7d45c7c3f6
This change introduces a new function, dwarf2_string_attr(), which is
a wrapper for dwarf2_attr(). dwarf2read.c has been updated to
call dwarf2_string_attr in most instances where a string-valued
attribute is decoded to produce a string value. In most cases, it
simplifies the code; in some instances, the complexity of the code
remains unchanged.
I performed this change by looking for instances where the
result of DW_STRING was used in an assignment. Many of these
had a pattern which (roughly) looks something like this:
struct attribute *attr = NULL;
attr = dwarf2_attr (die, name, cu);
if (attr != NULL && DW_STRING (attr))
{
const char *str;
...
str = DW_STRING (attr);
... /* Use str in some fashion. */
}
Code of this form is transformed to look like this instead:
const char *str;
str = dwarf2_string_attr (die, name, cu)
if (str != NULL)
{
...
/* Use str in some fashion. */
...
}
In addition to invoking dwarf2_attr() and DW_STRING(),
dwarf2_string_attr() checks to make sure that the attribute's
`form' field matches one of DW_FORM_strp, DW_FORM_string, or
DW_FORM_GNU_strp_alt. If it does not match one of these forms,
it will return a NULL value in addition to calling complaint().
An earlier version of this patch did this type checking for one
particular instance where a string attribute was being decoded.
The situation that I was attempting to handle in that earlier patch is
this:
The Texas Instruments compiler uses the encoding for
DW_AT_MIPS_linkage_name for other purposes. TI uses the encoding,
0x2007, for TI_AT_TI_end_line which, unlike DW_AT_MIPS_linkage_name,
does not have a string-typed value. In this instance, GDB was attempting
to use an integer value as a string pointer, with predictable results.
(GDB would die with a segmentation fault.)
I've added a test which reproduces the problem that I was orignally
wanting to fix. It uses DW_AT_MIPS_linkage name with an associate
value which is a string, and again, where the value is a small
integer.
My test case causes GDB to segfault in an unpatched GDB. There
will be two PASSes in a patched GDB.
Unpatched GDB:
(gdb) ptype f
ERROR: Process no longer exists
UNRESOLVED: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype f
ERROR: Couldn't send ptype g to GDB.
UNRESOLVED: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype g
Patched GDB:
(gdb) ptype f
type = bool ()
(gdb) PASS: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype f
ptype g
type = bool ()
(gdb) PASS: gdb.dwarf2/dw2-bad-mips-linkage-name.exp: ptype g
I see no regressions on an x86_64 native target.
gdb/ChangeLog:
* dwarf2read.c (dwarf2_string_attr): New function.
(lookup_dwo_unit, process_psymtab_comp_unit_reader)
(dwarf2_compute_name, dwarf2_physname, find_file_and_directory)
(read_call_site_scope, namespace_name, guess_full_die_structure_name)
(anonymous_struct_prefix, prepare_one_comp_unit): Use
dwarf2_string_attr in place of dwarf2_attr and DW_STRING.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/dw2-bad-mips-linkage-name.c: New file.
* gdb.dwarf2/dw2-bad-mips-linkage-name.exp: New file.
72 lines
2.1 KiB
Text
72 lines
2.1 KiB
Text
# Copyright 2015 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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load_lib dwarf.exp
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# This test can only be run on targets which support DWARF-2 and use gas.
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if {![dwarf2_support]} {
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return 0
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}
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standard_testfile dw2-bad-mips-linkage-name.c dw2-bad-mips-linkage-name.S
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# Set up the DWARF for the test.
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set asm_file [standard_output_file $srcfile2]
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Dwarf::assemble $asm_file {
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cu {} {
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DW_TAG_compile_unit {
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{DW_AT_language @DW_LANG_C}
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{DW_AT_name dw2-bad-mips-linkage-name.c}
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{DW_AT_comp_dir /tmp}
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} {
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declare_labels b_l
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b_l: DW_TAG_base_type {
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{DW_AT_byte_size 1 DW_FORM_sdata}
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{DW_AT_encoding @DW_ATE_signed}
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{DW_AT_name bool}
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}
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DW_TAG_subprogram {
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{name f}
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{low_pc f addr}
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{high_pc f_end_lbl addr}
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{type :$b_l}
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{DW_AT_MIPS_linkage_name _Z1fv}
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}
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DW_TAG_subprogram {
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{name g}
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{low_pc g addr}
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{high_pc g_end_lbl addr}
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{type :$b_l}
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{DW_AT_MIPS_linkage_name 42 DW_FORM_data1}
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}
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}
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}
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}
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if { [prepare_for_testing ${testfile}.exp ${testfile} \
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[list $srcfile $asm_file] {nodebug}] } {
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return -1
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}
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# A successful run will have two PASSes. A GDB that's lacking
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# attribute type checking will segfault at some point. It doesn't
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# much matter what we test here, so long as we do something to make
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# sure that the DWARF is read.
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gdb_test "ptype f" " = bool \\(\\)"
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gdb_test "ptype g" " = bool \\(\\)"
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