+ * 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;
+ }
+
+ errno = 0;
+ return options;
+
+err:
+ po_destroy(options);
+ return NULL;
+}
+
+/*
+ * Do the mount(2) system call.
+ *
+ * Returns 1 if successful, otherwise zero.
+ * "errno" is set to reflect the individual error.
+ */
+static int nfs_sys_mount(const struct nfsmount_info *mi, const char *type,
+ const char *options)
+{
+ int result;
+
+ result = mount(mi->spec, mi->node, type,
+ mi->flags & ~(MS_USER|MS_USERS), options);
+ if (verbose && result) {
+ int save = errno;
+ nfs_error(_("%s: mount(2): %s"), progname, strerror(save));
+ errno = save;
+ }
+ return !result;
+}
+
+/*
+ * Retry an NFS mount that failed because the requested service isn't
+ * available on the server.
+ *
+ * Returns 1 if successful. Otherwise, returns zero.
+ * "errno" is set to reflect the individual error.
+ *
+ * Side effect: If the retry is successful, both 'options' and
+ * 'extra_opts' are updated to reflect the mount options that worked.
+ * If the retry fails, 'options' and 'extra_opts' are left unchanged.
+ */
+static int nfs_retry_nfs23mount(struct nfsmount_info *mi)
+{
+ struct mount_options *retry_options;
+ char *retry_str = NULL;
+ char **extra_opts = mi->extra_opts;
+
+ retry_options = nfs_rewrite_mount_options(*extra_opts);
+ if (!retry_options)
+ return 0;
+
+ if (po_join(retry_options, &retry_str) == PO_FAILED) {
+ po_destroy(retry_options);
+ errno = EIO;
+ return 0;
+ }
+
+ if (verbose)
+ printf(_("%s: text-based options (retry): '%s'\n"),
+ progname, retry_str);
+
+ if (!nfs_sys_mount(mi, "nfs", retry_str)) {
+ po_destroy(retry_options);
+ free(retry_str);
+ return 0;
+ }
+
+ free(*extra_opts);
+ *extra_opts = retry_str;
+ po_replace(mi->options, retry_options);
+ return 1;
+}
+
+/*
+ * Attempt an NFSv2/3 mount via a mount(2) system call. If the kernel
+ * claims the requested service isn't supported on the server, probe
+ * the server to see what's supported, rewrite the mount options,
+ * and retry the request.