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>
diff --git a/Makefile b/Makefile
index 2b873fa..fd02dec 100644
--- a/Makefile
+++ b/Makefile
@@ -388,6 +388,7 @@
LIB_H += run-command.h
LIB_H += sha1-lookup.h
LIB_H += sideband.h
+LIB_H += sigchain.h
LIB_H += strbuf.h
LIB_H += tag.h
LIB_H += transport.h
@@ -481,6 +482,7 @@
LIB_OBJS += sha1_name.o
LIB_OBJS += shallow.o
LIB_OBJS += sideband.o
+LIB_OBJS += sigchain.o
LIB_OBJS += strbuf.o
LIB_OBJS += symlinks.o
LIB_OBJS += tag.o
@@ -1364,6 +1366,7 @@
TEST_PROGRAMS += test-parse-options$X
TEST_PROGRAMS += test-path-utils$X
TEST_PROGRAMS += test-sha1$X
+TEST_PROGRAMS += test-sigchain$X
all:: $(TEST_PROGRAMS)
