Re: [PATCH] Add git-bundle: move objects and references by archive

> Junio C Hamano <junkio@cox.net> writes:
> 
> >> +static int verify_bundle(struct bundle_header *header)
> >> +{
> >> +	/*
> >> +	 * Do fast check, then if any prereqs are missing then go line by line
> >> +	 * to be verbose about the errors
> >> +	 */
> >> +	struct ref_list *p = &header->prerequisites;
> >> +	const char *argv[5] = {"rev-list", "--stdin", "--not", "--all", NULL};
> >> +	int pid, in, out, i, ret = 0;
> >> +	char buffer[1024];
> >> +
> >> +	in = out = -1;
> >> +	pid = fork_with_pipe(argv, &in, &out);
> >> +	if (pid < 0)
> >> +		return error("Could not fork rev-list");
> >> +	if (!fork()) {
> >> +		for (i = 0; i < p->nr; i++) {
> >> +			write(in, sha1_to_hex(p->list[i].sha1), 40);
> >> +			write(in, "\n", 1);
> >> +		}
> >> +		close(in);
> >> +		exit(0);
> >> +	}
> >> +	close(in);
> >
> > What if write() fails?  That can happen when one of the objects
> > you feed here, or its parent objects, is missing from your
> > repository -- receiving rev-list would die() and the writing
> > child would sigpipe.
> >
> > I also wonder who waits for this child...
> 
> In general, fork() to avoid bidirectional pipe deadlock is a
> good discipline, but in this particular case I think it would be
> easier to handle errors if you don't (and it would save another
> process).  The other side "rev-list --stdin --not --all" is
> running a limited traversal, and would not emit anything until
> you stop feeding it from --stdin, or until it dies because you
> fed it a commit that does not exist.  So as long as you check
> the error condition from write() for EPIPE to notice the other
> end died, I think you are Ok.