fixes + mirror

*** 20,29 ****
--- 20,30 ----
  #include <grub/types.h>
  #include <grub/misc.h>
  #include <grub/mm.h>
  #include <grub/err.h>
  #include <grub/dl.h>
+ #include <grub/zfs/zfs.h>
  #include <grub/device.h>
  #include <grub/file.h>
  #include <grub/env.h>
  #include <grub/command.h>
  #include <grub/search.h>
*** 42,55 ****
  
  static struct cache_entry *cache;
  
  void
  FUNC_NAME (const char *key, const char *var, int no_floppy,
!            char **hints, unsigned nhints)
  {
    int count = 0;
    int is_cache = 0;
    grub_fs_autoload_hook_t saved_autoload;
  
    auto int iterate_device (const char *name);
    int iterate_device (const char *name)
    {
--- 43,57 ----
  
  static struct cache_entry *cache;
  
  void
  FUNC_NAME (const char *key, const char *var, int no_floppy,
!            char **hints, unsigned nhints, int mirror)
  {
    int count = 0;
    int is_cache = 0;
+   grub_uint64_t txg = 0;
    grub_fs_autoload_hook_t saved_autoload;
  
    auto int iterate_device (const char *name);
    int iterate_device (const char *name)
    {
*** 146,163 ****
        }
  
      if (found)
        {
          count++;
!         if (var)
            grub_env_set (var, name);
!         else
            grub_printf (" %s", name);
        }
  
      grub_errno = GRUB_ERR_NONE;
!     return (found && var);
    }
  
    auto int part_hook (grub_disk_t disk, const grub_partition_t partition);
    int part_hook (grub_disk_t disk, const grub_partition_t partition)
    {
--- 148,186 ----
        }
  
      if (found)
        {
          count++;
!         if (var) {
!           if (! mirror) {
              grub_env_set (var, name);
!           } else {
!             grub_uint64_t tmp_txg = 0;
!             char * nvlist = NULL;
!             grub_device_t dev = grub_device_open (name);
!             if (! dev) {
!               grub_errno = GRUB_ERR_BAD_DEVICE;
!               return 0;
!             }
!             grub_errno = grub_zfs_fetch_nvlist (dev, &nvlist);
!             grub_device_close (dev);
!             if (grub_errno)
!               return 0;
!             grub_zfs_nvlist_lookup_uint64 (nvlist, ZPOOL_CONFIG_POOL_TXG, &tmp_txg);
!             if (tmp_txg > txg) {
!               grub_env_set (var, name);
!               txg = tmp_txg;
!             }
!             grub_free (nvlist);
!           }
!         } else {
            grub_printf (" %s", name);
          }
+       }
  
      grub_errno = GRUB_ERR_NONE;
!     return (found && var && !mirror);
    }
  
    auto int part_hook (grub_disk_t disk, const grub_partition_t partition);
    int part_hook (grub_disk_t disk, const grub_partition_t partition)
    {
*** 278,288 ****
  {
    if (argc == 0)
      return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected"));
  
    FUNC_NAME (args[0], argc == 1 ? 0 : args[1], 0, (args + 2),
!              argc > 2 ? argc - 2 : 0);
  
    return grub_errno;
  }
  
  static grub_command_t cmd;
--- 301,311 ----
  {
    if (argc == 0)
      return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected"));
  
    FUNC_NAME (args[0], argc == 1 ? 0 : args[1], 0, (args + 2),
!              argc > 2 ? argc - 2 : 0, 0);
  
    return grub_errno;
  }
  
  static grub_command_t cmd;