PATCH: (2) Re: FreeBSD compatability feature request

[Peter Stephenson <pws@csr.com>]

OK, plan B.

I am now frightened about what happens when any signals are blocked
while we are waiting for a child.  So instead of doing that, I propose
queuing traps separately from signals.  This can't cause any races,
since no extra signal or process handling is involved.  The code is a
bit more verbose, but should be much safer.  This patches on top of the
other one.

Again, this should be exactly equivalent to 4.2.0 unless TRAPS_ASYNC is
unset (POSIX compatibility mode).

This ought to fix the hang.

Index: Src/jobs.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/jobs.c,v
retrieving revision 1.26
diff -u -r1.26 jobs.c
--- Src/jobs.c	19 Apr 2004 16:02:22 -0000	1.26
+++ Src/jobs.c	21 Apr 2004 10:40:30 -0000
@@ -994,11 +994,8 @@
     int q = queue_signal_level();
     Job jn = jobtab + job;
 
-    queue_not_sigchld++;
-    if (isset(TRAPSASYNC))
-	dont_queue_signals();
-    else
-	queue_signals();
+    dont_queue_signals();
+    queue_traps();
     child_block();		 /* unblocked during child_suspend() */
     if (jn->procs || jn->auxprocs) { /* if any forks were done         */
 	jn->stat |= STAT_LOCKED;
@@ -1029,10 +1026,8 @@
 	numpipestats = 1;
     }
     child_unblock();
+    dont_queue_traps();
     restore_queue_signals(q);
-    if (!queueing_enabled)
-	run_queued_signals();
-    queue_not_sigchld--;
 }
 
 /* wait for running job to finish */
Index: Src/signals.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/signals.c,v
retrieving revision 1.26
diff -u -r1.26 signals.c
--- Src/signals.c	19 Apr 2004 16:02:22 -0000	1.26
+++ Src/signals.c	21 Apr 2004 10:40:30 -0000
@@ -49,12 +49,19 @@
 /* Variables used by signal queueing */
 
 /**/
-mod_export int queueing_enabled, queue_front, queue_rear, queue_not_sigchld;
+mod_export int queueing_enabled, queue_front, queue_rear;
 /**/
 mod_export int signal_queue[MAX_QUEUE_SIZE];
 /**/
 mod_export sigset_t signal_mask_queue[MAX_QUEUE_SIZE];
 
+/* Variables used by trap queueing */
+
+/**/
+mod_export int trap_queueing_enabled, trap_queue_front, trap_queue_rear;
+/**/
+mod_export int trap_queue[MAX_QUEUE_SIZE];
+
 /* This is only used on machines that don't understand signal sets.  *
  * On SYSV machines this will represent the signals that are blocked *
  * (held) using sighold.  On machines which can't block signals at   *
@@ -426,7 +433,7 @@
 #endif
 
     /* Are we queueing signals now?      */
-    if (queueing_enabled && (sig != SIGCHLD || !queue_not_sigchld)) {
+    if (queueing_enabled) {
         int temp_rear = ++queue_rear % MAX_QUEUE_SIZE;
 
 	DPUTS(temp_rear == queue_front, "BUG: signal queue full");
@@ -1058,5 +1065,17 @@
     if ((sigtrapped[sig] & ZSIG_IGNORED) || !sigfuncs[sig] || errflag)
 	return;
 
+    /* Adapted from signal queueing in zhandler */
+    if (trap_queueing_enabled && !isset(TRAPSASYNC)) {
+	int temp_rear = ++trap_queue_rear % MAX_QUEUE_SIZE;
+
+	DPUTS(temp_rear == trap_queue_front, "BUG: trap queue full");
+	if (temp_rear != trap_queue_front) {
+	    trap_queue_rear = temp_rear;
+	    trap_queue[trap_queue_rear] = sig;
+	}
+	return;
+    }
+
     dotrapargs(sig, sigtrapped+sig, sigfuncs[sig]);
 }
Index: Src/signals.h
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/signals.h,v
retrieving revision 1.4
diff -u -r1.4 signals.h
--- Src/signals.h	18 Jun 2001 07:24:23 -0000	1.4
+++ Src/signals.h	21 Apr 2004 10:40:30 -0000
@@ -101,6 +101,23 @@
 
 #define restore_queue_signals(q) (queueing_enabled = (q))
 
+/*
+ * Similar (but simpler) mechanism used for queueing traps.
+ * Only needed if NO_TRAPS_ASYNC is set.
+ */
+#define queue_traps()	(trap_queueing_enabled++)
+
+#define run_queued_traps() do { \
+    while (trap_queue_front != trap_queue_rear) { /* while traps in queue */ \
+	trap_queue_front = (trap_queue_front + 1) % MAX_QUEUE_SIZE; \
+	dotrap(trap_queue[trap_queue_front]);  /* handle queued trap   */ \
+    } \
+} while (0)
+
+#define dont_queue_traps() do { \
+    trap_queueing_enabled = 0; \
+    run_queued_traps(); \
+} while (0)
 
 /* Make some signal functions faster. */
 
-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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