[PATCH/RFC] Disallow NULL in struct commit_list
- From
Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
- Date
- Aug 17, 2011, 02:01 UTC
- Message-ID
- <1313546478-8833-1-git-send-email-pclouds@gmail.com>
It seems to me that in most cases commit_list is supposed to contain real commits. If someone puts a NULL there by accident, it'd be hard to track down because sigsegv would happen later when the the commit is used, not when added.
So perhaps we could safeguard commit_list_insert(). If a bug tries to put NULL in, it'd be caught earlier.
There is code that add NULL commit on purpose, "make test" only catches one in revert.c, but I may miss other cases and crash system unnecessarily.
Not sure if this patch is worth the trouble. Maybe make it permanent resident of next and never graduate to master?
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> --- builtin/merge.c | 2 +- builtin/revert.c | 2 +- commit.c | 3 +++ commit.h | 2 ++ 4 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/builtin/merge.c b/builtin/merge.c index 325891e..158008d 100644 --- a/builtin/merge.c +++ b/builtin/merge.c @@ -611,7 +611,7 @@ static void write_tree_trivial(unsigned char *sha1) static const char *merge_argument(struct commit *commit) { - if (commit) + if (commit && commit != &null_commit) return sha1_to_hex(commit->object.sha1); else return EMPTY_TREE_SHA1_HEX; diff --git a/builtin/revert.c b/builtin/revert.c index 1f27c63..7d5005e 100644 --- a/builtin/revert.c +++ b/builtin/revert.c @@ -471,7 +471,7 @@ static int do_pick_commit(void) } strbuf_addstr(&msgbuf, ".\n"); } else { - base = parent; + base = parent ? parent : &null_commit; base_label = msg.parent_label; next = commit; next_label = msg.label; diff --git a/commit.c b/commit.c index dc22695..604d2f1 100644 --- a/commit.c +++ b/commit.c @@ -11,6 +11,8 @@ int save_commit_buffer = 1; const char *commit_type = "commit"; +struct commit null_commit; + static struct commit *check_commit(struct object *obj, const unsigned char *sha1, int quiet) @@ -363,6 +365,7 @@ int find_commit_subject(const char *commit_buffer, const char **subject) struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p) { struct commit_list *new_list = xmalloc(sizeof(struct commit_list)); + assert(item != NULL); new_list->item = item; new_list->next = *list_p; *list_p = new_list; diff --git a/commit.h b/commit.h index 0e36fd0..c9f0743 100644 --- a/commit.h +++ b/commit.h @@ -21,6 +21,8 @@ struct commit { char *buffer; }; +extern struct commit null_commit; + extern int save_commit_buffer; extern const char *commit_type;
-- 1.7.4.74.g639db