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From: Junio C Hamano <gitster@pobox•com>
To: "Kyle J. McKay" <mackyle@gmail•com>
Cc: Git mailing list <git@vger•kernel.org>,
	Michael Blume <blume.mike@gmail•com>
Subject: Re: [PATCH] test: add git apply whitespace expansion tests
Date: Thu, 22 Jan 2015 11:23:32 -0800	[thread overview]
Message-ID: <xmqq7fwetya3.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <21FC5344-64BF-46B1-ADA9-DDE3B1FEC8C4@gmail.com> (Kyle J. McKay's message of "Wed, 21 Jan 2015 22:55:05 -0800")

"Kyle J. McKay" <mackyle@gmail•com> writes:

> On Jan 21, 2015, at 14:33, Junio C Hamano wrote:
>
>> "Kyle J. McKay" <mackyle@gmail•com> writes:
>>
>>> So since I've not been able to get test 2 or 3 to core dump (even
>>> before 250b3c6c) I tend to believe you are correct in that the code
>>> thinks (incorrectly) that the result should fit within the buffer.
>>
>> Thanks; let me steal your tests when I reroll.
>
> Awesome. :)
>
> But please squash in this tiny change if using the tests verbatim:

Thanks.  I actually have a question wrt the need for $MAKE_PATCHES.

It would have been more natural to do something like:

test_expect_success 'setup' '
	printf "\t%s\n" 1 2 3 4 5 6 >before &&
	printf "\t%s\n" 1 2 3 >after &&
	printf "%64s\n" a b c >>after &&
	printf "\t%s\n" 4 5 6 >>after &&
	git diff --no-index before after |
	sed -e "s/before/test-1/" -e "s/after/test-1/" >patch1.patch &&
	printf "%64s\n" 1 2 3 4 5 6 >test-1 &&
	printf "%64s\n" 1 2 3 a b c 4 5 6 >expect-1 &&

	printf "\t%s\n" a b c d e f >before &&
	printf "\t%s\n" a b c >after &&
        ...
	cat test-4 >expect-4 &&
	printf "%64s\n" a b c >>expect-4 &&
	while test $x -lt 100
	do
		printf "%63s%02d\n" "" $x >>test-4
		printf "%63s%02d\n" "" $x >>expect-4
		x=$(( $x + 1 ))
	done &&

	git config core.whitespace tab-in-indent,tabwidth=63 &&
        git config apply.whitespace fix
'

test_expect_success 'apply with ws expansion (1)' '
	git apply patch1.patch &&
        test_cmp test-1 expect-1
'

and if you want test files you can just skip tests #2 and later,
without introducing an ad-hoc mechanism like you did.

Was there something more than that that you wanted from
$MAKE_PATCHES?

In any case, here is an update to that sanity check patch to catch
the two cases the BUG did not trigger.

Sometimes the caller under-counted the size of the result but
thought that it would still fit within the original (hence allowing
us to update in-place by passing postlen==0) but the actual result
was larger than the space we have allocated in the postimage,
clobbering the piece of memory after the postimage->buf.


diff --git a/builtin/apply.c b/builtin/apply.c
index 31f8733..3b7ba63 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -2171,6 +2171,12 @@ static void update_pre_post_images(struct image *preimage,
 		ctx++;
 	}
 
+	if (postlen
+	    ? postlen < new - postimage->buf
+	    : postimage->len < new - postimage->buf)
+		die("BUG: caller miscounted postlen: asked %d, orig = %d, used = %d",
+		    (int)postlen, (int) postimage->len, (int)(new - postimage->buf));
+
 	/* Fix the length of the whole thing */
 	postimage->len = new - postimage->buf;
 	postimage->nr -= reduced;

  reply	other threads:[~2015-01-22 19:23 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-14 18:20 Segmentation fault in git apply Michael Blume
2015-01-14 18:40 ` Michael Blume
2015-01-14 18:44   ` Michael Blume
2015-01-14 18:48     ` Michael Blume
2015-01-14 18:58       ` Michael Blume
2015-01-14 19:09         ` Michael Blume
2015-01-15  8:26           ` Kyle J. McKay
2015-01-15  9:10             ` Kyle J. McKay
2015-01-16 19:58               ` Junio C Hamano
2015-01-16 23:54                 ` [PATCH] apply: count the size of postimage correctly Junio C Hamano
2015-01-18 10:49                   ` [PATCH] test: add git apply whitespace expansion tests Kyle J. McKay
2015-01-18 22:11                     ` Junio C Hamano
2015-01-19  3:54                       ` Kyle J. McKay
2015-01-21 22:33                         ` Junio C Hamano
2015-01-22  6:55                           ` Kyle J. McKay
2015-01-22 19:23                             ` Junio C Hamano [this message]
2015-01-23  0:12                               ` Kyle J. McKay
2015-01-22 22:58                           ` [PATCH v2 0/4] apply --whitespace=fix buffer corruption fix Junio C Hamano
2015-01-22 22:58                             ` [PATCH v2 1/4] apply.c: typofix Junio C Hamano
2015-01-22 23:17                               ` Stefan Beller
2015-01-22 23:42                                 ` Junio C Hamano
2015-01-22 23:48                                   ` Stefan Beller
2015-01-22 22:58                             ` [PATCH v2 2/4] apply: make update_pre_post_images() sanity check the given postlen Junio C Hamano
2015-01-22 22:58                             ` [PATCH v2 3/4] apply: count the size of postimage correctly Junio C Hamano
2015-01-22 22:58                             ` [PATCH v2 4/4] apply: detect and mark whitespace errors in context lines when fixing Junio C Hamano
2015-01-14 18:50 ` Segmentation fault in git apply Junio C Hamano

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