trans.c : reworking of transaction interruptions

My two previous hacks related to this part
(8038190c7c4786e1c49494eea1b40cdddcbd5136 and
b15a5194d1a8485a2769560e49e6ff03e1862533) were caused by the lack of
understanding of a feature introduced a while ago:
Better control over CTRL-C interruptions -- do not leave the DB in an
inconsistent state (54008798efcc9646f622f6b052ecd83281d57cda).

Now I have been looking at this commit, and the added feature is indeed
interesting. The main problem I had with it is that it does a rather
unusual use of alpm_trans_release, which caused a few problems that I tried
to fix in a weird way. I think these problems were caused by the fact that
there weren't any difference between "interrupt transaction" and "release a
transaction which failed" actions from the alpm_trans_release POV.  So I
decided to add a new function instead, alpm_trans_interrupt, which is
called on Ctrl+C, and which only sets trans->state to STATE_INTERRUPTED so
that remove_commit and add_commit can exit cleanly at a safe moment. This
allowed me to revert my two previous hacks as well.

Also ensure we handle SIGINT correctly in all cases- if a transaction is
not ongoing, then we can free the transaction and exit quickly.

Signed-off-by: Chantry Xavier <shiningxc@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 23 insertions, 11 deletions

diff --git a/lib/libalpm/trans.c b/lib/libalpm/trans.c
index fe37a1f9..9eb27c30 100644
--- a/lib/libalpm/trans.c
+++ b/lib/libalpm/trans.c
@@ -165,13 +165,34 @@ int SYMEXPORT alpm_trans_commit(alpm_list_t **data)
 	return(_alpm_trans_commit(handle->trans, data));
 }
 
+/** Interrupt a transaction.
+ * @return 0 on success, -1 on error (pm_errno is set accordingly)
+ */
+int SYMEXPORT alpm_trans_interrupt()
+{
+	pmtrans_t *trans;
+
+	ALPM_LOG_FUNC;
+
+	/* Sanity checks */
+	ASSERT(handle != NULL, RET_ERR(PM_ERR_HANDLE_NULL, -1));
+
+	trans = handle->trans;
+	ASSERT(trans != NULL, RET_ERR(PM_ERR_TRANS_NULL, -1));
+	ASSERT(trans->state == STATE_COMMITING || trans->state == STATE_INTERRUPTED,
+			RET_ERR(PM_ERR_TRANS_TYPE, -1));
+
+	trans->state = STATE_INTERRUPTED;
+
+	return(0);
+}
+
 /** Release a transaction.
  * @return 0 on success, -1 on error (pm_errno is set accordingly)
  */
 int SYMEXPORT alpm_trans_release()
 {
 	pmtrans_t *trans;
-	int ret = 0;
 
 	ALPM_LOG_FUNC;
 
@@ -182,15 +203,6 @@ int SYMEXPORT alpm_trans_release()
 	ASSERT(trans != NULL, RET_ERR(PM_ERR_TRANS_NULL, -1));
 	ASSERT(trans->state != STATE_IDLE, RET_ERR(PM_ERR_TRANS_NULL, -1));
 
-	/* during a commit do not interrupt immediately, just after a target */
-	if(trans->state == STATE_COMMITING || trans->state == STATE_INTERRUPTED) {
-		if(trans->state == STATE_COMMITING) {
-			trans->state = STATE_INTERRUPTED;
-		}
-		pm_errno = PM_ERR_TRANS_COMMITING;
-		ret = -1;
-	}
-
 	_alpm_trans_free(trans);
 	handle->trans = NULL;
 
@@ -206,7 +218,7 @@ int SYMEXPORT alpm_trans_release()
 				alpm_option_get_lockfile());
 	}
 
-	return(ret);
+	return(0);
 }
 
 /** @} */