binutils-gdb/gdb/python/py-block.c
Christian Biesinger 0b27c27d0d Add block['var'] accessor
Currently we support iteration on blocks; this patch extends that to make
subscript access work as well.

gdb/ChangeLog:

2019-08-05  Christian Biesinger  <cbiesinger@google.com>

	* NEWS: Mention dictionary access on blocks.
	* python/py-block.c (blpy_getitem): New function.
	(block_object_as_mapping): New struct.
	(block_object_type): Use new struct for tp_as_mapping field.

gdb/doc/ChangeLog:

2019-08-05  Christian Biesinger  <cbiesinger@google.com>

	* python.texi (Blocks In Python): Document dictionary access on blocks.

gdb/testsuite/ChangeLog:

2019-08-05  Christian Biesinger  <cbiesinger@google.com>

	* gdb.python/py-block.exp: Test dictionary access on blocks.
2019-08-05 13:06:18 -05:00

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/* Python interface to blocks.
Copyright (C) 2008-2019 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "block.h"
#include "dictionary.h"
#include "symtab.h"
#include "python-internal.h"
#include "objfiles.h"
typedef struct blpy_block_object {
PyObject_HEAD
/* The GDB block structure that represents a frame's code block. */
const struct block *block;
/* The backing object file. There is no direct relationship in GDB
between a block and an object file. When a block is created also
store a pointer to the object file for later use. */
struct objfile *objfile;
/* Keep track of all blocks with a doubly-linked list. Needed for
block invalidation if the source object file has been freed. */
struct blpy_block_object *prev;
struct blpy_block_object *next;
} block_object;
typedef struct {
PyObject_HEAD
/* The block. */
const struct block *block;
/* The iterator for that block. */
struct block_iterator iter;
/* Has the iterator been initialized flag. */
int initialized_p;
/* Pointer back to the original source block object. Needed to
check if the block is still valid, and has not been invalidated
when an object file has been freed. */
struct blpy_block_object *source;
} block_syms_iterator_object;
/* Require a valid block. All access to block_object->block should be
gated by this call. */
#define BLPY_REQUIRE_VALID(block_obj, block) \
do { \
block = block_object_to_block (block_obj); \
if (block == NULL) \
{ \
PyErr_SetString (PyExc_RuntimeError, \
_("Block is invalid.")); \
return NULL; \
} \
} while (0)
/* Require a valid block. This macro is called during block iterator
creation, and at each next call. */
#define BLPY_ITER_REQUIRE_VALID(block_obj) \
do { \
if (block_obj->block == NULL) \
{ \
PyErr_SetString (PyExc_RuntimeError, \
_("Source block for iterator is invalid.")); \
return NULL; \
} \
} while (0)
extern PyTypeObject block_syms_iterator_object_type
CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("block_syms_iterator_object");
static const struct objfile_data *blpy_objfile_data_key;
static PyObject *
blpy_iter (PyObject *self)
{
block_syms_iterator_object *block_iter_obj;
const struct block *block = NULL;
BLPY_REQUIRE_VALID (self, block);
block_iter_obj = PyObject_New (block_syms_iterator_object,
&block_syms_iterator_object_type);
if (block_iter_obj == NULL)
return NULL;
block_iter_obj->block = block;
block_iter_obj->initialized_p = 0;
Py_INCREF (self);
block_iter_obj->source = (block_object *) self;
return (PyObject *) block_iter_obj;
}
static PyObject *
blpy_get_start (PyObject *self, void *closure)
{
const struct block *block = NULL;
BLPY_REQUIRE_VALID (self, block);
return gdb_py_object_from_ulongest (BLOCK_START (block)).release ();
}
static PyObject *
blpy_get_end (PyObject *self, void *closure)
{
const struct block *block = NULL;
BLPY_REQUIRE_VALID (self, block);
return gdb_py_object_from_ulongest (BLOCK_END (block)).release ();
}
static PyObject *
blpy_get_function (PyObject *self, void *closure)
{
struct symbol *sym;
const struct block *block;
BLPY_REQUIRE_VALID (self, block);
sym = BLOCK_FUNCTION (block);
if (sym)
return symbol_to_symbol_object (sym);
Py_RETURN_NONE;
}
static PyObject *
blpy_get_superblock (PyObject *self, void *closure)
{
const struct block *block;
const struct block *super_block;
block_object *self_obj = (block_object *) self;
BLPY_REQUIRE_VALID (self, block);
super_block = BLOCK_SUPERBLOCK (block);
if (super_block)
return block_to_block_object (super_block, self_obj->objfile);
Py_RETURN_NONE;
}
/* Return the global block associated to this block. */
static PyObject *
blpy_get_global_block (PyObject *self, void *closure)
{
const struct block *block;
const struct block *global_block;
block_object *self_obj = (block_object *) self;
BLPY_REQUIRE_VALID (self, block);
global_block = block_global_block (block);
return block_to_block_object (global_block,
self_obj->objfile);
}
/* Return the static block associated to this block. Return None
if we cannot get the static block (this is the global block). */
static PyObject *
blpy_get_static_block (PyObject *self, void *closure)
{
const struct block *block;
const struct block *static_block;
block_object *self_obj = (block_object *) self;
BLPY_REQUIRE_VALID (self, block);
if (BLOCK_SUPERBLOCK (block) == NULL)
Py_RETURN_NONE;
static_block = block_static_block (block);
return block_to_block_object (static_block, self_obj->objfile);
}
/* Implementation of gdb.Block.is_global (self) -> Boolean.
Returns True if this block object is a global block. */
static PyObject *
blpy_is_global (PyObject *self, void *closure)
{
const struct block *block;
BLPY_REQUIRE_VALID (self, block);
if (BLOCK_SUPERBLOCK (block))
Py_RETURN_FALSE;
Py_RETURN_TRUE;
}
/* Implementation of gdb.Block.is_static (self) -> Boolean.
Returns True if this block object is a static block. */
static PyObject *
blpy_is_static (PyObject *self, void *closure)
{
const struct block *block;
BLPY_REQUIRE_VALID (self, block);
if (BLOCK_SUPERBLOCK (block) != NULL
&& BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) == NULL)
Py_RETURN_TRUE;
Py_RETURN_FALSE;
}
/* Given a string, returns the gdb.Symbol representing that symbol in this
block. If such a symbol does not exist, returns NULL with a Python
exception. */
static PyObject *
blpy_getitem (PyObject *self, PyObject *key)
{
const struct block *block;
BLPY_REQUIRE_VALID (self, block);
gdb::unique_xmalloc_ptr<char> name = python_string_to_host_string (key);
if (name == nullptr)
return nullptr;
lookup_name_info lookup_name (name.get(), symbol_name_match_type::FULL);
/* We use ALL_BLOCK_SYMBOLS_WITH_NAME instead of block_lookup_symbol so
that we can look up symbols irrespective of the domain, matching the
iterator. It would be confusing if the iterator returns symbols you
can't find via getitem. */
struct block_iterator iter;
struct symbol *sym = nullptr;
ALL_BLOCK_SYMBOLS_WITH_NAME (block, lookup_name, iter, sym)
{
/* Just stop at the first match */
break;
}
if (sym == nullptr)
{
PyErr_SetObject (PyExc_KeyError, key);
return nullptr;
}
return symbol_to_symbol_object (sym);
}
static void
blpy_dealloc (PyObject *obj)
{
block_object *block = (block_object *) obj;
if (block->prev)
block->prev->next = block->next;
else if (block->objfile)
{
set_objfile_data (block->objfile, blpy_objfile_data_key,
block->next);
}
if (block->next)
block->next->prev = block->prev;
block->block = NULL;
}
/* Given a block, and a block_object that has previously been
allocated and initialized, populate the block_object with the
struct block data. Also, register the block_object life-cycle
with the life-cycle of the object file associated with this
block, if needed. */
static void
set_block (block_object *obj, const struct block *block,
struct objfile *objfile)
{
obj->block = block;
obj->prev = NULL;
if (objfile)
{
obj->objfile = objfile;
obj->next = ((struct blpy_block_object *)
objfile_data (objfile, blpy_objfile_data_key));
if (obj->next)
obj->next->prev = obj;
set_objfile_data (objfile, blpy_objfile_data_key, obj);
}
else
obj->next = NULL;
}
/* Create a new block object (gdb.Block) that encapsulates the struct
block object from GDB. */
PyObject *
block_to_block_object (const struct block *block, struct objfile *objfile)
{
block_object *block_obj;
block_obj = PyObject_New (block_object, &block_object_type);
if (block_obj)
set_block (block_obj, block, objfile);
return (PyObject *) block_obj;
}
/* Return struct block reference that is wrapped by this object. */
const struct block *
block_object_to_block (PyObject *obj)
{
if (! PyObject_TypeCheck (obj, &block_object_type))
return NULL;
return ((block_object *) obj)->block;
}
/* Return a reference to the block iterator. */
static PyObject *
blpy_block_syms_iter (PyObject *self)
{
block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) self;
BLPY_ITER_REQUIRE_VALID (iter_obj->source);
Py_INCREF (self);
return self;
}
/* Return the next symbol in the iteration through the block's
dictionary. */
static PyObject *
blpy_block_syms_iternext (PyObject *self)
{
block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) self;
struct symbol *sym;
BLPY_ITER_REQUIRE_VALID (iter_obj->source);
if (!iter_obj->initialized_p)
{
sym = block_iterator_first (iter_obj->block, &(iter_obj->iter));
iter_obj->initialized_p = 1;
}
else
sym = block_iterator_next (&(iter_obj->iter));
if (sym == NULL)
{
PyErr_SetString (PyExc_StopIteration, _("Symbol is null."));
return NULL;
}
return symbol_to_symbol_object (sym);
}
static void
blpy_block_syms_dealloc (PyObject *obj)
{
block_syms_iterator_object *iter_obj = (block_syms_iterator_object *) obj;
Py_XDECREF (iter_obj->source);
}
/* Implementation of gdb.Block.is_valid (self) -> Boolean.
Returns True if this block object still exists in GDB. */
static PyObject *
blpy_is_valid (PyObject *self, PyObject *args)
{
const struct block *block;
block = block_object_to_block (self);
if (block == NULL)
Py_RETURN_FALSE;
Py_RETURN_TRUE;
}
/* Implementation of gdb.BlockIterator.is_valid (self) -> Boolean.
Returns True if this block iterator object still exists in GDB */
static PyObject *
blpy_iter_is_valid (PyObject *self, PyObject *args)
{
block_syms_iterator_object *iter_obj =
(block_syms_iterator_object *) self;
if (iter_obj->source->block == NULL)
Py_RETURN_FALSE;
Py_RETURN_TRUE;
}
/* This function is called when an objfile is about to be freed.
Invalidate the block as further actions on the block would result
in bad data. All access to obj->symbol should be gated by
BLPY_REQUIRE_VALID which will raise an exception on invalid
blocks. */
static void
del_objfile_blocks (struct objfile *objfile, void *datum)
{
block_object *obj = (block_object *) datum;
while (obj)
{
block_object *next = obj->next;
obj->block = NULL;
obj->objfile = NULL;
obj->next = NULL;
obj->prev = NULL;
obj = next;
}
}
int
gdbpy_initialize_blocks (void)
{
block_object_type.tp_new = PyType_GenericNew;
if (PyType_Ready (&block_object_type) < 0)
return -1;
block_syms_iterator_object_type.tp_new = PyType_GenericNew;
if (PyType_Ready (&block_syms_iterator_object_type) < 0)
return -1;
/* Register an objfile "free" callback so we can properly
invalidate blocks when an object file is about to be
deleted. */
blpy_objfile_data_key
= register_objfile_data_with_cleanup (NULL, del_objfile_blocks);
if (gdb_pymodule_addobject (gdb_module, "Block",
(PyObject *) &block_object_type) < 0)
return -1;
return gdb_pymodule_addobject (gdb_module, "BlockIterator",
(PyObject *) &block_syms_iterator_object_type);
}
static PyMethodDef block_object_methods[] = {
{ "is_valid", blpy_is_valid, METH_NOARGS,
"is_valid () -> Boolean.\n\
Return true if this block is valid, false if not." },
{NULL} /* Sentinel */
};
static gdb_PyGetSetDef block_object_getset[] = {
{ "start", blpy_get_start, NULL, "Start address of the block.", NULL },
{ "end", blpy_get_end, NULL, "End address of the block.", NULL },
{ "function", blpy_get_function, NULL,
"Symbol that names the block, or None.", NULL },
{ "superblock", blpy_get_superblock, NULL,
"Block containing the block, or None.", NULL },
{ "global_block", blpy_get_global_block, NULL,
"Block containing the global block.", NULL },
{ "static_block", blpy_get_static_block, NULL,
"Block containing the static block.", NULL },
{ "is_static", blpy_is_static, NULL,
"Whether this block is a static block.", NULL },
{ "is_global", blpy_is_global, NULL,
"Whether this block is a global block.", NULL },
{ NULL } /* Sentinel */
};
static PyMappingMethods block_object_as_mapping = {
NULL,
blpy_getitem,
NULL
};
PyTypeObject block_object_type = {
PyVarObject_HEAD_INIT (NULL, 0)
"gdb.Block", /*tp_name*/
sizeof (block_object), /*tp_basicsize*/
0, /*tp_itemsize*/
blpy_dealloc, /*tp_dealloc*/
0, /*tp_print*/
0, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_compare*/
0, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
&block_object_as_mapping, /*tp_as_mapping*/
0, /*tp_hash */
0, /*tp_call*/
0, /*tp_str*/
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_ITER, /*tp_flags*/
"GDB block object", /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
blpy_iter, /* tp_iter */
0, /* tp_iternext */
block_object_methods, /* tp_methods */
0, /* tp_members */
block_object_getset /* tp_getset */
};
static PyMethodDef block_iterator_object_methods[] = {
{ "is_valid", blpy_iter_is_valid, METH_NOARGS,
"is_valid () -> Boolean.\n\
Return true if this block iterator is valid, false if not." },
{NULL} /* Sentinel */
};
PyTypeObject block_syms_iterator_object_type = {
PyVarObject_HEAD_INIT (NULL, 0)
"gdb.BlockIterator", /*tp_name*/
sizeof (block_syms_iterator_object), /*tp_basicsize*/
0, /*tp_itemsize*/
blpy_block_syms_dealloc, /*tp_dealloc*/
0, /*tp_print*/
0, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_compare*/
0, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
0, /*tp_as_mapping*/
0, /*tp_hash */
0, /*tp_call*/
0, /*tp_str*/
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_ITER, /*tp_flags*/
"GDB block syms iterator object", /*tp_doc */
0, /*tp_traverse */
0, /*tp_clear */
0, /*tp_richcompare */
0, /*tp_weaklistoffset */
blpy_block_syms_iter, /*tp_iter */
blpy_block_syms_iternext, /*tp_iternext */
block_iterator_object_methods /*tp_methods */
};