tdb2: TDB_SEQNUM and tdb_get_seqnum support.

[ccan] / ccan / tdb2 / io.c

diff --git a/ccan/tdb2/io.c b/ccan/tdb2/io.c
index 7e5dcb73160f4a441e6e978349e04c2bca5cbaa4..0e27e1d0faea07a2d8640e46db187a0298afcfb8 100644 (file)
--- a/ccan/tdb2/io.c
+++ b/ccan/tdb2/io.c
@@ -563,6 +563,35 @@ static void *tdb_direct(struct tdb_context *tdb, tdb_off_t off, size_t len,
        return (char *)tdb->file->map_ptr + off;
 }
 
+void tdb_inc_seqnum(struct tdb_context *tdb)
+{
+       tdb_off_t seq;
+
+       if (likely(!(tdb->flags & TDB_CONVERT))) {
+               int64_t *direct;
+
+               direct = tdb->methods->direct(tdb,
+                                             offsetof(struct tdb_header,
+                                                      seqnum),
+                                             sizeof(*direct), true);
+               if (likely(direct)) {
+                       /* Don't let it go negative, even briefly */
+                       if (unlikely((*direct) + 1) < 0)
+                               *direct = 0;
+                       (*direct)++;
+                       return;
+               }
+       }
+
+       seq = tdb_read_off(tdb, offsetof(struct tdb_header, seqnum));
+       if (!TDB_OFF_IS_ERR(seq)) {
+               seq++;
+               if (unlikely((int64_t)seq < 0))
+                       seq = 0;
+               tdb_write_off(tdb, offsetof(struct tdb_header, seqnum), seq);
+       }
+}
+
 void add_stat_(struct tdb_context *tdb, uint64_t *s, size_t val)
 {
        if ((uintptr_t)s < (uintptr_t)tdb->stats + tdb->stats->size)