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[PATCH] diff.c: increment buffer pointer in all code path

From
Stefan Beller <sbeller@google.com>
Date
Oct 12, 2017, 23:33 UTC
Message-ID
<20171012233322.31203-1-sbeller@google.com>
In-Reply-To
<20171012200536.m6oz4zrjcze3yw4i@sigill.intra.peff.net>

The added test would hang up Git due to an infinite loop. The function `next_byte()` doesn't make any forward progress in the buffer with `--ignore-space-change`.

Fix this by only returning early when there was actual white space to be covered, fall back to the default case at the end of the function when there is no white space.

Reported-by: Orgad Shaneh <orgads@gmail.com>
Debugged-by: Jeff King <peff@peff.net>
Signed-off-by: Stefan Beller <sbeller@google.com>
---
Peff, feel free to take ownership here. I merely made it to a patch.

Thanks, Stefan

 diff.c                     | 12 ++++++++----
 t/t4015-diff-whitespace.sh |  8 ++++++++
 2 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/diff.c b/diff.c
index 69f03570ad..6fe84e6994 100644
--- a/diff.c
+++ b/diff.c
@@ -713,13 +713,17 @@ static int next_byte(const char **cp, const char **endp,
 		return -1;
 
 	if (DIFF_XDL_TST(diffopt, IGNORE_WHITESPACE_CHANGE)) {
-		while (*cp < *endp && isspace(**cp))
+		int saw_whitespace = 0;
+		while (*cp < *endp && isspace(**cp)) {
 			(*cp)++;
+			saw_whitespace = 1;
+		}
 		/*
-		 * After skipping a couple of whitespaces, we still have to
-		 * account for one space.
+		 * After skipping a couple of whitespaces,
+		 * we still have to account for one space.
 		 */
-		return (int)' ';
+		if (saw_whitespace)
+			return (int)' ';
 	}
 
 	if (DIFF_XDL_TST(diffopt, IGNORE_WHITESPACE)) {
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index bd0f75d9f7..c088ae86af 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1530,4 +1530,12 @@ test_expect_success 'move detection with submodules' '
 	test_cmp expect decoded_actual
 '
 
+test_expect_success 'move detection with whitespace changes' '
+	test_seq 10 > test &&
+	git add test &&
+	sed -i "s/3/42/" test &&
+	git -c diff.colormoved diff --ignore-space-change -- test &&
+	git reset --hard
+'
+
 test_done
-- 
2.14.0.rc0.3.g6c2e499285
Previous: Stefan BellerNext: Jeff King
Message 4 of 34 in “Out of memory with diff.colormoved enabled”
  1. Orgad ShanehOct 12, 2017
  2. Jeff KingOct 12, 2017
  3. Stefan BellerOct 12, 2017
  4. diff.c: increment buffer pointer in all code pathStefan Beller, Oct 12, 2017
  5. Jeff KingOct 13, 2017
  6. Jeff KingOct 13, 2017
  7. Stefan BellerOct 13, 2017
  8. Jeff KingOct 19, 2017
  9. Jeff KingOct 19, 2017
  10. Junio C HamanoOct 19, 2017
  11. Junio C HamanoOct 19, 2017
  12. Jeff KingOct 19, 2017
  13. Jeff KingOct 19, 2017
  14. Stefan BellerOct 19, 2017
  15. 0/5 fix "diff --color-moved --ignore-space-at-eol"Jeff King, Oct 19, 2017
  16. 1/5 t4015: refactor --color-moved whitespace testJeff King, Oct 19, 2017
  17. Stefan BellerOct 19, 2017
  18. Jeff KingOct 19, 2017
  19. 2/5 t4015: check "negative" case for "-w --color-moved"Jeff King, Oct 19, 2017
  20. Stefan BellerOct 19, 2017
  21. 3/5 t4015: test the output of "diff --color-moved -b"Jeff King, Oct 19, 2017
  22. Stefan BellerOct 19, 2017
  23. Jeff KingOct 19, 2017
  24. 4/5 diff: fix whitespace-skipping with --color-movedJeff King, Oct 19, 2017
  25. Stefan BellerOct 19, 2017
  26. Jeff KingOct 19, 2017
  27. Simon RuderichOct 20, 2017
  28. Jeff KingOct 20, 2017
  29. 5/5 diff: handle NULs in get_string_hash()Jeff King, Oct 19, 2017
  30. Stefan BellerOct 19, 2017
  31. Jeff KingOct 19, 2017
  32. Stefan BellerOct 19, 2017
  33. Stefan BellerOct 19, 2017
  34. Jeff KingOct 19, 2017

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