git/sigchain.h

#ifndef SIGCHAIN_H
#define SIGCHAIN_H

typedef void (*sigchain_fun)(int);

int sigchain_push(int sig, sigchain_fun f);
int sigchain_pop(int sig);

void sigchain_push_common(sigchain_fun f);

#endif /* SIGCHAIN_H */
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 <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com> 2009-01-22 14:02:35 +08:00			`#ifndef SIGCHAIN_H`
			`#define SIGCHAIN_H`

			`typedef void (*sigchain_fun)(int);`

			`int sigchain_push(int sig, sigchain_fun f);`
			`int sigchain_pop(int sig);`

refactor signal handling for cleanup functions The current code is very inconsistent about which signals are caught for doing cleanup of temporary files and lock files. Some callsites checked only SIGINT, while others checked a variety of death-dealing signals. This patch factors out those signals to a single function, and then calls it everywhere. For some sites, that means this is a simple clean up. For others, it is an improvement in that they will now properly clean themselves up after a larger variety of signals. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com> 2009-01-22 14:03:08 +08:00			`void sigchain_push_common(sigchain_fun f);`

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 <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com> 2009-01-22 14:02:35 +08:00			`#endif /* SIGCHAIN_H */`