           gdb_assert_not_reached ("bad return from before_prompt");
  1018.         }
  1019.     }
  1020. }

  1022. extern initialize_file_ftype _initialize_extension;

  1024. void
  1025. ‌_initialize_extension (void)
  1026. {
  1027.   observer_attach_before_prompt (ext_lang_before_prompt);
  1028. }