diff options
Diffstat (limited to 'gdb/event-top.c')
| -rw-r--r-- | gdb/event-top.c | 140 |
1 files changed, 129 insertions, 11 deletions
diff --git a/gdb/event-top.c b/gdb/event-top.c index 972b540..210440a 100644 --- a/gdb/event-top.c +++ b/gdb/event-top.c @@ -46,6 +46,10 @@ #include "readline/readline.h" #include "readline/history.h" +#ifdef HAVE_EXECINFO_H +# include <execinfo.h> +#endif /* HAVE_EXECINFO_H */ + /* readline defines this. */ #undef savestring @@ -96,6 +100,38 @@ bool exec_done_display_p = false; run again. */ int call_stdin_event_handler_again_p; +/* When true GDB will produce a minimal backtrace when a fatal signal is + reached (within GDB code). */ +static bool bt_on_fatal_signal +#ifdef HAVE_EXECINFO_BACKTRACE + = true; +#else + = false; +#endif /* HAVE_EXECINFO_BACKTRACE */ + +/* Implement 'maintenance show backtrace-on-fatal-signal'. */ + +static void +show_bt_on_fatal_signal (struct ui_file *file, int from_tty, + struct cmd_list_element *cmd, const char *value) +{ + fprintf_filtered (file, _("Backtrace on a fatal signal is %s.\n"), value); +} + +/* Implement 'maintenance set backtrace-on-fatal-signal'. */ + +static void +set_bt_on_fatal_signal (const char *args, int from_tty, cmd_list_element *c) +{ +#ifndef HAVE_EXECINFO_BACKTRACE + if (bt_on_fatal_signal) + { + bt_on_fatal_signal = false; + error (_("support for this feature is not compiled into GDB")); + } +#endif +} + /* Signal handling variables. */ /* Each of these is a pointer to a function that the event loop will invoke if the corresponding signal has received. The real signal @@ -846,6 +882,84 @@ gdb_readline_no_editing_callback (gdb_client_data client_data) } +/* Attempt to unblock signal SIG, return true if the signal was unblocked, + otherwise, return false. */ + +static bool +unblock_signal (int sig) +{ +#if HAVE_SIGPROCMASK + sigset_t sigset; + sigemptyset (&sigset); + sigaddset (&sigset, sig); + gdb_sigmask (SIG_UNBLOCK, &sigset, 0); + return true; +#endif + + return false; +} + +/* Called to handle fatal signals. SIG is the signal number. */ + +static void ATTRIBUTE_NORETURN +handle_fatal_signal (int sig) +{ +#ifdef HAVE_EXECINFO_BACKTRACE + const auto sig_write = [] (const char *msg) -> void + { + gdb_stderr->write_async_safe (msg, strlen (msg)); + }; + + if (bt_on_fatal_signal) + { + sig_write ("\n\n"); + sig_write (_("Fatal signal: ")); + sig_write (strsignal (sig)); + sig_write ("\n"); + + /* Allow up to 25 frames of backtrace. */ + void *buffer[25]; + int frames = backtrace (buffer, ARRAY_SIZE (buffer)); + sig_write (_("----- Backtrace -----\n")); + if (gdb_stderr->fd () > -1) + { + backtrace_symbols_fd (buffer, frames, gdb_stderr->fd ()); + if (frames == ARRAY_SIZE (buffer)) + sig_write (_("Backtrace might be incomplete.\n")); + } + else + sig_write (_("Backtrace unavailable\n")); + sig_write ("---------------------\n"); + sig_write (_("A fatal error internal to GDB has been detected, " + "further\ndebugging is not possible. GDB will now " + "terminate.\n\n")); + sig_write (_("This is a bug, please report it.")); + if (REPORT_BUGS_TO[0] != '\0') + { + sig_write (_(" For instructions, see:\n")); + sig_write (REPORT_BUGS_TO); + sig_write ("."); + } + sig_write ("\n\n"); + + gdb_stderr->flush (); + } +#endif /* HAVE_EXECINF_BACKTRACE */ + + /* If possible arrange for SIG to have its default behaviour (which + should be to terminate the current process), unblock SIG, and reraise + the signal. This ensures GDB terminates with the expected signal. */ + if (signal (sig, SIG_DFL) != SIG_ERR + && unblock_signal (sig)) + raise (sig); + + /* The above failed, so try to use SIGABRT to terminate GDB. */ +#ifdef SIGABRT + signal (SIGABRT, SIG_DFL); +#endif + abort (); /* ARI: abort */ +} + /* The SIGSEGV handler for this thread, or NULL if there is none. GDB always installs a global SIGSEGV handler, and then lets threads indicate their interest in handling the signal by setting this @@ -887,7 +1001,7 @@ handle_sigsegv (int sig) install_handle_sigsegv (); if (thread_local_segv_handler == nullptr) - abort (); /* ARI: abort */ + handle_fatal_signal (sig); thread_local_segv_handler (sig); } @@ -1160,16 +1274,7 @@ async_sigtstp_handler (gdb_client_data arg) char *prompt = get_prompt (); signal (SIGTSTP, SIG_DFL); -#if HAVE_SIGPROCMASK - { - sigset_t zero; - - sigemptyset (&zero); - gdb_sigmask (SIG_SETMASK, &zero, 0); - } -#elif HAVE_SIGSETMASK - sigsetmask (0); -#endif + unblock_signal (SIGTSTP); raise (SIGTSTP); signal (SIGTSTP, handle_sigtstp); printf_unfiltered ("%s", prompt); @@ -1320,4 +1425,17 @@ Control whether to show event loop-related debug messages."), set_debug_event_loop_command, show_debug_event_loop_command, &setdebuglist, &showdebuglist); + + add_setshow_boolean_cmd ("backtrace-on-fatal-signal", class_maintenance, + &bt_on_fatal_signal, _("\ +Set whether to produce a backtrace if GDB receives a fatal signal."), _("\ +Show whether GDB will produce a backtrace if it receives a fatal signal."), _("\ +Use \"on\" to enable, \"off\" to disable.\n\ +If enabled, GDB will produce a minimal backtrace if it encounters a fatal\n\ +signal from within GDB itself. This is a mechanism to help diagnose\n\ +crashes within GDB, not a mechanism for debugging inferiors."), + set_bt_on_fatal_signal, + show_bt_on_fatal_signal, + &maintenance_set_cmdlist, + &maintenance_show_cmdlist); } |