[PATCH v9 06/44] refs.c: add an err argument to delete_ref_loose

[Ronnie Sahlberg <sahlberg@google.com>]

Add an err argument to delete_loose_ref so that we can pass a descriptive
error string back to the caller. Pass the err argument from transaction
commit to this function so that transaction users will have a nice error
string if the transaction failed due to delete_loose_ref.

Add a new function unlink_or_err that we can call from delete_ref_loose. This
function is similar to unlink_or_warn except that we can pass it an err
argument. If err is non-NULL the function will populate err instead of
printing a warning().

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 39 +++++++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/refs.c b/refs.c
index 4ebf130..e4d35c9 100644
--- a/refs.c
+++ b/refs.c
@@ -2491,17 +2491,43 @@ static int repack_without_ref(const char *refname)
 	return repack_without_refs(&refname, 1, NULL);
 }
 
-static int delete_ref_loose(struct ref_lock *lock, int flag)
+static int add_err_if_unremovable(const char *op, const char *file,
+				  struct strbuf *e, int rc)
+{
+	int err = errno;
+	if (rc < 0 && err != ENOENT) {
+		strbuf_addf(e, "unable to %s %s: %s",
+			    op, file, strerror(errno));
+		errno = err;
+	}
+	return rc;
+}
+
+static int unlink_or_err(const char *file, struct strbuf *err)
+{
+	if (err)
+		return add_err_if_unremovable("unlink", file, err,
+					      unlink(file));
+	else
+		return unlink_or_warn(file);
+}
+
+static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
 {
 	if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
 		/* loose */
-		int err, i = strlen(lock->lk->filename) - 5; /* .lock */
+		int res, i = strlen(lock->lk->filename) - 5; /* .lock */
 
 		lock->lk->filename[i] = 0;
-		err = unlink_or_warn(lock->lk->filename);
+		res = unlink_or_err(lock->lk->filename, err);
 		lock->lk->filename[i] = '.';
-		if (err && errno != ENOENT)
+		if (res && errno != ENOENT) {
+			if (err)
+				strbuf_addf(err,
+					    "failed to delete loose ref '%s'",
+					    lock->lk->filename);
 			return 1;
+		}
 	}
 	return 0;
 }
@@ -2514,7 +2540,7 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 	lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
 	if (!lock)
 		return 1;
-	ret |= delete_ref_loose(lock, flag);
+	ret |= delete_ref_loose(lock, flag, NULL);
 
 	/* removing the loose one could have resurrected an earlier
 	 * packed one.  Also, if it was not loose we need to repack
@@ -3499,7 +3525,8 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 
 		if (update->lock) {
 			delnames[delnum++] = update->lock->ref_name;
-			ret |= delete_ref_loose(update->lock, update->type);
+			ret |= delete_ref_loose(update->lock, update->type,
+						err);
 		}
 	}
 
-- 
2.0.0.rc3.477.gffe78a2