chain kill signals for cleanup functions
commit4a16d072723b48699ea162da24eff05eba298834
authorJeff King <peff@peff.net>
Thu, 22 Jan 2009 06:02:35 +0000 (22 01:02 -0500)
committerJunio C Hamano <gitster@pobox.com>
Thu, 22 Jan 2009 06:46:52 +0000 (21 22:46 -0800)
tree04d834214e8448f254118278ec057c77e3f8f1f1
parent479b0ae81c9291a8bb8d7b2347cc58eeaa701304
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>
12 files changed:
.gitignore
Makefile
builtin-clone.c
builtin-fetch--tool.c
builtin-fetch.c
diff.c
http-push.c
lockfile.c
sigchain.c [new file with mode: 0644]
sigchain.h [new file with mode: 0644]
t/t0005-signals.sh [new file with mode: 0755]
test-sigchain.c [new file with mode: 0644]