tdb2: careful on wrap.

[ccan] / ccan / tdb2 / open.c

diff --git a/ccan/tdb2/open.c b/ccan/tdb2/open.c
index 3e3b083e59d788906169b3fc0dcaf5ae9d9a3571..e238d99248b6ed5813418661a9bb86f3c1f966da 100644 (file)
--- a/ccan/tdb2/open.c
+++ b/ccan/tdb2/open.c
@@ -135,6 +135,7 @@ static enum TDB_ERROR tdb_new_database(struct tdb_context *tdb,
        newdb.hdr.recovery = 0;
        newdb.hdr.features_used = newdb.hdr.features_offered = TDB_FEATURE_MASK;
        newdb.hdr.seqnum = 0;
+       newdb.hdr.capabilities = 0;
        memset(newdb.hdr.reserved, 0, sizeof(newdb.hdr.reserved));
        /* Initial hashes are empty. */
        memset(newdb.hdr.hashtable, 0, sizeof(newdb.hdr.hashtable));
@@ -375,6 +376,54 @@ static bool is_tdb1(struct tdb1_header *hdr, const void *buf, ssize_t rlen)
                || hdr->version == TDB1_BYTEREV(TDB1_VERSION);
 }
 
+/* The top three bits of the capability tell us whether it matters. */
+enum TDB_ERROR unknown_capability(struct tdb_context *tdb, const char *caller,
+                                 tdb_off_t type)
+{
+       if (type & TDB_CAP_NOOPEN) {
+               return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                                 "%s: file has unknown capability %llu",
+                                 caller, type & TDB_CAP_NOOPEN);
+       }
+
+       if ((type & TDB_CAP_NOWRITE) && !(tdb->flags & TDB_RDONLY)) {
+               return tdb_logerr(tdb, TDB_ERR_RDONLY, TDB_LOG_ERROR,
+                                 "%s: file has unknown capability %llu"
+                                 " (cannot write to it)",
+                                 caller, type & TDB_CAP_NOOPEN);
+       }
+
+       if (type & TDB_CAP_NOCHECK) {
+               tdb->flags |= TDB_CANT_CHECK;
+       }
+       return TDB_SUCCESS;
+}
+
+static enum TDB_ERROR capabilities_ok(struct tdb_context *tdb,
+                                     tdb_off_t capabilities)
+{
+       tdb_off_t off, next;
+       enum TDB_ERROR ecode = TDB_SUCCESS;
+       const struct tdb_capability *cap;
+
+       /* Check capability list. */
+       for (off = capabilities; off && ecode == TDB_SUCCESS; off = next) {
+               cap = tdb_access_read(tdb, off, sizeof(*cap), true);
+               if (TDB_PTR_IS_ERR(cap)) {
+                       return TDB_PTR_ERR(cap);
+               }
+
+               switch (cap->type & TDB_CAP_TYPE_MASK) {
+               /* We don't understand any capabilities (yet). */
+               default:
+                       ecode = unknown_capability(tdb, "tdb_open", cap->type);
+               }
+               next = cap->next;
+               tdb_access_release(tdb, cap);
+       }
+       return ecode;
+}
+
 struct tdb_context *tdb_open(const char *name, int tdb_flags,
                             int open_flags, mode_t mode,
                             union tdb_attribute *attr)
@@ -647,12 +696,9 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
                goto fail;
        }
 
+       /* This is a version2 tdb. */
        if (tdb->flags & TDB_VERSION1) {
-               ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
-                                  "tdb_open:"
-                                  " %s does not need TDB_VERSION1",
-                                  name);
-               goto fail;
+               tdb->flags &= ~TDB_VERSION1;
        }
 
        tdb2_context_init(tdb);
@@ -670,6 +716,11 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
                goto fail;
        }
 
+       ecode = capabilities_ok(tdb, hdr.capabilities);
+       if (ecode != TDB_SUCCESS) {
+               goto fail;
+       }
+
        /* Clear any features we don't understand. */
        if ((open_flags & O_ACCMODE) != O_RDONLY) {
                hdr.features_used &= TDB_FEATURE_MASK;
@@ -696,7 +747,7 @@ finished:
        if (tdb->flags & TDB_VERSION1) {
                ecode = tdb1_probe_length(tdb);
        } else {
-               ecode = tdb->tdb2.io->oob(tdb, tdb->file->map_size + 1, true);
+               ecode = tdb->tdb2.io->oob(tdb, tdb->file->map_size, 1, true);
        }
        if (unlikely(ecode != TDB_SUCCESS))
                goto fail;
@@ -706,7 +757,7 @@ finished:
                berr = tdb_needs_recovery(tdb);
                if (unlikely(berr != false)) {
                        if (berr < 0) {
-                               ecode = berr;
+                               ecode = TDB_OFF_TO_ERR(berr);
                                goto fail;
                        }
                        ecode = tdb_lock_and_recover(tdb);
@@ -727,18 +778,18 @@ finished:
 
  fail:
        /* Map ecode to some logical errno. */
-       switch (ecode) {
-       case TDB_ERR_CORRUPT:
-       case TDB_ERR_IO:
+       switch (TDB_ERR_TO_OFF(ecode)) {
+       case TDB_ERR_TO_OFF(TDB_ERR_CORRUPT):
+       case TDB_ERR_TO_OFF(TDB_ERR_IO):
                saved_errno = EIO;
                break;
-       case TDB_ERR_LOCK:
+       case TDB_ERR_TO_OFF(TDB_ERR_LOCK):
                saved_errno = EWOULDBLOCK;
                break;
-       case TDB_ERR_OOM:
+       case TDB_ERR_TO_OFF(TDB_ERR_OOM):
                saved_errno = ENOMEM;
                break;
-       case TDB_ERR_EINVAL:
+       case TDB_ERR_TO_OFF(TDB_ERR_EINVAL):
                saved_errno = EINVAL;
                break;
        default: