libzfs_sendrecv: Style pass on send_iterate_snap

* Add a high level comment.
* Use local variables to reduce line wrapping.
* Remove extra braces and insert space for clarity.
* Assert precondition that the dataset name contains '@' for sanity.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes #12967

diff --git a/lib/libzfs/libzfs_sendrecv.c b/lib/libzfs/libzfs_sendrecv.c
index 8cfb8185854a7f943c9094fb359e07d809673659..8e037cde66a8cce90bcbee16b3cdc248be70d2c1 100644 (file)
--- a/lib/libzfs/libzfs_sendrecv.c
+++ b/lib/libzfs/libzfs_sendrecv.c
@@ -283,51 +283,54 @@ typedef struct send_data {
 static void
 send_iterate_prop(zfs_handle_t *zhp, boolean_t received_only, nvlist_t *nv);
 
+/*
+ * Collect guid, valid props, optionally holds, etc. of a snapshot.
+ * This interface is intended for use as a zfs_iter_snapshots_sorted visitor.
+ */
 static int
 send_iterate_snap(zfs_handle_t *zhp, void *arg)
 {
        send_data_t *sd = arg;
        uint64_t guid = zhp->zfs_dmustats.dds_guid;
        uint64_t txg = zhp->zfs_dmustats.dds_creation_txg;
-       char *snapname;
-       nvlist_t *nv;
        boolean_t isfromsnap, istosnap, istosnapwithnofrom;
+       char *snapname = strrchr(zhp->zfs_name, '@') + 1;
+       const char *from = sd->fromsnap;
+       const char *to = sd->tosnap;
 
-       snapname = strrchr(zhp->zfs_name, '@')+1;
-       isfromsnap = (sd->fromsnap != NULL &&
-           strcmp(sd->fromsnap, snapname) == 0);
-       istosnap = (sd->tosnap != NULL && (strcmp(sd->tosnap, snapname) == 0));
-       istosnapwithnofrom = (istosnap && sd->fromsnap == NULL);
+       assert(snapname != (NULL + 1));
+
+       isfromsnap = (from != NULL && strcmp(from, snapname) == 0);
+       istosnap = (to != NULL && strcmp(to, snapname) == 0);
+       istosnapwithnofrom = (istosnap && from == NULL);
 
        if (sd->tosnap_txg != 0 && txg > sd->tosnap_txg) {
                if (sd->verbose) {
                        (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                            "skipping snapshot %s because it was created "
                            "after the destination snapshot (%s)\n"),
-                           zhp->zfs_name, sd->tosnap);
+                           zhp->zfs_name, to);
                }
                zfs_close(zhp);
                return (0);
        }
 
        fnvlist_add_uint64(sd->parent_snaps, snapname, guid);
+
        /*
         * NB: if there is no fromsnap here (it's a newly created fs in
         * an incremental replication), we will substitute the tosnap.
         */
-       if (isfromsnap || (sd->parent_fromsnap_guid == 0 && istosnap)) {
+       if (isfromsnap || (sd->parent_fromsnap_guid == 0 && istosnap))
                sd->parent_fromsnap_guid = guid;
-       }
 
        if (!sd->recursive) {
-
                /*
                 * To allow a doall stream to work properly
                 * with a NULL fromsnap
                 */
-               if (sd->doall && sd->fromsnap == NULL && !sd->seenfrom) {
+               if (sd->doall && from == NULL && !sd->seenfrom)
                        sd->seenfrom = B_TRUE;
-               }
 
                if (!sd->seenfrom && isfromsnap) {
                        sd->seenfrom = B_TRUE;
@@ -344,10 +347,11 @@ send_iterate_snap(zfs_handle_t *zhp, void *arg)
                        sd->seento = B_TRUE;
        }
 
-       nv = fnvlist_alloc();
+       nvlist_t *nv = fnvlist_alloc();
        send_iterate_prop(zhp, sd->backup, nv);
        fnvlist_add_nvlist(sd->snapprops, snapname, nv);
        fnvlist_free(nv);
+
        if (sd->holds) {
                nvlist_t *holds;
                if (lzc_get_holds(zhp->zfs_name, &holds) == 0) {