[PATCH v6 28/42] refs.c: add transaction.status and track OPEN/CLOSED/ERROR

[Ronnie Sahlberg <sahlberg@xxxxxxxxxx>]

Track the status of a transaction in a new status field. Check the field for
sanity, i.e. that status must be OPEN when _commit/_create/_delete or
_update is called or else die(BUG:...)

Signed-off-by: Ronnie Sahlberg <sahlberg@xxxxxxxxxx>
---
 refs.c | 37 +++++++++++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/refs.c b/refs.c
index a82d6ba..206e1a2 100644
--- a/refs.c
+++ b/refs.c
@@ -3288,6 +3288,12 @@ struct ref_update {
 	const char refname[FLEX_ARRAY];
 };
 
+enum ref_transaction_status {
+	REF_TRANSACTION_OPEN   = 0,
+	REF_TRANSACTION_CLOSED = 1,
+	REF_TRANSACTION_ERROR  = 2,
+};
+
 /*
  * Data structure for holding a reference transaction, which can
  * consist of checks and updates to multiple references, carried out
@@ -3297,6 +3303,7 @@ struct ref_transaction {
 	struct ref_update **updates;
 	size_t alloc;
 	size_t nr;
+	enum ref_transaction_status status;
 };
 
 struct ref_transaction *ref_transaction_begin(void)
@@ -3320,6 +3327,11 @@ void ref_transaction_free(struct ref_transaction *transaction)
 
 void ref_transaction_rollback(struct ref_transaction *transaction)
 {
+	if (!transaction)
+		return;
+
+	transaction->status = REF_TRANSACTION_ERROR;
+
 	ref_transaction_free(transaction);
 }
 
@@ -3344,7 +3356,10 @@ int ref_transaction_update(struct ref_transaction *transaction,
 	struct ref_update *update;
 
 	if (have_old && !old_sha1)
-		die("have_old is true but old_sha1 is NULL");
+		die("BUG: have_old is true but old_sha1 is NULL");
+
+	if (transaction->status != REF_TRANSACTION_OPEN)
+		die("BUG: update on transaction that is not open");
 
 	update = add_update(transaction, refname);
 	hashcpy(update->new_sha1, new_sha1);
@@ -3363,7 +3378,10 @@ int ref_transaction_create(struct ref_transaction *transaction,
 	struct ref_update *update;
 
 	if (!new_sha1 || is_null_sha1(new_sha1))
-		die("create ref with null new_sha1");
+		die("BUG: create ref with null new_sha1");
+
+	if (transaction->status != REF_TRANSACTION_OPEN)
+		die("BUG: create on transaction that is not open");
 
 	update = add_update(transaction, refname);
 
@@ -3382,7 +3400,10 @@ int ref_transaction_delete(struct ref_transaction *transaction,
 	struct ref_update *update;
 
 	if (have_old && !old_sha1)
-		die("have_old is true but old_sha1 is NULL");
+		die("BUG: have_old is true but old_sha1 is NULL");
+
+	if (transaction->status != REF_TRANSACTION_OPEN)
+		die("BUG: delete on transaction that is not open");
 
 	update = add_update(transaction, refname);
 	update->flags = flags;
@@ -3454,8 +3475,13 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 	int n = transaction->nr;
 	struct ref_update **updates = transaction->updates;
 
-	if (!n)
+	if (transaction->status != REF_TRANSACTION_OPEN)
+		die("BUG: commit on transaction that is not open");
+
+	if (!n) {
+		transaction->status = REF_TRANSACTION_CLOSED;
 		return 0;
+	}
 
 	/* Allocate work space */
 	delnames = xmalloc(sizeof(*delnames) * n);
@@ -3517,6 +3543,9 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 	clear_loose_ref_cache(&ref_cache);
 
 cleanup:
+	transaction->status = ret ? REF_TRANSACTION_ERROR
+	  : REF_TRANSACTION_CLOSED;
+
 	for (i = 0; i < n; i++)
 		if (updates[i]->lock)
 			unlock_ref(updates[i]->lock);
-- 
2.0.0.rc1.351.g4d2c8e4

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