X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb%2Fcheck.c;h=fa003b79aebabd28aed807c4f9ca1d65d3014d09;hp=c741cef3316ee36d21a4b4b0926e697b5e8ba317;hb=c4c5fed020ba44b9930119672a36a1cb33aff090;hpb=426c8dc977d0fb46286042f7072d86bc053836a1;ds=sidebyside

diff --git a/ccan/tdb/check.c b/ccan/tdb/check.c
index c741cef3..fa003b79 100644
--- a/ccan/tdb/check.c
+++ b/ccan/tdb/check.c
@@ -29,8 +29,9 @@
 static bool tdb_check_header(struct tdb_context *tdb, tdb_off_t *recovery)
 {
 	struct tdb_header hdr;
+	uint32_t h1, h2;
 
-	if (tdb->methods->tdb_read(tdb, 0, &hdr, sizeof(hdr), DOCONV()) == -1)
+	if (tdb->methods->tdb_read(tdb, 0, &hdr, sizeof(hdr), 0) == -1)
 		return false;
 	if (strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0)
 		goto corrupt;
@@ -39,7 +40,12 @@ static bool tdb_check_header(struct tdb_context *tdb, tdb_off_t *recovery)
 	if (hdr.version != TDB_VERSION)
 		goto corrupt;
 
-	if (hdr.hashcheck != hashcheck(tdb))
+	if (hdr.rwlocks != 0 && hdr.rwlocks != TDB_HASH_RWLOCK_MAGIC)
+		goto corrupt;
+
+	tdb_header_hash(tdb, &h1, &h2);
+	if (hdr.magic1_hash && hdr.magic2_hash &&
+	    (hdr.magic1_hash != h1 || hdr.magic2_hash != h2))
 		goto corrupt;
 
 	if (hdr.hash_size == 0)
@@ -302,6 +308,21 @@ static bool tdb_check_free_record(struct tdb_context *tdb,
 	return true;
 }
 
+/* Slow, but should be very rare. */
+static size_t dead_space(struct tdb_context *tdb, tdb_off_t off)
+{
+	size_t len;
+
+	for (len = 0; off + len < tdb->map_size; len++) {
+		char c;
+		if (tdb->methods->tdb_read(tdb, off, &c, 1, 0))
+			return 0;
+		if (c != 0 && c != 0x42)
+			break;
+	}
+	return len;
+}
+
 int tdb_check(struct tdb_context *tdb,
 	      int (*check)(TDB_DATA key, TDB_DATA data, void *private_data),
 	      void *private_data)
@@ -311,9 +332,18 @@ int tdb_check(struct tdb_context *tdb,
 	tdb_off_t off, recovery_start;
 	struct tdb_record rec;
 	bool found_recovery = false;
-
-	if (tdb_lockall(tdb) == -1)
-		return -1;
+	tdb_len_t dead;
+	bool locked;
+
+	/* Read-only databases use no locking at all: it's best-effort.
+	 * We may have a write lock already, so skip that case too. */
+	if (tdb->read_only || tdb->allrecord_lock.count != 0) {
+		locked = false;
+	} else {
+		if (tdb_lockall_read(tdb) == -1)
+			return -1;
+		locked = true;
+	}
 
 	/* Make sure we know true size of the underlying file. */
 	tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
@@ -370,8 +400,23 @@ int tdb_check(struct tdb_context *tdb,
 			if (!tdb_check_free_record(tdb, off, &rec, hashes))
 				goto free;
 			break;
-		case TDB_RECOVERY_MAGIC:
+		/* If we crash after ftruncate, we can get zeroes or fill. */
 		case TDB_RECOVERY_INVALID_MAGIC:
+		case 0x42424242:
+			if (recovery_start == off) {
+				found_recovery = true;
+				break;
+			}
+			dead = dead_space(tdb, off);
+			if (dead < sizeof(rec))
+				goto corrupt;
+
+			TDB_LOG((tdb, TDB_DEBUG_ERROR,
+				 "Dead space at %d-%d (of %u)\n",
+				 off, off + dead, tdb->map_size));
+			rec.rec_len = dead - sizeof(rec);
+			break;
+		case TDB_RECOVERY_MAGIC:
 			if (recovery_start != off) {
 				TDB_LOG((tdb, TDB_DEBUG_ERROR,
 					 "Unexpected recovery record at offset %d\n",
@@ -380,7 +425,8 @@ int tdb_check(struct tdb_context *tdb,
 			}
 			found_recovery = true;
 			break;
-		default:
+		default: ;
+		corrupt:
 			tdb->ecode = TDB_ERR_CORRUPT;
 			TDB_LOG((tdb, TDB_DEBUG_ERROR,
 				 "Bad magic 0x%x at offset %d\n",
@@ -406,19 +452,22 @@ int tdb_check(struct tdb_context *tdb,
 	/* We must have found recovery area if there was one. */
 	if (recovery_start != 0 && !found_recovery) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR,
-			 "Expected %s recovery area, got %s\n",
-			 recovery_start ? "a" : "no",
-			 found_recovery ? "one" : "none"));
+			 "Expected a recovery area at %u\n",
+			 recovery_start));
 		goto free;
 	}
 
 	free(hashes);
-	tdb_unlockall(tdb);
+	if (locked) {
+		tdb_unlockall_read(tdb);
+	}
 	return 0;
 
 free:
 	free(hashes);
 unlock:
-	tdb_unlockall(tdb);
+	if (locked) {
+		tdb_unlockall_read(tdb);
+	}
 	return -1;
 }