@matheusbsbs / matheus-bagliano / commits / 47bf4b0fc5

prepare_packed_git_one: refactor duplicate-pack check

When we are reloading the list of packs, we check whether a particular pack has been loaded. This is slightly tricky, because we load packs based on the presence of their ".idx" files, but record the name of the matching ".pack" file. Therefore we want to compare their bases. The existing code stripped off ".idx" from a file we found, then compared that whole base length to strings containing the ".pack" version. This meant we could end up comparing bytes past what the ".pack" string contained, if the ".idx" file name was much longer. In practice, it worked OK because memcmp would end up seeing a difference in the two strings and would return early before hitting the full length. However, memcmp may sometimes read extra bytes past a difference (e.g., because it is comparing 64-bit words), or is even free to compare in reverse order. Furthermore, our memcmp made no guarantees that we matched the whole pack name, up to ".pack". So "foo.idx" would match "foo-bar.pack", which is wrong (but does not typically happen, because our pack names have a fixed size). We can fix both issues, avoid magic numbers, and document that we expect to compare against a string with ".pack" by using strip_suffix. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Jun 30, 2014 at 13:04 UTC 47bf4b0fc52f3ad5823185a85f5f82325787c84b

1 file changed +7 -2

sha1_file.c

+7 -2

@@ -1197,6 +1197,7 @@ static void prepare_packed_git_one(char *objdir, int local)

1197 dirnamelen = path.len;

1198 while ((de = readdir(dir)) != NULL) {

1199 struct packed_git *p;

1200 + size_t base_len;

1201

1202 if (is_dot_or_dotdot(de->d_name))

1203 continue;

@@ -1204,10 +1205,14 @@ static void prepare_packed_git_one(char *objdir, int local)

1205 strbuf_setlen(&path, dirnamelen);

1206 strbuf_addstr(&path, de->d_name);

1207

1207 - if (ends_with(de->d_name, ".idx")) {

1208 + base_len = path.len;

1209 + if (strip_suffix_mem(path.buf, &base_len, ".idx")) {

1210 /* Don't reopen a pack we already have. */

1211 for (p = packed_git; p; p = p->next) {

1210 - if (!memcmp(path.buf, p->pack_name, path.len - 4))

1212 + size_t len;

1213 + if (strip_suffix(p->pack_name, ".pack", &len) &&

1214 + len == base_len &&

1215 + !memcmp(p->pack_name, path.buf, len))

1216 break;

1217 }

1218 if (p == NULL &&