+ po_remove_all(options, "mountvers");
+ snprintf(new_option, sizeof(new_option) - 1,
+ "mountvers=%lu", mnt_pmap->pm_vers);
+ if (po_append(options, new_option) == PO_FAILED)
+ return 0;
+
+ po_remove_all(options, "mountproto");
+ switch (mnt_pmap->pm_prot) {
+ case IPPROTO_TCP:
+ snprintf(new_option, sizeof(new_option) - 1,
+ "mountproto=tcp");
+ if (po_append(options, new_option) == PO_FAILED)
+ return 0;
+ break;
+ case IPPROTO_UDP:
+ snprintf(new_option, sizeof(new_option) - 1,
+ "mountproto=udp");
+ if (po_append(options, new_option) == PO_FAILED)
+ return 0;
+ break;
+ }
+
+ po_remove_all(options, "mountport");
+ snprintf(new_option, sizeof(new_option) - 1,
+ "mountport=%lu", mnt_pmap->pm_port);
+ if (po_append(options, new_option) == PO_FAILED)
+ return 0;
+
+ return 1;
+}
+
+/*
+ * Reconstruct the mount option string based on a portmapper probe
+ * of the server. Returns one if the server's portmapper returned
+ * something we can use, otherwise zero.
+ *
+ * To handle version and transport protocol fallback properly, we
+ * need to parse some of the mount options in order to set up a
+ * portmap probe. Mount options that nfs_rewrite_mount_options()
+ * doesn't recognize are left alone.
+ *
+ * Returns a new group of mount options if successful; otherwise
+ * NULL is returned if some failure occurred.
+ */
+static struct mount_options *nfs_rewrite_mount_options(char *str)
+{
+ struct mount_options *options;
+ char *option;
+ clnt_addr_t mnt_server = { };
+ clnt_addr_t nfs_server = { };
+
+ options = po_split(str);
+ if (!options) {
+ errno = EFAULT;
+ return NULL;
+ }
+
+ errno = EINVAL;
+ option = po_get(options, "addr");
+ if (option) {
+ nfs_server.saddr.sin_family = AF_INET;
+ if (!inet_aton((const char *)option, &nfs_server.saddr.sin_addr))
+ goto err;
+ } else
+ goto err;
+
+ option = po_get(options, "mountaddr");
+ if (option) {
+ mnt_server.saddr.sin_family = AF_INET;
+ if (!inet_aton((const char *)option, &mnt_server.saddr.sin_addr))
+ goto err;
+ } else
+ memcpy(&mnt_server.saddr, &nfs_server.saddr,
+ sizeof(mnt_server.saddr));
+
+ nfs_options2pmap(options, &nfs_server.pmap, &mnt_server.pmap);
+
+ /* The kernel NFS client doesn't support changing the RPC program
+ * number for these services, so reset these fields before probing
+ * the server's ports. */
+ nfs_server.pmap.pm_prog = NFS_PROGRAM;
+ mnt_server.pmap.pm_prog = MOUNTPROG;
+
+ if (!probe_bothports(&mnt_server, &nfs_server)) {
+ errno = ESPIPE;
+ goto err;
+ }
+
+ if (!nfs_construct_new_options(options,
+ &nfs_server.pmap, &mnt_server.pmap)) {
+ errno = EINVAL;
+ goto err;