gdb/extension-priv.h

   1 /* Private implementation details of interface between gdb and its
   2    extension languages.
   3
   4    Copyright (C) 2014-2018 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   int (*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 at the end of gdb initialization to give the extension language
 113      an opportunity to finish up.  This is useful for things like adding
 114      new commands where one has to wait until gdb itself is initialized.  */
 115   void (*finish_initialization) (const struct extension_language_defn *);
 116
 117   /* Return non-zero if the extension language successfully initialized.
 118      This method is required.  */
 119   int (*initialized) (const struct extension_language_defn *);
 120
 121   /* Process a sequence of commands embedded in GDB's own scripting language.
 122      E.g.,
 123      python
 124      print 42
 125      end  */
 126   void (*eval_from_control_command) (const struct extension_language_defn *,
 127                                      struct command_line *);
 128
 129   /* Type-printing support:
 130      start_type_printers, apply_type_printers, free_type_printers.
 131      These methods are optional and may be NULL, but if one of them is
 132      implemented then they all must be.  */
 133
 134   /* Called before printing a type.  */
 135   void (*start_type_printers) (const struct extension_language_defn *,
 136                                struct ext_lang_type_printers *);
 137
 138   /* Try to pretty-print TYPE.  If successful the pretty-printed type is
 139      stored in *PRETTIED_TYPE, and the caller must free it.
 140      Returns EXT_LANG_RC_OK upon success, EXT_LANG_RC_NOP if the type
 141      is not recognized, and EXT_LANG_RC_ERROR if an error was encountered.
 142      This function has a bit of a funny name, since it actually applies
 143      recognizers, but this seemed clearer given the start_type_printers
 144      and free_type_printers functions.  */
 145   enum ext_lang_rc (*apply_type_printers)
 146     (const struct extension_language_defn *,
 147      const struct ext_lang_type_printers *,
 148      struct type *, char **prettied_type);
 149
 150   /* Called after a type has been printed to give the type pretty-printer
 151      mechanism an opportunity to clean up.  */
 152   void (*free_type_printers) (const struct extension_language_defn *,
 153                               struct ext_lang_type_printers *);
 154
 155   /* Try to pretty-print a value of type TYPE located at VAL's contents
 156      buffer + EMBEDDED_OFFSET, which came from the inferior at address
 157      ADDRESS + EMBEDDED_OFFSET, onto stdio stream STREAM according to
 158      OPTIONS.
 159      VAL is the whole object that came from ADDRESS.
 160      Returns EXT_LANG_RC_OK upon success, EXT_LANG_RC_NOP if the value
 161      is not recognized, and EXT_LANG_RC_ERROR if an error was encountered.  */
 162   enum ext_lang_rc (*apply_val_pretty_printer)
 163     (const struct extension_language_defn *,
 164      struct type *type,
 165      LONGEST embedded_offset, CORE_ADDR address,
 166      struct ui_file *stream, int recurse,
 167      struct value *val, const struct value_print_options *options,
 168      const struct language_defn *language);
 169
 170   /* GDB access to the "frame filter" feature.
 171      FRAME is the source frame to start frame-filter invocation.  FLAGS is an
 172      integer holding the flags for printing.  The following elements of
 173      the FRAME_FILTER_FLAGS enum denotes the make-up of FLAGS:
 174      PRINT_LEVEL is a flag indicating whether to print the frame's
 175      relative level in the output.  PRINT_FRAME_INFO is a flag that
 176      indicates whether this function should print the frame
 177      information, PRINT_ARGS is a flag that indicates whether to print
 178      frame arguments, and PRINT_LOCALS, likewise, with frame local
 179      variables.  ARGS_TYPE is an enumerator describing the argument
 180      format, OUT is the output stream to print.  FRAME_LOW is the
 181      beginning of the slice of frames to print, and FRAME_HIGH is the
 182      upper limit of the frames to count.  Returns SCR_BT_ERROR on error,
 183      or SCR_BT_COMPLETED on success.  */
 184   enum ext_lang_bt_status (*apply_frame_filter)
 185     (const struct extension_language_defn *,
 186      struct frame_info *frame, frame_filter_flags flags,
 187      enum ext_lang_frame_args args_type,
 188      struct ui_out *out, int frame_low, int frame_high);
 189
 190   /* Update values held by the extension language when OBJFILE is discarded.
 191      New global types must be created for every such value, which must then be
 192      updated to use the new types.
 193      This function typically just iterates over all appropriate values and
 194      calls preserve_one_value for each one.
 195      COPIED_TYPES is used to prevent cycles / duplicates and is passed to
 196      preserve_one_value.  */
 197   void (*preserve_values) (const struct extension_language_defn *,
 198                            struct objfile *objfile, htab_t copied_types);
 199
 200   /* Return non-zero if there is a stop condition for the breakpoint.
 201      This is used to implement the restriction that a breakpoint may have
 202      at most one condition.  */
 203   int (*breakpoint_has_cond) (const struct extension_language_defn *,
 204                               struct breakpoint *);
 205
 206   /* Return a value of enum ext_lang_bp_stop indicating if there is a stop
 207      condition for the breakpoint, and if so whether the program should
 208      stop.  This is called when the program has stopped at the specified
 209      breakpoint.
 210      While breakpoints can have at most one condition, this is called for
 211      every extension language, even if another extension language has a
 212      "stop" method: other kinds of breakpoints may be implemented using
 213      this method, e.g., "finish breakpoints" in Python.  */
 214   enum ext_lang_bp_stop (*breakpoint_cond_says_stop)
 215     (const struct extension_language_defn *, struct breakpoint *);
 216
 217   /* The next two are used to connect GDB's SIGINT handling with the
 218      extension language's.
 219
 220      Terminology: If an extension language can use GDB's SIGINT handling then
 221      we say the extension language has "cooperative SIGINT handling".
 222      Python is an example of this.
 223
 224      These need not be implemented, but if one of them is implemented
 225      then they all must be.  */
 226
 227   /* Set the SIGINT indicator.
 228      This is called by GDB's SIGINT handler and must be async-safe.  */
 229   void (*set_quit_flag) (const struct extension_language_defn *);
 230
 231   /* Return non-zero if a SIGINT has occurred.
 232      This is expected to also clear the indicator.  */
 233   int (*check_quit_flag) (const struct extension_language_defn *);
 234
 235   /* Called before gdb prints its prompt, giving extension languages an
 236      opportunity to change it with set_prompt.
 237      Returns EXT_LANG_RC_OK if the prompt was changed, EXT_LANG_RC_NOP if
 238      the prompt was not changed, and EXT_LANG_RC_ERROR if an error was
 239      encountered.
 240      Extension languages are called in order, and once the prompt is
 241      changed or an error occurs no further languages are called.  */
 242   enum ext_lang_rc (*before_prompt) (const struct extension_language_defn *,
 243                                      const char *current_gdb_prompt);
 244
 245   /* Return a vector of matching xmethod workers defined in this
 246      extension language.  The workers service methods with name
 247      METHOD_NAME on objects of type OBJ_TYPE.  The vector is returned
 248      in DM_VEC.
 249
 250      This field may be NULL if the extension language does not support
 251      xmethods.  */
 252   enum ext_lang_rc (*get_matching_xmethod_workers)
 253     (const struct extension_language_defn *extlang,
 254      struct type *obj_type,
 255      const char *method_name,
 256      std::vector<xmethod_worker_up> *dm_vec);
 257 };
 258
 259 /* State necessary to restore a signal handler to its previous value.  */
 260
 261 struct signal_handler
 262 {
 263   /* Non-zero if "handler" has been set.  */
 264   int handler_saved;
 265
 266   /* The signal handler.  */
 267   sighandler_t handler;
 268 };
 269
 270 /* State necessary to restore the currently active extension language
 271    to its previous value.  */
 272
 273 struct active_ext_lang_state
 274 {
 275   /* The previously active extension language.  */
 276   const struct extension_language_defn *ext_lang;
 277
 278   /* Its SIGINT handler.  */
 279   struct signal_handler sigint_handler;
 280 };
 281
 282 extern const struct extension_language_defn *get_active_ext_lang (void);
 283
 284 extern struct active_ext_lang_state *set_active_ext_lang
 285   (const struct extension_language_defn *);
 286
 287 extern void restore_active_ext_lang (struct active_ext_lang_state *previous);
 288
 289 #endif /* EXTENSION_PRIV_H */