@matheusbsbs / matheus-bagliano / commits / 2bc1a87e42

rerere: check dirname format while iterating rr_cache directory

In rerere_gc(), we walk over the .git/rr_cache directory and create a struct for each entry we find. We feed any name we get from readdir() to find_rerere_dir(), which then calls get_sha1_hex() on it (since we use the binary hash as a lookup key). If that fails (i.e., the directory name is not what we expected), it returns NULL. But the comment in find_rerere_dir() says "BUG". It _would_ be a bug for the call from new_rerere_id_hex(), the only other code path, to fail here; it's generating the hex internally. But the call in rerere_gc() is using it say "is this a plausible directory name". Let's instead have rerere_gc() do its own "is this plausible" check. That has two benefits: - we can now reliably BUG() inside find_rerere_dir(), which would catch bugs in the other code path (and we now will never return NULL from the function, which makes it easier to see that a rerere_id struct will always have a non-NULL "collection" field). - it makes the use of the binary hash an implementation detail of find_rerere_dir(), not known by callers. That will free us up to change it in a future patch. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Jan 28, 2021 at 01:14 UTC 2bc1a87e42cc07408a1e7442a3315d1e27b8737f

1 file changed +11 -3

rerere.c

+11 -3

@@ -146,7 +146,7 @@ static struct rerere_dir *find_rerere_dir(const char *hex)

146 int pos;

147

148 if (get_sha1_hex(hex, hash))

149 - return NULL; /* BUG */

149 + BUG("cannot parse rerere dir hex?");

150 pos = hash_pos(hash, rerere_dir, rerere_dir_nr, rerere_dir_hash);

151 if (pos < 0) {

152 rr_dir = xmalloc(sizeof(*rr_dir));

@@ -1178,6 +1178,13 @@ static void prune_one(struct rerere_id *id,

1178 unlink_rr_item(id);

1179 }

1180

1181 +/* Does the basename in "path" look plausibly like an rr-cache entry? */

1182 +static int is_rr_cache_dirname(const char *path)

1183 +{

1184 + unsigned char hash[GIT_MAX_RAWSZ];

1185 + return !get_sha1_hex(path, hash);

1186 +}

1187 +

1188 void rerere_gc(struct repository *r, struct string_list *rr)

1189 {

1190 struct string_list to_remove = STRING_LIST_INIT_DUP;

@@ -1205,10 +1212,11 @@ void rerere_gc(struct repository *r, struct string_list *rr)

1212

1213 if (is_dot_or_dotdot(e->d_name))

1214 continue;

1208 - rr_dir = find_rerere_dir(e->d_name);

1209 - if (!rr_dir)

1215 + if (!is_rr_cache_dirname(e->d_name))

1216 continue; /* or should we remove e->d_name? */

1217

1218 + rr_dir = find_rerere_dir(e->d_name);

1219 +

1220 now_empty = 1;

1221 for (id.variant = 0, id.collection = rr_dir;

1222 id.variant < id.collection->status_nr;