From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Stefan Beller <sbeller@google.com>,
git@vger.kernel.org, orgads@gmail.com
Subject: Re: [PATCH] diff.c: increment buffer pointer in all code path
Date: Thu, 19 Oct 2017 01:42:46 -0400 [thread overview]
Message-ID: <20171019054246.jii62lq2druohbpo@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqzi8niu1r.fsf@gitster.mtv.corp.google.com>
On Thu, Oct 19, 2017 at 02:30:08PM +0900, Junio C Hamano wrote:
> Jeff King <peff@peff.net> writes:
>
> > it does. It just adjusts our "end pointer" to point to the last valid
> > character in the string (rather than one past), which seems to be the
> > convention that those loops (and next_byte) expect.
>
> Yeah I am not sure if I like this comparison at the beginning of the
> function:
>
> static int next_byte(const char **cp, const char **endp,
> const struct diff_options *diffopt)
> {
> int retval;
>
> if (*cp > *endp)
> return -1;
>
> but it says endp _is_ part of valid input, contrary to my intuition.
Actually, I think even this function is confused about its convention.
In the line you quote, we clearly treat *endp as part of the input. But
later we do:
while (*cp < *endp && isspace(**cp))
(*cp)++;
meaning that we'd fail to soak up whitespace at *endp. That wouldn't be
so bad if not for the other bug which fails to eat whitespace at endp in
the first place. :)
So I think the right fix is this:
diff --git a/diff.c b/diff.c
index 6fd288420b..09081a207c 100644
--- a/diff.c
+++ b/diff.c
@@ -712,7 +712,7 @@ static int next_byte(const char **cp, const char **endp,
{
int retval;
- if (*cp > *endp)
+ if (*cp >= *endp)
return -1;
if (isspace(**cp)) {
@@ -729,7 +729,12 @@ static int next_byte(const char **cp, const char **endp,
if (DIFF_XDL_TST(diffopt, IGNORE_WHITESPACE)) {
while (*cp < *endp && isspace(**cp))
(*cp)++;
- /* return the first non-ws character via the usual below */
+ /*
+ * return the first non-ws character via the usual
+ * below, unless we ate all of the bytes
+ */
+ if (*cp >= *endp)
+ return -1;
}
}
@@ -750,9 +755,9 @@ static int moved_entry_cmp(const struct diff_options *diffopt,
return a->es->len != b->es->len || memcmp(ap, bp, a->es->len);
if (DIFF_XDL_TST(diffopt, IGNORE_WHITESPACE_AT_EOL)) {
- while (ae > ap && isspace(*ae))
+ while (ae > ap && isspace(ae[-1]))
ae--;
- while (be > bp && isspace(*be))
+ while (be > bp && isspace(be[-1]))
be--;
}
@@ -775,7 +780,7 @@ static unsigned get_string_hash(struct emitted_diff_symbol *es, struct diff_opti
int c;
strbuf_reset(&sb);
- while (ae > ap && isspace(*ae))
+ while (ae > ap && isspace(ae[-1]))
ae--;
while ((c = next_byte(&ap, &ae, o)) > 0)
strbuf_addch(&sb, c);
It's late here, so I'll wait for comments from Stefan and then try to
wrap it up with a commit message and test tomorrow.
-Peff
next prev parent reply other threads:[~2017-10-19 5:42 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-12 19:53 Out of memory with diff.colormoved enabled Orgad Shaneh
2017-10-12 20:05 ` Jeff King
2017-10-12 22:39 ` Stefan Beller
2017-10-12 23:33 ` [PATCH] diff.c: increment buffer pointer in all code path Stefan Beller
2017-10-13 0:18 ` Jeff King
2017-10-13 0:20 ` Jeff King
2017-10-13 0:24 ` Stefan Beller
2017-10-19 5:04 ` Jeff King
2017-10-19 5:24 ` Jeff King
2017-10-19 5:30 ` Junio C Hamano
2017-10-19 5:32 ` Junio C Hamano
2017-10-19 5:32 ` Jeff King
2017-10-19 5:42 ` Jeff King [this message]
2017-10-19 19:55 ` Stefan Beller
2017-10-19 20:23 ` [PATCH 0/5] fix "diff --color-moved --ignore-space-at-eol" Jeff King
2017-10-19 20:24 ` [PATCH 1/5] t4015: refactor --color-moved whitespace test Jeff King
2017-10-19 20:56 ` Stefan Beller
2017-10-19 21:10 ` Jeff King
2017-10-19 20:25 ` [PATCH 2/5] t4015: check "negative" case for "-w --color-moved" Jeff King
2017-10-19 20:54 ` Stefan Beller
2017-10-19 20:26 ` [PATCH 3/5] t4015: test the output of "diff --color-moved -b" Jeff King
2017-10-19 21:03 ` Stefan Beller
2017-10-19 21:14 ` Jeff King
2017-10-19 20:29 ` [PATCH 4/5] diff: fix whitespace-skipping with --color-moved Jeff King
2017-10-19 21:15 ` Stefan Beller
2017-10-19 21:19 ` Jeff King
2017-10-20 7:23 ` Simon Ruderich
2017-10-20 22:37 ` Jeff King
2017-10-19 20:31 ` [PATCH 5/5] diff: handle NULs in get_string_hash() Jeff King
2017-10-19 21:31 ` Stefan Beller
2017-10-19 21:39 ` Jeff King
2017-10-19 21:50 ` Stefan Beller
2017-10-19 19:53 ` [PATCH] diff.c: increment buffer pointer in all code path Stefan Beller
2017-10-19 19:55 ` Jeff King
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