Re: [PATCH 13/33] peel_ref(): fix return value for non-peelable, not-current reference

> The old version was inconsistent: when a reference was
> REF_KNOWS_PEELED but with a null peeled value, it returned non-zero
> for the current reference but zero for other references.  Change the
> behavior for non-current references to match that of current_ref,
> which is what callers expect.  Document the behavior.
>
> Current callers did not trigger the previously-buggy behavior.

>
> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
> ---
>  refs.c | 5 ++++-
>  refs.h | 8 ++++++++
>  2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/refs.c b/refs.c
> index 84c2497..a0d8e32 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -120,7 +120,8 @@ struct ref_value {
>  	/*
>  	 * If REF_KNOWS_PEELED, then this field holds the peeled value
>  	 * of this reference, or null if the reference is known not to
> -	 * be peelable.
> +	 * be peelable.  See the documentation for peel_ref() for an
> +	 * exact definition of "peelable".
>  	 */
>  	unsigned char peeled[20];
>  };
> @@ -1339,6 +1340,8 @@ int peel_ref(const char *refname, unsigned char *sha1)
>  		struct ref_entry *r = get_packed_ref(refname);
>  
>  		if (r && (r->flag & REF_KNOWS_PEELED)) {
> +			if (is_null_sha1(r->u.value.peeled))
> +			    return -1;
>  			hashcpy(sha1, r->u.value.peeled);
>  			return 0;
>  		}
> diff --git a/refs.h b/refs.h
> index 17bc1c1..ac0ff92 100644
> --- a/refs.h
> +++ b/refs.h
> @@ -74,6 +74,14 @@ extern void add_packed_ref(const char *refname, const unsigned char *sha1);
>  
>  extern int ref_exists(const char *);
>  
> +/*
> + * If refname is a non-symbolic reference that refers to a tag object,
> + * and the tag can be (recursively) dereferenced to a non-tag object,
> + * store the SHA1 of the referred-to object to sha1 and return 0.  If
> + * any of these conditions are not met, return a non-zero value.
> + * Symbolic references are considered unpeelable, even if they
> + * ultimately resolve to a peelable tag.
> + */
>  extern int peel_ref(const char *refname, unsigned char *sha1);
>  
>  /** Locks a "refs/" ref returning the lock on success and NULL on failure. **/