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[PATCH] dir.c(common_prefix): Fix two bugs

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Apr 23, 2007, 08:21 UTC
Message-ID
<Pine.LNX.4.64.0704231020070.8822@racer.site>

The function common_prefix() is used to find the common subdirectory of a couple of pathnames. When checking if the next pathname matches up with the prefix, it incorrectly checked the whole path, not just the prefix (including the slash). Thus, the expensive part of the loop was executed always.

The other bug is more serious: if the first and the last pathname in the list have a longer common prefix than the common prefix for _all_ pathnames in the list, the longer one would be chosen. This bug was probably hidden by the fact that bash's wildcard expansion sorts the results, and the code just so happens to work with sorted input.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
	If you're up for a very surprising error message, run the test 
	without compiling git-add first...
 dir.c          |    3 ++-
 t/t3700-add.sh |    6 ++++++
 2 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/dir.c b/dir.c
index 6564a92..d306352 100644
--- a/dir.c
+++ b/dir.c
@@ -34,8 +34,9 @@ int common_prefix(const char **pathspec)
 	prefix = slash - path + 1;
 	while ((next = *++pathspec) != NULL) {
 		int len = strlen(next);
-		if (len >= prefix && !memcmp(path, next, len))
+		if (len >= prefix && !memcmp(path, next, prefix))
 			continue;
+		len = prefix - 1;
 		for (;;) {
 			if (!len)
 				return 0;
diff --git a/t/t3700-add.sh b/t/t3700-add.sh
index 08e0352..ad8cc7d 100755
--- a/t/t3700-add.sh
+++ b/t/t3700-add.sh
@@ -104,4 +104,10 @@ test_expect_success 'add ignored ones with -f' '
 	git-ls-files --error-unmatch d.ig/d.if d.ig/d.ig
 '
 
+mkdir 1 1/2 1/3
+touch 1/2/a 1/3/b 1/2/c
+test_expect_success 'check correct prefix detection' '
+	git add 1/2/a 1/3/b 1/2/c
+'
+
 test_done
-- 
1.5.1.1.2671.g2bc0-dirty
Next: Junio C Hamano
Message 1 of 4 in “dir.c(common_prefix): Fix two bugs”
  1. dir.c(common_prefix): Fix two bugsJohannes Schindelin, Apr 23, 2007
  2. Junio C HamanoApr 23, 2007
  3. Johannes SchindelinApr 23, 2007
  4. Junio C HamanoApr 23, 2007

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