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[PATCH v21 19/19] refs.c: change ref_transaction_update() to do error checking and return status

From
Ronnie Sahlberg <sahlberg@google.com>
Date
Jul 14, 2014, 20:59 UTC
Message-ID
<1405371541-32121-20-git-send-email-sahlberg@google.com>
In-Reply-To
<1405371541-32121-1-git-send-email-sahlberg@google.com>

Update ref_transaction_update() do some basic error checking and return non-zero on error. Update all callers to check ref_transaction_update() for error. There are currently no conditions in _update that will return error but there will be in the future. Add an err argument that will be updated on failure. In future patches we will start doing both locking and checking for name conflicts in _update instead of _commit at which time this function will start returning errors for these conditions.

Also check for BUGs during update and die(BUG:...) if we are calling _update with have_old but the old_sha1 pointer is NULL.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/update-ref.c | 12 +++++++-----
 refs.c               | 18 ++++++++++++------
 refs.h               | 14 +++++++++-----
 3 files changed, 28 insertions(+), 16 deletions(-)
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 88ab785..3067b11 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -16,6 +16,7 @@ static struct ref_transaction *transaction;
 
 static char line_termination = '\n';
 static int update_flags;
+static struct strbuf err = STRBUF_INIT;
 
 /*
  * Parse one whitespace- or NUL-terminated, possibly C-quoted argument
@@ -197,8 +198,9 @@ static const char *parse_cmd_update(struct strbuf *input, const char *next)
 	if (*next != line_termination)
 		die("update %s: extra input: %s", refname, next);
 
-	ref_transaction_update(transaction, refname, new_sha1, old_sha1,
-			       update_flags, have_old);
+	if (ref_transaction_update(transaction, refname, new_sha1, old_sha1,
+				   update_flags, have_old, &err))
+		die("%s", err.buf);
 
 	update_flags = 0;
 	free(refname);
@@ -286,8 +288,9 @@ static const char *parse_cmd_verify(struct strbuf *input, const char *next)
 	if (*next != line_termination)
 		die("verify %s: extra input: %s", refname, next);
 
-	ref_transaction_update(transaction, refname, new_sha1, old_sha1,
-			       update_flags, have_old);
+	if (ref_transaction_update(transaction, refname, new_sha1, old_sha1,
+				   update_flags, have_old, &err))
+		die("%s", err.buf);
 
 	update_flags = 0;
 	free(refname);
@@ -342,7 +345,6 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 	const char *refname, *oldval, *msg = NULL;
 	unsigned char sha1[20], oldsha1[20];
 	int delete = 0, no_deref = 0, read_stdin = 0, end_null = 0, flags = 0;
-	struct strbuf err = STRBUF_INIT;
 	struct option options[] = {
 		OPT_STRING( 'm', NULL, &msg, N_("reason"), N_("reason of the update")),
 		OPT_BOOL('d', NULL, &delete, N_("delete the reference")),
diff --git a/refs.c b/refs.c
index 4f78bd9..3f05e88 100644
--- a/refs.c
+++ b/refs.c
@@ -3428,19 +3428,25 @@ static struct ref_update *add_update(struct ref_transaction *transaction,
 	return update;
 }
 
-void ref_transaction_update(struct ref_transaction *transaction,
-			    const char *refname,
-			    const unsigned char *new_sha1,
-			    const unsigned char *old_sha1,
-			    int flags, int have_old)
+int ref_transaction_update(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *new_sha1,
+			   const unsigned char *old_sha1,
+			   int flags, int have_old,
+			   struct strbuf *err)
 {
-	struct ref_update *update = add_update(transaction, refname);
+	struct ref_update *update;
+
+	if (have_old && !old_sha1)
+		die("BUG: have_old is true but old_sha1 is NULL");
 
+	update = add_update(transaction, refname);
 	hashcpy(update->new_sha1, new_sha1);
 	update->flags = flags;
 	update->have_old = have_old;
 	if (have_old)
 		hashcpy(update->old_sha1, old_sha1);
+	return 0;
 }
 
 void ref_transaction_create(struct ref_transaction *transaction,
diff --git a/refs.h b/refs.h
index 163b45c..c5376ce 100644
--- a/refs.h
+++ b/refs.h
@@ -246,12 +246,16 @@ struct ref_transaction *ref_transaction_begin(void);
  * be deleted.  If have_old is true, then old_sha1 holds the value
  * that the reference should have had before the update, or zeros if
  * it must not have existed beforehand.
+ * Function returns 0 on success and non-zero on failure. A failure to update
+ * 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_update(struct ref_transaction *transaction,
-			    const char *refname,
-			    const unsigned char *new_sha1,
-			    const unsigned char *old_sha1,
-			    int flags, int have_old);
+int ref_transaction_update(struct ref_transaction *transaction,
+			   const char *refname,
+			   const unsigned char *new_sha1,
+			   const unsigned char *old_sha1,
+			   int flags, int have_old,
+			   struct strbuf *err);
 
 /*
  * Add a reference creation to transaction.  new_sha1 is the value

-- 
2.0.1.546.gf603308
Previous: Ronnie Sahlberg
Message 20 of 20 in “Use ref transactions”
  1. 00/19 Use ref transactionsRonnie Sahlberg, Jul 14, 2014
  2. 01/19 refs.c: remove ref_transaction_rollbackRonnie Sahlberg, Jul 14, 2014
  3. 02/19 refs.c: ref_transaction_commit should not free the transactionRonnie Sahlberg, Jul 14, 2014
  4. 03/19 refs.c: constify the sha arguments for ref_transaction_create|delete|updateRonnie Sahlberg, Jul 14, 2014
  5. 04/19 refs.c: allow passing NULL to ref_transaction_freeRonnie Sahlberg, Jul 14, 2014
  6. 05/19 refs.c: add a strbuf argument to ref_transaction_commit for error loggingRonnie Sahlberg, Jul 14, 2014
  7. 06/19 lockfile.c: add a new public function unable_to_lock_messageRonnie Sahlberg, Jul 14, 2014
  8. 07/19 lockfile.c: make lock_file return a meaningful errno on failureRonnie Sahlberg, Jul 14, 2014
  9. 08/19 refs.c: add an err argument to repack_without_refsRonnie Sahlberg, Jul 14, 2014
  10. 09/19 refs.c: make sure log_ref_setup returns a meaningful errnoRonnie Sahlberg, Jul 14, 2014
  11. 10/19 refs.c: verify_lock should set errno to something meaningfulRonnie Sahlberg, Jul 14, 2014
  12. 11/19 refs.c: make remove_empty_directories always set errno to something saneRonnie Sahlberg, Jul 14, 2014
  13. 12/19 refs.c: commit_packed_refs to return a meaningful errno on failureRonnie Sahlberg, Jul 14, 2014
  14. 13/19 refs.c: make resolve_ref_unsafe set errno to something meaningful on errorRonnie Sahlberg, Jul 14, 2014
  15. 14/19 refs.c: log_ref_write should try to return meaningful errnoRonnie Sahlberg, Jul 14, 2014
  16. 15/19 refs.c: make ref_update_reject_duplicates take a strbuf argument for errorsRonnie Sahlberg, Jul 14, 2014
  17. 16/19 refs.c: make update_ref_write update a strbuf on failureRonnie Sahlberg, Jul 14, 2014
  18. 17/19 update-ref: use err argument to get error from ref_transaction_commitRonnie Sahlberg, Jul 14, 2014
  19. 18/19 refs.c: remove the onerr argument to ref_transaction_commitRonnie Sahlberg, Jul 14, 2014
  20. 19/19 refs.c: change ref_transaction_update() to do error checking and return statusRonnie Sahlberg, Jul 14, 2014

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