Demangler crash handler
This commit wraps calls to the demangler with a segmentation fault handler. The first time a segmentation fault is caught a core file is generated and the user is prompted to file a bug and offered the choice to exit or to continue their GDB session. A maintainence option is provided to allow the user to disable the crash handler if required. gdb/ 2014-06-19 Gary Benson <gbenson@redhat.com> * configure.ac [AC_CHECK_FUNCS] <sigaltstack>: New check. * configure: Regenerate. * config.in: Likewise. * main.c (signal.h): New include. (setup_alternate_signal_stack): New function. (captured_main): Call the above. * cp-support.c (signal.h): New include. (catch_demangler_crashes): New flag. (SIGJMP_BUF): New define. (SIGSETJMP): Likewise. (SIGLONGJMP): Likewise. (gdb_demangle_jmp_buf): New static global. (gdb_demangle_attempt_core_dump): Likewise. (gdb_demangle_signal_handler): New function. (gdb_demangle): If catch_demangler_crashes is set, install the above signal handler before calling bfd_demangle, and restore the original signal handler afterwards. Display the offending symbol and call demangler_warning the first time a segmentation fault is caught. (_initialize_cp_support): New maint set/show command. gdb/doc/ 2014-06-19 Gary Benson <gbenson@redhat.com> * gdb.texinfo (Maintenance Commands): Document new "maint set/show catch-demangler-crashes" option.
This commit is contained in:
Gary Benson
parent
eae7090bea
commit
992c7d700f
8 changed files with 214 additions and 3 deletions
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@ -1,3 +1,26 @@
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2014-06-19 Gary Benson <gbenson@redhat.com>
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* configure.ac [AC_CHECK_FUNCS] <sigaltstack>: New check.
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* configure: Regenerate.
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* config.in: Likewise.
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* main.c (signal.h): New include.
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(setup_alternate_signal_stack): New function.
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(captured_main): Call the above.
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* cp-support.c (signal.h): New include.
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(catch_demangler_crashes): New flag.
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(SIGJMP_BUF): New define.
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(SIGSETJMP): Likewise.
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(SIGLONGJMP): Likewise.
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(gdb_demangle_jmp_buf): New static global.
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(gdb_demangle_attempt_core_dump): Likewise.
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(gdb_demangle_signal_handler): New function.
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(gdb_demangle): If catch_demangler_crashes is set, install the
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above signal handler before calling bfd_demangle, and restore
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the original signal handler afterwards. Display the offending
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symbol and call demangler_warning the first time a segmentation
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fault is caught.
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(_initialize_cp_support): New maint set/show command.
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2014-06-19 Gary Benson <gbenson@redhat.com>
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* utils.h (resource_limit_kind): New enum.
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@ -366,6 +366,9 @@
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/* Define to 1 if you have the `sigaction' function. */
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#undef HAVE_SIGACTION
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/* Define to 1 if you have the `sigaltstack' function. */
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#undef HAVE_SIGALTSTACK
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/* Define to 1 if you have the <signal.h> header file. */
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#undef HAVE_SIGNAL_H
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2
gdb/configure
vendored
2
gdb/configure
vendored
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@ -10507,7 +10507,7 @@ for ac_func in canonicalize_file_name realpath getrusage getuid getgid \
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sigaction sigprocmask sigsetmask socketpair \
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ttrace wborder wresize setlocale iconvlist libiconvlist btowc \
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setrlimit getrlimit posix_madvise waitpid lstat \
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ptrace64
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ptrace64 sigaltstack
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do :
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as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
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ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
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@ -1328,7 +1328,7 @@ AC_CHECK_FUNCS([canonicalize_file_name realpath getrusage getuid getgid \
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sigaction sigprocmask sigsetmask socketpair \
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ttrace wborder wresize setlocale iconvlist libiconvlist btowc \
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setrlimit getrlimit posix_madvise waitpid lstat \
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ptrace64])
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ptrace64 sigaltstack])
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AM_LANGINFO_CODESET
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GDB_AC_COMMON
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146
gdb/cp-support.c
146
gdb/cp-support.c
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@ -35,6 +35,7 @@
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#include "expression.h"
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#include "value.h"
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#include "cp-abi.h"
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#include <signal.h>
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#include "safe-ctype.h"
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@ -1482,12 +1483,142 @@ cp_lookup_rtti_type (const char *name, struct block *block)
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return rtti_type;
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}
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#ifdef HAVE_WORKING_FORK
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/* If nonzero, attempt to catch crashes in the demangler and print
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useful debugging information. */
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static int catch_demangler_crashes = 1;
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/* Wrap set/long jmp so that it's more portable. */
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#if defined(HAVE_SIGSETJMP)
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#define SIGJMP_BUF sigjmp_buf
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#define SIGSETJMP(buf) sigsetjmp((buf), 1)
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#define SIGLONGJMP(buf,val) siglongjmp((buf), (val))
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#else
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#define SIGJMP_BUF jmp_buf
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#define SIGSETJMP(buf) setjmp(buf)
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#define SIGLONGJMP(buf,val) longjmp((buf), (val))
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#endif
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/* Stack context and environment for demangler crash recovery. */
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static SIGJMP_BUF gdb_demangle_jmp_buf;
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/* If nonzero, attempt to dump core from the signal handler. */
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static int gdb_demangle_attempt_core_dump = 1;
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/* Signal handler for gdb_demangle. */
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static void
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gdb_demangle_signal_handler (int signo)
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{
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if (gdb_demangle_attempt_core_dump)
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{
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if (fork () == 0)
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dump_core ();
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gdb_demangle_attempt_core_dump = 0;
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}
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SIGLONGJMP (gdb_demangle_jmp_buf, signo);
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}
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#endif
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/* A wrapper for bfd_demangle. */
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char *
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gdb_demangle (const char *name, int options)
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{
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return bfd_demangle (NULL, name, options);
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char *result = NULL;
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int crash_signal = 0;
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#ifdef HAVE_WORKING_FORK
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#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
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struct sigaction sa, old_sa;
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#else
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void (*ofunc) ();
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#endif
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static int core_dump_allowed = -1;
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if (core_dump_allowed == -1)
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{
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core_dump_allowed = can_dump_core (LIMIT_CUR);
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if (!core_dump_allowed)
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gdb_demangle_attempt_core_dump = 0;
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}
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if (catch_demangler_crashes)
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{
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#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
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sa.sa_handler = gdb_demangle_signal_handler;
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sigemptyset (&sa.sa_mask);
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sa.sa_flags = SA_ONSTACK;
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sigaction (SIGSEGV, &sa, &old_sa);
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#else
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ofunc = (void (*)()) signal (SIGSEGV, gdb_demangle_signal_handler);
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#endif
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crash_signal = SIGSETJMP (gdb_demangle_jmp_buf);
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}
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#endif
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if (crash_signal == 0)
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result = bfd_demangle (NULL, name, options);
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#ifdef HAVE_WORKING_FORK
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if (catch_demangler_crashes)
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{
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#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
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sigaction (SIGSEGV, &old_sa, NULL);
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#else
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signal (SIGSEGV, ofunc);
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#endif
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if (crash_signal != 0)
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{
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static int error_reported = 0;
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if (!error_reported)
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{
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char *short_msg, *long_msg;
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struct cleanup *back_to;
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short_msg = xstrprintf (_("unable to demangle '%s' "
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"(demangler failed with signal %d)"),
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name, crash_signal);
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back_to = make_cleanup (xfree, short_msg);
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long_msg = xstrprintf ("%s:%d: %s: %s", __FILE__, __LINE__,
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"demangler-warning", short_msg);
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make_cleanup (xfree, long_msg);
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target_terminal_ours ();
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begin_line ();
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if (core_dump_allowed)
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fprintf_unfiltered (gdb_stderr,
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_("%s\nAttempting to dump core.\n"),
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long_msg);
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else
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warn_cant_dump_core (long_msg);
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demangler_warning (__FILE__, __LINE__, "%s", short_msg);
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do_cleanups (back_to);
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error_reported = 1;
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}
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result = NULL;
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}
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}
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#endif
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return result;
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}
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/* Don't allow just "maintenance cplus". */
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@ -1562,4 +1693,17 @@ _initialize_cp_support (void)
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Usage: info vtbl EXPRESSION\n\
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Evaluate EXPRESSION and display the virtual function table for the\n\
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resulting object."));
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#ifdef HAVE_WORKING_FORK
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add_setshow_boolean_cmd ("catch-demangler-crashes", class_maintenance,
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&catch_demangler_crashes, _("\
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Set whether to attempt to catch demangler crashes."), _("\
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Show whether to attempt to catch demangler crashes."), _("\
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If enabled GDB will attempt to catch demangler crashes and\n\
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display the offending symbol."),
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NULL,
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NULL,
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&maintenance_set_cmdlist,
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&maintenance_show_cmdlist);
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#endif
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}
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@ -1,3 +1,8 @@
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2014-06-19 Gary Benson <gbenson@redhat.com>
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* gdb.texinfo (Maintenance Commands): Document new
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"maint set/show catch-demangler-crashes" option.
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2014-06-19 Gary Benson <gbenson@redhat.com>
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* gdb.texinfo (Maintenance Commands): Document new
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@ -33236,6 +33236,17 @@ Expand symbol tables.
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If @var{regexp} is specified, only expand symbol tables for file
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names matching @var{regexp}.
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@kindex maint set catch-demangler-crashes
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@kindex maint show catch-demangler-crashes
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@cindex demangler crashes
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@item maint set catch-demangler-crashes [on|off]
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@itemx maint show catch-demangler-crashes
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Control whether @value{GDBN} should attempt to catch crashes in the
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symbol name demangler. The default is to attempt to catch crashes.
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If enabled, the first time a crash is caught, a core file is created,
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the offending symbol is displayed and the user is presented with the
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option to terminate the current session.
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@kindex maint cplus first_component
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@item maint cplus first_component @var{name}
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Print the first C@t{++} class/namespace component of @var{name}.
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25
gdb/main.c
25
gdb/main.c
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#include "filenames.h"
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#include "filestuff.h"
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#include <signal.h>
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/* The selected interpreter. This will be used as a set command
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variable, so it should always be malloc'ed - since
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@ -288,6 +289,27 @@ get_init_files (const char **system_gdbinit,
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*local_gdbinit = localinit;
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}
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/* Try to set up an alternate signal stack for SIGSEGV handlers.
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This allows us to handle SIGSEGV signals generated when the
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normal process stack is exhausted. If this stack is not set
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up (sigaltstack is unavailable or fails) and a SIGSEGV is
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generated when the normal stack is exhausted then the program
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will behave as though no SIGSEGV handler was installed. */
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static void
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setup_alternate_signal_stack (void)
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{
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#ifdef HAVE_SIGALTSTACK
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stack_t ss;
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ss.ss_sp = xmalloc (SIGSTKSZ);
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ss.ss_size = SIGSTKSZ;
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ss.ss_flags = 0;
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sigaltstack(&ss, NULL);
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#endif
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}
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/* Call command_loop. If it happens to return, pass that through as a
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non-zero return status. */
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@ -785,6 +807,9 @@ captured_main (void *data)
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quiet = 1;
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}
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/* Try to set up an alternate signal stack for SIGSEGV handlers. */
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setup_alternate_signal_stack ();
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/* Initialize all files. Give the interpreter a chance to take
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control of the console via the deprecated_init_ui_hook (). */
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gdb_init (gdb_program_name);
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