gdb/python/py-symbol.c

   1 /* Python interface to symbols.
   2
   3    Copyright (C) 2008-2015 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 #include "defs.h"
  21 #include "block.h"
  22 #include "frame.h"
  23 #include "symtab.h"
  24 #include "python-internal.h"
  25 #include "objfiles.h"
  26
  27 typedef struct sympy_symbol_object {
  28   PyObject_HEAD
  29   /* The GDB symbol structure this object is wrapping.  */
  30   struct symbol *symbol;
  31   /* A symbol object is associated with an objfile, so keep track with
  32      doubly-linked list, rooted in the objfile.  This lets us
  33      invalidate the underlying struct symbol when the objfile is
  34      deleted.  */
  35   struct sympy_symbol_object *prev;
  36   struct sympy_symbol_object *next;
  37 } symbol_object;
  38
  39 /* Require a valid symbol.  All access to symbol_object->symbol should be
  40    gated by this call.  */
  41 #define SYMPY_REQUIRE_VALID(symbol_obj, symbol)         \
  42   do {                                                  \
  43     symbol = symbol_object_to_symbol (symbol_obj);      \
  44     if (symbol == NULL)                                 \
  45       {                                                 \
  46         PyErr_SetString (PyExc_RuntimeError,            \
  47                          _("Symbol is invalid."));      \
  48         return NULL;                                    \
  49       }                                                 \
  50   } while (0)
  51
  52 static const struct objfile_data *sympy_objfile_data_key;
  53
  54 static PyObject *
  55 sympy_str (PyObject *self)
  56 {
  57   PyObject *result;
  58   struct symbol *symbol = NULL;
  59
  60   SYMPY_REQUIRE_VALID (self, symbol);
  61
  62   result = PyString_FromString (SYMBOL_PRINT_NAME (symbol));
  63
  64   return result;
  65 }
  66
  67 static PyObject *
  68 sympy_get_type (PyObject *self, void *closure)
  69 {
  70   struct symbol *symbol = NULL;
  71
  72   SYMPY_REQUIRE_VALID (self, symbol);
  73
  74   if (SYMBOL_TYPE (symbol) == NULL)
  75     {
  76       Py_INCREF (Py_None);
  77       return Py_None;
  78     }
  79
  80   return type_to_type_object (SYMBOL_TYPE (symbol));
  81 }
  82
  83 static PyObject *
  84 sympy_get_symtab (PyObject *self, void *closure)
  85 {
  86   struct symbol *symbol = NULL;
  87
  88   SYMPY_REQUIRE_VALID (self, symbol);
  89
  90   if (!SYMBOL_OBJFILE_OWNED (symbol))
  91     Py_RETURN_NONE;
  92
  93   return symtab_to_symtab_object (symbol_symtab (symbol));
  94 }
  95
  96 static PyObject *
  97 sympy_get_name (PyObject *self, void *closure)
  98 {
  99   struct symbol *symbol = NULL;
 100
 101   SYMPY_REQUIRE_VALID (self, symbol);
 102
 103   return PyString_FromString (SYMBOL_NATURAL_NAME (symbol));
 104 }
 105
 106 static PyObject *
 107 sympy_get_linkage_name (PyObject *self, void *closure)
 108 {
 109   struct symbol *symbol = NULL;
 110
 111   SYMPY_REQUIRE_VALID (self, symbol);
 112
 113   return PyString_FromString (SYMBOL_LINKAGE_NAME (symbol));
 114 }
 115
 116 static PyObject *
 117 sympy_get_print_name (PyObject *self, void *closure)
 118 {
 119   struct symbol *symbol = NULL;
 120
 121   SYMPY_REQUIRE_VALID (self, symbol);
 122
 123   return sympy_str (self);
 124 }
 125
 126 static PyObject *
 127 sympy_get_addr_class (PyObject *self, void *closure)
 128 {
 129   struct symbol *symbol = NULL;
 130
 131   SYMPY_REQUIRE_VALID (self, symbol);
 132
 133   return PyInt_FromLong (SYMBOL_CLASS (symbol));
 134 }
 135
 136 static PyObject *
 137 sympy_is_argument (PyObject *self, void *closure)
 138 {
 139   struct symbol *symbol = NULL;
 140
 141   SYMPY_REQUIRE_VALID (self, symbol);
 142
 143   return PyBool_FromLong (SYMBOL_IS_ARGUMENT (symbol));
 144 }
 145
 146 static PyObject *
 147 sympy_is_constant (PyObject *self, void *closure)
 148 {
 149   struct symbol *symbol = NULL;
 150   enum address_class theclass;
 151
 152   SYMPY_REQUIRE_VALID (self, symbol);
 153
 154   theclass = SYMBOL_CLASS (symbol);
 155
 156   return PyBool_FromLong (theclass == LOC_CONST || theclass == LOC_CONST_BYTES);
 157 }
 158
 159 static PyObject *
 160 sympy_is_function (PyObject *self, void *closure)
 161 {
 162   struct symbol *symbol = NULL;
 163   enum address_class theclass;
 164
 165   SYMPY_REQUIRE_VALID (self, symbol);
 166
 167   theclass = SYMBOL_CLASS (symbol);
 168
 169   return PyBool_FromLong (theclass == LOC_BLOCK);
 170 }
 171
 172 static PyObject *
 173 sympy_is_variable (PyObject *self, void *closure)
 174 {
 175   struct symbol *symbol = NULL;
 176   enum address_class theclass;
 177
 178   SYMPY_REQUIRE_VALID (self, symbol);
 179
 180   theclass = SYMBOL_CLASS (symbol);
 181
 182   return PyBool_FromLong (!SYMBOL_IS_ARGUMENT (symbol)
 183                           && (theclass == LOC_LOCAL || theclass == LOC_REGISTER
 184                               || theclass == LOC_STATIC || theclass == LOC_COMPUTED
 185                               || theclass == LOC_OPTIMIZED_OUT));
 186 }
 187
 188 /* Implementation of gdb.Symbol.needs_frame -> Boolean.
 189    Returns true iff the symbol needs a frame for evaluation.  */
 190
 191 static PyObject *
 192 sympy_needs_frame (PyObject *self, void *closure)
 193 {
 194   struct symbol *symbol = NULL;
 195   int result = 0;
 196
 197   SYMPY_REQUIRE_VALID (self, symbol);
 198
 199   TRY
 200     {
 201       result = symbol_read_needs_frame (symbol);
 202     }
 203   CATCH (except, RETURN_MASK_ALL)
 204     {
 205       GDB_PY_HANDLE_EXCEPTION (except);
 206     }
 207   END_CATCH
 208
 209   if (result)
 210     Py_RETURN_TRUE;
 211   Py_RETURN_FALSE;
 212 }
 213
 214 /* Implementation of gdb.Symbol.line -> int.
 215    Returns the line number at which the symbol was defined.  */
 216
 217 static PyObject *
 218 sympy_line (PyObject *self, void *closure)
 219 {
 220   struct symbol *symbol = NULL;
 221
 222   SYMPY_REQUIRE_VALID (self, symbol);
 223
 224   return PyInt_FromLong (SYMBOL_LINE (symbol));
 225 }
 226
 227 /* Implementation of gdb.Symbol.is_valid (self) -> Boolean.
 228    Returns True if this Symbol still exists in GDB.  */
 229
 230 static PyObject *
 231 sympy_is_valid (PyObject *self, PyObject *args)
 232 {
 233   struct symbol *symbol = NULL;
 234
 235   symbol = symbol_object_to_symbol (self);
 236   if (symbol == NULL)
 237     Py_RETURN_FALSE;
 238
 239   Py_RETURN_TRUE;
 240 }
 241
 242 /* Implementation of gdb.Symbol.value (self[, frame]) -> gdb.Value.  Returns
 243    the value of the symbol, or an error in various circumstances.  */
 244
 245 static PyObject *
 246 sympy_value (PyObject *self, PyObject *args)
 247 {
 248   struct symbol *symbol = NULL;
 249   struct frame_info *frame_info = NULL;
 250   PyObject *frame_obj = NULL;
 251   struct value *value = NULL;
 252
 253   if (!PyArg_ParseTuple (args, "|O", &frame_obj))
 254     return NULL;
 255
 256   if (frame_obj != NULL && !PyObject_TypeCheck (frame_obj, &frame_object_type))
 257     {
 258       PyErr_SetString (PyExc_TypeError, "argument is not a frame");
 259       return NULL;
 260     }
 261
 262   SYMPY_REQUIRE_VALID (self, symbol);
 263   if (SYMBOL_CLASS (symbol) == LOC_TYPEDEF)
 264     {
 265       PyErr_SetString (PyExc_TypeError, "cannot get the value of a typedef");
 266       return NULL;
 267     }
 268
 269   TRY
 270     {
 271       if (frame_obj != NULL)
 272         {
 273           frame_info = frame_object_to_frame_info (frame_obj);
 274           if (frame_info == NULL)
 275             error (_("invalid frame"));
 276         }
 277
 278       if (symbol_read_needs_frame (symbol) && frame_info == NULL)
 279         error (_("symbol requires a frame to compute its value"));
 280
 281       /* TODO: currently, we have no way to recover the block in which SYMBOL
 282          was found, so we have no block to pass to read_var_value.  This will
 283          yield an incorrect value when symbol is not local to FRAME_INFO (this
 284          can happen with nested functions).  */
 285       value = read_var_value (symbol, NULL, frame_info);
 286     }
 287   CATCH (except, RETURN_MASK_ALL)
 288     {
 289       GDB_PY_HANDLE_EXCEPTION (except);
 290     }
 291   END_CATCH
 292
 293   return value_to_value_object (value);
 294 }
 295
 296 /* Given a symbol, and a symbol_object that has previously been
 297    allocated and initialized, populate the symbol_object with the
 298    struct symbol data.  Also, register the symbol_object life-cycle
 299    with the life-cycle of the object file associated with this
 300    symbol, if needed.  */
 301 static void
 302 set_symbol (symbol_object *obj, struct symbol *symbol)
 303 {
 304   obj->symbol = symbol;
 305   obj->prev = NULL;
 306   if (SYMBOL_OBJFILE_OWNED (symbol)
 307       && symbol_symtab (symbol) != NULL)
 308     {
 309       struct objfile *objfile = symbol_objfile (symbol);
 310
 311       obj->next = objfile_data (objfile, sympy_objfile_data_key);
 312       if (obj->next)
 313         obj->next->prev = obj;
 314       set_objfile_data (objfile, sympy_objfile_data_key, obj);
 315     }
 316   else
 317     obj->next = NULL;
 318 }
 319
 320 /* Create a new symbol object (gdb.Symbol) that encapsulates the struct
 321    symbol object from GDB.  */
 322 PyObject *
 323 symbol_to_symbol_object (struct symbol *sym)
 324 {
 325   symbol_object *sym_obj;
 326
 327   sym_obj = PyObject_New (symbol_object, &symbol_object_type);
 328   if (sym_obj)
 329     set_symbol (sym_obj, sym);
 330
 331   return (PyObject *) sym_obj;
 332 }
 333
 334 /* Return the symbol that is wrapped by this symbol object.  */
 335 struct symbol *
 336 symbol_object_to_symbol (PyObject *obj)
 337 {
 338   if (! PyObject_TypeCheck (obj, &symbol_object_type))
 339     return NULL;
 340   return ((symbol_object *) obj)->symbol;
 341 }
 342
 343 static void
 344 sympy_dealloc (PyObject *obj)
 345 {
 346   symbol_object *sym_obj = (symbol_object *) obj;
 347
 348   if (sym_obj->prev)
 349     sym_obj->prev->next = sym_obj->next;
 350   else if (sym_obj->symbol != NULL
 351            && SYMBOL_OBJFILE_OWNED (sym_obj->symbol)
 352            && symbol_symtab (sym_obj->symbol) != NULL)
 353     {
 354       set_objfile_data (symbol_objfile (sym_obj->symbol),
 355                         sympy_objfile_data_key, sym_obj->next);
 356     }
 357   if (sym_obj->next)
 358     sym_obj->next->prev = sym_obj->prev;
 359   sym_obj->symbol = NULL;
 360 }
 361
 362 /* Implementation of
 363    gdb.lookup_symbol (name [, block] [, domain]) -> (symbol, is_field_of_this)
 364    A tuple with 2 elements is always returned.  The first is the symbol
 365    object or None, the second is a boolean with the value of
 366    is_a_field_of_this (see comment in lookup_symbol_in_language).  */
 367
 368 PyObject *
 369 gdbpy_lookup_symbol (PyObject *self, PyObject *args, PyObject *kw)
 370 {
 371   int domain = VAR_DOMAIN;
 372   struct field_of_this_result is_a_field_of_this;
 373   const char *name;
 374   static char *keywords[] = { "name", "block", "domain", NULL };
 375   struct symbol *symbol = NULL;
 376   PyObject *block_obj = NULL, *ret_tuple, *sym_obj, *bool_obj;
 377   const struct block *block = NULL;
 378
 379   if (! PyArg_ParseTupleAndKeywords (args, kw, "s|O!i", keywords, &name,
 380                                      &block_object_type, &block_obj, &domain))
 381     return NULL;
 382
 383   if (block_obj)
 384     block = block_object_to_block (block_obj);
 385   else
 386     {
 387       struct frame_info *selected_frame;
 388
 389       TRY
 390         {
 391           selected_frame = get_selected_frame (_("No frame selected."));
 392           block = get_frame_block (selected_frame, NULL);
 393         }
 394       CATCH (except, RETURN_MASK_ALL)
 395         {
 396           GDB_PY_HANDLE_EXCEPTION (except);
 397         }
 398       END_CATCH
 399     }
 400
 401   TRY
 402     {
 403       symbol = lookup_symbol (name, block, (domain_enum) domain,
 404                               &is_a_field_of_this).symbol;
 405     }
 406   CATCH (except, RETURN_MASK_ALL)
 407     {
 408       GDB_PY_HANDLE_EXCEPTION (except);
 409     }
 410   END_CATCH
 411
 412   ret_tuple = PyTuple_New (2);
 413   if (!ret_tuple)
 414     return NULL;
 415
 416   if (symbol)
 417     {
 418       sym_obj = symbol_to_symbol_object (symbol);
 419       if (!sym_obj)
 420         {
 421           Py_DECREF (ret_tuple);
 422           return NULL;
 423         }
 424     }
 425   else
 426     {
 427       sym_obj = Py_None;
 428       Py_INCREF (Py_None);
 429     }
 430   PyTuple_SET_ITEM (ret_tuple, 0, sym_obj);
 431
 432   bool_obj = (is_a_field_of_this.type != NULL) ? Py_True : Py_False;
 433   Py_INCREF (bool_obj);
 434   PyTuple_SET_ITEM (ret_tuple, 1, bool_obj);
 435
 436   return ret_tuple;
 437 }
 438
 439 /* Implementation of
 440    gdb.lookup_global_symbol (name [, domain]) -> symbol or None.  */
 441
 442 PyObject *
 443 gdbpy_lookup_global_symbol (PyObject *self, PyObject *args, PyObject *kw)
 444 {
 445   int domain = VAR_DOMAIN;
 446   const char *name;
 447   static char *keywords[] = { "name", "domain", NULL };
 448   struct symbol *symbol = NULL;
 449   PyObject *sym_obj;
 450
 451   if (! PyArg_ParseTupleAndKeywords (args, kw, "s|i", keywords, &name,
 452                                      &domain))
 453     return NULL;
 454
 455   TRY
 456     {
 457       symbol = lookup_global_symbol (name, NULL, (domain_enum) domain).symbol;
 458     }
 459   CATCH (except, RETURN_MASK_ALL)
 460     {
 461       GDB_PY_HANDLE_EXCEPTION (except);
 462     }
 463   END_CATCH
 464
 465   if (symbol)
 466     {
 467       sym_obj = symbol_to_symbol_object (symbol);
 468       if (!sym_obj)
 469         return NULL;
 470     }
 471   else
 472     {
 473       sym_obj = Py_None;
 474       Py_INCREF (Py_None);
 475     }
 476
 477   return sym_obj;
 478 }
 479
 480 /* This function is called when an objfile is about to be freed.
 481    Invalidate the symbol as further actions on the symbol would result
 482    in bad data.  All access to obj->symbol should be gated by
 483    SYMPY_REQUIRE_VALID which will raise an exception on invalid
 484    symbols.  */
 485 static void
 486 del_objfile_symbols (struct objfile *objfile, void *datum)
 487 {
 488   symbol_object *obj = datum;
 489   while (obj)
 490     {
 491       symbol_object *next = obj->next;
 492
 493       obj->symbol = NULL;
 494       obj->next = NULL;
 495       obj->prev = NULL;
 496
 497       obj = next;
 498     }
 499 }
 500
 501 int
 502 gdbpy_initialize_symbols (void)
 503 {
 504   if (PyType_Ready (&symbol_object_type) < 0)
 505     return -1;
 506
 507   /* Register an objfile "free" callback so we can properly
 508      invalidate symbol when an object file that is about to be
 509      deleted.  */
 510   sympy_objfile_data_key
 511     = register_objfile_data_with_cleanup (NULL, del_objfile_symbols);
 512
 513   if (PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_UNDEF", LOC_UNDEF) < 0
 514       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_CONST",
 515                                   LOC_CONST) < 0
 516       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_STATIC",
 517                                   LOC_STATIC) < 0
 518       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_REGISTER",
 519                                   LOC_REGISTER) < 0
 520       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_ARG",
 521                                   LOC_ARG) < 0
 522       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_REF_ARG",
 523                                   LOC_REF_ARG) < 0
 524       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_LOCAL",
 525                                   LOC_LOCAL) < 0
 526       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_TYPEDEF",
 527                                   LOC_TYPEDEF) < 0
 528       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_LABEL",
 529                                   LOC_LABEL) < 0
 530       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_BLOCK",
 531                                   LOC_BLOCK) < 0
 532       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_CONST_BYTES",
 533                                   LOC_CONST_BYTES) < 0
 534       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_UNRESOLVED",
 535                                   LOC_UNRESOLVED) < 0
 536       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_OPTIMIZED_OUT",
 537                                   LOC_OPTIMIZED_OUT) < 0
 538       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_COMPUTED",
 539                                   LOC_COMPUTED) < 0
 540       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_REGPARM_ADDR",
 541                                   LOC_REGPARM_ADDR) < 0
 542       || PyModule_AddIntConstant (gdb_module, "SYMBOL_UNDEF_DOMAIN",
 543                                   UNDEF_DOMAIN) < 0
 544       || PyModule_AddIntConstant (gdb_module, "SYMBOL_VAR_DOMAIN",
 545                                   VAR_DOMAIN) < 0
 546       || PyModule_AddIntConstant (gdb_module, "SYMBOL_STRUCT_DOMAIN",
 547                                   STRUCT_DOMAIN) < 0
 548       || PyModule_AddIntConstant (gdb_module, "SYMBOL_LABEL_DOMAIN",
 549                                   LABEL_DOMAIN) < 0
 550       || PyModule_AddIntConstant (gdb_module, "SYMBOL_VARIABLES_DOMAIN",
 551                                   VARIABLES_DOMAIN) < 0
 552       || PyModule_AddIntConstant (gdb_module, "SYMBOL_FUNCTIONS_DOMAIN",
 553                                   FUNCTIONS_DOMAIN) < 0
 554       || PyModule_AddIntConstant (gdb_module, "SYMBOL_TYPES_DOMAIN",
 555                                   TYPES_DOMAIN) < 0)
 556     return -1;
 557
 558   return gdb_pymodule_addobject (gdb_module, "Symbol",
 559                                  (PyObject *) &symbol_object_type);
 560 }
 561
 562 \f
 563
 564 static PyGetSetDef symbol_object_getset[] = {
 565   { "type", sympy_get_type, NULL,
 566     "Type of the symbol.", NULL },
 567   { "symtab", sympy_get_symtab, NULL,
 568     "Symbol table in which the symbol appears.", NULL },
 569   { "name", sympy_get_name, NULL,
 570     "Name of the symbol, as it appears in the source code.", NULL },
 571   { "linkage_name", sympy_get_linkage_name, NULL,
 572     "Name of the symbol, as used by the linker (i.e., may be mangled).",
 573     NULL },
 574   { "print_name", sympy_get_print_name, NULL,
 575     "Name of the symbol in a form suitable for output.\n\
 576 This is either name or linkage_name, depending on whether the user asked GDB\n\
 577 to display demangled or mangled names.", NULL },
 578   { "addr_class", sympy_get_addr_class, NULL, "Address class of the symbol." },
 579   { "is_argument", sympy_is_argument, NULL,
 580     "True if the symbol is an argument of a function." },
 581   { "is_constant", sympy_is_constant, NULL,
 582     "True if the symbol is a constant." },
 583   { "is_function", sympy_is_function, NULL,
 584     "True if the symbol is a function or method." },
 585   { "is_variable", sympy_is_variable, NULL,
 586     "True if the symbol is a variable." },
 587   { "needs_frame", sympy_needs_frame, NULL,
 588     "True if the symbol requires a frame for evaluation." },
 589   { "line", sympy_line, NULL,
 590     "The source line number at which the symbol was defined." },
 591   { NULL }  /* Sentinel */
 592 };
 593
 594 static PyMethodDef symbol_object_methods[] = {
 595   { "is_valid", sympy_is_valid, METH_NOARGS,
 596     "is_valid () -> Boolean.\n\
 597 Return true if this symbol is valid, false if not." },
 598   { "value", sympy_value, METH_VARARGS,
 599     "value ([frame]) -> gdb.Value\n\
 600 Return the value of the symbol." },
 601   {NULL}  /* Sentinel */
 602 };
 603
 604 PyTypeObject symbol_object_type = {
 605   PyVarObject_HEAD_INIT (NULL, 0)
 606   "gdb.Symbol",                   /*tp_name*/
 607   sizeof (symbol_object),         /*tp_basicsize*/
 608   0,                              /*tp_itemsize*/
 609   sympy_dealloc,                  /*tp_dealloc*/
 610   0,                              /*tp_print*/
 611   0,                              /*tp_getattr*/
 612   0,                              /*tp_setattr*/
 613   0,                              /*tp_compare*/
 614   0,                              /*tp_repr*/
 615   0,                              /*tp_as_number*/
 616   0,                              /*tp_as_sequence*/
 617   0,                              /*tp_as_mapping*/
 618   0,                              /*tp_hash */
 619   0,                              /*tp_call*/
 620   sympy_str,                      /*tp_str*/
 621   0,                              /*tp_getattro*/
 622   0,                              /*tp_setattro*/
 623   0,                              /*tp_as_buffer*/
 624   Py_TPFLAGS_DEFAULT,             /*tp_flags*/
 625   "GDB symbol object",            /*tp_doc */
 626   0,                              /*tp_traverse */
 627   0,                              /*tp_clear */
 628   0,                              /*tp_richcompare */
 629   0,                              /*tp_weaklistoffset */
 630   0,                              /*tp_iter */
 631   0,                              /*tp_iternext */
 632   symbol_object_methods,          /*tp_methods */
 633   0,                              /*tp_members */
 634   symbol_object_getset            /*tp_getset */
 635 };