On Wed, Jul 9, 2008 at 8:34 PM, Geoffrey Irving <irving@xxxxxxx> wrote: > Add cached-sha-map.[ch] implementing a persistent hash map from sha1 to > sha1. The map is read with mmap, and completely rewritten if any entries > change. It would be good to add incremental update to handle the usual case > where only a few entries change. > > This structure is used by patch-ids.c to cache the mapping from commit to > patch-id into $GIT_DIR/patch-id-cache. In the one case I've tested so far, > this speeds up the second invocation of git-cherry by two orders of > magnitude. The caching can be disabled by setting cherry.cachepatchids to > false. > > Original code cannibalized from Johannes Schindelin's notes-index structure. > > Signed-off-by: Geoffrey Irving <irving@xxxxxxx> > --- > > Note: there are at least two "holes" in this code. First, it is impossible > to verify the validity of the entries (this is impossible to fix). Second, > it is possible to write a malicious patch-id-cache file that causes git-cherry > to go into an infinite loop. Fixing the loop requires either traversing every > entry on load (bad) or adding a second loop termination condition to > find_helper. Since looping forever is better than returning incorrect > results, I figured fixing the weaker hole would just result in a false sense > of security. Oops: avoiding the infinite loop only requires reading expected O(1) entries on load, so I can fix that if you like. It would only be all of them if it actually did detect the infinite loop. Geoffrey -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
