FITS: generating send-streams in portable format
This commit adds the command 'zfs fits-send', analogous to zfs send. The
generated send stream is compatible with the stream generated with that
from 'btrfs send' and can in principle easily be received to any filesystem.

*** 87,96 ****
--- 87,97 ----
  static int zfs_do_snapshot(int argc, char **argv);
  static int zfs_do_unmount(int argc, char **argv);
  static int zfs_do_share(int argc, char **argv);
  static int zfs_do_unshare(int argc, char **argv);
  static int zfs_do_send(int argc, char **argv);
+ static int zfs_do_fits_send(int argc, char **argv);
  static int zfs_do_receive(int argc, char **argv);
  static int zfs_do_promote(int argc, char **argv);
  static int zfs_do_userspace(int argc, char **argv);
  static int zfs_do_allow(int argc, char **argv);
  static int zfs_do_unallow(int argc, char **argv);
*** 129,138 ****
--- 130,140 ----
          HELP_PROMOTE,
          HELP_RECEIVE,
          HELP_RENAME,
          HELP_ROLLBACK,
          HELP_SEND,
+         HELP_FITS_SEND,
          HELP_SET,
          HELP_SHARE,
          HELP_SNAPSHOT,
          HELP_UNMOUNT,
          HELP_UNSHARE,
*** 186,195 ****
--- 188,199 ----
          { "unshare",    zfs_do_unshare,         HELP_UNSHARE            },
          { NULL },
          { "send",       zfs_do_send,            HELP_SEND               },
          { "receive",    zfs_do_receive,         HELP_RECEIVE            },
          { NULL },
+         { "fits-send",  zfs_do_fits_send,       HELP_FITS_SEND          },
+         { NULL },
          { "allow",      zfs_do_allow,           HELP_ALLOW              },
          { NULL },
          { "unallow",    zfs_do_unallow,         HELP_UNALLOW            },
          { NULL },
          { "hold",       zfs_do_hold,            HELP_HOLD               },
*** 252,261 ****
--- 256,268 ----
          case HELP_ROLLBACK:
                  return (gettext("\trollback [-rRf] <snapshot>\n"));
          case HELP_SEND:
                  return (gettext("\tsend [-DnPpRv] [-[iI] snapshot] "
                      "<snapshot>\n"));
+         case HELP_FITS_SEND:
+                 return (gettext("\tfits-send [-v] [-i snapshot] "
+                     "<snapshot>\n"));
          case HELP_SET:
                  return (gettext("\tset <property=value> "
                      "<filesystem|volume|snapshot> ...\n"));
          case HELP_SHARE:
                  return (gettext("\tshare <-a | filesystem>\n"));
*** 3723,3732 ****
--- 3730,3847 ----
  
          return (err != 0);
  }
  
  /*
+  * Send a backup stream to stdout in fits format.
+  */
+ static int
+ zfs_do_fits_send(int argc, char **argv)
+ {
+         char *fromname = NULL;
+         char *toname = NULL;
+         char *cp;
+         zfs_handle_t *zhp;
+         sendflags_t flags = { 0 };
+         int c, err;
+ 
+         /* check options */
+         while ((c = getopt(argc, argv, ":i:v")) != -1) {
+                 switch (c) {
+                 case 'i':
+                         if (fromname)
+                                 usage(B_FALSE);
+                         fromname = optarg;
+                         break;
+                 case 'v':
+                         flags.verbose = B_TRUE;
+                         break;
+                 case ':':
+                         (void) fprintf(stderr, gettext("missing argument for "
+                             "'%c' option\n"), optopt);
+                         usage(B_FALSE);
+                         break;
+                 case '?':
+                         (void) fprintf(stderr, gettext("invalid option '%c'\n"),
+                             optopt);
+                         usage(B_FALSE);
+                 }
+         }
+ 
+         argc -= optind;
+         argv += optind;
+ 
+         /* check number of arguments */
+         if (argc < 1) {
+                 (void) fprintf(stderr, gettext("missing snapshot argument\n"));
+                 usage(B_FALSE);
+         }
+         if (argc > 1) {
+                 (void) fprintf(stderr, gettext("too many arguments\n"));
+                 usage(B_FALSE);
+         }
+ 
+         if (isatty(STDOUT_FILENO)) {
+                 (void) fprintf(stderr,
+                     gettext("Error: Stream can not be written to a terminal.\n"
+                     "You must redirect standard output.\n"));
+                 return (1);
+         }
+ 
+         cp = strchr(argv[0], '@');
+         if (cp == NULL) {
+                 (void) fprintf(stderr,
+                     gettext("argument must be a snapshot\n"));
+                 usage(B_FALSE);
+         }
+         *cp = '\0';
+         toname = cp + 1;
+         zhp = zfs_open(g_zfs, argv[0], ZFS_TYPE_FILESYSTEM);
+         if (zhp == NULL)
+                 return (1);
+ 
+         /*
+          * If they specified the full path to the snapshot, chop off
+          * everything except the short name of the snapshot, but special
+          * case if they specify the origin.
+          */
+         if (fromname && (cp = strchr(fromname, '@')) != NULL) {
+                 char origin[ZFS_MAXNAMELEN];
+                 zprop_source_t src;
+ 
+                 (void) zfs_prop_get(zhp, ZFS_PROP_ORIGIN,
+                     origin, sizeof (origin), &src, NULL, 0, B_FALSE);
+ 
+                 if (strcmp(origin, fromname) == 0) {
+                         fromname = NULL;
+                         flags.fromorigin = B_TRUE;
+                 } else {
+                         *cp = '\0';
+                         if (cp != fromname && strcmp(argv[0], fromname)) {
+                                 (void) fprintf(stderr,
+                                     gettext("incremental source must be "
+                                     "in same filesystem\n"));
+                                 usage(B_FALSE);
+                         }
+                         fromname = cp + 1;
+                         if (strchr(fromname, '@') || strchr(fromname, '/')) {
+                                 (void) fprintf(stderr,
+                                     gettext("invalid incremental source\n"));
+                                 usage(B_FALSE);
+                         }
+                 }
+         }
+ 
+         err = zfs_fits_send(zhp, fromname, toname, &flags, STDOUT_FILENO,
+             NULL, 0);
+ 
+         zfs_close(zhp);
+ 
+         return (err != 0);
+ }
+ 
+ /*
   * allow/unallow stuff
   */
  /* copied from zfs/sys/dsl_deleg.h */
  #define ZFS_DELEG_PERM_CREATE           "create"
  #define ZFS_DELEG_PERM_DESTROY          "destroy"