Re: [PATCH 07/18] convert trivial cases to FLEX_ARRAY macros

On Mon, Feb 15, 2016 at 11:18:56PM -0500, Eric Sunshine wrote:

quoted

diff --git a/builtin/reflog.c b/builtin/reflog.c

@@ -408,13 +407,12 @@ static struct reflog_expire_cfg *find_cfg_ent(const char *pattern, size_t len)
                reflog_expire_cfg_tail = &reflog_expire_cfg;

        for (ent = reflog_expire_cfg; ent; ent = ent->next)
-               if (ent->len == len &&
-                   !memcmp(ent->pattern, pattern, len))
+               if (!strncmp(ent->pattern, pattern, len) &&
+                   ent->pattern[len] == '\0')

If 'ent->pattern' is shorter than 'pattern' then the strncmp() will
fail, thus it will short-circuit before ent->pattern[len] has a chance
to access beyond the end of memory allocated for 'ent->pattern'. Okay,
makes sense.

Yeah. It took me a minute to convince myself that this was correct. If
you have a shorter or more clear way of writing it, I'm open to it. The
best I could come up with is running an extra "strlen" and otherwise
keeping the loop as it is; the performance on that is not as good, but
if performance is a concern, maybe something besides a linear search
would be in order. :)

-Peff