tdb2: make summary command handle recovery "dead zone"

[ccan] / ccan / tdb2 / check.c

diff --git a/ccan/tdb2/check.c b/ccan/tdb2/check.c
index f73d01c3d7541fac049a7fd16cda21b51234f740..54f96bb0ea8283583faf91693decd8d467970423 100644 (file)
--- a/ccan/tdb2/check.c
+++ b/ccan/tdb2/check.c
@@ -30,7 +30,7 @@ static bool append(tdb_off_t **arr, size_t *num, tdb_off_t off)
        return true;
 }
 
-static bool check_header(struct tdb_context *tdb)
+static bool check_header(struct tdb_context *tdb, tdb_off_t *recovery)
 {
        uint64_t hash_test;
        struct tdb_header hdr;
@@ -57,6 +57,16 @@ static bool check_header(struct tdb_context *tdb)
                return false;
        }
 
+       *recovery = hdr.recovery;
+       if (*recovery) {
+               if (*recovery < sizeof(hdr) || *recovery > tdb->map_size) {
+                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                                "tdb_check: invalid recovery offset %zu\n",
+                                (size_t)*recovery);
+                       return false;
+               }
+       }
+
        /* Don't check reserved: they *can* be used later. */
        return true;
 }
@@ -370,23 +380,73 @@ static bool check_free_list(struct tdb_context *tdb,
        return true;
 }
 
+/* Slow, but should be very rare. */
+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->read(tdb, off, &c, 1))
+                       return 0;
+               if (c != 0 && c != 0x43)
+                       break;
+       }
+       return len;
+}
+
 static bool check_linear(struct tdb_context *tdb,
                         tdb_off_t **used, size_t *num_used,
-                        tdb_off_t **free, size_t *num_free)
+                        tdb_off_t **free, size_t *num_free,
+                        tdb_off_t recovery)
 {
        tdb_off_t off;
        tdb_len_t len;
+       bool found_recovery = false;
 
        for (off = sizeof(struct tdb_header); off < tdb->map_size; off += len) {
                union {
                        struct tdb_used_record u;
                        struct tdb_free_record f;
+                       struct tdb_recovery_record r;
                } pad, *p;
                p = tdb_get(tdb, off, &pad, sizeof(pad));
                if (!p)
                        return false;
-               if (frec_magic(&p->f) == TDB_FREE_MAGIC
-                   || frec_magic(&p->f) == TDB_COALESCING_MAGIC) {
+
+               /* If we crash after ftruncate, we can get zeroes or fill. */
+               if (p->r.magic == TDB_RECOVERY_INVALID_MAGIC
+                   || p->r.magic ==  0x4343434343434343ULL) {
+                       if (recovery == off) {
+                               found_recovery = true;
+                               len = sizeof(p->r) + p->r.max_len;
+                       } else {
+                               len = dead_space(tdb, off);
+                               if (len < sizeof(p->r)) {
+                                       tdb->log(tdb, TDB_DEBUG_ERROR,
+                                                tdb->log_priv,
+                                                "tdb_check: invalid dead space"
+                                                " at %zu\n", (size_t)off);
+                                       return false;
+                               }
+
+                               tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
+                                        "Dead space at %zu-%zu (of %zu)\n",
+                                        (size_t)off, (size_t)(off + len),
+                                        (size_t)tdb->map_size);
+                       }
+               } else if (p->r.magic == TDB_RECOVERY_MAGIC) {
+                       if (recovery != off) {
+                               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                                        "tdb_check: unexpected recovery"
+                                        " record at offset %zu\n",
+                                        (size_t)off);
+                               return false;
+                       }
+                       found_recovery = true;
+                       len = sizeof(p->r) + p->r.max_len;
+               } else if (frec_magic(&p->f) == TDB_FREE_MAGIC
+                          || frec_magic(&p->f) == TDB_COALESCING_MAGIC) {
                        len = sizeof(p->u) + p->f.data_len;
                        if (off + len > tdb->map_size) {
                                tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
@@ -437,6 +497,15 @@ static bool check_linear(struct tdb_context *tdb,
                        }
                }
        }
+
+       /* We must have found recovery area if there was one. */
+       if (recovery != 0 && !found_recovery) {
+               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
+                        "tdb_check: expected a recovery area at %zu\n",
+                        (size_t)recovery);
+               return false;
+       }
+
        return true;
 }
 
@@ -445,7 +514,7 @@ int tdb_check(struct tdb_context *tdb,
              int (*check)(TDB_DATA key, TDB_DATA data, void *private_data),
              void *private_data)
 {
-       tdb_off_t *free = NULL, *used = NULL, flist;
+       tdb_off_t *free = NULL, *used = NULL, flist, recovery;
        size_t num_free = 0, num_used = 0, num_found = 0, num_flists = 0;
 
        if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false) != 0)
@@ -456,11 +525,11 @@ int tdb_check(struct tdb_context *tdb,
                return -1;
        }
 
-       if (!check_header(tdb))
+       if (!check_header(tdb, &recovery))
                goto fail;
 
        /* First we do a linear scan, checking all records. */
-       if (!check_linear(tdb, &used, &num_used, &free, &num_free))
+       if (!check_linear(tdb, &used, &num_used, &free, &num_free, recovery))
                goto fail;
 
        for (flist = first_flist(tdb); flist; flist = next_flist(tdb, flist)) {