From 4a16d072723b48699ea162da24eff05eba298834 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Thu, 22 Jan 2009 01:02:35 -0500 Subject: 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 --- test-sigchain.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 test-sigchain.c (limited to 'test-sigchain.c') diff --git a/test-sigchain.c b/test-sigchain.c new file mode 100644 index 0000000000..8747deac62 --- /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); \ +} +X(one) +X(two) +X(three) +#undef X + +int main(int argc, char **argv) { + sigchain_push(SIGINT, one); + sigchain_push(SIGINT, two); + sigchain_push(SIGINT, three); + raise(SIGINT); + return 0; +} -- cgit v1.2.3