- /* Set SIGPIPE action to ignore and save current signal action */
- act.sa_handler = SIG_IGN;
- if (sigaction(SIGPIPE, &act, &oldact)) {
- perror("sigaction");
- sent = -1;
- goto end;
+ /*
+ * Discard the SIGPIPE from send(), not disturbing any SIGPIPE
+ * that might be already pending. If a bogus SIGPIPE is sent to
+ * the entire process concurrently by a malicious user, it may
+ * be simply discarded.
+ */
+ if (sigemptyset(&pending_set)) {
+ return -1;
+ }
+ /*
+ * sigpending returns the mask of signals that are _both_
+ * blocked for the thread _and_ pending for either the thread or
+ * the entire process.
+ */
+ if (sigpending(&pending_set)) {
+ return -1;
+ }
+ sigpipe_was_pending = sigismember(&pending_set, SIGPIPE);
+ /*
+ * If sigpipe was pending, it means it was already blocked, so
+ * no need to block it.
+ */
+ if (!sigpipe_was_pending) {
+ if (sigemptyset(&sigpipe_set)) {
+ return -1;
+ }
+ if (sigaddset(&sigpipe_set, SIGPIPE)) {
+ return -1;
+ }
+ if (pthread_sigmask(SIG_BLOCK, &sigpipe_set, &old_set)) {
+ return -1;
+ }