Re: [PATCH v18 10/48] refs.c: verify_lock should set errno to something meaningful

[Michael Haggerty <mhagger@alum.mit.edu>]

On 06/17/2014 05:53 PM, Ronnie Sahlberg wrote:
> Making errno when returning from verify_lock() meaningful, which
> should almost but not completely fix
> 
>  * a bug in "git fetch"'s s_update_ref, which trusts the result of an
>    errno == ENOTDIR check to detect D/F conflicts
> 
> ENOTDIR makes sense as a sign that a file was in the way of a
> directory we wanted to create.  Should "git fetch" also look for
> ENOTEMPTY or EEXIST to catch cases where a directory was in the way
> of a file to be created?
> 
> Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
> ---
>  refs.c | 4 ++++
>  refs.h | 6 +++++-
>  2 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/refs.c b/refs.c
> index 9ea519c..a48f805 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -1932,18 +1932,22 @@ int refname_match(const char *abbrev_name, const char *full_name)
>  	return 0;
>  }
>  
> +/* This function should make sure errno is meaningful on error */
>  static struct ref_lock *verify_lock(struct ref_lock *lock,
>  	const unsigned char *old_sha1, int mustexist)
>  {
>  	if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
> +		int save_errno = errno;
>  		error("Can't verify ref %s", lock->ref_name);
>  		unlock_ref(lock);
> +		errno = save_errno;
>  		return NULL;
>  	}
>  	if (hashcmp(lock->old_sha1, old_sha1)) {
>  		error("Ref %s is at %s but expected %s", lock->ref_name,
>  			sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
>  		unlock_ref(lock);
> +		errno = EBUSY;
>  		return NULL;
>  	}
>  	return lock;
> diff --git a/refs.h b/refs.h
> index 82cc5cb..af4fcdc 100644
> --- a/refs.h
> +++ b/refs.h
> @@ -137,11 +137,15 @@ extern int ref_exists(const char *);
>   */
>  extern int peel_ref(const char *refname, unsigned char *sha1);
>  
> -/** Locks a "refs/" ref returning the lock on success and NULL on failure. **/
> +/*
> + * Locks a "refs/" ref returning the lock on success and NULL on failure.
> + * On failure errno is set to something meaningfull.

s/meaningfull/meaningful/

> + */
>  extern struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1);
>  
>  /** Locks any ref (for 'HEAD' type refs). */
>  #define REF_NODEREF	0x01
> +/* errno is set to something meaningful on failure */
>  extern struct ref_lock *lock_any_ref_for_update(const char *refname,
>  						const unsigned char *old_sha1,
>  						int flags, int *type_p);
> 


-- 
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/