forkfd: Make sure we handle SIGPIPE too

We can't depend on the application/library ignoring the signal for us,
so we do it. O_NOSIGPIPE exists on the BSDs and I'll add it to Linux. If
it isn't supported, then we need to ignore SIGPIPE globally.

Change-Id: I25d85d86649448d5b2b3fffd1450f6afeaea8b18
Reviewed-by: Ralf Nolden <nolden@kde.org>
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>

1 files changed, 37 insertions, 2 deletions

diff --git a/src/3rdparty/forkfd/forkfd.c b/src/3rdparty/forkfd/forkfd.c
index fef710a79e..9284a67674 100644
--- a/src/3rdparty/forkfd/forkfd.c
+++ b/src/3rdparty/forkfd/forkfd.c
@@ -410,6 +410,26 @@ chain_handler:
         old_sigaction.sa_handler(signum);
 }
 
+static void ignore_sigpipe()
+{
+#ifdef O_NOSIGPIPE
+    static ffd_atomic_int done = FFD_ATOMIC_INIT(0);
+    if (ffd_atomic_load(&done, FFD_ATOMIC_RELAXED))
+        return;
+#endif
+
+    struct sigaction action;
+    memset(&action, 0, sizeof action);
+    sigemptyset(&action.sa_mask);
+    action.sa_handler = SIG_IGN;
+    action.sa_flags = 0;
+    sigaction(SIGPIPE, &action, NULL);
+
+#ifdef O_NOSIGPIPE
+    ffd_atomic_store(&done, 1, FFD_ATOMIC_RELAXED);
+#endif
+}
+
 static void forkfd_initialize()
 {
 #if defined(HAVE_BROKEN_WAITID)
@@ -446,6 +466,11 @@ static void forkfd_initialize()
      */
     sigaction(SIGCHLD, &action, &old_sigaction);
 
+#ifndef O_NOSIGPIPE
+    /* disable SIGPIPE too */
+    ignore_sigpipe();
+#endif
+
 #ifndef __GNUC__
     atexit(cleanup);
 #endif
@@ -486,13 +511,23 @@ static void cleanup()
 
 static int create_pipe(int filedes[], int flags)
 {
-    int ret;
+    int ret = -1;
 #ifdef HAVE_PIPE2
     /* use pipe2(2) whenever possible, since it can thread-safely create a
      * cloexec pair of pipes. Without it, we have a race condition setting
      * FD_CLOEXEC
      */
-    ret = pipe2(filedes, O_CLOEXEC);
+
+#  ifdef O_NOSIGPIPE
+    /* try first with O_NOSIGPIPE */
+    ret = pipe2(filedes, O_CLOEXEC | O_NOSIGPIPE);
+    if (ret == -1) {
+        /* O_NOSIGPIPE not supported, ignore SIGPIPE */
+        ignore_sigpipe();
+    }
+#  endif
+    if (ret == -1)
+        ret = pipe2(filedes, O_CLOEXEC);
     if (ret == -1)
         return ret;