lib-sieve: Fixed handling of an early explicit keep during multiscrip…

…t execution.

Applies to LDA/LMTP context in general, not only when sieve_before/sieve_after are used.
Action side-effects and the message snapshot would be lost at the final stage where the implicit keep is evaluated.
This happened because the keep action itself is not actually executed, but rather its presence is noted to determine whether more scripts need to be executed.
So, when finally execution of the actual keep action is due, i.e. when there are no more scripts in the sequence, it overrides the explicit keep from the last script.
This didn't take the side-effects and message snapshot into account.

src/lib-sieve/sieve-result.c

@@ -928,7 +928,7 @@ static int _sieve_result_implicit_keep
 (struct sieve_result *result, bool rollback)
 {
 	const struct sieve_action_exec_env *aenv = &result->action_env;
-	struct sieve_result_action *rac;
+	struct sieve_result_action *rac, *kac;
 	int status = SIEVE_EXEC_OK;
 	struct sieve_result_side_effect *rsef, *rsef_first = NULL;
 	void *tr_context = NULL;
@@ -937,38 +937,54 @@ static int _sieve_result_implicit_keep
 	if ( (aenv->flags & SIEVE_EXECUTE_FLAG_DEFER_KEEP) != 0 )
 		return SIEVE_EXEC_OK;
 
-	if ( rollback ) {
+	if ( rollback )
 		act_keep = result->failure_action;
-		act_keep.mail = NULL;
-	} else {
+	else
 		act_keep = result->keep_action;
-		act_keep.mail = sieve_message_get_mail(aenv->msgctx);
-	}
+	act_keep.mail = NULL;
 
 	/* If keep is a non-action, return right away */
 	if ( act_keep.def == NULL )
 		return SIEVE_EXEC_OK;
 
-	/* Scan for execution of keep-equal actions */
-	rac = result->first_action;
-	while ( rac != NULL ) {
-		if ( rac->action.def == act_keep.def && act_keep.def->equals != NULL &&
-			act_keep.def->equals(aenv->scriptenv, NULL, &rac->action) &&
-			rac->action.executed )
-			return SIEVE_EXEC_OK;
-
-		rac = rac->next;
+	/* Scan for deferred keep */
+	kac = result->last_action;
+	while ( kac != NULL && kac->action.executed ) {
+		if ( kac->keep && kac->action.def == NULL )
+			break;
+		kac = kac->prev;
 	}
 
-	/* Apply any implicit side effects if applicable */
-	if ( !rollback && hash_table_is_created(result->action_contexts) ) {
-		struct sieve_result_action_context *actctx;
+	if (kac == NULL) {
+		if ( !rollback )
+			act_keep.mail = sieve_message_get_mail(aenv->msgctx);
 
-		/* Check for implicit side effects to keep action */
-		actctx = hash_table_lookup(result->action_contexts, act_keep.def);
+		/* Scan for execution of keep-equal actions */
+		rac = result->first_action;
+		while ( rac != NULL ) {
+			if ( rac->action.def == act_keep.def && act_keep.def->equals != NULL &&
+				act_keep.def->equals(aenv->scriptenv, NULL, &rac->action) &&
+				rac->action.executed )
+				return SIEVE_EXEC_OK;
 
-		if ( actctx != NULL && actctx->seffects != NULL )
-			rsef_first = actctx->seffects->first_effect;
+			rac = rac->next;
+		}
+
+		/* Apply any implicit side effects if applicable */
+		if ( !rollback && hash_table_is_created(result->action_contexts) ) {
+			struct sieve_result_action_context *actctx;
+
+			/* Check for implicit side effects to keep action */
+			actctx = hash_table_lookup(result->action_contexts, act_keep.def);
+
+			if ( actctx != NULL && actctx->seffects != NULL )
+				rsef_first = actctx->seffects->first_effect;
+		}
+	} else if ( !rollback ) {
+		act_keep.location = kac->action.location;
+		act_keep.mail = kac->action.mail;
+		if ( kac->seffects != NULL )
+			rsef_first = kac->seffects->first_effect;
 	}
 
 	/* Start keep action */