From: Junio C Hamano <gitster@xxxxxxxxx>
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@xxxxxxxxxxxxxxx>
---
Junio C Hamano wrote:
> Thomas Rast <trast@xxxxxxxxxxxxxxx> writes:
> > I really didn't like the two-interleaved-loops version in your last
> > mail, but this one is way more readable than even the original.
> >
> > (Why did you wrap the for loop? It's only 76 chars.)
>
> Because I was writing it in my MUA ;-)
Well then, perhaps I can at least repay the favour by suggesting a
commit message.
dir.c | 21 ++++++++-------------
1 files changed, 8 insertions(+), 13 deletions(-)
diff --git a/dir.c b/dir.c
index 5e36f8e..78eb869 100644
--- a/dir.c
+++ b/dir.c
@@ -33,20 +33,15 @@ static int common_prefix(const char **pathspec)
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;
}
--
1.7.1.608.g80d39f
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