do not create "struct commit" with xcalloc

In both blame and merge-recursive, we sometimes create a
"fake" commit struct for convenience (e.g., to represent the
HEAD state as if we would commit it). By allocating
ourselves rather than using alloc_commit_node, we do not
properly set the "index" field of the commit. This can
produce subtle bugs if we then use commit-slab on the
resulting commit, as we will share the "0" index with
another commit.

We can fix this by using alloc_commit_node() to allocate.
Note that we cannot free the result, as it is part of our
commit allocator. However, both cases were already leaking
the allocated commit anyway, so there's nothing to fix up.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/blame.c b/builtin/blame.c
index 88cb7997274de6f9ab6f8a5944748334ce605f60..6e22bdfbfab9088bb58f67c3fc07dd819ed5bec5 100644 (file)
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -2019,7 +2019,7 @@ static struct commit *fake_working_tree_commit(struct diff_options *opt,
        struct strbuf msg = STRBUF_INIT;
 
        time(&now);
-       commit = xcalloc(1, sizeof(*commit));
+       commit = alloc_commit_node();
        commit->object.parsed = 1;
        commit->date = now;
        commit->object.type = OBJ_COMMIT;

diff --git a/merge-recursive.c b/merge-recursive.c
index 41770929420da4cba934b0b86b9cd2f55f9cab31..fc2a68a0d1c01a6023effc6dd7b14200741f144b 100644 (file)
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -40,7 +40,7 @@ static struct tree *shift_tree_object(struct tree *one, struct tree *two,
 
 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
 {
-       struct commit *commit = xcalloc(1, sizeof(struct commit));
+       struct commit *commit = alloc_commit_node();
        struct merge_remote_desc *desc = xmalloc(sizeof(*desc));
 
        desc->name = comment;