Files
binutils-gdb/gdb/python/py-symbol.c
Tom Tromey 9ba5ef4bf1 Omit artificial symbols from DAP variables response
While testing DAP, we found a situation where a compiler-generated
variable caused the "variables" request to fail -- the variable in
question being an apparent 67-megabyte string.

It seems to me that artificial variables like this aren't interesting
to DAP users, and the gdb CLI omits these as well.

This patch changes DAP to omit these variables, adding a new
gdb.Symbol.is_artificial attribute to make this possible.
2024-12-09 14:05:02 -07:00

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/* Python interface to symbols.
Copyright (C) 2008-2024 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 "top.h"
#include "block.h"
#include "frame.h"
#include "symtab.h"
#include "python-internal.h"
#include "objfiles.h"
#include "symfile.h"
struct symbol_object {
PyObject_HEAD
/* The GDB symbol structure this object is wrapping. */
struct symbol *symbol;
/* A symbol object is associated with an objfile, so keep track with
doubly-linked list, rooted in the objfile. This lets us
invalidate the underlying struct symbol when the objfile is
deleted. */
symbol_object *prev;
symbol_object *next;
};
/* Require a valid symbol. All access to symbol_object->symbol should be
gated by this call. */
#define SYMPY_REQUIRE_VALID(symbol_obj, symbol) \
do { \
symbol = symbol_object_to_symbol (symbol_obj); \
if (symbol == NULL) \
{ \
PyErr_SetString (PyExc_RuntimeError, \
_("Symbol is invalid.")); \
return NULL; \
} \
} while (0)
/* A deleter that is used when an objfile is about to be freed. */
struct symbol_object_deleter
{
void operator() (symbol_object *obj)
{
while (obj)
{
symbol_object *next = obj->next;
obj->symbol = NULL;
obj->next = NULL;
obj->prev = NULL;
obj = next;
}
}
};
static const registry<objfile>::key<symbol_object, symbol_object_deleter>
sympy_objfile_data_key;
static PyObject *
sympy_str (PyObject *self)
{
PyObject *result;
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
result = PyUnicode_FromString (symbol->print_name ());
return result;
}
static PyObject *
sympy_get_type (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
if (symbol->type () == NULL)
{
Py_INCREF (Py_None);
return Py_None;
}
return type_to_type_object (symbol->type ());
}
static PyObject *
sympy_get_symtab (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
if (!symbol->is_objfile_owned ())
Py_RETURN_NONE;
return symtab_to_symtab_object (symbol->symtab ());
}
static PyObject *
sympy_get_name (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
return PyUnicode_FromString (symbol->natural_name ());
}
static PyObject *
sympy_get_linkage_name (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
return PyUnicode_FromString (symbol->linkage_name ());
}
static PyObject *
sympy_get_print_name (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
return sympy_str (self);
}
static PyObject *
sympy_get_addr_class (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
return gdb_py_object_from_longest (symbol->aclass ()).release ();
}
static PyObject *
sympy_is_argument (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
return PyBool_FromLong (symbol->is_argument ());
}
static PyObject *
sympy_is_constant (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
enum address_class theclass;
SYMPY_REQUIRE_VALID (self, symbol);
theclass = symbol->aclass ();
return PyBool_FromLong (theclass == LOC_CONST || theclass == LOC_CONST_BYTES);
}
static PyObject *
sympy_is_function (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
enum address_class theclass;
SYMPY_REQUIRE_VALID (self, symbol);
theclass = symbol->aclass ();
return PyBool_FromLong (theclass == LOC_BLOCK);
}
static PyObject *
sympy_is_variable (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
enum address_class theclass;
SYMPY_REQUIRE_VALID (self, symbol);
theclass = symbol->aclass ();
return PyBool_FromLong (!symbol->is_argument ()
&& (theclass == LOC_LOCAL || theclass == LOC_REGISTER
|| theclass == LOC_STATIC || theclass == LOC_COMPUTED
|| theclass == LOC_OPTIMIZED_OUT));
}
/* Implementation of Symbol.is_artificial. */
static PyObject *
sympy_is_artificial (PyObject *self, void *closure)
{
struct symbol *symbol = nullptr;
SYMPY_REQUIRE_VALID (self, symbol);
return PyBool_FromLong (symbol->is_artificial ());
}
/* Implementation of gdb.Symbol.needs_frame -> Boolean.
Returns true iff the symbol needs a frame for evaluation. */
static PyObject *
sympy_needs_frame (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
int result = 0;
SYMPY_REQUIRE_VALID (self, symbol);
try
{
result = symbol_read_needs_frame (symbol);
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (nullptr, except);
}
if (result)
Py_RETURN_TRUE;
Py_RETURN_FALSE;
}
/* Implementation of gdb.Symbol.line -> int.
Returns the line number at which the symbol was defined. */
static PyObject *
sympy_line (PyObject *self, void *closure)
{
struct symbol *symbol = NULL;
SYMPY_REQUIRE_VALID (self, symbol);
return gdb_py_object_from_longest (symbol->line ()).release ();
}
/* Implementation of gdb.Symbol.is_valid (self) -> Boolean.
Returns True if this Symbol still exists in GDB. */
static PyObject *
sympy_is_valid (PyObject *self, PyObject *args)
{
struct symbol *symbol = NULL;
symbol = symbol_object_to_symbol (self);
if (symbol == NULL)
Py_RETURN_FALSE;
Py_RETURN_TRUE;
}
/* Implementation of gdb.Symbol.value (self[, frame]) -> gdb.Value. Returns
the value of the symbol, or an error in various circumstances. */
static PyObject *
sympy_value (PyObject *self, PyObject *args)
{
struct symbol *symbol = NULL;
frame_info_ptr frame_info = NULL;
PyObject *frame_obj = NULL;
if (!PyArg_ParseTuple (args, "|O", &frame_obj))
return NULL;
if (frame_obj != NULL && !PyObject_TypeCheck (frame_obj, &frame_object_type))
{
PyErr_SetString (PyExc_TypeError, "argument is not a frame");
return NULL;
}
SYMPY_REQUIRE_VALID (self, symbol);
if (symbol->aclass () == LOC_TYPEDEF)
{
PyErr_SetString (PyExc_TypeError, "cannot get the value of a typedef");
return NULL;
}
PyObject *result = nullptr;
try
{
if (frame_obj != NULL)
{
frame_info = frame_object_to_frame_info (frame_obj);
if (frame_info == NULL)
error (_("invalid frame"));
}
if (symbol_read_needs_frame (symbol) && frame_info == NULL)
error (_("symbol requires a frame to compute its value"));
/* TODO: currently, we have no way to recover the block in which SYMBOL
was found, so we have no block to pass to read_var_value. This will
yield an incorrect value when symbol is not local to FRAME_INFO (this
can happen with nested functions). */
scoped_value_mark free_values;
struct value *value = read_var_value (symbol, NULL, frame_info);
result = value_to_value_object (value);
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (nullptr, except);
}
return result;
}
/* Given a symbol, and a symbol_object that has previously been
allocated and initialized, populate the symbol_object with the
struct symbol data. Also, register the symbol_object life-cycle
with the life-cycle of the object file associated with this
symbol, if needed. */
static void
set_symbol (symbol_object *obj, struct symbol *symbol)
{
obj->symbol = symbol;
obj->prev = NULL;
if (symbol->is_objfile_owned ()
&& symbol->symtab () != NULL)
{
struct objfile *objfile = symbol->objfile ();
obj->next = sympy_objfile_data_key.get (objfile);
if (obj->next)
obj->next->prev = obj;
sympy_objfile_data_key.set (objfile, obj);
}
else
obj->next = NULL;
}
/* Create a new symbol object (gdb.Symbol) that encapsulates the struct
symbol object from GDB. */
PyObject *
symbol_to_symbol_object (struct symbol *sym)
{
symbol_object *sym_obj;
sym_obj = PyObject_New (symbol_object, &symbol_object_type);
if (sym_obj)
set_symbol (sym_obj, sym);
return (PyObject *) sym_obj;
}
/* Return the symbol that is wrapped by this symbol object. */
struct symbol *
symbol_object_to_symbol (PyObject *obj)
{
if (! PyObject_TypeCheck (obj, &symbol_object_type))
return NULL;
return ((symbol_object *) obj)->symbol;
}
static void
sympy_dealloc (PyObject *obj)
{
symbol_object *sym_obj = (symbol_object *) obj;
if (sym_obj->prev)
sym_obj->prev->next = sym_obj->next;
else if (sym_obj->symbol != NULL
&& sym_obj->symbol->is_objfile_owned ()
&& sym_obj->symbol->symtab () != NULL)
sympy_objfile_data_key.set (sym_obj->symbol->objfile (), sym_obj->next);
if (sym_obj->next)
sym_obj->next->prev = sym_obj->prev;
sym_obj->symbol = NULL;
Py_TYPE (obj)->tp_free (obj);
}
/* __repr__ implementation for gdb.Symbol. */
static PyObject *
sympy_repr (PyObject *self)
{
const auto symbol = symbol_object_to_symbol (self);
if (symbol == nullptr)
return gdb_py_invalid_object_repr (self);
return PyUnicode_FromFormat ("<%s print_name=%s>", Py_TYPE (self)->tp_name,
symbol->print_name ());
}
/* Implementation of
gdb.lookup_symbol (name [, block] [, domain]) -> (symbol, is_field_of_this)
A tuple with 2 elements is always returned. The first is the symbol
object or None, the second is a boolean with the value of
is_a_field_of_this (see comment in lookup_symbol_in_language). */
PyObject *
gdbpy_lookup_symbol (PyObject *self, PyObject *args, PyObject *kw)
{
int domain = VAR_DOMAIN;
struct field_of_this_result is_a_field_of_this;
const char *name;
static const char *keywords[] = { "name", "block", "domain", NULL };
struct symbol *symbol = NULL;
PyObject *block_obj = NULL, *sym_obj, *bool_obj;
const struct block *block = NULL;
if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "s|O!i", keywords, &name,
&block_object_type, &block_obj,
&domain))
return NULL;
if (block_obj)
block = block_object_to_block (block_obj);
else
{
frame_info_ptr selected_frame;
try
{
selected_frame = get_selected_frame (_("No frame selected."));
block = get_frame_block (selected_frame, NULL);
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (nullptr, except);
}
}
try
{
domain_search_flags flags = from_scripting_domain (domain);
symbol = lookup_symbol (name, block, flags, &is_a_field_of_this).symbol;
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (nullptr, except);
}
gdbpy_ref<> ret_tuple (PyTuple_New (2));
if (ret_tuple == NULL)
return NULL;
if (symbol)
{
sym_obj = symbol_to_symbol_object (symbol);
if (!sym_obj)
return NULL;
}
else
{
sym_obj = Py_None;
Py_INCREF (Py_None);
}
PyTuple_SET_ITEM (ret_tuple.get (), 0, sym_obj);
bool_obj = PyBool_FromLong (is_a_field_of_this.type != NULL);
PyTuple_SET_ITEM (ret_tuple.get (), 1, bool_obj);
return ret_tuple.release ();
}
/* Implementation of
gdb.lookup_global_symbol (name [, domain]) -> symbol or None. */
PyObject *
gdbpy_lookup_global_symbol (PyObject *self, PyObject *args, PyObject *kw)
{
int domain = VAR_DOMAIN;
const char *name;
static const char *keywords[] = { "name", "domain", NULL };
struct symbol *symbol = NULL;
PyObject *sym_obj;
if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "s|i", keywords, &name,
&domain))
return NULL;
try
{
domain_search_flags flags = from_scripting_domain (domain);
symbol = lookup_global_symbol (name, NULL, flags).symbol;
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (nullptr, except);
}
if (symbol)
{
sym_obj = symbol_to_symbol_object (symbol);
if (!sym_obj)
return NULL;
}
else
{
sym_obj = Py_None;
Py_INCREF (Py_None);
}
return sym_obj;
}
/* Implementation of
gdb.lookup_static_symbol (name [, domain]) -> symbol or None. */
PyObject *
gdbpy_lookup_static_symbol (PyObject *self, PyObject *args, PyObject *kw)
{
const char *name;
int domain = VAR_DOMAIN;
static const char *keywords[] = { "name", "domain", NULL };
struct symbol *symbol = NULL;
PyObject *sym_obj;
if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "s|i", keywords, &name,
&domain))
return NULL;
/* In order to find static symbols associated with the "current" object
file ahead of those from other object files, we first need to see if
we can acquire a current block. If this fails however, then we still
want to search all static symbols, so don't throw an exception just
yet. */
const struct block *block = NULL;
try
{
frame_info_ptr selected_frame
= get_selected_frame (_("No frame selected."));
block = get_frame_block (selected_frame, NULL);
}
catch (const gdb_exception_forced_quit &e)
{
quit_force (NULL, 0);
}
catch (const gdb_exception &except)
{
/* Nothing. */
}
try
{
domain_search_flags flags = from_scripting_domain (domain);
if (block != nullptr)
symbol
= lookup_symbol_in_static_block (name, block, flags).symbol;
if (symbol == nullptr)
symbol = lookup_static_symbol (name, flags).symbol;
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (nullptr, except);
}
if (symbol)
{
sym_obj = symbol_to_symbol_object (symbol);
if (!sym_obj)
return NULL;
}
else
{
sym_obj = Py_None;
Py_INCREF (Py_None);
}
return sym_obj;
}
/* Implementation of
gdb.lookup_static_symbols (name [, domain]) -> symbol list.
Returns a list of all static symbols matching NAME in DOMAIN. */
PyObject *
gdbpy_lookup_static_symbols (PyObject *self, PyObject *args, PyObject *kw)
{
const char *name;
int domain = VAR_DOMAIN;
static const char *keywords[] = { "name", "domain", NULL };
if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "s|i", keywords, &name,
&domain))
return NULL;
gdbpy_ref<> return_list (PyList_New (0));
if (return_list == NULL)
return NULL;
try
{
domain_search_flags flags = from_scripting_domain (domain);
/* Expand any symtabs that contain potentially matching symbols. */
lookup_name_info lookup_name (name, symbol_name_match_type::FULL);
expand_symtabs_matching (NULL, lookup_name, NULL, NULL,
SEARCH_GLOBAL_BLOCK | SEARCH_STATIC_BLOCK,
SEARCH_ALL_DOMAINS);
for (objfile *objfile : current_program_space->objfiles ())
{
for (compunit_symtab *cust : objfile->compunits ())
{
/* Skip included compunits to prevent including compunits from
being searched twice. */
if (cust->user != nullptr)
continue;
const struct blockvector *bv = cust->blockvector ();
const struct block *block = bv->static_block ();
if (block != nullptr)
{
symbol *symbol = lookup_symbol_in_static_block
(name, block, flags).symbol;
if (symbol != nullptr)
{
PyObject *sym_obj
= symbol_to_symbol_object (symbol);
if (PyList_Append (return_list.get (), sym_obj) == -1)
return NULL;
}
}
}
}
}
catch (const gdb_exception &except)
{
return gdbpy_handle_gdb_exception (nullptr, except);
}
return return_list.release ();
}
static int CPYCHECKER_NEGATIVE_RESULT_SETS_EXCEPTION
gdbpy_initialize_symbols (void)
{
if (gdbpy_type_ready (&symbol_object_type) < 0)
return -1;
if (PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_UNDEF", LOC_UNDEF) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_CONST",
LOC_CONST) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_STATIC",
LOC_STATIC) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_REGISTER",
LOC_REGISTER) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_ARG",
LOC_ARG) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_REF_ARG",
LOC_REF_ARG) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_LOCAL",
LOC_LOCAL) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_TYPEDEF",
LOC_TYPEDEF) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_LABEL",
LOC_LABEL) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_BLOCK",
LOC_BLOCK) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_CONST_BYTES",
LOC_CONST_BYTES) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_UNRESOLVED",
LOC_UNRESOLVED) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_OPTIMIZED_OUT",
LOC_OPTIMIZED_OUT) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_COMPUTED",
LOC_COMPUTED) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_COMMON_BLOCK",
LOC_COMMON_BLOCK) < 0
|| PyModule_AddIntConstant (gdb_module, "SYMBOL_LOC_REGPARM_ADDR",
LOC_REGPARM_ADDR) < 0)
return -1;
#define SYM_DOMAIN(X) \
if (PyModule_AddIntConstant (gdb_module, "SYMBOL_" #X "_DOMAIN", \
to_scripting_domain (X ## _DOMAIN)) < 0 \
|| PyModule_AddIntConstant (gdb_module, "SEARCH_" #X "_DOMAIN", \
to_scripting_domain (SEARCH_ ## X ## _DOMAIN)) < 0) \
return -1;
#include "sym-domains.def"
#undef SYM_DOMAIN
return 0;
}
GDBPY_INITIALIZE_FILE (gdbpy_initialize_symbols);
static gdb_PyGetSetDef symbol_object_getset[] = {
{ "type", sympy_get_type, NULL,
"Type of the symbol.", NULL },
{ "symtab", sympy_get_symtab, NULL,
"Symbol table in which the symbol appears.", NULL },
{ "name", sympy_get_name, NULL,
"Name of the symbol, as it appears in the source code.", NULL },
{ "linkage_name", sympy_get_linkage_name, NULL,
"Name of the symbol, as used by the linker (i.e., may be mangled).",
NULL },
{ "print_name", sympy_get_print_name, NULL,
"Name of the symbol in a form suitable for output.\n\
This is either name or linkage_name, depending on whether the user asked GDB\n\
to display demangled or mangled names.", NULL },
{ "addr_class", sympy_get_addr_class, NULL, "Address class of the symbol." },
{ "is_argument", sympy_is_argument, NULL,
"True if the symbol is an argument of a function." },
{ "is_artificial", sympy_is_artificial, nullptr,
"True if the symbol is marked artificial." },
{ "is_constant", sympy_is_constant, NULL,
"True if the symbol is a constant." },
{ "is_function", sympy_is_function, NULL,
"True if the symbol is a function or method." },
{ "is_variable", sympy_is_variable, NULL,
"True if the symbol is a variable." },
{ "needs_frame", sympy_needs_frame, NULL,
"True if the symbol requires a frame for evaluation." },
{ "line", sympy_line, NULL,
"The source line number at which the symbol was defined." },
{ NULL } /* Sentinel */
};
static PyMethodDef symbol_object_methods[] = {
{ "is_valid", sympy_is_valid, METH_NOARGS,
"is_valid () -> Boolean.\n\
Return true if this symbol is valid, false if not." },
{ "value", sympy_value, METH_VARARGS,
"value ([frame]) -> gdb.Value\n\
Return the value of the symbol." },
{NULL} /* Sentinel */
};
PyTypeObject symbol_object_type = {
PyVarObject_HEAD_INIT (NULL, 0)
"gdb.Symbol", /*tp_name*/
sizeof (symbol_object), /*tp_basicsize*/
0, /*tp_itemsize*/
sympy_dealloc, /*tp_dealloc*/
0, /*tp_print*/
0, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_compare*/
sympy_repr, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
0, /*tp_as_mapping*/
0, /*tp_hash */
0, /*tp_call*/
sympy_str, /*tp_str*/
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT, /*tp_flags*/
"GDB symbol object", /*tp_doc */
0, /*tp_traverse */
0, /*tp_clear */
0, /*tp_richcompare */
0, /*tp_weaklistoffset */
0, /*tp_iter */
0, /*tp_iternext */
symbol_object_methods, /*tp_methods */
0, /*tp_members */
symbol_object_getset /*tp_getset */
};