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authorJunio C Hamano <gitster@pobox.com>2010-06-16 01:02:03 +0200
committerJunio C Hamano <gitster@pobox.com>2010-06-16 12:13:12 -0700
commit42f9852f3c7476b5608ad297443e6d459516f8c0 (patch)
tree9956d2c14b6c2cdddf405156e5ba31a0a51f5a14
parente0a9110176e3b17414b1b38fae8febd0791eaa0c (diff)
downloadgit-42f9852f3c7476b5608ad297443e6d459516f8c0.tar.gz
common_prefix: simplify and fix scanning for prefixes
common_prefix() scans backwards from the far end of each 'next' pathspec, starting from 'len', shortening the 'prefix' using 'path' as a reference. However, there is a small opportunity for an out-of-bounds access because len is unconditionally set to prefix-1 after a "direct match" test failed. This means that if 'next' is shorter than prefix+2, we read past it. Instead of a minimal fix, simplify the loop: scan *forward* over the 'next' entry, remembering the last '/' where it matched the prefix known so far. This is far easier to read and also has the advantage that we only scan over each entry once. Acked-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--dir.c26
1 files changed, 13 insertions, 13 deletions
diff --git a/dir.c b/dir.c
index 5615f33af1..7f912c76f2 100644
--- a/dir.c
+++ b/dir.c
@@ -31,22 +31,22 @@ static int common_prefix(const char **pathspec)
if (!slash)
return 0;
+ /*
+ * The first 'prefix' characters of 'path' are common leading
+ * path components among the pathspecs we have seen so far,
+ * including the trailing slash.
+ */
prefix = slash - path + 1;
while ((next = *++pathspec) != NULL) {
- int len = strlen(next);
- if (len >= prefix && !memcmp(path, next, prefix))
+ int len, last_matching_slash = -1;
+ for (len = 0; len < prefix && next[len] == path[len]; len++)
+ if (next[len] == '/')
+ last_matching_slash = len;
+ if (len == prefix)
continue;
- len = prefix - 1;
- for (;;) {
- if (!len)
- return 0;
- if (next[--len] != '/')
- continue;
- if (memcmp(path, next, len+1))
- continue;
- prefix = len + 1;
- break;
- }
+ if (last_matching_slash < 0)
+ return 0;
+ prefix = last_matching_slash + 1;
}
return prefix;
}