gdb/extension.h

   1 /* Interface between gdb and its extension languages.
   2
   3    Copyright (C) 2014-2020 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 EXTENSION_H
  21 #define EXTENSION_H
  22
  23 #include "mi/mi-cmds.h" /* For PRINT_NO_VALUES, etc.  */
  24 #include "gdbsupport/array-view.h"
  25
  26 struct breakpoint;
  27 struct command_line;
  28 struct frame_info;
  29 struct language_defn;
  30 struct objfile;
  31 struct extension_language_defn;
  32 struct type;
  33 struct ui_file;
  34 struct ui_out;
  35 struct value;
  36 struct value_print_options;
  37
  38 /* A function to load and process a script file.
  39    The file has been opened and is ready to be read from the beginning.
  40    Any exceptions are not caught, and are passed to the caller.  */
  41 typedef void script_sourcer_func (const struct extension_language_defn *,
  42                                   FILE *stream, const char *filename);
  43
  44 /* A function to load and process a script for an objfile.
  45    The file has been opened and is ready to be read from the beginning.
  46    Any exceptions are not caught, and are passed to the caller.  */
  47 typedef void objfile_script_sourcer_func
  48   (const struct extension_language_defn *,
  49    struct objfile *, FILE *stream, const char *filename);
  50
  51 /* A function to execute a script for an objfile.
  52    Any exceptions are not caught, and are passed to the caller.  */
  53 typedef void objfile_script_executor_func
  54   (const struct extension_language_defn *,
  55    struct objfile *, const char *name, const char *script);
  56
  57 /* Enum of each extension(/scripting) language.  */
  58
  59 enum extension_language
  60   {
  61     EXT_LANG_NONE,
  62     EXT_LANG_GDB,
  63     EXT_LANG_PYTHON,
  64     EXT_LANG_GUILE
  65   };
  66
  67 /* Extension language frame-filter status return values.  */
  68
  69 enum ext_lang_bt_status
  70   {
  71     /* Return when an error has occurred in processing frame filters,
  72        or when printing the stack.  */
  73     EXT_LANG_BT_ERROR = -1,
  74
  75     /* Return from internal routines to indicate that the function
  76        succeeded.  */
  77     EXT_LANG_BT_OK = 1,
  78
  79     /* Return when the frame filter process is complete, but there
  80        were no filter registered and enabled to process.  */
  81     EXT_LANG_BT_NO_FILTERS = 2
  82   };
  83
  84 /* Flags to pass to apply_extlang_frame_filter.  */
  85
  86 enum frame_filter_flag
  87   {
  88     /* Set this flag if frame level is to be printed.  */
  89     PRINT_LEVEL = 1 << 0,
  90
  91     /* Set this flag if frame information is to be printed.  */
  92     PRINT_FRAME_INFO = 1 << 1,
  93
  94     /* Set this flag if frame arguments are to be printed.  */
  95     PRINT_ARGS = 1 << 2,
  96
  97     /* Set this flag if frame locals are to be printed.  */
  98     PRINT_LOCALS = 1 << 3,
  99
 100     /* Set this flag if a "More frames" message is to be printed.  */
 101     PRINT_MORE_FRAMES = 1 << 4,
 102
 103     /* Set this flag if elided frames should not be printed.  */
 104     PRINT_HIDE = 1 << 5,
 105   };
 106
 107 DEF_ENUM_FLAGS_TYPE (enum frame_filter_flag, frame_filter_flags);
 108
 109 /* A choice of the different frame argument printing strategies that
 110    can occur in different cases of frame filter instantiation.  */
 111
 112 enum ext_lang_frame_args
 113   {
 114     /* Print no values for arguments when invoked from the MI. */
 115     NO_VALUES = PRINT_NO_VALUES,
 116
 117     MI_PRINT_ALL_VALUES = PRINT_ALL_VALUES,
 118
 119     /* Print only simple values (what MI defines as "simple") for
 120        arguments when invoked from the MI. */
 121     MI_PRINT_SIMPLE_VALUES = PRINT_SIMPLE_VALUES,
 122
 123     /* Print only scalar values for arguments when invoked from the CLI. */
 124     CLI_SCALAR_VALUES,
 125
 126     /* Print all values for arguments when invoked from the CLI. */
 127     CLI_ALL_VALUES,
 128
 129     /* Only indicate the presence of arguments when invoked from the CLI.  */
 130     CLI_PRESENCE
 131   };
 132
 133 /* The possible results of
 134    extension_language_ops.breakpoint_cond_says_stop.  */
 135
 136 enum ext_lang_bp_stop
 137   {
 138     /* No "stop" condition is set.  */
 139     EXT_LANG_BP_STOP_UNSET,
 140
 141     /* A "stop" condition is set, and it says "don't stop".  */
 142     EXT_LANG_BP_STOP_NO,
 143
 144     /* A "stop" condition is set, and it says "stop".  */
 145     EXT_LANG_BP_STOP_YES
 146   };
 147
 148 /* Table of type printers associated with the global typedef table.  */
 149
 150 struct ext_lang_type_printers
 151 {
 152   ext_lang_type_printers ();
 153   ~ext_lang_type_printers ();
 154
 155   DISABLE_COPY_AND_ASSIGN (ext_lang_type_printers);
 156
 157   /* Type-printers from Python.  */
 158   void *py_type_printers = nullptr;
 159 };
 160
 161 /* The return code for some API calls.  */
 162
 163 enum ext_lang_rc
 164 {
 165   /* The operation completed successfully.  */
 166   EXT_LANG_RC_OK,
 167
 168   /* The operation was not performed (e.g., no pretty-printer).  */
 169   EXT_LANG_RC_NOP,
 170
 171   /* There was an error (e.g., Python error while printing a value).
 172      When an error occurs no further extension languages are tried.
 173      This is to preserve existing behaviour, and because it's convenient
 174      for Python developers.
 175      Note: This is different than encountering a memory error trying to read
 176      a value for pretty-printing.  Here we're referring to, e.g., programming
 177      errors that trigger an exception in the extension language.  */
 178   EXT_LANG_RC_ERROR
 179 };
 180
 181 /* A type which holds its extension language specific xmethod worker data.  */
 182
 183 struct xmethod_worker
 184 {
 185   xmethod_worker (const extension_language_defn *extlang)
 186   : m_extlang (extlang)
 187   {}
 188
 189   virtual ~xmethod_worker () = default;
 190
 191   /* Invoke the xmethod encapsulated in this worker and return the result.
 192      The method is invoked on OBJ with arguments in the ARGS array.  */
 193
 194   virtual value *invoke (value *obj, gdb::array_view<value *> args) = 0;
 195
 196   /* Return the arg types of the xmethod encapsulated in this worker.
 197      The type of the 'this' object is returned as the first element of
 198      the vector.  */
 199
 200   std::vector<type *> get_arg_types ();
 201
 202   /* Return the type of the result of the xmethod encapsulated in this worker.
 203      OBJECT and ARGS are the same as for invoke.  */
 204
 205   type *get_result_type (value *object, gdb::array_view<value *> args);
 206
 207 private:
 208
 209   /* Return the types of the arguments the method takes.  The types
 210      are returned in TYPE_ARGS, one per argument.  */
 211
 212   virtual enum ext_lang_rc do_get_arg_types
 213     (std::vector<type *> *type_args) = 0;
 214
 215   /* Fetch the type of the result of the method implemented by this
 216      worker.  OBJECT and ARGS are the same as for the invoked method.
 217      The result type is stored in *RESULT_TYPE.  */
 218
 219   virtual enum ext_lang_rc do_get_result_type
 220     (struct value *obj, gdb::array_view<value *> args,
 221      struct type **result_type_ptr) = 0;
 222
 223   /* The language the xmethod worker is implemented in.  */
 224
 225   const extension_language_defn *m_extlang;
 226 };
 227
 228 typedef std::unique_ptr<xmethod_worker> xmethod_worker_up;
 229
 230 /* The interface for gdb's own extension(/scripting) language.  */
 231 extern const struct extension_language_defn extension_language_gdb;
 232
 233 extern const struct extension_language_defn *get_ext_lang_defn
 234   (enum extension_language lang);
 235
 236 extern const struct extension_language_defn *get_ext_lang_of_file
 237   (const char *file);
 238
 239 extern int ext_lang_present_p (const struct extension_language_defn *);
 240
 241 extern int ext_lang_initialized_p (const struct extension_language_defn *);
 242
 243 extern void throw_ext_lang_unsupported
 244   (const struct extension_language_defn *);
 245
 246 /* Accessors for "public" attributes of the extension language definition.  */
 247
 248 extern enum extension_language ext_lang_kind
 249   (const struct extension_language_defn *);
 250
 251 extern const char *ext_lang_name (const struct extension_language_defn *);
 252
 253 extern const char *ext_lang_capitalized_name
 254   (const struct extension_language_defn *);
 255
 256 extern const char *ext_lang_suffix (const struct extension_language_defn *);
 257
 258 extern const char *ext_lang_auto_load_suffix
 259   (const struct extension_language_defn *);
 260
 261 extern script_sourcer_func *ext_lang_script_sourcer
 262   (const struct extension_language_defn *);
 263
 264 extern objfile_script_sourcer_func *ext_lang_objfile_script_sourcer
 265   (const struct extension_language_defn *);
 266
 267 extern objfile_script_executor_func *ext_lang_objfile_script_executor
 268   (const struct extension_language_defn *);
 269
 270 extern int ext_lang_auto_load_enabled (const struct extension_language_defn *);
 271
 272 /* Wrappers for each extension language API function that iterate over all
 273    extension languages.  */
 274
 275 extern void finish_ext_lang_initialization (void);
 276
 277 extern void eval_ext_lang_from_control_command (struct command_line *cmd);
 278
 279 extern void auto_load_ext_lang_scripts_for_objfile (struct objfile *);
 280
 281 extern char *apply_ext_lang_type_printers (struct ext_lang_type_printers *,
 282                                            struct type *);
 283
 284 extern int apply_ext_lang_val_pretty_printer
 285   (struct type *type,
 286    LONGEST embedded_offset, CORE_ADDR address,
 287    struct ui_file *stream, int recurse,
 288    struct value *val, const struct value_print_options *options,
 289    const struct language_defn *language);
 290
 291 extern enum ext_lang_bt_status apply_ext_lang_frame_filter
 292   (struct frame_info *frame, frame_filter_flags flags,
 293    enum ext_lang_frame_args args_type,
 294    struct ui_out *out, int frame_low, int frame_high);
 295
 296 extern void preserve_ext_lang_values (struct objfile *, htab_t copied_types);
 297
 298 extern const struct extension_language_defn *get_breakpoint_cond_ext_lang
 299   (struct breakpoint *b, enum extension_language skip_lang);
 300
 301 extern int breakpoint_ext_lang_cond_says_stop (struct breakpoint *);
 302
 303 /* If a method with name METHOD_NAME is to be invoked on an object of type
 304    TYPE, then all extension languages are searched for implementations of
 305    methods with name METHOD_NAME.  All matches found are appended to the WORKERS
 306    vector.  */
 307
 308 extern void get_matching_xmethod_workers
 309   (struct type *type, const char *method_name,
 310    std::vector<xmethod_worker_up> *workers);
 311
 312 #endif /* EXTENSION_H */