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authorMichael Haggerty <mhagger@alum.mit.edu>2015-02-17 18:00:21 +0100
committerJunio C Hamano <gitster@pobox.com>2015-02-17 11:24:59 -0800
commit16180334015ab44b0310b9d896e554a66c36a1a4 (patch)
tree367a45d10a3186a88121c42d28551650d814be94 /refs.h
parent60294596ba6bf2f63506ffad60b9a94fc04612a1 (diff)
downloadgit-16180334015ab44b0310b9d896e554a66c36a1a4.tar.gz
ref_transaction_verify(): new function to check a reference's value
If NULL is passed to ref_transaction_update()'s new_sha1 parameter, then just verify old_sha1 (under lock) without trying to change the new value of the reference. Use this functionality to add a new function ref_transaction_verify(), which checks the current value of the reference under lock but doesn't change it. Use ref_transaction_verify() in the implementation of "git update-ref --stdin"'s "verify" command to avoid the awkward need to "update" the reference to its existing value. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Reviewed-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'refs.h')
-rw-r--r--refs.h34
1 files changed, 26 insertions, 8 deletions
diff --git a/refs.h b/refs.h
index 100731d1c8..5e139d5f8c 100644
--- a/refs.h
+++ b/refs.h
@@ -263,14 +263,19 @@ struct ref_transaction *ref_transaction_begin(struct strbuf *err);
*/
/*
- * Add a reference update to transaction. new_sha1 is the value that
- * the reference should have after the update, or null_sha1 if it should
- * be deleted. If old_sha1 is non-NULL, then it is the value
- * that the reference should have had before the update, or null_sha1 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.
+ * Add a reference update to transaction. new_sha1 is the value that
+ * the reference should have after the update, or null_sha1 if it
+ * should be deleted. If new_sha1 is NULL, then the reference is not
+ * changed at all. old_sha1 is the value that the reference must have
+ * before the update, or null_sha1 if it must not have existed
+ * beforehand. The old value is checked after the lock is taken to
+ * prevent races. If the old value doesn't agree with old_sha1, the
+ * whole transaction fails. If old_sha1 is NULL, then the previous
+ * value is not checked.
+ *
+ * Return 0 on success and non-zero on failure. Any failure in the
+ * transaction means that the transaction as a whole has failed and
+ * will need to be rolled back.
*/
int ref_transaction_update(struct ref_transaction *transaction,
const char *refname,
@@ -309,6 +314,19 @@ int ref_transaction_delete(struct ref_transaction *transaction,
struct strbuf *err);
/*
+ * Verify, within a transaction, that refname has the value old_sha1,
+ * or, if old_sha1 is null_sha1, then verify that the reference
+ * doesn't exist. old_sha1 must be non-NULL. Function returns 0 on
+ * success and non-zero on failure. A failure to verify means that the
+ * transaction as a whole has failed and will need to be rolled back.
+ */
+int ref_transaction_verify(struct ref_transaction *transaction,
+ const char *refname,
+ const unsigned char *old_sha1,
+ unsigned int flags,
+ struct strbuf *err);
+
+/*
* Commit all of the changes that have been queued in transaction, as
* atomically as possible.
*