fsck --name-objects: be more careful parsing generation numbers

In 7b35efd734 (fsck_walk(): optionally name objects on the go,
2016-07-17), the `fsck` machinery learned to optionally name the
objects, so that it is easier to see what part of the repository is in a
bad shape, say, when objects are missing.

To save on complexity, this machinery uses a parser to determine the
name of a parent given a commit's name: any `~<n>` suffix is parsed and
the parent's name is formed from the prefix together with `~<n+1>`.

However, this parser has a bug: if it finds a suffix `<n>` that is _not_
`~<n>`, it will mistake the empty string for the prefix and `<n>` for
the generation number. In other words, it will generate a name of the
form `~<bogus-number>`.

Let's fix this.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Schindelin 2021-02-10 18:01:30 +00:00 committed by Junio C Hamano
parent 8c891eed3a
commit e89f89361c
2 changed files with 11 additions and 4 deletions

5
fsck.c
View File

@ -461,6 +461,11 @@ static int fsck_walk_commit(struct commit *commit, void *data, struct fsck_optio
generation += power * (name[--len] - '0');
if (power > 1 && len && name[len - 1] == '~')
name_prefix_len = len - 1;
else {
/* Maybe a non-first parent, e.g. HEAD^2 */
generation = 0;
name_prefix_len = len;
}
}
}

View File

@ -658,13 +658,15 @@ test_expect_success 'fsck --name-objects' '
git init name-objects &&
(
cd name-objects &&
git config core.logAllRefUpdates false &&
test_commit julius caesar.t &&
test_commit augustus &&
test_commit augustus44 &&
test_commit caesar &&
remove_object $(git rev-parse julius:caesar.t) &&
test_must_fail git fsck --name-objects >out &&
tree=$(git rev-parse --verify julius:) &&
test_i18ngrep "$tree (refs/tags/julius:" out
git tag -d julius &&
test_must_fail git fsck --name-objects >out &&
test_i18ngrep "$tree (refs/tags/augustus44\\^:" out
)
'