[PATCH] Restore SIGCHLD to SIG_DFL where we care about waitpid().
It was reported that under one implementation of socks client, "git clone" fails with "error: waitpid failed (No child processes)", because "git" is spawned after setting SIGCHLD to SIG_IGN.
Arguably it may be a broken setting, but we should protect ourselves so that we can get reliable results from waitpid() for the children we care about.
This patch resets SIGCHLD to SIG_DFL in three places:
- connect.c::git_connect() - initiators of git native
protocol transfer are covered with this.
- daemon.c::main() - obviously.
- merge-index.c::main() - obviously.
There are other programs that do fork() but do not waitpid(): http-push, imap-send. upload-pack does not either, but in the case of that program, each of the forked halves runs exec() another program, so this change would not have much effect there.
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
Linus Torvalds <torvalds@osdl.org> writes:
> On Mon, 19 Jun 2006, Junio C Hamano wrote:
>
>> I do not offhand think of a place where we do fork() but not
>> waitpid(), and it is very tempting to cheat and do that in the
>> main(), since I do not see a downside to it.
>
> Yeah, it probably does make sense. That said, there are several "main()"
> functions, so you'd still end up having to verify that we catch all the
> paths.. Are all users of fork() built-in by now?
Not really. But git native protocol initiators all use
git_connect() so they are easy, and there are only few
remaining ones that matter.
connect.c | 5 +++++
daemon.c | 5 +++++
merge-index.c | 5 +++++
3 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/connect.c b/connect.c
index 52d709e..db7342e 100644
--- a/connect.c
+++ b/connect.c
@@ -581,6 +581,11 @@ int git_connect(int fd[2], char *url, co
enum protocol protocol = PROTO_LOCAL;
int free_path = 0;
+ /* Without this we cannot rely on waitpid() to tell
+ * what happened to our children.
+ */
+ signal(SIGCHLD, SIG_DFL);
+
host = strstr(url, "://");
if(host) {
*host = '\0';
diff --git a/daemon.c b/daemon.c
index 2f03f99..1067004 100644
--- a/daemon.c
+++ b/daemon.c
@@ -671,6 +671,11 @@ int main(int argc, char **argv)
int inetd_mode = 0;
int i;
+ /* Without this we cannot rely on waitpid() to tell
+ * what happened to our children.
+ */
+ signal(SIGCHLD, SIG_DFL);
+
for (i = 1; i < argc; i++) {
char *arg = argv[i];
diff --git a/merge-index.c b/merge-index.c
index 024196e..190e12f 100644
--- a/merge-index.c
+++ b/merge-index.c
@@ -99,6 +99,11 @@ int main(int argc, char **argv)
{
int i, force_file = 0;
+ /* Without this we cannot rely on waitpid() to tell
+ * what happened to our children.
+ */
+ signal(SIGCHLD, SIG_DFL);
+
if (argc < 3)
usage("git-merge-index [-o] [-q] <merge-program> (-a | <filename>*)");
--
1.4.0.g275f
Junio C Hamano
