Handle sigmask better with nested signal handlers.

* atimer.c (sigmask_atimers): Remove.
Remaining use rewritten to use body of this function.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* sysdep.c (block_tty_out_signal, unblock_tty_out_signal):
New arg OLDSET.  All callers changed.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* keyboard.c (handle_interrupt):
* sound.c (vox_configure, vox_close):
Restore the old signal mask rather than unilaterally clearing bits
from the mask, in case a handler is running within another
handler.  All callers changed.
* lisp.h, process.c, process.h, term.c:
Adjust decls and callers to match new API.
* sysdep.c (emacs_sigaction_init): Don't worry about masking SIGFPE;
signal handlers aren't supposed to use floating point anyway.
(handle_arith_signal): Unblock just SIGFPE rather than clearing mask.

Fixes: debbugs:15561

1 files changed, 11 insertions, 9 deletions

diff --git a/src/callproc.c b/src/callproc.c
index 0831291b0dd..2147c173655 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -108,20 +108,20 @@ static Lisp_Object call_process (ptrdiff_t, Lisp_Object *, int, ptrdiff_t);
 /* Block SIGCHLD.  */
 
 void
-block_child_signal (void)
+block_child_signal (sigset_t *oldset)
 {
   sigset_t blocked;
   sigemptyset (&blocked);
   sigaddset (&blocked, SIGCHLD);
-  pthread_sigmask (SIG_BLOCK, &blocked, 0);
+  pthread_sigmask (SIG_BLOCK, &blocked, oldset);
 }
 
 /* Unblock SIGCHLD.  */
 
 void
-unblock_child_signal (void)
+unblock_child_signal (sigset_t const *oldset)
 {
-  pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
+  pthread_sigmask (SIG_SETMASK, oldset, 0);
 }
 
 /* Return the current buffer's working directory, or the home
@@ -162,7 +162,8 @@ encode_current_directory (void)
 void
 record_kill_process (struct Lisp_Process *p, Lisp_Object tempfile)
 {
-  block_child_signal ();
+  sigset_t oldset;
+  block_child_signal (&oldset);
 
   if (p->alive)
     {
@@ -171,7 +172,7 @@ record_kill_process (struct Lisp_Process *p, Lisp_Object tempfile)
       kill (- p->pid, SIGKILL);
     }
 
-  unblock_child_signal ();
+  unblock_child_signal (&oldset);
 }
 
 /* Clean up files, file descriptors and processes created by Fcall_process.  */
@@ -313,6 +314,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
   char *tempfile = NULL;
   int pid;
 #else
+  sigset_t oldset;
   pid_t pid;
 #endif
   int child_errno;
@@ -629,7 +631,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
 #ifndef MSDOS
 
   block_input ();
-  block_child_signal ();
+  block_child_signal (&oldset);
 
 #ifdef WINDOWSNT
   pid = child_setup (filefd, fd_output, fd_error, new_argv, 0, current_dir);
@@ -671,7 +673,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
 
   if (pid == 0)
     {
-      unblock_child_signal ();
+      unblock_child_signal (&oldset);
 
       setsid ();
 
@@ -707,7 +709,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
         }
     }
 
-  unblock_child_signal ();
+  unblock_child_signal (&oldset);
   unblock_input ();
 
 #endif /* not MSDOS */