cache: Use sigaction() instead of signal()

Signal() has an unavoidable race-condition on "broken by
backwards-compatibility" systems like Solaris. (Upon receiving a
signal, the handler is reset to SIG_DFL, thus a second signal will
kill the process. The problem could also be reduced by re-installing
the handler inside the handler, but there's still a race-condition and
the risk of the handler being called inside the handler).

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@31738 b3059339-0415-0410-9bf9-f77b7e298cf2

1 files changed, 6 insertions, 3 deletions

diff --git a/stream/cache2.c b/stream/cache2.c
index b492a17cd8..6e77cbcc7e 100644
--- a/stream/cache2.c
+++ b/stream/cache2.c
@@ -365,7 +365,8 @@ static void dummy_sighandler(int x) {
 static void cache_mainloop(cache_vars_t *s) {
     int sleep_count = 0;
 #if FORKED_CACHE
-    signal(SIGUSR1, SIG_IGN);
+    struct sigaction sa = { .sa_handler = SIG_IGN };
+    sigaction(SIGUSR1, &sa, NULL);
 #endif
     do {
         if (!cache_fill(s)) {
@@ -373,7 +374,8 @@ static void cache_mainloop(cache_vars_t *s) {
             // Let signal wake us up, we cannot leave this
             // enabled since we do not handle EINTR in most places.
             // This might need extra code to work on BSD.
-            signal(SIGUSR1, dummy_sighandler);
+            sa.sa_handler = dummy_sighandler;
+            sigaction(SIGUSR1, &sa, NULL);
 #endif
             if (sleep_count < INITIAL_FILL_USLEEP_COUNT) {
                 sleep_count++;
@@ -381,7 +383,8 @@ static void cache_mainloop(cache_vars_t *s) {
             } else
                 usec_sleep(FILL_USLEEP_TIME); // idle
 #if FORKED_CACHE
-            signal(SIGUSR1, SIG_IGN);
+            sa.sa_handler = SIG_IGN;
+            sigaction(SIGUSR1, &sa, NULL);
 #endif
         } else
             sleep_count = 0;