Fix race conditions with signal handlers and errno.

Be more systematic about preserving errno whenever a signal
handler returns, even if it's not in the main thread.  Do this by
renaming signal handlers to distinguish between signal delivery
and signal handling.  All uses changed.
* atimer.c (deliver_alarm_signal): Rename from alarm_signal_handler.
* data.c (deliver_arith_signal): Rename from arith_error.
* dispnew.c (deliver_window_change_signal): Rename from
window_change_signal.
* emacs.c (deliver_error_signal): Rename from fatal_error_signal.
(deliver_danger_signal) [SIGDANGER]: Rename from memory_warning_signal.
* keyboard.c (deliver_input_available_signal): Rename from
input_available_signal.
(deliver_user_signal): Rename from handle_user_signal.
(deliver_interrupt_signal): Rename from interrupt_signal.
* process.c (deliver_pipe_signal): Rename from send_process_trap.
(deliver_child_signal): Rename from sigchld_handler.
* atimer.c (handle_alarm_signal):
* data.c (handle_arith_signal):
* dispnew.c (handle_window_change_signal):
* emacs.c (handle_fatal_signal, handle_danger_signal):
* keyboard.c (handle_input_available_signal):
* keyboard.c (handle_user_signal, handle_interrupt_signal):
* process.c (handle_pipe_signal, handle_child_signal):
New functions, with the actual signal-handling code taken from the
original respective signal handlers, sans the sporadic attempts to
preserve errno, since that's now done by handle_on_main_thread.
* atimer.c (alarm_signal_handler): Remove unnecessary decl.
* emacs.c, floatfns.c, lisp.h: Remove unused FLOAT_CATCH_SIGKILL cruft.
* emacs.c (main_thread) [FORWARD_SIGNAL_TO_MAIN_THREAD]:
Move to sysdep.c.
(main) [FORWARD_SIGNAL_TO_MAIN_THREAD]:
Move initialization of main_thread to sysdep.c's init_signals.
* process.c (waitpid) [!WNOHANG]: #define to wait; that's good enough for
our usage, and simplifies the mainline code.
(record_child_status_change): New static function, as a helper
for handle_child_signal, and with most of the old child handler's
contents.
(CAN_HANDLE_MULTIPLE_CHILDREN): New constant.
(handle_child_signal): Use the above.
* sysdep.c (main_thread) [FORWARD_SIGNAL_TO_MAIN_THREAD]:
Moved here from emacs.c.
(init_signals) [FORWARD_SIGNAL_TO_MAIN_THREAD]: Initialize it;
code moved here from emacs.c's main function.
* sysdep.c, syssignal.h (handle_on_main_thread): New function,
replacing the old SIGNAL_THREAD_CHECK.  All uses changed.  This
lets callers save and restore errno properly.

1 files changed, 0 insertions, 35 deletions

diff --git a/src/floatfns.c b/src/floatfns.c
index 706fe7ae1a0..f59cf58228a 100644
--- a/src/floatfns.c
+++ b/src/floatfns.c
@@ -37,9 +37,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
    Define FLOAT_CHECK_ERRNO if the float library routines set errno.
    This has no effect if HAVE_MATHERR is defined.
 
-   Define FLOAT_CATCH_SIGILL if the float library routines signal SIGILL.
-   (What systems actually do this?  Please let us know.)
-
    Define FLOAT_CHECK_DOMAIN if the float library doesn't handle errors by
    either setting errno, or signaling SIGFPE/SIGILL.  Otherwise, domain and
    range checking will happen before calling the float routines.  This has
@@ -99,10 +96,6 @@ extern double logb (double);
 # include <errno.h>
 #endif
 
-#ifdef FLOAT_CATCH_SIGILL
-static void float_error ();
-#endif
-
 /* True while executing in floating point.
    This tells float_error what to do.  */
 
@@ -947,31 +940,6 @@ Rounds the value toward zero.  */)
   return make_float (d);
 }
 
-#ifdef FLOAT_CATCH_SIGILL
-static void
-float_error (int signo)
-{
-  if (! in_float)
-    fatal_error_signal (signo);
-
-#ifdef BSD_SYSTEM
-  sigsetmask (SIGEMPTYMASK);
-#else
-  /* Must reestablish handler each time it is called.  */
-  signal (SIGILL, float_error);
-#endif /* BSD_SYSTEM */
-
-  SIGNAL_THREAD_CHECK (signo);
-  in_float = 0;
-
-  xsignal1 (Qarith_error, float_error_arg);
-}
-
-/* Another idea was to replace the library function `infnan'
-   where SIGILL is signaled.  */
-
-#endif /* FLOAT_CATCH_SIGILL */
-
 #ifdef HAVE_MATHERR
 int
 matherr (struct exception *x)
@@ -1006,9 +974,6 @@ matherr (struct exception *x)
 void
 init_floatfns (void)
 {
-#ifdef FLOAT_CATCH_SIGILL
-  signal (SIGILL, float_error);
-#endif
   in_float = 0;
 }