+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.
+
2014-06-19 Gary Benson <gbenson@redhat.com>
* utils.h (resource_limit_kind): New enum.
#include "expression.h"
#include "value.h"
#include "cp-abi.h"
+#include <signal.h>
#include "safe-ctype.h"
return rtti_type;
}
+#ifdef HAVE_WORKING_FORK
+
+/* If nonzero, attempt to catch crashes in the demangler and print
+ useful debugging information. */
+
+static int catch_demangler_crashes = 1;
+
+/* Wrap set/long jmp so that it's more portable. */
+
+#if defined(HAVE_SIGSETJMP)
+#define SIGJMP_BUF sigjmp_buf
+#define SIGSETJMP(buf) sigsetjmp((buf), 1)
+#define SIGLONGJMP(buf,val) siglongjmp((buf), (val))
+#else
+#define SIGJMP_BUF jmp_buf
+#define SIGSETJMP(buf) setjmp(buf)
+#define SIGLONGJMP(buf,val) longjmp((buf), (val))
+#endif
+
+/* Stack context and environment for demangler crash recovery. */
+
+static SIGJMP_BUF gdb_demangle_jmp_buf;
+
+/* If nonzero, attempt to dump core from the signal handler. */
+
+static int gdb_demangle_attempt_core_dump = 1;
+
+/* Signal handler for gdb_demangle. */
+
+static void
+gdb_demangle_signal_handler (int signo)
+{
+ if (gdb_demangle_attempt_core_dump)
+ {
+ if (fork () == 0)
+ dump_core ();
+
+ gdb_demangle_attempt_core_dump = 0;
+ }
+
+ SIGLONGJMP (gdb_demangle_jmp_buf, signo);
+}
+
+#endif
+
/* A wrapper for bfd_demangle. */
char *
gdb_demangle (const char *name, int options)
{
- return bfd_demangle (NULL, name, options);
+ char *result = NULL;
+ int crash_signal = 0;
+
+#ifdef HAVE_WORKING_FORK
+#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
+ struct sigaction sa, old_sa;
+#else
+ void (*ofunc) ();
+#endif
+ static int core_dump_allowed = -1;
+
+ if (core_dump_allowed == -1)
+ {
+ core_dump_allowed = can_dump_core (LIMIT_CUR);
+
+ if (!core_dump_allowed)
+ gdb_demangle_attempt_core_dump = 0;
+ }
+
+ if (catch_demangler_crashes)
+ {
+#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
+ sa.sa_handler = gdb_demangle_signal_handler;
+ sigemptyset (&sa.sa_mask);
+ sa.sa_flags = SA_ONSTACK;
+ sigaction (SIGSEGV, &sa, &old_sa);
+#else
+ ofunc = (void (*)()) signal (SIGSEGV, gdb_demangle_signal_handler);
+#endif
+
+ crash_signal = SIGSETJMP (gdb_demangle_jmp_buf);
+ }
+#endif
+
+ if (crash_signal == 0)
+ result = bfd_demangle (NULL, name, options);
+
+#ifdef HAVE_WORKING_FORK
+ if (catch_demangler_crashes)
+ {
+#if defined (HAVE_SIGACTION) && defined (SA_RESTART)
+ sigaction (SIGSEGV, &old_sa, NULL);
+#else
+ signal (SIGSEGV, ofunc);
+#endif
+
+ if (crash_signal != 0)
+ {
+ static int error_reported = 0;
+
+ if (!error_reported)
+ {
+ char *short_msg, *long_msg;
+ struct cleanup *back_to;
+
+ short_msg = xstrprintf (_("unable to demangle '%s' "
+ "(demangler failed with signal %d)"),
+ name, crash_signal);
+ back_to = make_cleanup (xfree, short_msg);
+
+ long_msg = xstrprintf ("%s:%d: %s: %s", __FILE__, __LINE__,
+ "demangler-warning", short_msg);
+ make_cleanup (xfree, long_msg);
+
+ target_terminal_ours ();
+ begin_line ();
+ if (core_dump_allowed)
+ fprintf_unfiltered (gdb_stderr,
+ _("%s\nAttempting to dump core.\n"),
+ long_msg);
+ else
+ warn_cant_dump_core (long_msg);
+
+ demangler_warning (__FILE__, __LINE__, "%s", short_msg);
+
+ do_cleanups (back_to);
+
+ error_reported = 1;
+ }
+
+ result = NULL;
+ }
+ }
+#endif
+
+ return result;
}
/* Don't allow just "maintenance cplus". */
Usage: info vtbl EXPRESSION\n\
Evaluate EXPRESSION and display the virtual function table for the\n\
resulting object."));
+
+#ifdef HAVE_WORKING_FORK
+ add_setshow_boolean_cmd ("catch-demangler-crashes", class_maintenance,
+ &catch_demangler_crashes, _("\
+Set whether to attempt to catch demangler crashes."), _("\
+Show whether to attempt to catch demangler crashes."), _("\
+If enabled GDB will attempt to catch demangler crashes and\n\
+display the offending symbol."),
+ NULL,
+ NULL,
+ &maintenance_set_cmdlist,
+ &maintenance_show_cmdlist);
+#endif
}
If @var{regexp} is specified, only expand symbol tables for file
names matching @var{regexp}.
+@kindex maint set catch-demangler-crashes
+@kindex maint show catch-demangler-crashes
+@cindex demangler crashes
+@item maint set catch-demangler-crashes [on|off]
+@itemx maint show catch-demangler-crashes
+Control whether @value{GDBN} should attempt to catch crashes in the
+symbol name demangler. The default is to attempt to catch crashes.
+If enabled, the first time a crash is caught, a core file is created,
+the offending symbol is displayed and the user is presented with the
+option to terminate the current session.
+
@kindex maint cplus first_component
@item maint cplus first_component @var{name}
Print the first C@t{++} class/namespace component of @var{name}.
#include "filenames.h"
#include "filestuff.h"
+#include <signal.h>
/* The selected interpreter. This will be used as a set command
variable, so it should always be malloc'ed - since
*local_gdbinit = localinit;
}
+/* Try to set up an alternate signal stack for SIGSEGV handlers.
+ This allows us to handle SIGSEGV signals generated when the
+ normal process stack is exhausted. If this stack is not set
+ up (sigaltstack is unavailable or fails) and a SIGSEGV is
+ generated when the normal stack is exhausted then the program
+ will behave as though no SIGSEGV handler was installed. */
+
+static void
+setup_alternate_signal_stack (void)
+{
+#ifdef HAVE_SIGALTSTACK
+ stack_t ss;
+
+ ss.ss_sp = xmalloc (SIGSTKSZ);
+ ss.ss_size = SIGSTKSZ;
+ ss.ss_flags = 0;
+
+ sigaltstack(&ss, NULL);
+#endif
+}
+
/* Call command_loop. If it happens to return, pass that through as a
non-zero return status. */
quiet = 1;
}
+ /* Try to set up an alternate signal stack for SIGSEGV handlers. */
+ setup_alternate_signal_stack ();
+
/* Initialize all files. Give the interpreter a chance to take
control of the console via the deprecated_init_ui_hook (). */
gdb_init (gdb_program_name);
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