app_voicemail: fix moving when old messages full

When completing voicemail playback of a message in the 'INBOX', the
message gets moved to the 'Old' messages folder. Without this patch, if
the 'Old' folder is already at its set limit, then the 'INBOX' message will
simply be deleted. With this patch, the flag to delete the message will be
removed if the save_to_folder function indicates that the message could
not be moved due to a full folder.

ASTERISK-25082 #close
Reported by: Jonathan Rose
Review: https://gerrit.asterisk.org/#/c/448/

Change-Id: I2be440a09f42e2d06d50975c40d1ad7f836ecb3f

apps/app_voicemail.c

@@ -617,6 +617,7 @@ static AST_LIST_HEAD_STATIC(vmstates, vmstate);
 #define VM_MESSAGEWRAP   (1 << 17)  /*!< Wrap around from the last message to the first, and vice-versa */
 #define VM_FWDURGAUTO    (1 << 18)  /*!< Autoset of Urgent flag on forwarded Urgent messages set globally */
 #define ERROR_LOCK_PATH  -100
+#define ERROR_MAX_MSGS   -101
 #define OPERATOR_EXIT     300
 
 enum vm_box {
@@ -7093,7 +7094,7 @@ static int save_to_folder(struct ast_vm_user *vmu, struct vm_state *vms, int msg
 	} else {
 		if (x >= vmu->maxmsg) {
 			ast_unlock_path(ddir);
-			return -1;
+			return ERROR_MAX_MSGS;
 		}
 	}
 	make_file(sfn, sizeof(sfn), dir, msg);
@@ -8918,7 +8919,7 @@ static int close_mailbox(struct vm_state *vms, struct ast_vm_user *vmu)
 		} else if ((!strcasecmp(vms->curbox, "INBOX") || !strcasecmp(vms->curbox, "Urgent")) && vms->heard[x] && ast_test_flag(vmu, VM_MOVEHEARD) && !vms->deleted[x]) {
 			/* Move to old folder before deleting */
 			res = save_to_folder(vmu, vms, x, 1, NULL, 0);
-			if (res == ERROR_LOCK_PATH) {
+			if (res == ERROR_LOCK_PATH || res == ERROR_MAX_MSGS) {
 				/* If save failed do not delete the message */
 				ast_log(AST_LOG_WARNING, "Save failed.  Not moving message: %s.\n", res == ERROR_LOCK_PATH ? "unable to lock path" : "destination folder full");
 				vms->deleted[x] = 0;