mount: add unc option to CIFS mount (needed for Linux 3.4+)

unc option for CIFS mount is mandatory after CIFS option parsing
was rewritten in Linux 3.4

Signed-off-by: Martin Santesson <martinsn@axis.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/util-linux/mount.c b/util-linux/mount.c
index bcb298c07..d473fd0a1 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -1822,10 +1822,24 @@ static int singlemount(struct mntent *mp, int ignore_busy)
 
                 hostname = mp->mnt_fsname + 2;
                 len = strcspn(hostname, "/\\");
-                if (len == 0 || hostname[len] == '\0')
+                if (len == 0                // 1st char is a [back]slash (IOW: empty hostname)
+                 || hostname[len] == '\0'   // no [back]slash after hostname
+                 || hostname[len+1] == '\0' // empty share name
+                ) {
                         goto report_error;
+                }
                 c = hostname[len];
                 hostname[len] = '\0';
+
+                // "unc=\\hostname\share" option is mandatory
+                // after CIFS option parsing was rewritten in Linux 3.4.
+                // Must pass it to the kernel. Must use backslashes.
+                {
+                        char *unc = xasprintf("unc=\\\\%s\\%s", hostname, hostname + len + 1);
+                        parse_mount_options(unc, &filteropts);
+                        if (ENABLE_FEATURE_CLEAN_UP) free(unc);
+                }
+
                 lsa = host2sockaddr(hostname, 0);
                 hostname[len] = c;
                 if (!lsa)