Signal-handler cleanup.

Emacs's signal handlers were written in the old 4.2BSD style with
sigblock and sigmask and so forth, and this led to some
inefficiencies and confusion.  Rewrite these to use
pthread_sigmask etc. without copying signal sets around.  Also,
get rid of the confusing macros 'SIGNAL_THREAD_CHECK' and
'signal', and instead use functions that do not attempt to take
over the system name space.  This patch causes Emacs's text
segment to shrink by 0.7% on my platform, Fedora 17 x86-64.
* configure.ac (PTY_OPEN, PTY_TTY_NAME_SPRINTF):
Adjust to syssignal.h changes.
(SIGNAL_H_AB): Remove; no longer needed.
* src/alloc.c, src/emacsgtkfixed.c, src/nsfns.m, src/widget.c, src/xmenu.c:
Do not include <signal.h> or "syssignal.h", as these
modules do not use signals.
* src/atimer.c, src/callproc.c, src/data.c, src/dispnew.c, src/emacs.c:
* src/floatfns.c, src/gtkutil.c, src/keyboard.c, src/process.c, src/sound.c:
* src/sysdep.c, src/term.c, src/xterm.c:
Do not include <signal.h>, as "syssignal.h" does that for us now.
* src/atimer.c (sigmask_atimers): New function.
(block_atimers, unblock_atimers): New functions,
replacing the old macros BLOCK_ATIMERS and UNBLOCK_ATIMERS.
All uses replaced.
* src/conf_post.h [SIGNAL_H_AHB]: Do not include <signal.h>;
no longer needed here.
* src/emacs.c (main): Inspect existing signal handler with sigaction,
so that there's	no need to block and unblock SIGHUP.
* src/sysdep.c (struct save_signal): New member 'action', replacing
old member 'handler'.
(save_signal_handlers, restore_signal_handlers):
Use sigaction instead of 'signal' to save and restore.
(get_set_sighandler, set_sighandler) [!WINDOWSNT]:
New function.  All users of 'signal' modified to use set_sighandler
if they're writeonly, and to use sys_signal if they're read+write.
(emacs_sigaction_init, forwarded_signal): New functions.
(sys_signal): Remove.  All uses replaced by calls to sigaction
and emacs_sigaction_init, or by direct calls to 'signal'.
(sys_sigmask) [!__GNUC__]: Remove; no longer needed.
(sys_sigblock, sys_sigunblock, sys_sigsetmask): Remove;
all uses replaced by pthread_sigmask etc. calls.
* src/syssignal.h: Include <signal.h>.
(emacs_sigaction_init, forwarded_signal): New decls.
(SIGMASKTYPE): Remove.  All uses replaced by its definiens, sigset_t.
(SIGEMPTYMASK): Remove; all uses replaced by its definiens, empty_mask.
(sigmask, sys_sigmask): Remove; no longer needed.
(sigpause): Remove.  All uses replaced by its definiens, sigsuspend.
(sigblock, sigunblock, sigfree):
(sigsetmask) [!defined sigsetmask]:
Remove.  All uses replaced by pthread_sigmask.
(signal): Remove.  Its remaining uses (with SIG_DFL and SIG_IGN)
no longer need to be replaced, and its typical old uses
are now done via emacs_sigaction_init and sigaction.
(sys_sigblock, sys_sigunblock, sys_sigsetmask): Remove decls.
(sys_sigdel): Remove; unused.
(NSIG): Remove a FIXME; the code's fine.  Remove an unnecessary ifdef.

Fixes: debbugs:12327

1 files changed, 4 insertions, 14 deletions

diff --git a/configure.ac b/configure.ac
index 16e579c862a..dd5e322194a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3445,7 +3445,7 @@ case $opsys in
   cygwin )
     AC_DEFINE(PTY_ITERATION, [int i; for (i = 0; i < 1; i++)])
     dnl multi-line AC_DEFINEs are hard. :(
-    AC_DEFINE(PTY_OPEN, [ do { int dummy; SIGMASKTYPE mask; mask = sigblock (sigmask (SIGCHLD)); if (-1 == openpty (&fd, &dummy, pty_name, 0, 0)) fd = -1; sigsetmask (mask); if (fd >= 0) emacs_close (dummy); } while (0)])
+    AC_DEFINE(PTY_OPEN, [ do { int dummy; sigset_t blocked, procmask; sigemptyset (&blocked); sigaddset (&blocked, SIGCHLD); pthread_sigmask (SIG_BLOCK, &blocked, &procmask); if (-1 == openpty (&fd, &dummy, pty_name, 0, 0)) fd = -1; pthread_sigmask (SIG_SETMASK, &procmask, 0); if (fd >= 0) emacs_close (dummy); } while (0)])
     AC_DEFINE(PTY_NAME_SPRINTF, [])
     AC_DEFINE(PTY_TTY_NAME_SPRINTF, [])
     ;;
@@ -3474,7 +3474,7 @@ case $opsys in
       AC_DEFINE(PTY_ITERATION, [int i; for (i = 0; i < 1; i++)])
       dnl Note that grantpt and unlockpt may fork.  We must block SIGCHLD
       dnl to prevent sigchld_handler from intercepting the child's death.
-      AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptyname; sigblock (sigmask (SIGCHLD)); if (grantpt (fd) == -1 || unlockpt (fd) == -1 || !(ptyname = ptsname(fd))) { sigunblock (sigmask (SIGCHLD)); close (fd); return -1; } snprintf (pty_name, sizeof pty_name, "%s", ptyname); sigunblock (sigmask (SIGCHLD)); }])
+      AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptyname = 0; sigset_t blocked; sigemptyset (&blocked); sigaddset (&blocked, SIGCHLD); pthread_sigmask (SIG_BLOCK, &blocked, 0); if (grantpt (fd) != -1 && unlockpt (fd) != -1) ptyname = ptsname(fd); pthread_sigmask (SIG_UNBLOCK, &blocked, 0); if (!ptyname) { close (fd); return -1; } snprintf (pty_name, sizeof pty_name, "%s", ptyname); }])
       dnl if HAVE_POSIX_OPENPT
       if test "x$ac_cv_func_posix_openpt" = xyes; then
         AC_DEFINE(PTY_OPEN, [fd = posix_openpt (O_RDWR | O_NOCTTY)])
@@ -3519,18 +3519,15 @@ case $opsys in
     ;;
 
   sol2* )
-    dnl Uses sigblock/sigunblock rather than sighold/sigrelse,
-    dnl which appear to be BSD4.1 specific.  It may also be appropriate
-    dnl for SVR4.x (x<2) but I'm not sure.   fnf@cygnus.com
     dnl On SysVr4, grantpt(3) forks a subprocess, so keep sigchld_handler()
     dnl from intercepting that death.  If any child but grantpt's should die
     dnl within, it should be caught after sigrelse(2).
-    AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptsname (int), *ptyname; sigblock (sigmask (SIGCLD)); if (grantpt (fd) == -1) { emacs_close (fd); return -1; } sigunblock (sigmask (SIGCLD)); if (unlockpt (fd) == -1) { emacs_close (fd); return -1; } if (!(ptyname = ptsname (fd))) { emacs_close (fd); return -1; } snprintf (pty_name, sizeof pty_name, "%s", ptyname); }])
+    AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptsname (int), *ptyname; int grantpt_result; sigset_t blocked; sigemptyset (&blocked); sigaddset (&blocked, SIGCLD); pthread_sigmask (SIG_BLOCK, &blocked, 0); grantpt_result = grantpt (fd); pthread_sigmask (SIG_UNBLOCK, &blocked, 0); if (grantpt_result == -1 || unlockpt (fd) == -1 || !(ptyname = ptsname (fd))) { emacs_close (fd); return -1; } snprintf (pty_name, sizeof pty_name, "%s", ptyname); }])
     ;;
 
   unixware )
     dnl Comments are as per sol2*.
-    AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptsname (int), *ptyname; sigblock(sigmask(SIGCLD)); if (grantpt(fd) == -1) fatal("could not grant slave pty"); sigunblock(sigmask(SIGCLD)); if (unlockpt(fd) == -1) fatal("could not unlock slave pty"); if (!(ptyname = ptsname(fd))) fatal ("could not enable slave pty"); snprintf (pty_name, sizeof pty_name, "%s", ptyname); }])
+    AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptsname (int), *ptyname; int grantpt_result; sigset_t blocked; sigemptyset (&blocked); sigaddset (&blocked, SIGCLD); pthread_sigmask (SIG_BLOCK, &blocked, 0); grantpt_result = grantpt (fd); pthread_sigmask (SIG_UNBLOCK, &blocked, 0); if (grantpt_result == -1) fatal("could not grant slave pty"); if (unlockpt(fd) == -1) fatal("could not unlock slave pty"); if (!(ptyname = ptsname(fd))) fatal ("could not enable slave pty"); snprintf (pty_name, sizeof pty_name, "%s", ptyname); }])
     ;;
 esac
 
@@ -3820,13 +3817,6 @@ case $opsys in
     AC_DEFINE(XOS_NEEDS_TIME_H, 1, [Compensate for a bug in Xos.h on
       some systems, where it requires time.h.])
     ;;
-
-  netbsd | openbsd )
-    dnl Greg A. Woods <woods@weird.com> says we must include signal.h
-    dnl before syssignal.h is included, to work around interface conflicts
-    dnl that are handled with CPP __RENAME() macro in signal.h.
-    AC_DEFINE(SIGNAL_H_AHB, 1, [Define if AH_BOTTOM should include signal.h.])
-    ;;
 esac