gdb/python/py-finishbreakpoint.c

   1 /* Python interface to finish breakpoints
   2
   3    Copyright (C) 2011-2013 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
  21
  22 #include "defs.h"
  23 #include "exceptions.h"
  24 #include "python-internal.h"
  25 #include "breakpoint.h"
  26 #include "frame.h"
  27 #include "gdbthread.h"
  28 #include "arch-utils.h"
  29 #include "language.h"
  30 #include "observer.h"
  31 #include "inferior.h"
  32 #include "block.h"
  33
  34 /* Function that is called when a Python finish bp is found out of scope.  */
  35 static char * const outofscope_func = "out_of_scope";
  36
  37 /* struct implementing the gdb.FinishBreakpoint object by extending
  38    the gdb.Breakpoint class.  */
  39 struct finish_breakpoint_object
  40 {
  41   /* gdb.Breakpoint base class.  */
  42   breakpoint_object py_bp;
  43   /* gdb.Type object of the value return by the breakpointed function.
  44      May be NULL if no debug information was available or return type
  45      was VOID.  */
  46   PyObject *return_type;
  47   /* gdb.Value object of the function finished by this breakpoint.  Will be
  48      NULL if return_type is NULL.  */
  49   PyObject *function_value;
  50   /* When stopped at this FinishBreakpoint, gdb.Value object returned by
  51      the function; Py_None if the value is not computable; NULL if GDB is
  52      not stopped at a FinishBreakpoint.  */
  53   PyObject *return_value;
  54 };
  55
  56 static PyTypeObject finish_breakpoint_object_type
  57     CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("finish_breakpoint_object");
  58
  59 /* Python function to get the 'return_value' attribute of
  60    FinishBreakpoint.  */
  61
  62 static PyObject *
  63 bpfinishpy_get_returnvalue (PyObject *self, void *closure)
  64 {
  65   struct finish_breakpoint_object *self_finishbp =
  66       (struct finish_breakpoint_object *) self;
  67
  68   if (!self_finishbp->return_value)
  69     Py_RETURN_NONE;
  70
  71   Py_INCREF (self_finishbp->return_value);
  72   return self_finishbp->return_value;
  73 }
  74
  75 /* Deallocate FinishBreakpoint object.  */
  76
  77 static void
  78 bpfinishpy_dealloc (PyObject *self)
  79 {
  80   struct finish_breakpoint_object *self_bpfinish =
  81         (struct finish_breakpoint_object *) self;
  82
  83   Py_XDECREF (self_bpfinish->function_value);
  84   Py_XDECREF (self_bpfinish->return_type);
  85   Py_XDECREF (self_bpfinish->return_value);
  86 }
  87
  88 /* Triggered when gdbpy_should_stop is about to execute the `stop' callback
  89    of the gdb.FinishBreakpoint object BP_OBJ.  Will compute and cache the
  90    `return_value', if possible.  */
  91
  92 void
  93 bpfinishpy_pre_stop_hook (struct breakpoint_object *bp_obj)
  94 {
  95   struct finish_breakpoint_object *self_finishbp =
  96         (struct finish_breakpoint_object *) bp_obj;
  97   volatile struct gdb_exception except;
  98
  99   /* Can compute return_value only once.  */
 100   gdb_assert (!self_finishbp->return_value);
 101
 102   if (!self_finishbp->return_type)
 103     return;
 104
 105   TRY_CATCH (except, RETURN_MASK_ALL)
 106     {
 107       struct value *function =
 108         value_object_to_value (self_finishbp->function_value);
 109       struct type *value_type =
 110         type_object_to_type (self_finishbp->return_type);
 111       struct value *ret = get_return_value (function, value_type);
 112
 113       if (ret)
 114         {
 115           self_finishbp->return_value = value_to_value_object (ret);
 116           if (!self_finishbp->return_value)
 117               gdbpy_print_stack ();
 118         }
 119       else
 120         {
 121           Py_INCREF (Py_None);
 122           self_finishbp->return_value = Py_None;
 123         }
 124     }
 125   if (except.reason < 0)
 126     {
 127       gdbpy_convert_exception (except);
 128       gdbpy_print_stack ();
 129     }
 130 }
 131
 132 /* Triggered when gdbpy_should_stop has triggered the `stop' callback
 133    of the gdb.FinishBreakpoint object BP_OBJ.  */
 134
 135 void
 136 bpfinishpy_post_stop_hook (struct breakpoint_object *bp_obj)
 137 {
 138   volatile struct gdb_exception except;
 139
 140   TRY_CATCH (except, RETURN_MASK_ALL)
 141     {
 142       /* Can't delete it here, but it will be removed at the next stop.  */
 143       disable_breakpoint (bp_obj->bp);
 144       gdb_assert (bp_obj->bp->disposition == disp_del);
 145     }
 146   if (except.reason < 0)
 147     {
 148       gdbpy_convert_exception (except);
 149       gdbpy_print_stack ();
 150     }
 151 }
 152
 153 /* Python function to create a new breakpoint.  */
 154
 155 static int
 156 bpfinishpy_init (PyObject *self, PyObject *args, PyObject *kwargs)
 157 {
 158   static char *keywords[] = { "frame", "internal", NULL };
 159   struct finish_breakpoint_object *self_bpfinish =
 160       (struct finish_breakpoint_object *) self;
 161   int type = bp_breakpoint;
 162   PyObject *frame_obj = NULL;
 163   int thread;
 164   struct frame_info *frame = NULL; /* init for gcc -Wall */
 165   struct frame_info *prev_frame = NULL;
 166   struct frame_id frame_id;
 167   PyObject *internal = NULL;
 168   int internal_bp = 0;
 169   CORE_ADDR finish_pc, pc;
 170   volatile struct gdb_exception except;
 171   char *addr_str, small_buf[100];
 172   struct symbol *function;
 173
 174   if (!PyArg_ParseTupleAndKeywords (args, kwargs, "|OO", keywords,
 175                                     &frame_obj, &internal))
 176     return -1;
 177
 178   TRY_CATCH (except, RETURN_MASK_ALL)
 179     {
 180       /* Default frame to newest frame if necessary.  */
 181       if (frame_obj == NULL)
 182         frame = get_current_frame ();
 183       else
 184         frame = frame_object_to_frame_info (frame_obj);
 185
 186       if (frame == NULL)
 187         {
 188           PyErr_SetString (PyExc_ValueError,
 189                            _("Invalid ID for the `frame' object."));
 190         }
 191       else
 192         {
 193           prev_frame = get_prev_frame (frame);
 194           if (prev_frame == 0)
 195             {
 196               PyErr_SetString (PyExc_ValueError,
 197                                _("\"FinishBreakpoint\" not "
 198                                  "meaningful in the outermost "
 199                                  "frame."));
 200             }
 201           else if (get_frame_type (prev_frame) == DUMMY_FRAME)
 202             {
 203               PyErr_SetString (PyExc_ValueError,
 204                                _("\"FinishBreakpoint\" cannot "
 205                                  "be set on a dummy frame."));
 206             }
 207           else
 208             {
 209               frame_id = get_frame_id (prev_frame);
 210               if (frame_id_eq (frame_id, null_frame_id))
 211                 PyErr_SetString (PyExc_ValueError,
 212                                  _("Invalid ID for the `frame' object."));
 213             }
 214         }
 215     }
 216   if (except.reason < 0)
 217     {
 218       gdbpy_convert_exception (except);
 219       return -1;
 220     }
 221   else if (PyErr_Occurred ())
 222     return -1;
 223
 224   thread = pid_to_thread_id (inferior_ptid);
 225   if (thread == 0)
 226     {
 227       PyErr_SetString (PyExc_ValueError,
 228                        _("No thread currently selected."));
 229       return -1;
 230     }
 231
 232   if (internal)
 233     {
 234       internal_bp = PyObject_IsTrue (internal);
 235       if (internal_bp == -1)
 236         {
 237           PyErr_SetString (PyExc_ValueError,
 238                            _("The value of `internal' must be a boolean."));
 239           return -1;
 240         }
 241     }
 242
 243   /* Find the function we will return from.  */
 244   self_bpfinish->return_type = NULL;
 245   self_bpfinish->function_value = NULL;
 246
 247   TRY_CATCH (except, RETURN_MASK_ALL)
 248     {
 249       if (get_frame_pc_if_available (frame, &pc))
 250         {
 251           function = find_pc_function (pc);
 252           if (function != NULL)
 253             {
 254               struct type *ret_type =
 255                   TYPE_TARGET_TYPE (SYMBOL_TYPE (function));
 256
 257               /* Remember only non-void return types.  */
 258               if (TYPE_CODE (ret_type) != TYPE_CODE_VOID)
 259                 {
 260                   struct value *func_value;
 261
 262                   /* Ignore Python errors at this stage.  */
 263                   self_bpfinish->return_type = type_to_type_object (ret_type);
 264                   PyErr_Clear ();
 265                   func_value = read_var_value (function, frame);
 266                   self_bpfinish->function_value =
 267                       value_to_value_object (func_value);
 268                   PyErr_Clear ();
 269                 }
 270             }
 271         }
 272     }
 273   if (except.reason < 0
 274       || !self_bpfinish->return_type || !self_bpfinish->function_value)
 275     {
 276       /* Won't be able to compute return value.  */
 277       Py_XDECREF (self_bpfinish->return_type);
 278       Py_XDECREF (self_bpfinish->function_value);
 279
 280       self_bpfinish->return_type = NULL;
 281       self_bpfinish->function_value = NULL;
 282     }
 283
 284   bppy_pending_object = &self_bpfinish->py_bp;
 285   bppy_pending_object->number = -1;
 286   bppy_pending_object->bp = NULL;
 287
 288   TRY_CATCH (except, RETURN_MASK_ALL)
 289     {
 290       /* Set a breakpoint on the return address.  */
 291       finish_pc = get_frame_pc (prev_frame);
 292       xsnprintf (small_buf, sizeof (small_buf), "*%s", hex_string (finish_pc));
 293       addr_str = small_buf;
 294
 295       create_breakpoint (python_gdbarch,
 296                          addr_str, NULL, thread, NULL,
 297                          0,
 298                          1 /*temp_flag*/,
 299                          bp_breakpoint,
 300                          0,
 301                          AUTO_BOOLEAN_TRUE,
 302                          &bkpt_breakpoint_ops,
 303                          0, 1, internal_bp, 0);
 304     }
 305   GDB_PY_SET_HANDLE_EXCEPTION (except);
 306
 307   self_bpfinish->py_bp.bp->frame_id = frame_id;
 308   self_bpfinish->py_bp.is_finish_bp = 1;
 309
 310   /* Bind the breakpoint with the current program space.  */
 311   self_bpfinish->py_bp.bp->pspace = current_program_space;
 312
 313   return 0;
 314 }
 315
 316 /* Called when GDB notices that the finish breakpoint BP_OBJ is out of
 317    the current callstack.  Triggers the method OUT_OF_SCOPE if implemented,
 318    then delete the breakpoint.  */
 319
 320 static void
 321 bpfinishpy_out_of_scope (struct finish_breakpoint_object *bpfinish_obj)
 322 {
 323   breakpoint_object *bp_obj = (breakpoint_object *) bpfinish_obj;
 324   PyObject *py_obj = (PyObject *) bp_obj;
 325
 326   if (bpfinish_obj->py_bp.bp->enable_state == bp_enabled
 327       && PyObject_HasAttrString (py_obj, outofscope_func))
 328     {
 329       PyObject *meth_result;
 330
 331       meth_result = PyObject_CallMethod (py_obj, outofscope_func, NULL);
 332       if (meth_result == NULL)
 333         gdbpy_print_stack ();
 334       Py_XDECREF (meth_result);
 335     }
 336
 337   delete_breakpoint (bpfinish_obj->py_bp.bp);
 338 }
 339
 340 /* Callback for `bpfinishpy_detect_out_scope'.  Triggers Python's
 341    `B->out_of_scope' function if B is a FinishBreakpoint out of its scope.  */
 342
 343 static int
 344 bpfinishpy_detect_out_scope_cb (struct breakpoint *b, void *args)
 345 {
 346   volatile struct gdb_exception except;
 347   struct breakpoint *bp_stopped = (struct breakpoint *) args;
 348   PyObject *py_bp = (PyObject *) b->py_bp_object;
 349   struct gdbarch *garch = b->gdbarch ? b->gdbarch : get_current_arch ();
 350
 351   /* Trigger out_of_scope if this is a FinishBreakpoint and its frame is
 352      not anymore in the current callstack.  */
 353   if (py_bp != NULL && b->py_bp_object->is_finish_bp)
 354     {
 355       struct finish_breakpoint_object *finish_bp =
 356           (struct finish_breakpoint_object *) py_bp;
 357
 358       /* Check scope if not currently stopped at the FinishBreakpoint.  */
 359       if (b != bp_stopped)
 360         {
 361           TRY_CATCH (except, RETURN_MASK_ALL)
 362             {
 363               if (b->pspace == current_inferior ()->pspace
 364                   && (!target_has_registers
 365                       || frame_find_by_id (b->frame_id) == NULL))
 366                 bpfinishpy_out_of_scope (finish_bp);
 367             }
 368           if (except.reason < 0)
 369             {
 370               gdbpy_convert_exception (except);
 371               gdbpy_print_stack ();
 372             }
 373         }
 374     }
 375
 376   return 0;
 377 }
 378
 379 /* Attached to `stop' notifications, check if the execution has run
 380    out of the scope of any FinishBreakpoint before it has been hit.  */
 381
 382 static void
 383 bpfinishpy_handle_stop (struct bpstats *bs, int print_frame)
 384 {
 385   struct cleanup *cleanup = ensure_python_env (get_current_arch (),
 386                                                current_language);
 387
 388   iterate_over_breakpoints (bpfinishpy_detect_out_scope_cb,
 389                             bs == NULL ? NULL : bs->breakpoint_at);
 390
 391   do_cleanups (cleanup);
 392 }
 393
 394 /* Attached to `exit' notifications, triggers all the necessary out of
 395    scope notifications.  */
 396
 397 static void
 398 bpfinishpy_handle_exit (struct inferior *inf)
 399 {
 400   struct cleanup *cleanup = ensure_python_env (target_gdbarch (),
 401                                                current_language);
 402
 403   iterate_over_breakpoints (bpfinishpy_detect_out_scope_cb, NULL);
 404
 405   do_cleanups (cleanup);
 406 }
 407
 408 /* Initialize the Python finish breakpoint code.  */
 409
 410 void
 411 gdbpy_initialize_finishbreakpoints (void)
 412 {
 413   if (PyType_Ready (&finish_breakpoint_object_type) < 0)
 414       return;
 415
 416   Py_INCREF (&finish_breakpoint_object_type);
 417   PyModule_AddObject (gdb_module, "FinishBreakpoint",
 418                       (PyObject *) &finish_breakpoint_object_type);
 419
 420   observer_attach_normal_stop (bpfinishpy_handle_stop);
 421   observer_attach_inferior_exit (bpfinishpy_handle_exit);
 422 }
 423
 424 static PyGetSetDef finish_breakpoint_object_getset[] = {
 425   { "return_value", bpfinishpy_get_returnvalue, NULL,
 426   "gdb.Value object representing the return value, if any. \
 427 None otherwise.", NULL },
 428     { NULL }  /* Sentinel.  */
 429 };
 430
 431 static PyTypeObject finish_breakpoint_object_type =
 432 {
 433   PyVarObject_HEAD_INIT (NULL, 0)
 434   "gdb.FinishBreakpoint",         /*tp_name*/
 435   sizeof (struct finish_breakpoint_object),  /*tp_basicsize*/
 436   0,                              /*tp_itemsize*/
 437   bpfinishpy_dealloc,             /*tp_dealloc*/
 438   0,                              /*tp_print*/
 439   0,                              /*tp_getattr*/
 440   0,                              /*tp_setattr*/
 441   0,                              /*tp_compare*/
 442   0,                              /*tp_repr*/
 443   0,                              /*tp_as_number*/
 444   0,                              /*tp_as_sequence*/
 445   0,                              /*tp_as_mapping*/
 446   0,                              /*tp_hash */
 447   0,                              /*tp_call*/
 448   0,                              /*tp_str*/
 449   0,                              /*tp_getattro*/
 450   0,                              /*tp_setattro */
 451   0,                              /*tp_as_buffer*/
 452   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
 453   "GDB finish breakpoint object", /* tp_doc */
 454   0,                              /* tp_traverse */
 455   0,                              /* tp_clear */
 456   0,                              /* tp_richcompare */
 457   0,                              /* tp_weaklistoffset */
 458   0,                              /* tp_iter */
 459   0,                              /* tp_iternext */
 460   0,                              /* tp_methods */
 461   0,                              /* tp_members */
 462   finish_breakpoint_object_getset,/* tp_getset */
 463   &breakpoint_object_type,        /* tp_base */
 464   0,                              /* tp_dict */
 465   0,                              /* tp_descr_get */
 466   0,                              /* tp_descr_set */
 467   0,                              /* tp_dictoffset */
 468   bpfinishpy_init,                /* tp_init */
 469   0,                              /* tp_alloc */
 470   0                               /* tp_new */
 471 };