Adding upstream version 1.4.8.upstream/1.4.8upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 806 insertions, 0 deletions

diff --git a/common/io.c b/common/io.c
new file mode 100644
index 0000000..0de0dab
--- /dev/null
+++ b/common/io.c
@@ -0,0 +1,806 @@
+ /*
+   Unix SMB/CIFS implementation.
+
+   trivial database library
+
+   Copyright (C) Andrew Tridgell              1999-2005
+   Copyright (C) Paul `Rusty' Russell		   2000
+   Copyright (C) Jeremy Allison			   2000-2003
+
+     ** NOTE! The following LGPL license applies to the tdb
+     ** library. This does NOT imply that all of Samba is released
+     ** under the LGPL
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   This library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#include "tdb_private.h"
+
+/*
+ * We prepend the mutex area, so fixup offsets. See mutex.c for details.
+ * tdb->hdr_ofs is 0 or header.mutex_size.
+ *
+ * Note: that we only have the 4GB limit of tdb_off_t for
+ * tdb->map_size. The file size on disk can be 4GB + tdb->hdr_ofs!
+ */
+
+static bool tdb_adjust_offset(struct tdb_context *tdb, off_t *off)
+{
+	off_t tmp = tdb->hdr_ofs + *off;
+
+	if ((tmp < tdb->hdr_ofs) || (tmp < *off)) {
+		errno = EIO;
+		return false;
+	}
+
+	*off = tmp;
+	return true;
+}
+
+static ssize_t tdb_pwrite(struct tdb_context *tdb, const void *buf,
+			  size_t count, off_t offset)
+{
+	ssize_t ret;
+
+	if (!tdb_adjust_offset(tdb, &offset)) {
+		return -1;
+	}
+
+	do {
+		ret = pwrite(tdb->fd, buf, count, offset);
+	} while ((ret == -1) && (errno == EINTR));
+
+	return ret;
+}
+
+static ssize_t tdb_pread(struct tdb_context *tdb, void *buf,
+			 size_t count, off_t offset)
+{
+	ssize_t ret;
+
+	if (!tdb_adjust_offset(tdb, &offset)) {
+		return -1;
+	}
+
+	do {
+		ret = pread(tdb->fd, buf, count, offset);
+	} while ((ret == -1) && (errno == EINTR));
+
+	return ret;
+}
+
+static int tdb_ftruncate(struct tdb_context *tdb, off_t length)
+{
+	ssize_t ret;
+
+	if (!tdb_adjust_offset(tdb, &length)) {
+		return -1;
+	}
+
+	do {
+		ret = ftruncate(tdb->fd, length);
+	} while ((ret == -1) && (errno == EINTR));
+
+	return ret;
+}
+
+#ifdef HAVE_POSIX_FALLOCATE
+static int tdb_posix_fallocate(struct tdb_context *tdb, off_t offset,
+			       off_t len)
+{
+	ssize_t ret;
+
+	if (!tdb_adjust_offset(tdb, &offset)) {
+		return -1;
+	}
+
+	do {
+		ret = posix_fallocate(tdb->fd, offset, len);
+	} while ((ret == -1) && (errno == EINTR));
+
+	return ret;
+}
+#endif
+
+static int tdb_fstat(struct tdb_context *tdb, struct stat *buf)
+{
+	int ret;
+
+	ret = fstat(tdb->fd, buf);
+	if (ret == -1) {
+		return -1;
+	}
+
+	if (buf->st_size < tdb->hdr_ofs) {
+		errno = EIO;
+		return -1;
+	}
+	buf->st_size -= tdb->hdr_ofs;
+
+	return ret;
+}
+
+/* check for an out of bounds access - if it is out of bounds then
+   see if the database has been expanded by someone else and expand
+   if necessary
+*/
+static int tdb_notrans_oob(
+	struct tdb_context *tdb, tdb_off_t off, tdb_len_t len, int probe)
+{
+	struct stat st;
+	if (len + off < len) {
+		if (!probe) {
+			/* Ensure ecode is set for log fn. */
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob off %u len %u wrap\n",
+				 off, len));
+		}
+		return -1;
+	}
+
+	/*
+	 * This duplicates functionality from tdb_oob(). Don't remove:
+	 * we still have direct callers of tdb->methods->tdb_oob()
+	 * inside transaction.c.
+	 */
+	if (off + len <= tdb->map_size)
+		return 0;
+	if (tdb->flags & TDB_INTERNAL) {
+		if (!probe) {
+			/* Ensure ecode is set for log fn. */
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond internal malloc size %u\n",
+				 (int)(off + len), (int)tdb->map_size));
+		}
+		return -1;
+	}
+
+	if (tdb_fstat(tdb, &st) == -1) {
+		tdb->ecode = TDB_ERR_IO;
+		return -1;
+	}
+
+	/* Beware >4G files! */
+	if ((tdb_off_t)st.st_size != st.st_size) {
+		/* Ensure ecode is set for log fn. */
+		tdb->ecode = TDB_ERR_IO;
+		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_oob len %llu too large!\n",
+			 (long long)st.st_size));
+		return -1;
+	}
+
+	/* Unmap, update size, remap.  We do this unconditionally, to handle
+	 * the unusual case where the db is truncated.
+	 *
+	 * This can happen to a child using tdb_reopen_all(true) on a
+	 * TDB_CLEAR_IF_FIRST tdb whose parent crashes: the next
+	 * opener will truncate the database. */
+	if (tdb_munmap(tdb) == -1) {
+		tdb->ecode = TDB_ERR_IO;
+		return -1;
+	}
+	tdb->map_size = st.st_size;
+	if (tdb_mmap(tdb) != 0) {
+		return -1;
+	}
+
+	if (st.st_size < (size_t)off + len) {
+		if (!probe) {
+			/* Ensure ecode is set for log fn. */
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond eof at %u\n",
+				 (int)(off + len), (int)st.st_size));
+		}
+		return -1;
+	}
+	return 0;
+}
+
+/* write a lump of data at a specified offset */
+static int tdb_write(struct tdb_context *tdb, tdb_off_t off,
+		     const void *buf, tdb_len_t len)
+{
+	if (len == 0) {
+		return 0;
+	}
+
+	if (tdb->read_only || tdb->traverse_read) {
+		tdb->ecode = TDB_ERR_RDONLY;
+		return -1;
+	}
+
+	if (tdb_oob(tdb, off, len, 0) != 0)
+		return -1;
+
+	if (tdb->map_ptr) {
+		memcpy(off + (char *)tdb->map_ptr, buf, len);
+	} else {
+#ifdef HAVE_INCOHERENT_MMAP
+		tdb->ecode = TDB_ERR_IO;
+		return -1;
+#else
+		ssize_t written;
+
+		written = tdb_pwrite(tdb, buf, len, off);
+
+		if ((written != (ssize_t)len) && (written != -1)) {
+			/* try once more */
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: wrote only "
+				 "%zi of %u bytes at %u, trying once more\n",
+				 written, len, off));
+			written = tdb_pwrite(tdb, (const char *)buf+written,
+					     len-written, off+written);
+		}
+		if (written == -1) {
+			/* Ensure ecode is set for log fn. */
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_write failed at %u "
+				 "len=%u (%s)\n", off, len, strerror(errno)));
+			return -1;
+		} else if (written != (ssize_t)len) {
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: failed to "
+				 "write %u bytes at %u in two attempts\n",
+				 len, off));
+			return -1;
+		}
+#endif
+	}
+	return 0;
+}
+
+/* Endian conversion: we only ever deal with 4 byte quantities */
+void *tdb_convert(void *buf, uint32_t size)
+{
+	uint32_t i, *p = (uint32_t *)buf;
+	for (i = 0; i < size / 4; i++)
+		p[i] = TDB_BYTEREV(p[i]);
+	return buf;
+}
+
+
+/* read a lump of data at a specified offset, maybe convert */
+static int tdb_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
+		    tdb_len_t len, int cv)
+{
+	if (tdb_oob(tdb, off, len, 0) != 0) {
+		return -1;
+	}
+
+	if (tdb->map_ptr) {
+		memcpy(buf, off + (char *)tdb->map_ptr, len);
+	} else {
+#ifdef HAVE_INCOHERENT_MMAP
+		tdb->ecode = TDB_ERR_IO;
+		return -1;
+#else
+		ssize_t ret;
+
+		ret = tdb_pread(tdb, buf, len, off);
+		if (ret != (ssize_t)len) {
+			/* Ensure ecode is set for log fn. */
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_read failed at %u "
+				 "len=%u ret=%zi (%s) map_size=%u\n",
+				 off, len, ret, strerror(errno),
+				 tdb->map_size));
+			return -1;
+		}
+#endif
+	}
+	if (cv) {
+		tdb_convert(buf, len);
+	}
+	return 0;
+}
+
+
+
+/*
+  do an unlocked scan of the hash table heads to find the next non-zero head. The value
+  will then be confirmed with the lock held
+*/
+static void tdb_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
+{
+	uint32_t h = *chain;
+	if (tdb->map_ptr) {
+		for (;h < tdb->hash_size;h++) {
+			if (0 != *(uint32_t *)(TDB_HASH_TOP(h) + (unsigned char *)tdb->map_ptr)) {
+				break;
+			}
+		}
+	} else {
+		uint32_t off=0;
+		for (;h < tdb->hash_size;h++) {
+			if (tdb_ofs_read(tdb, TDB_HASH_TOP(h), &off) != 0 || off != 0) {
+				break;
+			}
+		}
+	}
+	(*chain) = h;
+}
+
+
+int tdb_munmap(struct tdb_context *tdb)
+{
+	if (tdb->flags & TDB_INTERNAL)
+		return 0;
+
+#ifdef HAVE_MMAP
+	if (tdb->map_ptr) {
+		int ret;
+
+		ret = munmap(tdb->map_ptr, tdb->map_size);
+		if (ret != 0)
+			return ret;
+	}
+#endif
+	tdb->map_ptr = NULL;
+	return 0;
+}
+
+/* If mmap isn't coherent, *everyone* must always mmap. */
+static bool should_mmap(const struct tdb_context *tdb)
+{
+#ifdef HAVE_INCOHERENT_MMAP
+	return true;
+#else
+	return !(tdb->flags & TDB_NOMMAP);
+#endif
+}
+
+int tdb_mmap(struct tdb_context *tdb)
+{
+	if (tdb->flags & TDB_INTERNAL)
+		return 0;
+
+#ifdef HAVE_MMAP
+	if (should_mmap(tdb)) {
+		tdb->map_ptr = mmap(NULL, tdb->map_size,
+				    PROT_READ|(tdb->read_only? 0:PROT_WRITE),
+				    MAP_SHARED|MAP_FILE, tdb->fd,
+				    tdb->hdr_ofs);
+
+		/*
+		 * NB. When mmap fails it returns MAP_FAILED *NOT* NULL !!!!
+		 */
+
+		if (tdb->map_ptr == MAP_FAILED) {
+			tdb->map_ptr = NULL;
+			TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_mmap failed for size %u (%s)\n",
+				 tdb->map_size, strerror(errno)));
+#ifdef HAVE_INCOHERENT_MMAP
+			tdb->ecode = TDB_ERR_IO;
+			return -1;
+#endif
+		}
+	} else {
+		tdb->map_ptr = NULL;
+	}
+#else
+	tdb->map_ptr = NULL;
+#endif
+	return 0;
+}
+
+/* expand a file.  we prefer to use ftruncate, as that is what posix
+  says to use for mmap expansion */
+static int tdb_expand_file(struct tdb_context *tdb, tdb_off_t size, tdb_off_t addition)
+{
+	char buf[8192];
+	tdb_off_t new_size;
+	int ret;
+
+	if (tdb->read_only || tdb->traverse_read) {
+		tdb->ecode = TDB_ERR_RDONLY;
+		return -1;
+	}
+
+	if (!tdb_add_off_t(size, addition, &new_size)) {
+		tdb->ecode = TDB_ERR_OOM;
+		TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write "
+			"overflow detected current size[%u] addition[%u]!\n",
+			(unsigned)size, (unsigned)addition));
+		errno = ENOSPC;
+		return -1;
+	}
+
+#ifdef HAVE_POSIX_FALLOCATE
+	ret = tdb_posix_fallocate(tdb, size, addition);
+	if (ret == 0) {
+		return 0;
+	}
+	if (ret == ENOSPC) {
+		/*
+		 * The Linux glibc (at least as of 2.24) fallback if
+		 * the file system does not support fallocate does not
+		 * reset the file size back to where it was. Also, to
+		 * me it is unclear from the posix spec of
+		 * posix_fallocate whether this is allowed or
+		 * not. Better be safe than sorry and "goto fail" but
+		 * "return -1" here, leaving the EOF pointer too
+		 * large.
+		 */
+		goto fail;
+	}
+
+	/*
+	 * Retry the "old" way. Possibly unnecessary, but looking at
+	 * our configure script there seem to be weird failure modes
+	 * for posix_fallocate. See commit 3264a98ff16de, which
+	 * probably refers to
+	 * https://sourceware.org/bugzilla/show_bug.cgi?id=1083.
+	 */
+#endif
+
+	ret = tdb_ftruncate(tdb, new_size);
+	if (ret == -1) {
+		char b = 0;
+		ssize_t written = tdb_pwrite(tdb, &b, 1, new_size - 1);
+		if (written == 0) {
+			/* try once more, potentially revealing errno */
+			written = tdb_pwrite(tdb, &b, 1, new_size - 1);
+		}
+		if (written == 0) {
+			/* again - give up, guessing errno */
+			errno = ENOSPC;
+		}
+		if (written != 1) {
+			tdb->ecode = TDB_ERR_OOM;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file to %u failed (%s)\n",
+				 (unsigned)new_size, strerror(errno)));
+			return -1;
+		}
+	}
+
+	/* now fill the file with something. This ensures that the
+	   file isn't sparse, which would be very bad if we ran out of
+	   disk. This must be done with write, not via mmap */
+	memset(buf, TDB_PAD_BYTE, sizeof(buf));
+	while (addition) {
+		size_t n = addition>sizeof(buf)?sizeof(buf):addition;
+		ssize_t written = tdb_pwrite(tdb, buf, n, size);
+		if (written == 0) {
+			/* prevent infinite loops: try _once_ more */
+			written = tdb_pwrite(tdb, buf, n, size);
+		}
+		if (written == 0) {
+			/* give up, trying to provide a useful errno */
+			tdb->ecode = TDB_ERR_OOM;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write "
+				"returned 0 twice: giving up!\n"));
+			errno = ENOSPC;
+			goto fail;
+		}
+		if (written == -1) {
+			tdb->ecode = TDB_ERR_OOM;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write of "
+				 "%u bytes failed (%s)\n", (int)n,
+				 strerror(errno)));
+			goto fail;
+		}
+		if (written != n) {
+			TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: wrote "
+				 "only %zu of %zi bytes - retrying\n", written,
+				 n));
+		}
+		addition -= written;
+		size += written;
+	}
+	return 0;
+
+fail:
+	{
+		int err = errno;
+
+		/*
+		 * We're holding the freelist lock or are inside a
+		 * transaction. Cutting the file is safe, the space we
+		 * tried to allocate can't have been used anywhere in
+		 * the meantime.
+		 */
+
+		ret = tdb_ftruncate(tdb, size);
+		if (ret == -1) {
+			TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: "
+				 "retruncate to %ju failed\n",
+				 (uintmax_t)size));
+		}
+		errno = err;
+	}
+
+	return -1;
+}
+
+
+/* You need 'size', this tells you how much you should expand by. */
+tdb_off_t tdb_expand_adjust(tdb_off_t map_size, tdb_off_t size, int page_size)
+{
+	tdb_off_t new_size, top_size, increment;
+	tdb_off_t max_size = UINT32_MAX - map_size;
+
+	if (size > max_size) {
+		/*
+		 * We can't round up anymore, just give back
+		 * what we're asked for.
+		 *
+		 * The caller has to take care of the ENOSPC handling.
+		 */
+		return size;
+	}
+
+	/* limit size in order to avoid using up huge amounts of memory for
+	 * in memory tdbs if an oddball huge record creeps in */
+	if (size > 100 * 1024) {
+		increment = size * 2;
+	} else {
+		increment = size * 100;
+	}
+	if (increment < size) {
+		goto overflow;
+	}
+
+	if (!tdb_add_off_t(map_size, increment, &top_size)) {
+		goto overflow;
+	}
+
+	/* always make room for at least top_size more records, and at
+	   least 25% more space. if the DB is smaller than 100MiB,
+	   otherwise grow it by 10% only. */
+	if (map_size > 100 * 1024 * 1024) {
+		new_size = map_size * 1.10;
+	} else {
+		new_size = map_size * 1.25;
+	}
+	if (new_size < map_size) {
+		goto overflow;
+	}
+
+	/* Round the database up to a multiple of the page size */
+	new_size = MAX(top_size, new_size);
+
+	if (new_size + page_size < new_size) {
+		/* There's a "+" in TDB_ALIGN that might overflow... */
+		goto overflow;
+	}
+
+	return TDB_ALIGN(new_size, page_size) - map_size;
+
+overflow:
+	/*
+	 * Somewhere in between we went over 4GB. Make one big jump to
+	 * exactly 4GB database size.
+	 */
+	return max_size;
+}
+
+/* expand the database at least size bytes by expanding the underlying
+   file and doing the mmap again if necessary */
+int tdb_expand(struct tdb_context *tdb, tdb_off_t size)
+{
+	struct tdb_record rec;
+	tdb_off_t offset;
+	tdb_off_t new_size;
+
+	if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
+		TDB_LOG((tdb, TDB_DEBUG_ERROR, "lock failed in tdb_expand\n"));
+		return -1;
+	}
+
+	/* must know about any previous expansions by another process */
+	tdb_oob(tdb, tdb->map_size, 1, 1);
+
+	/*
+	 * Note: that we don't care about tdb->hdr_ofs != 0 here
+	 *
+	 * The 4GB limitation is just related to tdb->map_size
+	 * and the offset calculation in the records.
+	 *
+	 * The file on disk can be up to 4GB + tdb->hdr_ofs
+	 */
+	size = tdb_expand_adjust(tdb->map_size, size, tdb->page_size);
+
+	if (!tdb_add_off_t(tdb->map_size, size, &new_size)) {
+		tdb->ecode = TDB_ERR_OOM;
+		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_expand "
+			"overflow detected current map_size[%u] size[%u]!\n",
+			(unsigned)tdb->map_size, (unsigned)size));
+		goto fail;
+	}
+
+	/* form a new freelist record */
+	offset = tdb->map_size;
+	memset(&rec,'\0',sizeof(rec));
+	rec.rec_len = size - sizeof(rec);
+
+	if (tdb->flags & TDB_INTERNAL) {
+		char *new_map_ptr;
+
+		new_map_ptr = (char *)realloc(tdb->map_ptr, new_size);
+		if (!new_map_ptr) {
+			tdb->ecode = TDB_ERR_OOM;
+			goto fail;
+		}
+		tdb->map_ptr = new_map_ptr;
+		tdb->map_size = new_size;
+	} else {
+		int ret;
+
+		/*
+		 * expand the file itself
+		 */
+		ret = tdb->methods->tdb_expand_file(tdb, tdb->map_size, size);
+		if (ret != 0) {
+			goto fail;
+		}
+
+		/* Explicitly remap: if we're in a transaction, this won't
+		 * happen automatically! */
+		tdb_munmap(tdb);
+		tdb->map_size = new_size;
+		if (tdb_mmap(tdb) != 0) {
+			goto fail;
+		}
+	}
+
+	/* link it into the free list */
+	if (tdb_free(tdb, offset, &rec) == -1)
+		goto fail;
+
+	tdb_unlock(tdb, -1, F_WRLCK);
+	return 0;
+ fail:
+	tdb_unlock(tdb, -1, F_WRLCK);
+	return -1;
+}
+
+int _tdb_oob(struct tdb_context *tdb, tdb_off_t off, tdb_len_t len, int probe)
+{
+	int ret = tdb->methods->tdb_oob(tdb, off, len, probe);
+	return ret;
+}
+
+/* read/write a tdb_off_t */
+int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
+{
+	return tdb->methods->tdb_read(tdb, offset, (char*)d, sizeof(*d), DOCONV());
+}
+
+int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
+{
+	tdb_off_t off = *d;
+	return tdb->methods->tdb_write(tdb, offset, CONVERT(off), sizeof(*d));
+}
+
+
+/* read a lump of data, allocating the space for it */
+unsigned char *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len)
+{
+	unsigned char *buf;
+
+	/* some systems don't like zero length malloc */
+
+	if (!(buf = (unsigned char *)malloc(len ? len : 1))) {
+		/* Ensure ecode is set for log fn. */
+		tdb->ecode = TDB_ERR_OOM;
+		TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_alloc_read malloc failed len=%u (%s)\n",
+			   len, strerror(errno)));
+		return NULL;
+	}
+	if (tdb->methods->tdb_read(tdb, offset, buf, len, 0) == -1) {
+		SAFE_FREE(buf);
+		return NULL;
+	}
+	return buf;
+}
+
+/* Give a piece of tdb data to a parser */
+
+int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key,
+		   tdb_off_t offset, tdb_len_t len,
+		   int (*parser)(TDB_DATA key, TDB_DATA data,
+				 void *private_data),
+		   void *private_data)
+{
+	TDB_DATA data;
+	int result;
+
+	data.dsize = len;
+
+	if ((tdb->transaction == NULL) && (tdb->map_ptr != NULL)) {
+		/*
+		 * Optimize by avoiding the malloc/memcpy/free, point the
+		 * parser directly at the mmap area.
+		 */
+		if (tdb_oob(tdb, offset, len, 0) != 0) {
+			return -1;
+		}
+		data.dptr = offset + (unsigned char *)tdb->map_ptr;
+		return parser(key, data, private_data);
+	}
+
+	if (!(data.dptr = tdb_alloc_read(tdb, offset, len))) {
+		return -1;
+	}
+
+	result = parser(key, data, private_data);
+	free(data.dptr);
+	return result;
+}
+
+/* read/write a record */
+int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec)
+{
+	int ret;
+	tdb_len_t overall_len;
+
+	if (tdb->methods->tdb_read(tdb, offset, rec, sizeof(*rec),DOCONV()) == -1)
+		return -1;
+	if (TDB_BAD_MAGIC(rec)) {
+		/* Ensure ecode is set for log fn. */
+		tdb->ecode = TDB_ERR_CORRUPT;
+		TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_rec_read bad magic 0x%x at offset=%u\n", rec->magic, offset));
+		return -1;
+	}
+
+	overall_len = rec->key_len + rec->data_len;
+	if (overall_len < rec->data_len) {
+		/* overflow */
+		return -1;
+	}
+
+	if (overall_len > rec->rec_len) {
+		/* invalid record */
+		return -1;
+	}
+
+	ret = tdb_oob(tdb, offset, rec->key_len, 1);
+	if (ret == -1) {
+		return -1;
+	}
+	ret = tdb_oob(tdb, offset, rec->data_len, 1);
+	if (ret == -1) {
+		return -1;
+	}
+	ret = tdb_oob(tdb, offset, rec->rec_len, 1);
+	if (ret == -1) {
+		return -1;
+	}
+
+	return tdb_oob(tdb, rec->next, sizeof(*rec), 0);
+}
+
+int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec)
+{
+	struct tdb_record r = *rec;
+	return tdb->methods->tdb_write(tdb, offset, CONVERT(r), sizeof(r));
+}
+
+static const struct tdb_methods io_methods = {
+	tdb_read,
+	tdb_write,
+	tdb_next_hash_chain,
+	tdb_notrans_oob,
+	tdb_expand_file,
+};
+
+/*
+  initialise the default methods table
+*/
+void tdb_io_init(struct tdb_context *tdb)
+{
+	tdb->methods = &io_methods;
+}