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binutils-gdb/gdb/bt-utils.h

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Automatic Copyright Year update after running gdb/copyright.py This commit brings all the changes made by running gdb/copyright.py as per GDB's Start of New Year Procedure. For the avoidance of doubt, all changes in this commits were performed by the script.
2022-01-01 22:56:03 +08:00
/* Copyright (C) 2021-2022 Free Software Foundation, Inc.
gdb: use libbacktrace to create a better backtrace for fatal signals GDB recently gained the ability to print a backtrace when a fatal signal is encountered. This backtrace is produced using the backtrace and backtrace_symbols_fd API available in glibc. However, in order for this API to actually map addresses to symbol names it is required that the application (GDB) be compiled with -rdynamic, which GDB is not by default. As a result, the backtrace produced often looks like this: Fatal signal: Bus error ----- Backtrace ----- ./gdb/gdb[0x80ec00] ./gdb/gdb[0x80ed56] /lib64/libc.so.6(+0x3c6b0)[0x7fc2ce1936b0] /lib64/libc.so.6(__poll+0x4f)[0x7fc2ce24da5f] ./gdb/gdb[0x15495ba] ./gdb/gdb[0x15489b8] ./gdb/gdb[0x9b794d] ./gdb/gdb[0x9b7a6d] ./gdb/gdb[0x9b943b] ./gdb/gdb[0x9b94a1] ./gdb/gdb[0x4175dd] /lib64/libc.so.6(__libc_start_main+0xf3)[0x7fc2ce17e1a3] ./gdb/gdb[0x4174de] --------------------- This is OK if you have access to the exact same build of GDB, you can manually map the addresses back to symbols, however, it is next to useless if all you have is a backtrace copied into a bug report. GCC uses libbacktrace for printing a backtrace when it encounters an error. In recent commits I added this library into the binutils-gdb repository, and in this commit I allow this library to be used by GDB. Now (when GDB is compiled with debug information) the backtrace looks like this: ----- Backtrace ----- 0x80ee08 gdb_internal_backtrace ../../src/gdb/event-top.c:989 0x80ef0b handle_fatal_signal ../../src/gdb/event-top.c:1036 0x7f24539dd6af ??? 0x7f2453a97a5f ??? 0x154976f gdb_wait_for_event ../../src/gdbsupport/event-loop.cc:613 0x1548b6d _Z16gdb_do_one_eventv ../../src/gdbsupport/event-loop.cc:237 0x9b7b02 start_event_loop ../../src/gdb/main.c:421 0x9b7c22 captured_command_loop ../../src/gdb/main.c:481 0x9b95f0 captured_main ../../src/gdb/main.c:1353 0x9b9656 _Z8gdb_mainP18captured_main_args ../../src/gdb/main.c:1368 0x4175ec main ../../src/gdb/gdb.c:32 --------------------- Which seems much more useful. Use of libbacktrace is optional. If GDB is configured with --disable-libbacktrace then the libbacktrace directory will not be built, and GDB will not try to use this library. In this case GDB would try to use the old backtrace and backtrace_symbols_fd API. All of the functions related to writing the backtrace of GDB itself have been moved into the new files gdb/by-utils.{c,h}.
2021-08-11 20:24:33 +08:00
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/>. */
/* Support for printing a backtrace when GDB hits an error. This is not
for printing backtraces of the inferior, but backtraces of GDB itself. */
Do not print anything when self-backtrace unavailable Right now, gdb's self-backtrace feature will still print something when a backtrace is unavailable: sig_write (_("----- Backtrace -----\n")); [...] sig_write (_("Backtrace unavailable\n")); sig_write ("---------------------\n"); However, if GDB_PRINT_INTERNAL_BACKTRACE is undefined, it seems better to me to print nothing at all. This patch implements this change. It also makes a couple of other small changes in this same module: it adds a header guard to bt-utils.h, and it protects the definitions of gdb_internal_backtrace_1 with a check of GDB_PRINT_INTERNAL_BACKTRACE.
2022-01-05 23:43:59 +08:00
#ifndef BT_UTILS_H
#define BT_UTILS_H
gdb: use libbacktrace to create a better backtrace for fatal signals GDB recently gained the ability to print a backtrace when a fatal signal is encountered. This backtrace is produced using the backtrace and backtrace_symbols_fd API available in glibc. However, in order for this API to actually map addresses to symbol names it is required that the application (GDB) be compiled with -rdynamic, which GDB is not by default. As a result, the backtrace produced often looks like this: Fatal signal: Bus error ----- Backtrace ----- ./gdb/gdb[0x80ec00] ./gdb/gdb[0x80ed56] /lib64/libc.so.6(+0x3c6b0)[0x7fc2ce1936b0] /lib64/libc.so.6(__poll+0x4f)[0x7fc2ce24da5f] ./gdb/gdb[0x15495ba] ./gdb/gdb[0x15489b8] ./gdb/gdb[0x9b794d] ./gdb/gdb[0x9b7a6d] ./gdb/gdb[0x9b943b] ./gdb/gdb[0x9b94a1] ./gdb/gdb[0x4175dd] /lib64/libc.so.6(__libc_start_main+0xf3)[0x7fc2ce17e1a3] ./gdb/gdb[0x4174de] --------------------- This is OK if you have access to the exact same build of GDB, you can manually map the addresses back to symbols, however, it is next to useless if all you have is a backtrace copied into a bug report. GCC uses libbacktrace for printing a backtrace when it encounters an error. In recent commits I added this library into the binutils-gdb repository, and in this commit I allow this library to be used by GDB. Now (when GDB is compiled with debug information) the backtrace looks like this: ----- Backtrace ----- 0x80ee08 gdb_internal_backtrace ../../src/gdb/event-top.c:989 0x80ef0b handle_fatal_signal ../../src/gdb/event-top.c:1036 0x7f24539dd6af ??? 0x7f2453a97a5f ??? 0x154976f gdb_wait_for_event ../../src/gdbsupport/event-loop.cc:613 0x1548b6d _Z16gdb_do_one_eventv ../../src/gdbsupport/event-loop.cc:237 0x9b7b02 start_event_loop ../../src/gdb/main.c:421 0x9b7c22 captured_command_loop ../../src/gdb/main.c:481 0x9b95f0 captured_main ../../src/gdb/main.c:1353 0x9b9656 _Z8gdb_mainP18captured_main_args ../../src/gdb/main.c:1368 0x4175ec main ../../src/gdb/gdb.c:32 --------------------- Which seems much more useful. Use of libbacktrace is optional. If GDB is configured with --disable-libbacktrace then the libbacktrace directory will not be built, and GDB will not try to use this library. In this case GDB would try to use the old backtrace and backtrace_symbols_fd API. All of the functions related to writing the backtrace of GDB itself have been moved into the new files gdb/by-utils.{c,h}.
2021-08-11 20:24:33 +08:00
#ifdef HAVE_LIBBACKTRACE
# include "backtrace.h"
# include "backtrace-supported.h"
# if BACKTRACE_SUPPORTED && (! BACKTRACE_USES_MALLOC)
# define GDB_PRINT_INTERNAL_BACKTRACE
# define GDB_PRINT_INTERNAL_BACKTRACE_USING_LIBBACKTRACE
# endif
#endif
#if defined HAVE_EXECINFO_H \
&& defined HAVE_EXECINFO_BACKTRACE \
&& !defined PRINT_BACKTRACE_ON_FATAL_SIGNAL
# include <execinfo.h>
# define GDB_PRINT_INTERNAL_BACKTRACE
# define GDB_PRINT_INTERNAL_BACKTRACE_USING_EXECINFO
#endif
/* Define GDB_PRINT_INTERNAL_BACKTRACE_INIT_ON. This is a boolean value
that can be used as an initial value for a set/show user setting, where
the setting controls printing a GDB internal backtrace.
If backtrace printing is supported then this will have the value true,
but if backtrace printing is not supported then this has the value
false. */
#ifdef GDB_PRINT_INTERNAL_BACKTRACE
# define GDB_PRINT_INTERNAL_BACKTRACE_INIT_ON true
#else
# define GDB_PRINT_INTERNAL_BACKTRACE_INIT_ON false
#endif
/* Print a backtrace of the current GDB process to the current
gdb: fix manor -> manner typo in some comments In a recent commit I used 'manor' in some comments rather than 'manner'. This commit fixes those two mistakes. I also looked through the gdb/ tree and found one additional instance of this mistake that this commit also fixes.
2021-09-29 16:16:52 +08:00
gdb_stderr. The output is done in a signal async manner, so it is safe
gdb: use libbacktrace to create a better backtrace for fatal signals GDB recently gained the ability to print a backtrace when a fatal signal is encountered. This backtrace is produced using the backtrace and backtrace_symbols_fd API available in glibc. However, in order for this API to actually map addresses to symbol names it is required that the application (GDB) be compiled with -rdynamic, which GDB is not by default. As a result, the backtrace produced often looks like this: Fatal signal: Bus error ----- Backtrace ----- ./gdb/gdb[0x80ec00] ./gdb/gdb[0x80ed56] /lib64/libc.so.6(+0x3c6b0)[0x7fc2ce1936b0] /lib64/libc.so.6(__poll+0x4f)[0x7fc2ce24da5f] ./gdb/gdb[0x15495ba] ./gdb/gdb[0x15489b8] ./gdb/gdb[0x9b794d] ./gdb/gdb[0x9b7a6d] ./gdb/gdb[0x9b943b] ./gdb/gdb[0x9b94a1] ./gdb/gdb[0x4175dd] /lib64/libc.so.6(__libc_start_main+0xf3)[0x7fc2ce17e1a3] ./gdb/gdb[0x4174de] --------------------- This is OK if you have access to the exact same build of GDB, you can manually map the addresses back to symbols, however, it is next to useless if all you have is a backtrace copied into a bug report. GCC uses libbacktrace for printing a backtrace when it encounters an error. In recent commits I added this library into the binutils-gdb repository, and in this commit I allow this library to be used by GDB. Now (when GDB is compiled with debug information) the backtrace looks like this: ----- Backtrace ----- 0x80ee08 gdb_internal_backtrace ../../src/gdb/event-top.c:989 0x80ef0b handle_fatal_signal ../../src/gdb/event-top.c:1036 0x7f24539dd6af ??? 0x7f2453a97a5f ??? 0x154976f gdb_wait_for_event ../../src/gdbsupport/event-loop.cc:613 0x1548b6d _Z16gdb_do_one_eventv ../../src/gdbsupport/event-loop.cc:237 0x9b7b02 start_event_loop ../../src/gdb/main.c:421 0x9b7c22 captured_command_loop ../../src/gdb/main.c:481 0x9b95f0 captured_main ../../src/gdb/main.c:1353 0x9b9656 _Z8gdb_mainP18captured_main_args ../../src/gdb/main.c:1368 0x4175ec main ../../src/gdb/gdb.c:32 --------------------- Which seems much more useful. Use of libbacktrace is optional. If GDB is configured with --disable-libbacktrace then the libbacktrace directory will not be built, and GDB will not try to use this library. In this case GDB would try to use the old backtrace and backtrace_symbols_fd API. All of the functions related to writing the backtrace of GDB itself have been moved into the new files gdb/by-utils.{c,h}.
2021-08-11 20:24:33 +08:00
to call from signal handlers. */
extern void gdb_internal_backtrace ();
/* A generic function that can be used as the set function for any set
command that enables printing of an internal backtrace. Command C must
be a boolean set command.
If GDB doesn't support printing a backtrace, and the user has tried to
set the variable associated with command C to true, then the associated
variable will be set back to false, and an error thrown.
If GDB does support printing a backtrace then this function does
nothing. */
extern void gdb_internal_backtrace_set_cmd (const char *args, int from_tty,
cmd_list_element *c);
Do not print anything when self-backtrace unavailable Right now, gdb's self-backtrace feature will still print something when a backtrace is unavailable: sig_write (_("----- Backtrace -----\n")); [...] sig_write (_("Backtrace unavailable\n")); sig_write ("---------------------\n"); However, if GDB_PRINT_INTERNAL_BACKTRACE is undefined, it seems better to me to print nothing at all. This patch implements this change. It also makes a couple of other small changes in this same module: it adds a header guard to bt-utils.h, and it protects the definitions of gdb_internal_backtrace_1 with a check of GDB_PRINT_INTERNAL_BACKTRACE.
2022-01-05 23:43:59 +08:00
#endif /* BT_UTILS_H */
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