branch.c: use ref transaction for all ref updates
Change create_branch to use a ref transaction when creating the new branch. This also fixes a race condition in the old code where two concurrent create_branch could race since the lock_any_ref_for_update/write_ref_sha1 did not protect against the ref already existing. I.e. one thread could end up overwriting a branch even if the forcing flag is false. Signed-off-by: Ronnie Sahlberg <sahlberg@google.com> Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ronnie Sahlberg committed
Apr 16, 2014 at 16:21 UTC
d43f990fac72264c1553beb7dbc6e8e795083d42
1 file changed
+17
-14
branch.c
+17
-14
@@ -226,7 +226,6 @@ void create_branch(const char *head,
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int force, int reflog, int clobber_head,
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int quiet, enum branch_track track)
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{
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- struct ref_lock *lock = NULL;
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struct commit *commit;
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unsigned char sha1[20];
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char *real_ref, msg[PATH_MAX + 20];
@@ -285,15 +284,6 @@ void create_branch(const char *head,
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die(_("Not a valid branch point: '%s'."), start_name);
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hashcpy(sha1, commit->object.sha1);
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- if (!dont_change_ref) {
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- lock = lock_any_ref_for_update(ref.buf, NULL, 0, NULL);
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- if (!lock)
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- die_errno(_("Failed to lock ref for update"));
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- }
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-
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- if (reflog)
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- log_all_ref_updates = 1;
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-
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if (forcing)
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snprintf(msg, sizeof msg, "branch: Reset to %s",
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start_name);
@@ -301,13 +291,26 @@ void create_branch(const char *head,
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snprintf(msg, sizeof msg, "branch: Created from %s",
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start_name);
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+ if (reflog)
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+ log_all_ref_updates = 1;
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+
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+ if (!dont_change_ref) {
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+ struct ref_transaction *transaction;
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+ struct strbuf err = STRBUF_INIT;
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+
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+ transaction = ref_transaction_begin(&err);
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+ if (!transaction ||
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+ ref_transaction_update(transaction, ref.buf, sha1,
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+ null_sha1, 0, !forcing, &err) ||
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+ ref_transaction_commit(transaction, msg, &err))
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+ die("%s", err.buf);
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+ ref_transaction_free(transaction);
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+ strbuf_release(&err);
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+ }
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+
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if (real_ref && track)
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setup_tracking(ref.buf + 11, real_ref, track, quiet);
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- if (!dont_change_ref)
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- if (write_ref_sha1(lock, sha1, msg) < 0)
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- die_errno(_("Failed to write ref"));
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-
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strbuf_release(&ref);
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free(real_ref);
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}