gdb/python/py-block.c

   1 /* Python interface to blocks.
   2
   3    Copyright (C) 2008-2018 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 "dictionary.h"
  23 #include "symtab.h"
  24 #include "python-internal.h"
  25 #include "objfiles.h"
  26 #include "symtab.h"
  27
  28 typedef struct blpy_block_object {
  29   PyObject_HEAD
  30   /* The GDB block structure that represents a frame's code block.  */
  31   const struct block *block;
  32   /* The backing object file.  There is no direct relationship in GDB
  33      between a block and an object file.  When a block is created also
  34      store a pointer to the object file for later use.  */
  35   struct objfile *objfile;
  36   /* Keep track of all blocks with a doubly-linked list.  Needed for
  37      block invalidation if the source object file has been freed.  */
  38   struct blpy_block_object *prev;
  39   struct blpy_block_object *next;
  40 } block_object;
  41
  42 typedef struct {
  43   PyObject_HEAD
  44   /* The block.  */
  45   const struct block *block;
  46   /* The iterator for that block.  */
  47   struct block_iterator iter;
  48   /* Has the iterator been initialized flag.  */
  49   int initialized_p;
  50   /* Pointer back to the original source block object.  Needed to
  51      check if the block is still valid, and has not been invalidated
  52      when an object file has been freed.  */
  53   struct blpy_block_object *source;
  54 } block_syms_iterator_object;
  55
  56 /* Require a valid block.  All access to block_object->block should be
  57    gated by this call.  */
  58 #define BLPY_REQUIRE_VALID(block_obj, block)            \
  59   do {                                                  \
  60     block = block_object_to_block (block_obj);          \
  61     if (block == NULL)                                  \
  62       {                                                 \
  63         PyErr_SetString (PyExc_RuntimeError,            \
  64                          _("Block is invalid."));       \
  65         return NULL;                                    \
  66       }                                                 \
  67   } while (0)
  68
  69 /* Require a valid block.  This macro is called during block iterator
  70    creation, and at each next call.  */
  71 #define BLPY_ITER_REQUIRE_VALID(block_obj)                              \
  72   do {                                                                  \
  73     if (block_obj->block == NULL)                                       \
  74       {                                                                 \
  75         PyErr_SetString (PyExc_RuntimeError,                            \
  76                          _("Source block for iterator is invalid."));   \
  77         return NULL;                                                    \
  78       }                                                                 \
  79   } while (0)
  80
  81 extern PyTypeObject block_syms_iterator_object_type
  82     CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("block_syms_iterator_object");
  83 static const struct objfile_data *blpy_objfile_data_key;
  84
  85 static PyObject *
  86 blpy_iter (PyObject *self)
  87 {
  88   block_syms_iterator_object *block_iter_obj;
  89   const struct block *block = NULL;
  90
  91   BLPY_REQUIRE_VALID (self, block);
  92
  93   block_iter_obj = PyObject_New (block_syms_iterator_object,
  94                                  &block_syms_iterator_object_type);
  95   if (block_iter_obj == NULL)
  96       return NULL;
  97
  98   block_iter_obj->block = block;
  99   block_iter_obj->initialized_p = 0;
 100   Py_INCREF (self);
 101   block_iter_obj->source = (block_object *) self;
 102
 103   return (PyObject *) block_iter_obj;
 104 }
 105
 106 static PyObject *
 107 blpy_get_start (PyObject *self, void *closure)
 108 {
 109   const struct block *block = NULL;
 110
 111   BLPY_REQUIRE_VALID (self, block);
 112
 113   return gdb_py_object_from_ulongest (BLOCK_START (block));
 114 }
 115
 116 static PyObject *
 117 blpy_get_end (PyObject *self, void *closure)
 118 {
 119   const struct block *block = NULL;
 120
 121   BLPY_REQUIRE_VALID (self, block);
 122
 123   return gdb_py_object_from_ulongest (BLOCK_END (block));
 124 }
 125
 126 static PyObject *
 127 blpy_get_function (PyObject *self, void *closure)
 128 {
 129   struct symbol *sym;
 130   const struct block *block;
 131
 132   BLPY_REQUIRE_VALID (self, block);
 133
 134   sym = BLOCK_FUNCTION (block);
 135   if (sym)
 136     return symbol_to_symbol_object (sym);
 137
 138   Py_RETURN_NONE;
 139 }
 140
 141 static PyObject *
 142 blpy_get_superblock (PyObject *self, void *closure)
 143 {
 144   const struct block *block;
 145   const struct block *super_block;
 146   block_object *self_obj  = (block_object *) self;
 147
 148   BLPY_REQUIRE_VALID (self, block);
 149
 150   super_block = BLOCK_SUPERBLOCK (block);
 151   if (super_block)
 152     return block_to_block_object (super_block, self_obj->objfile);
 153
 154   Py_RETURN_NONE;
 155 }
 156
 157 /* Return the global block associated to this block.  */
 158
 159 static PyObject *
 160 blpy_get_global_block (PyObject *self, void *closure)
 161 {
 162   const struct block *block;
 163   const struct block *global_block;
 164   block_object *self_obj  = (block_object *) self;
 165
 166   BLPY_REQUIRE_VALID (self, block);
 167
 168   global_block = block_global_block (block);
 169
 170   return block_to_block_object (global_block,
 171                                 self_obj->objfile);
 172
 173 }
 174
 175 /* Return the static block associated to this block.  Return None
 176    if we cannot get the static block (this is the global block).  */
 177
 178 static PyObject *
 179 blpy_get_static_block (PyObject *self, void *closure)
 180 {
 181   const struct block *block;
 182   const struct block *static_block;
 183   block_object *self_obj  = (block_object *) self;
 184
 185   BLPY_REQUIRE_VALID (self, block);
 186
 187   if (BLOCK_SUPERBLOCK (block) == NULL)
 188     Py_RETURN_NONE;
 189
 190   static_block = block_static_block (block);
 191
 192   return block_to_block_object (static_block, self_obj->objfile);
 193 }
 194
 195 /* Implementation of gdb.Block.is_global (self) -> Boolean.
 196    Returns True if this block object is a global block.  */
 197
 198 static PyObject *
 199 blpy_is_global (PyObject *self, void *closure)
 200 {
 201   const struct block *block;
 202
 203   BLPY_REQUIRE_VALID (self, block);
 204
 205   if (BLOCK_SUPERBLOCK (block))
 206     Py_RETURN_FALSE;
 207
 208   Py_RETURN_TRUE;
 209 }
 210
 211 /* Implementation of gdb.Block.is_static (self) -> Boolean.
 212    Returns True if this block object is a static block.  */
 213
 214 static PyObject *
 215 blpy_is_static (PyObject *self, void *closure)
 216 {
 217   const struct block *block;
 218
 219   BLPY_REQUIRE_VALID (self, block);
 220
 221   if (BLOCK_SUPERBLOCK (block) != NULL
 222      && BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) == NULL)
 223     Py_RETURN_TRUE;
 224
 225   Py_RETURN_FALSE;
 226 }
 227
 228 static void
 229 blpy_dealloc (PyObject *obj)
 230 {
 231   block_object *block = (block_object *) obj;
 232
 233   if (block->prev)
 234     block->prev->next = block->next;
 235   else if (block->objfile)
 236     {
 237       set_objfile_data (block->objfile, blpy_objfile_data_key,
 238                         block->next);
 239     }
 240   if (block->next)
 241     block->next->prev = block->prev;
 242   block->block = NULL;
 243 }
 244
 245 /* Given a block, and a block_object that has previously been
 246    allocated and initialized, populate the block_object with the
 247    struct block data.  Also, register the block_object life-cycle
 248    with the life-cycle of the object file associated with this
 249    block, if needed.  */
 250 static void
 251 set_block (block_object *obj, const struct block *block,
 252            struct objfile *objfile)
 253 {
 254   obj->block = block;
 255   obj->prev = NULL;
 256   if (objfile)
 257     {
 258       obj->objfile = objfile;
 259       obj->next = ((struct blpy_block_object *)
 260                    objfile_data (objfile, blpy_objfile_data_key));
 261       if (obj->next)
 262         obj->next->prev = obj;
 263       set_objfile_data (objfile, blpy_objfile_data_key, obj);
 264     }
 265   else
 266     obj->next = NULL;
 267 }
 268
 269 /* Create a new block object (gdb.Block) that encapsulates the struct
 270    block object from GDB.  */
 271 PyObject *
 272 block_to_block_object (const struct block *block, struct objfile *objfile)
 273 {
 274   block_object *block_obj;
 275
 276   block_obj = PyObject_New (block_object, &block_object_type);
 277   if (block_obj)
 278     set_block (block_obj, block, objfile);
 279
 280   return (PyObject *) block_obj;
 281 }
 282
 283 /* Return struct block reference that is wrapped by this object.  */
 284 const struct block *
 285 block_object_to_block (PyObject *obj)
 286 {
 287   if (! PyObject_TypeCheck (obj, &block_object_type))
 288     return NULL;
 289   return ((block_object *) obj)->block;
 290 }
 291
 292 /* Return a reference to the block iterator.  */
 293 static PyObject *
 294 blpy_block_syms_iter (PyObject *self)
 295 {
 296   block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) self;
 297
 298   BLPY_ITER_REQUIRE_VALID (iter_obj->source);
 299
 300   Py_INCREF (self);
 301   return self;
 302 }
 303
 304 /* Return the next symbol in the iteration through the block's
 305    dictionary.  */
 306 static PyObject *
 307 blpy_block_syms_iternext (PyObject *self)
 308 {
 309   block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) self;
 310   struct symbol *sym;
 311
 312   BLPY_ITER_REQUIRE_VALID (iter_obj->source);
 313
 314   if (!iter_obj->initialized_p)
 315     {
 316       sym = block_iterator_first (iter_obj->block,  &(iter_obj->iter));
 317       iter_obj->initialized_p = 1;
 318     }
 319   else
 320     sym = block_iterator_next (&(iter_obj->iter));
 321
 322   if (sym == NULL)
 323     {
 324       PyErr_SetString (PyExc_StopIteration, _("Symbol is null."));
 325       return NULL;
 326     }
 327
 328   return symbol_to_symbol_object (sym);
 329 }
 330
 331 static void
 332 blpy_block_syms_dealloc (PyObject *obj)
 333 {
 334   block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) obj;
 335
 336   Py_XDECREF (iter_obj->source);
 337 }
 338
 339 /* Implementation of gdb.Block.is_valid (self) -> Boolean.
 340    Returns True if this block object still exists in GDB.  */
 341
 342 static PyObject *
 343 blpy_is_valid (PyObject *self, PyObject *args)
 344 {
 345   const struct block *block;
 346
 347   block = block_object_to_block (self);
 348   if (block == NULL)
 349     Py_RETURN_FALSE;
 350
 351   Py_RETURN_TRUE;
 352 }
 353
 354 /* Implementation of gdb.BlockIterator.is_valid (self) -> Boolean.
 355    Returns True if this block iterator object still exists in GDB  */
 356
 357 static PyObject *
 358 blpy_iter_is_valid (PyObject *self, PyObject *args)
 359 {
 360   block_syms_iterator_object *iter_obj =
 361     (block_syms_iterator_object *) self;
 362
 363   if (iter_obj->source->block == NULL)
 364     Py_RETURN_FALSE;
 365
 366   Py_RETURN_TRUE;
 367 }
 368
 369 /* Return the innermost lexical block containing the specified pc value,
 370    or 0 if there is none.  */
 371 PyObject *
 372 gdbpy_block_for_pc (PyObject *self, PyObject *args)
 373 {
 374   gdb_py_ulongest pc;
 375   const struct block *block = NULL;
 376   struct compunit_symtab *cust = NULL;
 377
 378   if (!PyArg_ParseTuple (args, GDB_PY_LLU_ARG, &pc))
 379     return NULL;
 380
 381   TRY
 382     {
 383       cust = find_pc_compunit_symtab (pc);
 384
 385       if (cust != NULL && COMPUNIT_OBJFILE (cust) != NULL)
 386         block = block_for_pc (pc);
 387     }
 388   CATCH (except, RETURN_MASK_ALL)
 389     {
 390       GDB_PY_HANDLE_EXCEPTION (except);
 391     }
 392   END_CATCH
 393
 394   if (cust == NULL || COMPUNIT_OBJFILE (cust) == NULL)
 395     {
 396       PyErr_SetString (PyExc_RuntimeError,
 397                        _("Cannot locate object file for block."));
 398       return NULL;
 399     }
 400
 401   if (block)
 402     return block_to_block_object (block, COMPUNIT_OBJFILE (cust));
 403
 404   Py_RETURN_NONE;
 405 }
 406
 407 /* This function is called when an objfile is about to be freed.
 408    Invalidate the block as further actions on the block would result
 409    in bad data.  All access to obj->symbol should be gated by
 410    BLPY_REQUIRE_VALID which will raise an exception on invalid
 411    blocks.  */
 412 static void
 413 del_objfile_blocks (struct objfile *objfile, void *datum)
 414 {
 415   block_object *obj = (block_object *) datum;
 416
 417   while (obj)
 418     {
 419       block_object *next = obj->next;
 420
 421       obj->block = NULL;
 422       obj->objfile = NULL;
 423       obj->next = NULL;
 424       obj->prev = NULL;
 425
 426       obj = next;
 427     }
 428 }
 429
 430 int
 431 gdbpy_initialize_blocks (void)
 432 {
 433   block_object_type.tp_new = PyType_GenericNew;
 434   if (PyType_Ready (&block_object_type) < 0)
 435     return -1;
 436
 437   block_syms_iterator_object_type.tp_new = PyType_GenericNew;
 438   if (PyType_Ready (&block_syms_iterator_object_type) < 0)
 439     return -1;
 440
 441   /* Register an objfile "free" callback so we can properly
 442      invalidate blocks when an object file is about to be
 443      deleted.  */
 444   blpy_objfile_data_key
 445     = register_objfile_data_with_cleanup (NULL, del_objfile_blocks);
 446
 447   if (gdb_pymodule_addobject (gdb_module, "Block",
 448                               (PyObject *) &block_object_type) < 0)
 449     return -1;
 450
 451   return gdb_pymodule_addobject (gdb_module, "BlockIterator",
 452                                  (PyObject *) &block_syms_iterator_object_type);
 453 }
 454
 455 \f
 456
 457 static PyMethodDef block_object_methods[] = {
 458   { "is_valid", blpy_is_valid, METH_NOARGS,
 459     "is_valid () -> Boolean.\n\
 460 Return true if this block is valid, false if not." },
 461   {NULL}  /* Sentinel */
 462 };
 463
 464 static gdb_PyGetSetDef block_object_getset[] = {
 465   { "start", blpy_get_start, NULL, "Start address of the block.", NULL },
 466   { "end", blpy_get_end, NULL, "End address of the block.", NULL },
 467   { "function", blpy_get_function, NULL,
 468     "Symbol that names the block, or None.", NULL },
 469   { "superblock", blpy_get_superblock, NULL,
 470     "Block containing the block, or None.", NULL },
 471   { "global_block", blpy_get_global_block, NULL,
 472     "Block containing the global block.", NULL },
 473   { "static_block", blpy_get_static_block, NULL,
 474     "Block containing the static block.", NULL },
 475   { "is_static", blpy_is_static, NULL,
 476     "Whether this block is a static block.", NULL },
 477   { "is_global", blpy_is_global, NULL,
 478     "Whether this block is a global block.", NULL },
 479   { NULL }  /* Sentinel */
 480 };
 481
 482 PyTypeObject block_object_type = {
 483   PyVarObject_HEAD_INIT (NULL, 0)
 484   "gdb.Block",                    /*tp_name*/
 485   sizeof (block_object),          /*tp_basicsize*/
 486   0,                              /*tp_itemsize*/
 487   blpy_dealloc,                   /*tp_dealloc*/
 488   0,                              /*tp_print*/
 489   0,                              /*tp_getattr*/
 490   0,                              /*tp_setattr*/
 491   0,                              /*tp_compare*/
 492   0,                              /*tp_repr*/
 493   0,                              /*tp_as_number*/
 494   0,                              /*tp_as_sequence*/
 495   0,                              /*tp_as_mapping*/
 496   0,                              /*tp_hash */
 497   0,                              /*tp_call*/
 498   0,                              /*tp_str*/
 499   0,                              /*tp_getattro*/
 500   0,                              /*tp_setattro*/
 501   0,                              /*tp_as_buffer*/
 502   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_ITER,  /*tp_flags*/
 503   "GDB block object",             /* tp_doc */
 504   0,                              /* tp_traverse */
 505   0,                              /* tp_clear */
 506   0,                              /* tp_richcompare */
 507   0,                              /* tp_weaklistoffset */
 508   blpy_iter,                      /* tp_iter */
 509   0,                              /* tp_iternext */
 510   block_object_methods,           /* tp_methods */
 511   0,                              /* tp_members */
 512   block_object_getset             /* tp_getset */
 513 };
 514
 515 static PyMethodDef block_iterator_object_methods[] = {
 516   { "is_valid", blpy_iter_is_valid, METH_NOARGS,
 517     "is_valid () -> Boolean.\n\
 518 Return true if this block iterator is valid, false if not." },
 519   {NULL}  /* Sentinel */
 520 };
 521
 522 PyTypeObject block_syms_iterator_object_type = {
 523   PyVarObject_HEAD_INIT (NULL, 0)
 524   "gdb.BlockIterator",            /*tp_name*/
 525   sizeof (block_syms_iterator_object),        /*tp_basicsize*/
 526   0,                              /*tp_itemsize*/
 527   blpy_block_syms_dealloc,        /*tp_dealloc*/
 528   0,                              /*tp_print*/
 529   0,                              /*tp_getattr*/
 530   0,                              /*tp_setattr*/
 531   0,                              /*tp_compare*/
 532   0,                              /*tp_repr*/
 533   0,                              /*tp_as_number*/
 534   0,                              /*tp_as_sequence*/
 535   0,                              /*tp_as_mapping*/
 536   0,                              /*tp_hash */
 537   0,                              /*tp_call*/
 538   0,                              /*tp_str*/
 539   0,                              /*tp_getattro*/
 540   0,                              /*tp_setattro*/
 541   0,                              /*tp_as_buffer*/
 542   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_ITER,  /*tp_flags*/
 543   "GDB block syms iterator object",           /*tp_doc */
 544   0,                              /*tp_traverse */
 545   0,                              /*tp_clear */
 546   0,                              /*tp_richcompare */
 547   0,                              /*tp_weaklistoffset */
 548   blpy_block_syms_iter,           /*tp_iter */
 549   blpy_block_syms_iternext,       /*tp_iternext */
 550   block_iterator_object_methods   /*tp_methods */
 551 };