]> git.ozlabs.org Git - ccan/blobdiff - ccan/tdb2/tdb.c
tdb2: rework some io.c functions to return enum TDB_ERROR.
[ccan] / ccan / tdb2 / tdb.c
index f7a6a5b358a77b33692296479052f37e0a202ad5..8079dad7887d89a649d3ec8aa67daf215d0af041 100644 (file)
@@ -1,8 +1,7 @@
 #include "private.h"
 #include <ccan/tdb2/tdb2.h>
-#include <ccan/build_assert/build_assert.h>
-#include <ccan/likely/likely.h>
 #include <assert.h>
+#include <stdarg.h>
 
 /* The null return. */
 struct tdb_data tdb_null = { .dptr = NULL, .dsize = 0 };
@@ -10,13 +9,6 @@ struct tdb_data tdb_null = { .dptr = NULL, .dsize = 0 };
 /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
 static struct tdb_context *tdbs = NULL;
 
-PRINTF_FMT(4, 5) static void
-null_log_fn(struct tdb_context *tdb,
-           enum tdb_debug_level level, void *priv,
-           const char *fmt, ...)
-{
-}
-
 static bool tdb_already_open(dev_t device, ino_t ino)
 {
        struct tdb_context *i;
@@ -30,6 +22,24 @@ static bool tdb_already_open(dev_t device, ino_t ino)
        return false;
 }
 
+static bool read_all(int fd, void *buf, size_t len)
+{
+       while (len) {
+               ssize_t ret;
+               ret = read(fd, buf, len);
+               if (ret < 0)
+                       return false;
+               if (ret == 0) {
+                       /* ETOOSHORT? */
+                       errno = EWOULDBLOCK;
+                       return false;
+               }
+               buf = (char *)buf + ret;
+               len -= ret;
+       }
+       return true;
+}
+
 static uint64_t random_number(struct tdb_context *tdb)
 {
        int fd;
@@ -38,9 +48,7 @@ static uint64_t random_number(struct tdb_context *tdb)
 
        fd = open("/dev/urandom", O_RDONLY);
        if (fd >= 0) {
-               if (tdb_read_all(fd, &ret, sizeof(ret))) {
-                       tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
-                                "tdb_open: random from /dev/urandom\n");
+               if (read_all(fd, &ret, sizeof(ret))) {
                        close(fd);
                        return ret;
                }
@@ -55,9 +63,6 @@ static uint64_t random_number(struct tdb_context *tdb)
                        char reply[1 + sizeof(uint64_t)];
                        int r = read(fd, reply, sizeof(reply));
                        if (r > 1) {
-                               tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
-                                        "tdb_open: %u random bytes from"
-                                        " /dev/egd-pool\n", r-1);
                                /* Copy at least some bytes. */
                                memcpy(&ret, reply+1, r - 1);
                                if (reply[0] == sizeof(uint64_t)
@@ -73,14 +78,14 @@ static uint64_t random_number(struct tdb_context *tdb)
        /* Fallback: pid and time. */
        gettimeofday(&now, NULL);
        ret = getpid() * 100132289ULL + now.tv_sec * 1000000ULL + now.tv_usec;
-       tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
-                "tdb_open: random from getpid and time\n");
+       tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
+                  "tdb_open: random from getpid and time");
        return ret;
 }
 
 struct new_database {
        struct tdb_header hdr;
-       struct tdb_freelist flist;
+       struct tdb_freetable ftable;
 };
 
 /* initialise a new database */
@@ -91,6 +96,7 @@ static int tdb_new_database(struct tdb_context *tdb,
        /* We make it up in memory, then write it out if not internal */
        struct new_database newdb;
        unsigned int magic_len;
+       ssize_t rlen;
 
        /* Fill in the header */
        newdb.hdr.version = TDB_VERSION;
@@ -109,11 +115,11 @@ static int tdb_new_database(struct tdb_context *tdb,
        memset(newdb.hdr.hashtable, 0, sizeof(newdb.hdr.hashtable));
 
        /* Free is empty. */
-       newdb.hdr.free_list = offsetof(struct new_database, flist);
-       memset(&newdb.flist, 0, sizeof(newdb.flist));
-       set_used_header(NULL, &newdb.flist.hdr, 0,
-                       sizeof(newdb.flist) - sizeof(newdb.flist.hdr),
-                       sizeof(newdb.flist) - sizeof(newdb.flist.hdr), 1);
+       newdb.hdr.free_table = offsetof(struct new_database, ftable);
+       memset(&newdb.ftable, 0, sizeof(newdb.ftable));
+       set_header(NULL, &newdb.ftable.hdr, TDB_FTABLE_MAGIC, 0,
+                  sizeof(newdb.ftable) - sizeof(newdb.ftable.hdr),
+                  sizeof(newdb.ftable) - sizeof(newdb.ftable.hdr), 0);
 
        /* Magic food */
        memset(newdb.hdr.magic_food, 0, sizeof(newdb.hdr.magic_food));
@@ -130,7 +136,8 @@ static int tdb_new_database(struct tdb_context *tdb,
                tdb->map_size = sizeof(newdb);
                tdb->map_ptr = malloc(tdb->map_size);
                if (!tdb->map_ptr) {
-                       tdb->ecode = TDB_ERR_OOM;
+                       tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
+                                  "tdb_new_database: failed to allocate");
                        return -1;
                }
                memcpy(tdb->map_ptr, &newdb, tdb->map_size);
@@ -142,8 +149,13 @@ static int tdb_new_database(struct tdb_context *tdb,
        if (ftruncate(tdb->fd, 0) == -1)
                return -1;
 
-       if (!tdb_pwrite_all(tdb->fd, &newdb, sizeof(newdb), 0)) {
-               tdb->ecode = TDB_ERR_IO;
+       rlen = write(tdb->fd, &newdb, sizeof(newdb));
+       if (rlen != sizeof(newdb)) {
+               if (rlen >= 0)
+                       errno = ENOSPC;
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_new_database: %zi writing header: %s",
+                          rlen, strerror(errno));
                return -1;
        }
        return 0;
@@ -155,17 +167,19 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
 {
        struct tdb_context *tdb;
        struct stat st;
-       int save_errno;
+       int saved_errno = 0;
        uint64_t hash_test;
        unsigned v;
+       ssize_t rlen;
        struct tdb_header hdr;
        struct tdb_attribute_seed *seed = NULL;
+       enum TDB_ERROR ecode;
 
        tdb = malloc(sizeof(*tdb));
        if (!tdb) {
                /* Can't log this */
                errno = ENOMEM;
-               goto fail;
+               return NULL;
        }
        tdb->name = NULL;
        tdb->map_ptr = NULL;
@@ -174,9 +188,10 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        tdb->map_size = sizeof(struct tdb_header);
        tdb->ecode = TDB_SUCCESS;
        tdb->flags = tdb_flags;
-       tdb->log = null_log_fn;
-       tdb->log_priv = NULL;
+       tdb->logfn = NULL;
        tdb->transaction = NULL;
+       tdb->stats = NULL;
+       tdb->access = NULL;
        tdb_hash_init(tdb);
        tdb_io_init(tdb);
        tdb_lock_init(tdb);
@@ -184,8 +199,8 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        while (attr) {
                switch (attr->base.attr) {
                case TDB_ATTRIBUTE_LOG:
-                       tdb->log = attr->log.log_fn;
-                       tdb->log_priv = attr->log.log_private;
+                       tdb->logfn = attr->log.log_fn;
+                       tdb->log_private = attr->log.log_private;
                        break;
                case TDB_ATTRIBUTE_HASH:
                        tdb->khash = attr->hash.hash_fn;
@@ -194,20 +209,24 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
                case TDB_ATTRIBUTE_SEED:
                        seed = &attr->seed;
                        break;
+               case TDB_ATTRIBUTE_STATS:
+                       tdb->stats = &attr->stats;
+                       /* They have stats we don't know about?  Tell them. */
+                       if (tdb->stats->size > sizeof(attr->stats))
+                               tdb->stats->size = sizeof(attr->stats);
+                       break;
                default:
-                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                "tdb_open: unknown attribute type %u\n",
-                                attr->base.attr);
-                       errno = EINVAL;
+                       tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
+                                  "tdb_open: unknown attribute type %u",
+                                  attr->base.attr);
                        goto fail;
                }
                attr = attr->base.next;
        }
 
        if ((open_flags & O_ACCMODE) == O_WRONLY) {
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "tdb_open: can't open tdb %s write-only\n", name);
-               errno = EINVAL;
+               tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
+                          "tdb_open: can't open tdb %s write-only", name);
                goto fail;
        }
 
@@ -225,21 +244,21 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        if (tdb->flags & TDB_INTERNAL) {
                tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
                if (tdb_new_database(tdb, seed, &hdr) != 0) {
-                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                "tdb_open: tdb_new_database failed!");
                        goto fail;
                }
                tdb_convert(tdb, &hdr.hash_seed, sizeof(hdr.hash_seed));
                tdb->hash_seed = hdr.hash_seed;
-               tdb_flist_init(tdb);
+               tdb_ftable_init(tdb);
                return tdb;
        }
 
        if ((tdb->fd = open(name, open_flags, mode)) == -1) {
-               tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
-                        "tdb_open: could not open file %s: %s\n",
-                        name, strerror(errno));
-               goto fail;      /* errno set by open(2) */
+               /* errno set by open(2) */
+               saved_errno = errno;
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_open: could not open file %s: %s",
+                          name, strerror(errno));
+               goto fail;
        }
 
        /* on exec, don't inherit the fd */
@@ -247,31 +266,37 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 
        /* ensure there is only one process initialising at once */
-       if (tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK) == -1) {
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "tdb_open: failed to get open lock on %s: %s\n",
-                        name, strerror(errno));
-               goto fail;      /* errno set by tdb_brlock */
-       }
-
-       if (!tdb_pread_all(tdb->fd, &hdr, sizeof(hdr), 0)
-           || strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) {
-               if (!(open_flags & O_CREAT)
-                   || tdb_new_database(tdb, seed, &hdr) == -1) {
-                       if (errno == 0) {
-                               errno = EIO; /* ie bad format or something */
-                       }
+       tdb->ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
+       if (tdb->ecode != TDB_SUCCESS) {
+               goto fail;
+       }
+
+       /* If they used O_TRUNC, read will return 0. */
+       rlen = read(tdb->fd, &hdr, sizeof(hdr));
+       if (rlen == 0 && (open_flags & O_CREAT)) {
+               if (tdb_new_database(tdb, seed, &hdr) == -1) {
                        goto fail;
                }
-       } else if (hdr.version != TDB_VERSION) {
+       } else if (rlen < 0) {
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_open: error %s reading %s",
+                          strerror(errno), name);
+               goto fail;
+       } else if (rlen < sizeof(hdr)
+                  || strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) {
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_open: %s is not a tdb file", name);
+               goto fail;
+       }
+
+       if (hdr.version != TDB_VERSION) {
                if (hdr.version == bswap_64(TDB_VERSION))
                        tdb->flags |= TDB_CONVERT;
                else {
                        /* wrong version */
-                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                "tdb_open: %s is unknown version 0x%llx\n",
-                                name, (long long)hdr.version);
-                       errno = EIO;
+                       tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                                  "tdb_open: %s is unknown version 0x%llx",
+                                  name, (long long)hdr.version);
                        goto fail;
                }
        }
@@ -282,29 +307,34 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        hash_test = tdb_hash(tdb, &hash_test, sizeof(hash_test));
        if (hdr.hash_test != hash_test) {
                /* wrong hash variant */
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "tdb_open: %s uses a different hash function\n",
-                        name);
-               errno = EIO;
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_open: %s uses a different hash function",
+                          name);
                goto fail;
        }
 
-       if (fstat(tdb->fd, &st) == -1)
+       if (fstat(tdb->fd, &st) == -1) {
+               saved_errno = errno;
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_open: could not stat open %s: %s",
+                          name, strerror(errno));
                goto fail;
+       }
 
        /* Is it already in the open list?  If so, fail. */
        if (tdb_already_open(st.st_dev, st.st_ino)) {
                /* FIXME */
-               tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                        "tdb_open: %s (%d,%d) is already open in this process\n",
-                        name, (int)st.st_dev, (int)st.st_ino);
-               errno = EBUSY;
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_USE_ERROR,
+                          "tdb_open: %s (%d,%d) is already open in this"
+                          " process",
+                          name, (int)st.st_dev, (int)st.st_ino);
                goto fail;
        }
 
        tdb->name = strdup(name);
        if (!tdb->name) {
-               errno = ENOMEM;
+               tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
+                          "tdb_open: failed to allocate name");
                goto fail;
        }
 
@@ -316,12 +346,15 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        tdb->methods->oob(tdb, tdb->map_size + 1, true);
 
        /* Now it's fully formed, recover if necessary. */
-       if (tdb_needs_recovery(tdb) && tdb_lock_and_recover(tdb) == -1) {
-               errno = EIO;
-               goto fail;
+       if (tdb_needs_recovery(tdb)) {
+               ecode = tdb_lock_and_recover(tdb);
+               if (ecode != TDB_SUCCESS) {
+                       tdb->ecode = ecode;
+                       goto fail;
+               }
        }
 
-       if (tdb_flist_init(tdb) == -1)
+       if (tdb_ftable_init(tdb) == -1)
                goto fail;
 
        tdb->next = tdbs;
@@ -329,10 +362,27 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        return tdb;
 
  fail:
-       save_errno = errno;
-
-       if (!tdb)
-               return NULL;
+       /* Map ecode to some logical errno. */
+       if (!saved_errno) {
+               switch (tdb->ecode) {
+               case TDB_ERR_CORRUPT:
+               case TDB_ERR_IO:
+                       saved_errno = EIO;
+                       break;
+               case TDB_ERR_LOCK:
+                       saved_errno = EWOULDBLOCK;
+                       break;
+               case TDB_ERR_OOM:
+                       saved_errno = ENOMEM;
+                       break;
+               case TDB_ERR_EINVAL:
+                       saved_errno = EINVAL;
+                       break;
+               default:
+                       saved_errno = EINVAL;
+                       break;
+               }
+       }
 
 #ifdef TDB_TRACE
        close(tdb->tracefd);
@@ -343,18 +393,18 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
                } else
                        tdb_munmap(tdb);
        }
+       free(tdb->lockrecs);
        free((char *)tdb->name);
        if (tdb->fd != -1)
                if (close(tdb->fd) != 0)
-                       tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
-                                "tdb_open: failed to close tdb->fd"
-                                " on error!\n");
+                       tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                                  "tdb_open: failed to close tdb->fd"
+                                  " on error: %s", strerror(errno));
        free(tdb);
-       errno = save_errno;
+       errno = saved_errno;
        return NULL;
 }
 
-/* FIXME: modify, don't rewrite! */
 static int update_rec_hdr(struct tdb_context *tdb,
                          tdb_off_t off,
                          tdb_len_t keylen,
@@ -363,11 +413,18 @@ static int update_rec_hdr(struct tdb_context *tdb,
                          uint64_t h)
 {
        uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
+       enum TDB_ERROR ecode;
 
-       if (set_used_header(tdb, rec, keylen, datalen, keylen + dataroom, h))
+       if (set_header(tdb, rec, TDB_USED_MAGIC, keylen, datalen,
+                      keylen + dataroom, h))
                return -1;
 
-       return tdb_write_convert(tdb, off, rec, sizeof(*rec));
+       ecode = tdb_write_convert(tdb, off, rec, sizeof(*rec));
+       if (ecode != TDB_SUCCESS) {
+               tdb->ecode = ecode;
+               return -1;
+       }
+       return 0;
 }
 
 /* Returns -1 on error, 0 on OK */
@@ -378,14 +435,17 @@ static int replace_data(struct tdb_context *tdb,
                        bool growing)
 {
        tdb_off_t new_off;
+       enum TDB_ERROR ecode;
 
        /* Allocate a new record. */
-       new_off = alloc(tdb, key.dsize, dbuf.dsize, h->h, growing);
+       new_off = alloc(tdb, key.dsize, dbuf.dsize, h->h, TDB_USED_MAGIC,
+                       growing);
        if (unlikely(new_off == TDB_OFF_ERR))
                return -1;
 
        /* We didn't like the existing one: remove it. */
        if (old_off) {
+               add_stat(tdb, frees, 1);
                add_free_record(tdb, old_off,
                                sizeof(struct tdb_used_record)
                                + key.dsize + old_room);
@@ -397,12 +457,18 @@ static int replace_data(struct tdb_context *tdb,
        }
 
        new_off += sizeof(struct tdb_used_record);
-       if (tdb->methods->write(tdb, new_off, key.dptr, key.dsize) == -1)
+       ecode = tdb->methods->twrite(tdb, new_off, key.dptr, key.dsize);
+       if (ecode != TDB_SUCCESS) {
+               tdb->ecode = ecode;
                return -1;
+       }
 
        new_off += key.dsize;
-       if (tdb->methods->write(tdb, new_off, dbuf.dptr, dbuf.dsize) == -1)
+       ecode = tdb->methods->twrite(tdb, new_off, dbuf.dptr, dbuf.dsize);
+       if (ecode != TDB_SUCCESS) {
+               tdb->ecode = ecode;
                return -1;
+       }
 
        /* FIXME: tdb_increment_seqnum(tdb); */
        return 0;
@@ -416,6 +482,7 @@ int tdb_store(struct tdb_context *tdb,
        tdb_len_t old_room = 0;
        struct tdb_used_record rec;
        int ret;
+       enum TDB_ERROR ecode;
 
        off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
        if (unlikely(off == TDB_OFF_ERR))
@@ -437,15 +504,19 @@ int tdb_store(struct tdb_context *tdb,
                                                   key.dsize, dbuf.dsize,
                                                   &rec, h.h))
                                        goto fail;
-                               if (tdb->methods->write(tdb, off + sizeof(rec)
-                                                       + key.dsize,
-                                                       dbuf.dptr, dbuf.dsize))
+                               ecode = tdb->methods->twrite(tdb,
+                                                            off + sizeof(rec)
+                                                            + key.dsize,
+                                                            dbuf.dptr,
+                                                            dbuf.dsize);
+                               if (ecode != TDB_SUCCESS) {
+                                       tdb->ecode = ecode;
                                        goto fail;
+                               }
                                tdb_unlock_hashes(tdb, h.hlock_start,
                                                  h.hlock_range, F_WRLCK);
                                return 0;
                        }
-                       /* FIXME: See if right record is free? */
                } else {
                        if (flag == TDB_MODIFY) {
                                /* if the record doesn't exist and we
@@ -476,6 +547,7 @@ int tdb_append(struct tdb_context *tdb,
        tdb_len_t old_room = 0, old_dlen;
        unsigned char *newdata;
        struct tdb_data new_dbuf;
+       enum TDB_ERROR ecode;
        int ret;
 
        off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
@@ -493,28 +565,31 @@ int tdb_append(struct tdb_context *tdb,
                                goto fail;
 
                        off += sizeof(rec) + key.dsize + old_dlen;
-                       if (tdb->methods->write(tdb, off, dbuf.dptr,
-                                               dbuf.dsize) == -1)
+                       ecode = tdb->methods->twrite(tdb, off, dbuf.dptr,
+                                                    dbuf.dsize);
+                       if (ecode != TDB_SUCCESS) {
+                               tdb->ecode = ecode;
                                goto fail;
+                       }
 
                        /* FIXME: tdb_increment_seqnum(tdb); */
                        tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range,
                                          F_WRLCK);
                        return 0;
                }
-               /* FIXME: Check right record free? */
 
                /* Slow path. */
                newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
                if (!newdata) {
-                       tdb->ecode = TDB_ERR_OOM;
-                       tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
-                                "tdb_append: cannot allocate %llu bytes!\n",
-                                (long long)key.dsize + old_dlen + dbuf.dsize);
+                       tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
+                                  "tdb_append: failed to allocate %zu bytes",
+                                  (size_t)(key.dsize+old_dlen+dbuf.dsize));
                        goto fail;
                }
-               if (tdb->methods->read(tdb, off + sizeof(rec) + key.dsize,
-                                      newdata, old_dlen) != 0) {
+               ecode = tdb->methods->tread(tdb, off + sizeof(rec) + key.dsize,
+                                           newdata, old_dlen);
+               if (ecode != TDB_SUCCESS) {
+                       tdb->ecode = ecode;
                        free(newdata);
                        goto fail;
                }
@@ -582,6 +657,7 @@ int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
                goto unlock_err;
 
        /* Free the deleted entry. */
+       add_stat(tdb, frees, 1);
        if (add_free_record(tdb, off,
                            sizeof(struct tdb_used_record)
                            + rec_key_length(&rec)
@@ -637,12 +713,12 @@ int tdb_close(struct tdb_context *tdb)
        return ret;
 }
 
-enum TDB_ERROR tdb_error(struct tdb_context *tdb)
+enum TDB_ERROR tdb_error(const struct tdb_context *tdb)
 {
        return tdb->ecode;
 }
 
-const char *tdb_errorstr(struct tdb_context *tdb)
+const char *tdb_errorstr(const struct tdb_context *tdb)
 {
        /* Gcc warns if you miss a case in the switch, so use that. */
        switch (tdb->ecode) {
@@ -652,10 +728,46 @@ const char *tdb_errorstr(struct tdb_context *tdb)
        case TDB_ERR_LOCK: return "Locking error";
        case TDB_ERR_OOM: return "Out of memory";
        case TDB_ERR_EXISTS: return "Record exists";
-       case TDB_ERR_NESTING: return "Transaction already started";
        case TDB_ERR_EINVAL: return "Invalid parameter";
        case TDB_ERR_NOEXIST: return "Record does not exist";
        case TDB_ERR_RDONLY: return "write not permitted";
        }
        return "Invalid error code";
 }
+
+enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
+                              enum TDB_ERROR ecode,
+                              enum tdb_log_level level,
+                              const char *fmt, ...)
+{
+       char *message;
+       va_list ap;
+       size_t len;
+       /* tdb_open paths care about errno, so save it. */
+       int saved_errno = errno;
+
+       tdb->ecode = ecode;
+
+       if (!tdb->logfn)
+               return ecode;
+
+       /* FIXME: Doesn't assume asprintf. */
+       va_start(ap, fmt);
+       len = vsnprintf(NULL, 0, fmt, ap);
+       va_end(ap);
+
+       message = malloc(len + 1);
+       if (!message) {
+               tdb->logfn(tdb, TDB_LOG_ERROR, tdb->log_private,
+                          "out of memory formatting message:");
+               tdb->logfn(tdb, level, tdb->log_private, fmt);
+               return ecode;
+       }
+       va_start(ap, fmt);
+       len = vsprintf(message, fmt, ap);
+       va_end(ap);
+       tdb->logfn(tdb, level, tdb->log_private, message);
+       free(message);
+       errno = saved_errno;
+       return ecode;
+}