From: Junio C Hamano Date: Wed, 30 Apr 2008 01:28:40 GMT Subject: Re: bug: git-diff silently fails when run outside of a repository (v1.5.4.2) Message-ID: <7vwsmg2ks7.fsf@gitster.siamese.dyndns.org> In-Reply-To: Johannes Schindelin writes: >> > Even so, this seems like a bug. If I do this: >> > >> > $ cd / >> > $ git-diff >> > >> > there is no error message and no error status. A diagnostic would be >> > very helpful. >> >> Ah, that indeed is not very helpful. >> >> Unfortunately, every time I look at this hack, I seem to find an unrelated >> bug in it. Here is today's. >> >> $ for i in 1 2 3; do >/var/tmp/$i; done >> $ cd / >> $ git diff /var/tmp/1 >> Segmentation Fault >> >> When nongit is true, we know the user has to be asking --no-index diff, so >> perhaps we can fix it by doing something like this? >> >> diff --git a/diff-lib.c b/diff-lib.c >> index 069e450..cfd629d 100644 >> --- a/diff-lib.c >> +++ b/diff-lib.c >> @@ -264,6 +264,9 @@ int setup_diff_no_index(struct rev_info *revs, >> DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS); >> break; >> } >> + if (nongit && argc != i + 2) >> + die("git diff [--no-index] takes two paths"); >> + >> if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) && >> !is_outside_repo(argv[i], nongit, prefix))) >> return -1; > > That looks to me as if the second if() should have triggered, and the > caller of setup_diff_no_index() should have errored out. I think the above three-liner fix is something we should have done when we added --no-index codepath. Before the --no-index hack was introduced, we did not even got this far to the place the caller of this function is, if we are outside a repository. By returning -1 from here instead of dying, this code is driving the codepath that has always expected to already be in a repository into a nonrepository, causing them to segfault because there is no git-dir or work-tree set up done yet as they expect.