8264 want support for promoting datasets in libzfs_core

@@ -21,10 +21,11 @@
 
 /*
  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2014 Integros [integros.com]
+ * Copyright 2017 RackTop Systems.
  */
 
 /*
  * LibZFS_Core (lzc) is intended to replace most functionality in libzfs.
  * It has the following characteristics:

@@ -201,10 +202,31 @@
         error = lzc_ioctl(ZFS_IOC_CLONE, fsname, args, NULL);
         nvlist_free(args);
         return (error);
 }
 
+int
+lzc_promote(const char *fsname, char *snapnamebuf, int snapnamelen)
+{
+        /*
+         * The promote ioctl is still legacy, so we need to construct our
+         * own zfs_cmd_t rather than using lzc_ioctl().
+         */
+        zfs_cmd_t zc = { 0 };
+
+        ASSERT3S(g_refcount, >, 0);
+        VERIFY3S(g_fd, !=, -1);
+
+        (void) strlcpy(zc.zc_name, fsname, sizeof (zc.zc_name));
+        if (ioctl(g_fd, ZFS_IOC_PROMOTE, &zc) != 0) {
+                if (errno == EEXIST && snapnamebuf != NULL)
+                        (void) strlcpy(snapnamebuf, zc.zc_string, snapnamelen);
+                return (errno);
+        }
+        return (0);
+}
+
 /*
  * Creates snapshots.
  *
  * The keys in the snaps nvlist are the snapshots to be created.
  * They must all be in the same pool.

@@ -328,11 +350,11 @@
 boolean_t
 lzc_exists(const char *dataset)
 {
         /*
          * The objset_stats ioctl is still legacy, so we need to construct our
-         * own zfs_cmd_t rather than using zfsc_ioctl().
+         * own zfs_cmd_t rather than using lzc_ioctl().
          */
         zfs_cmd_t zc = { 0 };
 
         ASSERT3S(g_refcount, >, 0);
         VERIFY3S(g_fd, !=, -1);