On Mon, Mar 25, 2013 at 12:50:54PM -0700, Junio C Hamano wrote:
> >> transport.c: In function 'get_refs_via_rsync':
> >> transport.c:127:29: error: 'cmp' may be used uninitialized in this
> >> function [-Werror=uninitialized]
> >> transport.c:109:7: note: 'cmp' was declared here
> >>
> >> gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
> >
> > Right, that's the same version I noted above. Is 4.6.3 the default
> > compiler under a particular release of Ubuntu, or did you use their
> > gcc-4.6 package?
>
> I'll check later with one of my VMs. The copy of U 12.04 I happened
> to have handy has that version installed.
Ah, if you didn't explicitly run "gcc-4.6", then it was probably the
default version in 12.04 (as it was for a while in Debian testing, but
they never actually made a release with it, so everybody is now on 4.7
by default).
> By the way, I find this piece of code less than pleasant:
>
> * It uses "struct ref dummy = { NULL }, *tail = &dummy", and then
> accumulates things by appending to "&tail" and then returns
> dummy.next. Why doesn't it do
>
> struct ref *retval = NULL, **tail = &retval;
>
> and pass tail around to append things, like everybody else? Is
> this another instance of "People do not understand linked list"
> problem? Perhaps fixing that may unconfuse the compiler?
Ugh, that is horrible. At first I thought it was even wrong, as we pass
&tail and not &dummy.next to read_loose_refs. But two wrongs _do_ make a
right, because read_loose_refs, rather than do:
*tail = new;
tail = &new->next;
does:
(*tail)->next = new;
*tail = new;
> Later, the tail of the same list is passed to insert_packed_refs(),
> which does in-place merging of this list and the contents of the
> packed_refs file. These two data sources have to be sorted the
> same way for this merge to work correctly, but there is no
> validating the order of the entries it reads from the packed-refs
> file. At least, it should barf when the file is not sorted. It
> could be lenient and accept a mal-sorted input, but I do not think
> that is advisable.
Actually, it is the head of the loose list (though it is hard to
realize, because it is called tail!).
> I'll apply the attached on 'maint' for now, as rsync is not worth
> spending too many cycles on worrying about; I need to go to the
> bathroom to wash my eyes after staring this code for 20 minutes X-<.
Yeah, it's quite ugly. I really wonder if it is time to drop rsync
support. I'd be really surprised if anybody is actively using it.
I wonder, though, what made you look at this. It did not come up in my
list of -Wuninitialized warnings. Did it get triggered by one of the
other gcc versions?
> diff --git a/transport.c b/transport.c
> index 87b8f14..e6f9346 100644
> --- a/transport.c
> +++ b/transport.c
> @@ -106,7 +106,8 @@ static void insert_packed_refs(const char *packed_refs,
> struct ref **list)
> return;
>
> for (;;) {
> - int cmp, len;
> + int cmp = 0; /* assigned before used */
> + int len;
>
> if (!fgets(buffer, sizeof(buffer), f)) {
> fclose(f);
I think that's fine.
-Peff
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