From: Leon Timmermans <fawaka@gmail.com>
Date: Thu, 13 Jan 2011 17:30:29 +0000 (+0100)
Subject: Conditionally unblock after signal handler[#82040]
X-Git-Tag: accepted/trunk/20130322.191538~6052
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=555344425f04e96a72e4d29eab96b34bff8f96ae;p=platform%2Fupstream%2Fperl.git

Conditionally unblock after signal handler[#82040]

Only unblock signal after a safe-signal handler is executed if that signal was
also unblocked before the handler.
---

diff --git a/mg.c b/mg.c
index efc4d6e..f51cd47 100644
--- a/mg.c
+++ b/mg.c
@@ -1443,15 +1443,32 @@ Perl_despatch_signals(pTHX)
     for (sig = 1; sig < SIG_SIZE; sig++) {
 	if (PL_psig_pend[sig]) {
 	    dSAVE_ERRNO;
-	    PERL_BLOCKSIG_ADD(set, sig);
+#if defined(HAS_SIGPROCMASK)
+	    /* From sigaction(2) (FreeBSD man page):
+	     * | Signal routines normally execute with the signal that
+	     * | caused their invocation blocked, but other signals may
+	     * | yet occur.
+	     * Emulation of this behavior (from within Perl) is enabled
+	     * using sigprocmask
+	     */
+	    int was_blocked;
+	    sigset_t newset, oldset;
+
+	    sigemptyset(&newset);
+	    sigaddset(&newset, sig);
+	    sigprocmask(SIG_BLOCK, &newset, &oldset);
+	    was_blocked = sigismember(&oldset, sig);
+#endif
  	    PL_psig_pend[sig] = 0;
-	    PERL_BLOCKSIG_BLOCK(set);
 #if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
 	    (*PL_sighandlerp)(sig, NULL, NULL);
 #else
 	    (*PL_sighandlerp)(sig);
 #endif
-	    PERL_BLOCKSIG_UNBLOCK(set);
+#if defined(HAS_SIGPROCMASK)
+	    if (!was_blocked)
+		sigprocmask(SIG_UNBLOCK, &newset, NULL);
+#endif
 	    RESTORE_ERRNO;
 	}
     }