gdb/python/py-block.c

   1 /* Python interface to blocks.
   2
   3    Copyright (C) 2008-2019 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
  27 typedef struct blpy_block_object {
  28   PyObject_HEAD
  29   /* The GDB block structure that represents a frame's code block.  */
  30   const struct block *block;
  31   /* The backing object file.  There is no direct relationship in GDB
  32      between a block and an object file.  When a block is created also
  33      store a pointer to the object file for later use.  */
  34   struct objfile *objfile;
  35   /* Keep track of all blocks with a doubly-linked list.  Needed for
  36      block invalidation if the source object file has been freed.  */
  37   struct blpy_block_object *prev;
  38   struct blpy_block_object *next;
  39 } block_object;
  40
  41 typedef struct {
  42   PyObject_HEAD
  43   /* The block.  */
  44   const struct block *block;
  45   /* The iterator for that block.  */
  46   struct block_iterator iter;
  47   /* Has the iterator been initialized flag.  */
  48   int initialized_p;
  49   /* Pointer back to the original source block object.  Needed to
  50      check if the block is still valid, and has not been invalidated
  51      when an object file has been freed.  */
  52   struct blpy_block_object *source;
  53 } block_syms_iterator_object;
  54
  55 /* Require a valid block.  All access to block_object->block should be
  56    gated by this call.  */
  57 #define BLPY_REQUIRE_VALID(block_obj, block)            \
  58   do {                                                  \
  59     block = block_object_to_block (block_obj);          \
  60     if (block == NULL)                                  \
  61       {                                                 \
  62         PyErr_SetString (PyExc_RuntimeError,            \
  63                          _("Block is invalid."));       \
  64         return NULL;                                    \
  65       }                                                 \
  66   } while (0)
  67
  68 /* Require a valid block.  This macro is called during block iterator
  69    creation, and at each next call.  */
  70 #define BLPY_ITER_REQUIRE_VALID(block_obj)                              \
  71   do {                                                                  \
  72     if (block_obj->block == NULL)                                       \
  73       {                                                                 \
  74         PyErr_SetString (PyExc_RuntimeError,                            \
  75                          _("Source block for iterator is invalid."));   \
  76         return NULL;                                                    \
  77       }                                                                 \
  78   } while (0)
  79
  80 extern PyTypeObject block_syms_iterator_object_type
  81     CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("block_syms_iterator_object");
  82 static const struct objfile_data *blpy_objfile_data_key;
  83
  84 static PyObject *
  85 blpy_iter (PyObject *self)
  86 {
  87   block_syms_iterator_object *block_iter_obj;
  88   const struct block *block = NULL;
  89
  90   BLPY_REQUIRE_VALID (self, block);
  91
  92   block_iter_obj = PyObject_New (block_syms_iterator_object,
  93                                  &block_syms_iterator_object_type);
  94   if (block_iter_obj == NULL)
  95       return NULL;
  96
  97   block_iter_obj->block = block;
  98   block_iter_obj->initialized_p = 0;
  99   Py_INCREF (self);
 100   block_iter_obj->source = (block_object *) self;
 101
 102   return (PyObject *) block_iter_obj;
 103 }
 104
 105 static PyObject *
 106 blpy_get_start (PyObject *self, void *closure)
 107 {
 108   const struct block *block = NULL;
 109
 110   BLPY_REQUIRE_VALID (self, block);
 111
 112   return gdb_py_object_from_ulongest (BLOCK_START (block)).release ();
 113 }
 114
 115 static PyObject *
 116 blpy_get_end (PyObject *self, void *closure)
 117 {
 118   const struct block *block = NULL;
 119
 120   BLPY_REQUIRE_VALID (self, block);
 121
 122   return gdb_py_object_from_ulongest (BLOCK_END (block)).release ();
 123 }
 124
 125 static PyObject *
 126 blpy_get_function (PyObject *self, void *closure)
 127 {
 128   struct symbol *sym;
 129   const struct block *block;
 130
 131   BLPY_REQUIRE_VALID (self, block);
 132
 133   sym = BLOCK_FUNCTION (block);
 134   if (sym)
 135     return symbol_to_symbol_object (sym);
 136
 137   Py_RETURN_NONE;
 138 }
 139
 140 static PyObject *
 141 blpy_get_superblock (PyObject *self, void *closure)
 142 {
 143   const struct block *block;
 144   const struct block *super_block;
 145   block_object *self_obj  = (block_object *) self;
 146
 147   BLPY_REQUIRE_VALID (self, block);
 148
 149   super_block = BLOCK_SUPERBLOCK (block);
 150   if (super_block)
 151     return block_to_block_object (super_block, self_obj->objfile);
 152
 153   Py_RETURN_NONE;
 154 }
 155
 156 /* Return the global block associated to this block.  */
 157
 158 static PyObject *
 159 blpy_get_global_block (PyObject *self, void *closure)
 160 {
 161   const struct block *block;
 162   const struct block *global_block;
 163   block_object *self_obj  = (block_object *) self;
 164
 165   BLPY_REQUIRE_VALID (self, block);
 166
 167   global_block = block_global_block (block);
 168
 169   return block_to_block_object (global_block,
 170                                 self_obj->objfile);
 171
 172 }
 173
 174 /* Return the static block associated to this block.  Return None
 175    if we cannot get the static block (this is the global block).  */
 176
 177 static PyObject *
 178 blpy_get_static_block (PyObject *self, void *closure)
 179 {
 180   const struct block *block;
 181   const struct block *static_block;
 182   block_object *self_obj  = (block_object *) self;
 183
 184   BLPY_REQUIRE_VALID (self, block);
 185
 186   if (BLOCK_SUPERBLOCK (block) == NULL)
 187     Py_RETURN_NONE;
 188
 189   static_block = block_static_block (block);
 190
 191   return block_to_block_object (static_block, self_obj->objfile);
 192 }
 193
 194 /* Implementation of gdb.Block.is_global (self) -> Boolean.
 195    Returns True if this block object is a global block.  */
 196
 197 static PyObject *
 198 blpy_is_global (PyObject *self, void *closure)
 199 {
 200   const struct block *block;
 201
 202   BLPY_REQUIRE_VALID (self, block);
 203
 204   if (BLOCK_SUPERBLOCK (block))
 205     Py_RETURN_FALSE;
 206
 207   Py_RETURN_TRUE;
 208 }
 209
 210 /* Implementation of gdb.Block.is_static (self) -> Boolean.
 211    Returns True if this block object is a static block.  */
 212
 213 static PyObject *
 214 blpy_is_static (PyObject *self, void *closure)
 215 {
 216   const struct block *block;
 217
 218   BLPY_REQUIRE_VALID (self, block);
 219
 220   if (BLOCK_SUPERBLOCK (block) != NULL
 221      && BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) == NULL)
 222     Py_RETURN_TRUE;
 223
 224   Py_RETURN_FALSE;
 225 }
 226
 227 /* Given a string, returns the gdb.Symbol representing that symbol in this
 228    block.  If such a symbol does not exist, returns NULL with a Python
 229    exception.  */
 230
 231 static PyObject *
 232 blpy_getitem (PyObject *self, PyObject *key)
 233 {
 234   const struct block *block;
 235
 236   BLPY_REQUIRE_VALID (self, block);
 237
 238   gdb::unique_xmalloc_ptr<char> name = python_string_to_host_string (key);
 239   if (name == nullptr)
 240     return nullptr;
 241
 242   lookup_name_info lookup_name (name.get(), symbol_name_match_type::FULL);
 243
 244   /* We use ALL_BLOCK_SYMBOLS_WITH_NAME instead of block_lookup_symbol so
 245      that we can look up symbols irrespective of the domain, matching the
 246      iterator. It would be confusing if the iterator returns symbols you
 247      can't find via getitem.  */
 248   struct block_iterator iter;
 249   struct symbol *sym = nullptr;
 250   ALL_BLOCK_SYMBOLS_WITH_NAME (block, lookup_name, iter, sym)
 251     {
 252       /* Just stop at the first match */
 253       break;
 254     }
 255
 256   if (sym == nullptr)
 257     {
 258       PyErr_SetObject (PyExc_KeyError, key);
 259       return nullptr;
 260     }
 261   return symbol_to_symbol_object (sym);
 262 }
 263
 264 static void
 265 blpy_dealloc (PyObject *obj)
 266 {
 267   block_object *block = (block_object *) obj;
 268
 269   if (block->prev)
 270     block->prev->next = block->next;
 271   else if (block->objfile)
 272     {
 273       set_objfile_data (block->objfile, blpy_objfile_data_key,
 274                         block->next);
 275     }
 276   if (block->next)
 277     block->next->prev = block->prev;
 278   block->block = NULL;
 279 }
 280
 281 /* Given a block, and a block_object that has previously been
 282    allocated and initialized, populate the block_object with the
 283    struct block data.  Also, register the block_object life-cycle
 284    with the life-cycle of the object file associated with this
 285    block, if needed.  */
 286 static void
 287 set_block (block_object *obj, const struct block *block,
 288            struct objfile *objfile)
 289 {
 290   obj->block = block;
 291   obj->prev = NULL;
 292   if (objfile)
 293     {
 294       obj->objfile = objfile;
 295       obj->next = ((struct blpy_block_object *)
 296                    objfile_data (objfile, blpy_objfile_data_key));
 297       if (obj->next)
 298         obj->next->prev = obj;
 299       set_objfile_data (objfile, blpy_objfile_data_key, obj);
 300     }
 301   else
 302     obj->next = NULL;
 303 }
 304
 305 /* Create a new block object (gdb.Block) that encapsulates the struct
 306    block object from GDB.  */
 307 PyObject *
 308 block_to_block_object (const struct block *block, struct objfile *objfile)
 309 {
 310   block_object *block_obj;
 311
 312   block_obj = PyObject_New (block_object, &block_object_type);
 313   if (block_obj)
 314     set_block (block_obj, block, objfile);
 315
 316   return (PyObject *) block_obj;
 317 }
 318
 319 /* Return struct block reference that is wrapped by this object.  */
 320 const struct block *
 321 block_object_to_block (PyObject *obj)
 322 {
 323   if (! PyObject_TypeCheck (obj, &block_object_type))
 324     return NULL;
 325   return ((block_object *) obj)->block;
 326 }
 327
 328 /* Return a reference to the block iterator.  */
 329 static PyObject *
 330 blpy_block_syms_iter (PyObject *self)
 331 {
 332   block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) self;
 333
 334   BLPY_ITER_REQUIRE_VALID (iter_obj->source);
 335
 336   Py_INCREF (self);
 337   return self;
 338 }
 339
 340 /* Return the next symbol in the iteration through the block's
 341    dictionary.  */
 342 static PyObject *
 343 blpy_block_syms_iternext (PyObject *self)
 344 {
 345   block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) self;
 346   struct symbol *sym;
 347
 348   BLPY_ITER_REQUIRE_VALID (iter_obj->source);
 349
 350   if (!iter_obj->initialized_p)
 351     {
 352       sym = block_iterator_first (iter_obj->block,  &(iter_obj->iter));
 353       iter_obj->initialized_p = 1;
 354     }
 355   else
 356     sym = block_iterator_next (&(iter_obj->iter));
 357
 358   if (sym == NULL)
 359     {
 360       PyErr_SetString (PyExc_StopIteration, _("Symbol is null."));
 361       return NULL;
 362     }
 363
 364   return symbol_to_symbol_object (sym);
 365 }
 366
 367 static void
 368 blpy_block_syms_dealloc (PyObject *obj)
 369 {
 370   block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) obj;
 371
 372   Py_XDECREF (iter_obj->source);
 373 }
 374
 375 /* Implementation of gdb.Block.is_valid (self) -> Boolean.
 376    Returns True if this block object still exists in GDB.  */
 377
 378 static PyObject *
 379 blpy_is_valid (PyObject *self, PyObject *args)
 380 {
 381   const struct block *block;
 382
 383   block = block_object_to_block (self);
 384   if (block == NULL)
 385     Py_RETURN_FALSE;
 386
 387   Py_RETURN_TRUE;
 388 }
 389
 390 /* Implementation of gdb.BlockIterator.is_valid (self) -> Boolean.
 391    Returns True if this block iterator object still exists in GDB  */
 392
 393 static PyObject *
 394 blpy_iter_is_valid (PyObject *self, PyObject *args)
 395 {
 396   block_syms_iterator_object *iter_obj =
 397     (block_syms_iterator_object *) self;
 398
 399   if (iter_obj->source->block == NULL)
 400     Py_RETURN_FALSE;
 401
 402   Py_RETURN_TRUE;
 403 }
 404
 405 /* This function is called when an objfile is about to be freed.
 406    Invalidate the block as further actions on the block would result
 407    in bad data.  All access to obj->symbol should be gated by
 408    BLPY_REQUIRE_VALID which will raise an exception on invalid
 409    blocks.  */
 410 static void
 411 del_objfile_blocks (struct objfile *objfile, void *datum)
 412 {
 413   block_object *obj = (block_object *) datum;
 414
 415   while (obj)
 416     {
 417       block_object *next = obj->next;
 418
 419       obj->block = NULL;
 420       obj->objfile = NULL;
 421       obj->next = NULL;
 422       obj->prev = NULL;
 423
 424       obj = next;
 425     }
 426 }
 427
 428 int
 429 gdbpy_initialize_blocks (void)
 430 {
 431   block_object_type.tp_new = PyType_GenericNew;
 432   if (PyType_Ready (&block_object_type) < 0)
 433     return -1;
 434
 435   block_syms_iterator_object_type.tp_new = PyType_GenericNew;
 436   if (PyType_Ready (&block_syms_iterator_object_type) < 0)
 437     return -1;
 438
 439   /* Register an objfile "free" callback so we can properly
 440      invalidate blocks when an object file is about to be
 441      deleted.  */
 442   blpy_objfile_data_key
 443     = register_objfile_data_with_cleanup (NULL, del_objfile_blocks);
 444
 445   if (gdb_pymodule_addobject (gdb_module, "Block",
 446                               (PyObject *) &block_object_type) < 0)
 447     return -1;
 448
 449   return gdb_pymodule_addobject (gdb_module, "BlockIterator",
 450                                  (PyObject *) &block_syms_iterator_object_type);
 451 }
 452
 453 \f
 454
 455 static PyMethodDef block_object_methods[] = {
 456   { "is_valid", blpy_is_valid, METH_NOARGS,
 457     "is_valid () -> Boolean.\n\
 458 Return true if this block is valid, false if not." },
 459   {NULL}  /* Sentinel */
 460 };
 461
 462 static gdb_PyGetSetDef block_object_getset[] = {
 463   { "start", blpy_get_start, NULL, "Start address of the block.", NULL },
 464   { "end", blpy_get_end, NULL, "End address of the block.", NULL },
 465   { "function", blpy_get_function, NULL,
 466     "Symbol that names the block, or None.", NULL },
 467   { "superblock", blpy_get_superblock, NULL,
 468     "Block containing the block, or None.", NULL },
 469   { "global_block", blpy_get_global_block, NULL,
 470     "Block containing the global block.", NULL },
 471   { "static_block", blpy_get_static_block, NULL,
 472     "Block containing the static block.", NULL },
 473   { "is_static", blpy_is_static, NULL,
 474     "Whether this block is a static block.", NULL },
 475   { "is_global", blpy_is_global, NULL,
 476     "Whether this block is a global block.", NULL },
 477   { NULL }  /* Sentinel */
 478 };
 479
 480 static PyMappingMethods block_object_as_mapping = {
 481   NULL,
 482   blpy_getitem,
 483   NULL
 484 };
 485
 486 PyTypeObject block_object_type = {
 487   PyVarObject_HEAD_INIT (NULL, 0)
 488   "gdb.Block",                    /*tp_name*/
 489   sizeof (block_object),          /*tp_basicsize*/
 490   0,                              /*tp_itemsize*/
 491   blpy_dealloc,                   /*tp_dealloc*/
 492   0,                              /*tp_print*/
 493   0,                              /*tp_getattr*/
 494   0,                              /*tp_setattr*/
 495   0,                              /*tp_compare*/
 496   0,                              /*tp_repr*/
 497   0,                              /*tp_as_number*/
 498   0,                              /*tp_as_sequence*/
 499   &block_object_as_mapping,       /*tp_as_mapping*/
 500   0,                              /*tp_hash */
 501   0,                              /*tp_call*/
 502   0,                              /*tp_str*/
 503   0,                              /*tp_getattro*/
 504   0,                              /*tp_setattro*/
 505   0,                              /*tp_as_buffer*/
 506   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_ITER,  /*tp_flags*/
 507   "GDB block object",             /* tp_doc */
 508   0,                              /* tp_traverse */
 509   0,                              /* tp_clear */
 510   0,                              /* tp_richcompare */
 511   0,                              /* tp_weaklistoffset */
 512   blpy_iter,                      /* tp_iter */
 513   0,                              /* tp_iternext */
 514   block_object_methods,           /* tp_methods */
 515   0,                              /* tp_members */
 516   block_object_getset             /* tp_getset */
 517 };
 518
 519 static PyMethodDef block_iterator_object_methods[] = {
 520   { "is_valid", blpy_iter_is_valid, METH_NOARGS,
 521     "is_valid () -> Boolean.\n\
 522 Return true if this block iterator is valid, false if not." },
 523   {NULL}  /* Sentinel */
 524 };
 525
 526 PyTypeObject block_syms_iterator_object_type = {
 527   PyVarObject_HEAD_INIT (NULL, 0)
 528   "gdb.BlockIterator",            /*tp_name*/
 529   sizeof (block_syms_iterator_object),        /*tp_basicsize*/
 530   0,                              /*tp_itemsize*/
 531   blpy_block_syms_dealloc,        /*tp_dealloc*/
 532   0,                              /*tp_print*/
 533   0,                              /*tp_getattr*/
 534   0,                              /*tp_setattr*/
 535   0,                              /*tp_compare*/
 536   0,                              /*tp_repr*/
 537   0,                              /*tp_as_number*/
 538   0,                              /*tp_as_sequence*/
 539   0,                              /*tp_as_mapping*/
 540   0,                              /*tp_hash */
 541   0,                              /*tp_call*/
 542   0,                              /*tp_str*/
 543   0,                              /*tp_getattro*/
 544   0,                              /*tp_setattro*/
 545   0,                              /*tp_as_buffer*/
 546   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_ITER,  /*tp_flags*/
 547   "GDB block syms iterator object",           /*tp_doc */
 548   0,                              /*tp_traverse */
 549   0,                              /*tp_clear */
 550   0,                              /*tp_richcompare */
 551   0,                              /*tp_weaklistoffset */
 552   blpy_block_syms_iter,           /*tp_iter */
 553   blpy_block_syms_iternext,       /*tp_iternext */
 554   block_iterator_object_methods   /*tp_methods */
 555 };