[PATCH] Add missing position handling to mount parameters gid/backup_gid/snapshot

[Simon Arlott <simon@octiron.net>]

The code tries to optimise for the last parameter not needing to update
the position which means that every time a new one is added to the end
by copying and pasting, the string position is not updated.

That makes it impossible to use backup_uid=/backup_gid=/snapshot= after
gid= or snapshot= after backup_gid= because part of the string is
overwritten and contains invalid keys like "gbackup_uid".

Prepare for the next parameter to be added on the end by updating the
position for snapshot= even though it will be unused.
---
 mount.cifs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mount.cifs.c b/mount.cifs.c
index 4feb397..a169bc6 100644
--- a/mount.cifs.c
+++ b/mount.cifs.c
@@ -1229,6 +1229,7 @@ nocopy:
 			out_len++;
 		}
 		snprintf(out + out_len, word_len + 5, "gid=%s", txtbuf);
+		out_len = strlen(out);
 	}
 	if (got_bkupuid) {
 		word_len = snprintf(txtbuf, sizeof(txtbuf), "%u", bkupuid);
@@ -1260,6 +1261,7 @@ nocopy:
 			out_len++;
 		}
 		snprintf(out + out_len, word_len + 11, "backupgid=%s", txtbuf);
+		out_len = strlen(out);
 	}
 	if (got_snapshot) {
 		word_len = snprintf(txtbuf, sizeof(txtbuf), "%llu", snapshot);
@@ -1275,6 +1277,7 @@ nocopy:
 			out_len++;
 		}
 		snprintf(out + out_len, word_len + 11, "snapshot=%s", txtbuf);
+		out_len = strlen(out);
 	}
 
 	return 0;
-- 
2.17.1

-- 
Simon Arlott