Re: Bug in "git rev-parse --verify"

> Junio C Hamano <gitster@pobox.com> writes:
>
>> What we may want is another type peeling operator, ^{object}.
>> that makes sure it is an object, like this:
>>
>>     rev-parse --verify 572a535454612a046e7dd7404dcca94d6243c788^{object}
>>
>> It asks "I have this 40-hex; I want an object out of it", just like
>> frotz^{tree} is "I have 'frotz'; I want a tree-ish" for any value of
>> 'frotz'.
>>
>> With that, a use case that it wants to see _any_ object can safely
>> use 'rev-parse --verify "$userinput^{object}' without an annotated
>> tag getting in the way.
>>
>> How does that sound?
>
> Perhaps something like this.  Note that the last hunk is unrelated
> thinko-fix I noticed while browsing the code.
>
> -- >8 --
> Subject: sha1_name.c: ^{object} peeler
>
> A string that names an object can be suffixed with ^{type} peeler to
> say "I have this object name; peel it until you get this type. If
> you cannot do so, it is an error".  v1.8.2^{commit} asks for a commit
> that is pointed at an annotated tag v1.8.2; v1.8.2^{tree} unwraps it
> further to the top-level tree object.  A special suffix ^{} (i.e. no
> type specified) means "I do not care what it unwraps to; just peel
> annotated tag until you get something that is not a tag".
>
> When you have a random user-supplied string, you can turn it to a
> bare 40-hex object name, and cause it to error out if such an object
> does not exist, with:
>
> 	git rev-parse --verify "$userstring^{}"
>
> for most objects, but this does not yield the tag object name when
> $userstring refers to an annotated tag.
>
> Introduce a new suffix, ^{object}, that only makes sure the given
> name refers to an existing object.  Then
>
> 	git rev-parse --verify "$userstring^{object}"
>
> becomes a way to make sure $userstring refers to an existing object.
>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  sha1_name.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/sha1_name.c b/sha1_name.c
> index c50630a..85b6e75 100644
> --- a/sha1_name.c
> +++ b/sha1_name.c
> @@ -594,7 +594,7 @@ struct object *peel_to_type(const char *name, int
> namelen,
>  	while (1) {
>  		if (!o || (!o->parsed && !parse_object(o->sha1)))
>  			return NULL;
> -		if (o->type == expected_type)
> +		if (expected_type == OBJ_ANY || o->type == expected_type)
>  			return o;
>  		if (o->type == OBJ_TAG)
>  			o = ((struct tag*) o)->tagged;
> @@ -645,6 +645,8 @@ static int peel_onion(const char *name, int len,
> unsigned char *sha1)
>  		expected_type = OBJ_TREE;
>  	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
>  		expected_type = OBJ_BLOB;
> +	else if (!prefixcmp(sp, "object}"))
> +		expected_type = OBJ_ANY;
>  	else if (sp[0] == '}')
>  		expected_type = OBJ_NONE;
>  	else if (sp[0] == '/')
> @@ -654,6 +656,8 @@ static int peel_onion(const char *name, int len,
> unsigned char *sha1)
>
>  	if (expected_type == OBJ_COMMIT)
>  		lookup_flags = GET_SHA1_COMMITTISH;
> +	else if (expected_type == OBJ_TREE)
> +		lookup_flags = GET_SHA1_TREEISH;
>
>  	if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
>  		return -1;
> --
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