[FFmpeg-devel] [PATCH 1/2] ffmpeg: use sigaction() instead of signal() on linux

[Andriy Gelman]

From: Andriy Gelman <andriy.gelman at gmail.com>

As per signal() help (man 2 signal) the semantics of using signal may
vary across platforms. It is suggested to use sigaction() instead.

On my system, the capture signal is reset to the default handler after
the first call thus failing to properly handle multiple SIGINTs.

Signed-off-by: Andriy Gelman <andriy.gelman at gmail.com>
---
 fftools/ffmpeg.c | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 80f436eab3..01f4ef15d8 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -393,8 +393,30 @@ static BOOL WINAPI CtrlHandler(DWORD fdwCtrlType)
 }
 #endif
 
+#ifdef __linux__
+#define SIGNAL(sig, func)               \
+    do {                                \
+        action.sa_handler = func;       \
+        sigaction(sig, &action, NULL);  \
+    } while (0)
+#else
+#define SIGNAL(sig, func) \
+    signal(sig, func)
+#endif
+
 void term_init(void)
 {
+#if defined __linux__
+    struct sigaction action;
+    action.sa_handler = sigterm_handler;
+
+    /* block other interrupts while processing this one */
+    sigfillset(&action.sa_mask);
+
+    /* restart interruptible functions (i.e. don't fail with EINTR)  */
+    action.sa_flags = SA_RESTART;
+#endif
+
 #if HAVE_TERMIOS_H
     if (!run_as_daemon && stdin_interaction) {
         struct termios tty;
@@ -413,14 +435,15 @@ void term_init(void)
 
             tcsetattr (0, TCSANOW, &tty);
         }
-        signal(SIGQUIT, sigterm_handler); /* Quit (POSIX).  */
+        SIGNAL(SIGQUIT, sigterm_handler); /* Quit (POSIX).  */
     }
 #endif
 
-    signal(SIGINT , sigterm_handler); /* Interrupt (ANSI).    */
-    signal(SIGTERM, sigterm_handler); /* Termination (ANSI).  */
+    SIGNAL(SIGINT, sigterm_handler);
+    SIGNAL(SIGTERM, sigterm_handler);
+
 #ifdef SIGXCPU
-    signal(SIGXCPU, sigterm_handler);
+    SIGNAL(SIGXCPU, sigterm_handler);
 #endif
 #ifdef SIGPIPE
     signal(SIGPIPE, SIG_IGN); /* Broken pipe (POSIX). */
-- 
2.28.0