tdb: Add tdb_chainwalk_check

[samba.git] / lib / tdb / common / tdb.c

diff --git a/lib/tdb/common/tdb.c b/lib/tdb/common/tdb.c
index 04f7f97eade2389009aed3aecbe59d3c7421cca6..62df8eb1d320fefe5dd3ba97d05ed08dbb28c17f 100644 (file)
--- a/lib/tdb/common/tdb.c
+++ b/lib/tdb/common/tdb.c
@@ -79,6 +79,35 @@ static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data)
        return memcmp(data.dptr, key.dptr, data.dsize);
 }
 
+void tdb_chainwalk_init(struct tdb_chainwalk_ctx *ctx, tdb_off_t ptr)
+{
+       *ctx = (struct tdb_chainwalk_ctx) { .slow_ptr = ptr };
+}
+
+bool tdb_chainwalk_check(struct tdb_context *tdb,
+                        struct tdb_chainwalk_ctx *ctx,
+                        tdb_off_t next_ptr)
+{
+       int ret;
+
+       if (ctx->slow_chase) {
+               ret = tdb_ofs_read(tdb, ctx->slow_ptr, &ctx->slow_ptr);
+               if (ret == -1) {
+                       return false;
+               }
+       }
+       ctx->slow_chase = !ctx->slow_chase;
+
+       if (next_ptr == ctx->slow_ptr) {
+               tdb->ecode = TDB_ERR_CORRUPT;
+               TDB_LOG((tdb, TDB_DEBUG_ERROR,
+                        "tdb_chainwalk_check: circular chain\n"));
+               return false;
+       }
+
+       return true;
+}
+
 /* Returns 0 on fail.  On success, return offset of record, and fills
    in rec */
 static tdb_off_t tdb_find(struct tdb_context *tdb, TDB_DATA key, uint32_t hash,