From 4d7e6e51dd4acecff466a28d958c50f34fc130b8 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sun, 23 Sep 2012 01:44:20 -0700 Subject: Simplify and avoid signal-handling races. * nt/inc/ms-w32.h (emacs_raise): New macro. * src/alloc.c (die): * src/sysdep.c (emacs_abort) [HAVE_NTGUI]: Avoid recursive loop if there's a fatal error in the function itself. * src/atimer.c (pending_atimers): * src/blockinput.h: Don't include "atimer.h"; no longer needed. (interrupt_input_pending): Remove. All uses removed. pending_signals now counts both atimers and ordinary interrupts. This is less racy than having three separate pending-signal flags. (block_input, unblock_input, totally_unblock_input, unblock_input_to) (input_blocked_p): Rename from their upper-case counterparts BLOCK_INPUT, UNBLOCK_INPUT, TOTALLY_UNBLOCK_INPUT, UNBLOCK_INPUT_TO, INPUT_BLOCKED_P, and turn into functions. All uses changed. This makes it easier to access volatile variables more accurately. (BLOCK_INPUT_RESIGNAL): Remove. All uses replaced by unblock_input (). (input_blocked_p): Prefer this to 'interrupt_input_blocked', as that's more reliable if the code is buggy and sets interrupt_input_blocked to a negative value. All uses changed. * src/atimer.c (deliver_alarm_signal): Remove. No need to deliver this to the parent; any thread can handle this signal now. All uses replaced by underlying handler. * src/atimer.c (turn_on_atimers): * src/dispnew.c (handle_window_change_signal): * src/emacs.c (handle_danger_signal): * src/keyboard.c (kbd_buffer_get_event): Don't reestablish signal handler; not needed with sigaction. * src/blockinput.h (UNBLOCK_INPUT_TO, TOTALLY_UNBLOCK_INPUT) (UNBLOCK_INPUT_TO): Rework to avoid unnecessary accesses to volatile variables. (UNBLOCK_INPUT_TO): Now a function. (totally_unblock_input, unblock_input): New decls. * src/data.c (handle_arith_signal, deliver_arith_signal): Move to sysdep.c (init_data): Remove. Necessary stuff now done in init_signal. * src/emacs.c, src/xdisp.c: Include "atimer.h", since we invoke atimer functions. * src/emacs.c (handle_fatal_signal, deliver_fatal_signal): Move to sysdep.c. (fatal_error_code): Remove; no longer needed. (terminate_due_to_signal): Rename from fatal_error_backtrace, since it doesn't always backtrace. All uses changed. No need to reset signal to default, since sigaction and/or die does that for us now. Use emacs_raise (FOO), not kill (getpid (), FOO). (main): Check more-accurately whether we're dumping. Move fatal-error setup to sysdep.c * src/floatfns.c: Do not include "syssignal.h"; no longer needed. * src/gtkutil.c (xg_get_file_name, xg_get_font): Remove no-longer-needed signal-mask manipulation. * src/keyboard.c, src/process.c (POLL_FOR_INPUT): Don't depend on USE_ASYNC_EVENTS, a symbol that is never defined. * src/keyboard.c (read_avail_input): Remove. All uses replaced by gobble_input. (Ftop_level): Use TOTALLY_UNBLOCK_INPUT rather than open code. (kbd_buffer_store_event_hold, gobble_input): (record_asynch_buffer_change) [USABLE_SIGIO]: (store_user_signal_events): No need to mess with signal mask. (gobble_input): If blocking input and there are terminals, simply set pending_signals to 1 and return. All hooks changed to not worry about whether input is blocked. (process_pending_signals): Clear pending_signals before processing them, in case a signal comes in while we're processing. By convention callers now test pending_signals before calling us. (UNBLOCK_INPUT_TO, unblock_input, totally_unblock_input): New functions, to support changes to blockinput.h. (handle_input_available_signal): Now extern. (reinvoke_input_signal): Remove. All uses replaced by handle_async_input. (quit_count): Now volatile, since a signal handler uses it. (handle_interrupt): Now takes bool IN_SIGNAL_HANDLER as arg. All callers changed. Block SIGINT only if not already blocked. Clear sigmask reliably, even if Fsignal returns, which it can. Omit unnecessary accesses to volatile var. (quit_throw_to_read_char): No need to restore sigmask. * src/keyboard.c (gobble_input, handle_user_signal): * src/process.c (wait_reading_process_output): Call signal-handling code rather than killing ourselves. * src/lisp.h: Include , for... (IEEE_FLOATING_POINT): New macro, moved here to avoid duplication. (pending_signals): Now volatile. (syms_of_data): Now const if IEEE floating point. (handle_input_available_signal) [USABLE_SIGIO]: (terminate_due_to_signal, record_child_status_change): New decls. * src/process.c (create_process): Avoid disaster if memory is exhausted while we're processing a vfork, by tightening the critical section around the vfork. (send_process_frame, process_sent_to, handle_pipe_signal) (deliver_pipe_signal): Remove. No longer needed, as Emacs now ignores SIGPIPE. (send_process): No need for setjmp/longjmp any more, since the SIGPIPE stuff is now gone. Instead, report an error if errno is EPIPE. (record_child_status_change): Now extern. PID and W are now args. Return void, not bool. All callers changed. * src/sysdep.c (wait_debugging) [(BSD_SYSTEM || HPUX) && !defined (__GNU__)]: Remove. All uses removed. This bug should be fixed now in a different way. (wait_for_termination_1): Use waitpid rather than sigsuspend, and record the child status change directly. This avoids the need to futz with the signal mask. (process_fatal_action): Move here from emacs.c. (emacs_sigaction_flags): New function, containing much of what used to be in emacs_sigaction_init. (emacs_sigaction_init): Use it. Block nonfatal system signals that are caught by emacs, to make races less likely. (deliver_process_signal): Rename from handle_on_main_thread. All uses changed. (BACKTRACE_LIMIT_MAX): Now at top level. (thread_backtrace_buffer, threadback_backtrace_pointers): New static vars. (deliver_thread_signal, deliver_fatal_thread_signal): New functions, for more-accurate delivery of thread-specific signals. (handle_fatal_signal, deliver_fatal_signal): Move here from emacs.c. (deliver_arith_signal): Handle in this thread, not in the main thread, since it's triggered by this thread. (maybe_fatal_sig): New function. (init_signals): New arg DUMPING so that we can be more accurate about whether we're dumping. Caller changed. Treat thread-specific signals differently from process-general signals. Block all signals while handling fatal error; that's safer. xsignal from SIGFPE only on non-IEEE hosts, treating it as fatal on IEEE hosts. When batch, ignore SIGHUP, SIGINT, SIGTERM if they were already ignored. Ignore SIGPIPE unless batch. (emacs_backtrace): Output backtrace for the appropriate thread, which is not necessarily the main thread. * src/syssignal.h: Include . (emacs_raise): New macro. * src/xterm.c (x_connection_signal): Remove; no longer needed now that we use sigaction. (x_connection_closed): No need to mess with sigmask now. (x_initialize): No need to reset SIGPIPE handler here, since init_signals does this for us now. Fixes: debbugs:12471 --- src/xsettings.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/xsettings.c') diff --git a/src/xsettings.c b/src/xsettings.c index 58c84495489..7c68ff295cf 100644 --- a/src/xsettings.c +++ b/src/xsettings.c @@ -929,7 +929,7 @@ init_xsettings (struct x_display_info *dpyinfo) { Display *dpy = dpyinfo->display; - BLOCK_INPUT; + block_input (); /* Select events so we can detect client messages sent when selection owner changes. */ @@ -939,7 +939,7 @@ init_xsettings (struct x_display_info *dpyinfo) if (dpyinfo->xsettings_window != None) read_and_apply_settings (dpyinfo, False); - UNBLOCK_INPUT; + unblock_input (); } void -- cgit v1.2.1