path: root/test-sigchain.c
diff options
authorJeff King <>2009-01-22 06:02:35 (GMT)
committerJunio C Hamano <>2009-01-22 06:46:52 (GMT)
commit4a16d072723b48699ea162da24eff05eba298834 (patch)
tree04d834214e8448f254118278ec057c77e3f8f1f1 /test-sigchain.c
parent479b0ae81c9291a8bb8d7b2347cc58eeaa701304 (diff)
chain kill signals for cleanup functions
If a piece of code wanted to do some cleanup before exiting (e.g., cleaning up a lockfile or a tempfile), our usual strategy was to install a signal handler that did something like this: do_cleanup(); /* actual work */ signal(signo, SIG_DFL); /* restore previous behavior */ raise(signo); /* deliver signal, killing ourselves */ For a single handler, this works fine. However, if we want to clean up two _different_ things, we run into a problem. The most recently installed handler will run, but when it removes itself as a handler, it doesn't put back the first handler. This patch introduces sigchain, a tiny library for handling a stack of signal handlers. You sigchain_push each handler, and use sigchain_pop to restore whoever was before you in the stack. Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'test-sigchain.c')
1 files changed, 22 insertions, 0 deletions
diff --git a/test-sigchain.c b/test-sigchain.c
new file mode 100644
index 0000000..8747dea
--- /dev/null
+++ b/test-sigchain.c
@@ -0,0 +1,22 @@
+#include "sigchain.h"
+#include "cache.h"
+#define X(f) \
+static void f(int sig) { \
+ puts(#f); \
+ fflush(stdout); \
+ sigchain_pop(sig); \
+ raise(sig); \
+#undef X
+int main(int argc, char **argv) {
+ sigchain_push(SIGINT, one);
+ sigchain_push(SIGINT, two);
+ sigchain_push(SIGINT, three);
+ raise(SIGINT);
+ return 0;