[PATCH v9 11/44] refs.c: change ref_transaction_create to do error checking and return status

[Ronnie Sahlberg <sahlberg@xxxxxxxxxx>]

Do basic error checking in ref_transaction_create() and make it return
non-zero on error. Update all callers to check the result of
ref_transaction_create(). There are currently no conditions in _create that
will return error but there will be in the future. Add an err argument that
will be updated on failure.

Signed-off-by: Ronnie Sahlberg <sahlberg@xxxxxxxxxx>
---
 builtin/update-ref.c |  4 +++-
 refs.c               | 18 ++++++++++++------
 refs.h               | 12 ++++++++----
 3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 9f328b2..e9c216e 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -226,7 +226,9 @@ static const char *parse_cmd_create(struct strbuf *input, const char *next)
 	if (*next != line_termination)
 		die("create %s: extra input: %s", refname, next);
 
-	ref_transaction_create(transaction, refname, new_sha1, update_flags);
+	if (ref_transaction_create(transaction, refname, new_sha1,
+				   update_flags, NULL))
+		die("cannot create ref '%s'", refname);
 
 	update_flags = 0;
 	free(refname);
diff --git a/refs.c b/refs.c
index 3c9b981..344e27a 100644
--- a/refs.c
+++ b/refs.c
@@ -3402,18 +3402,24 @@ int ref_transaction_update(struct ref_transaction *transaction,
 	return 0;
 }
 
-void ref_transaction_create(struct ref_transaction *transaction,
-			    const char *refname,
-			    const unsigned char *new_sha1,
-			    int flags)
+int ref_transaction_create(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *new_sha1,
+			   int flags,
+			   struct strbuf *err)
 {
-	struct ref_update *update = add_update(transaction, refname);
+	struct ref_update *update;
+
+	if (!new_sha1 || is_null_sha1(new_sha1))
+		die("BUG: create ref with null new_sha1");
+
+	update = add_update(transaction, refname);
 
-	assert(!is_null_sha1(new_sha1));
 	hashcpy(update->new_sha1, new_sha1);
 	hashclr(update->old_sha1);
 	update->flags = flags;
 	update->have_old = 1;
+	return 0;
 }
 
 void ref_transaction_delete(struct ref_transaction *transaction,
diff --git a/refs.h b/refs.h
index 11d07ee..0af5ba7 100644
--- a/refs.h
+++ b/refs.h
@@ -258,11 +258,15 @@ int ref_transaction_update(struct ref_transaction *transaction,
  * that the reference should have after the update; it must not be the
  * null SHA-1.  It is verified that the reference does not exist
  * already.
+ * Function returns 0 on success and non-zero on failure. A failure to create
+ * means that the transaction as a whole has failed and will need to be
+ * rolled back. On failure the err buffer will be updated.
  */
-void ref_transaction_create(struct ref_transaction *transaction,
-			    const char *refname,
-			    const unsigned char *new_sha1,
-			    int flags);
+int ref_transaction_create(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *new_sha1,
+			   int flags,
+			   struct strbuf *err);
 
 /*
  * Add a reference deletion to transaction.  If have_old is true, then
-- 
2.0.0.rc3.477.gffe78a2

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