Adding upstream version 1:9.11.5.P4+dfsg.upstream/1%9.11.5.P4+dfsgupstream

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

1 files changed, 2364 insertions, 0 deletions

diff --git a/lib/dns/journal.c b/lib/dns/journal.c
new file mode 100644
index 0000000..bdbc459
--- /dev/null
+++ b/lib/dns/journal.c
@@ -0,0 +1,2364 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <config.h>
+
+#include <inttypes.h>
+#include <stdbool.h>
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <isc/file.h>
+#include <isc/mem.h>
+#include <isc/print.h>
+#include <isc/stdio.h>
+#include <isc/string.h>
+#include <isc/util.h>
+
+#include <dns/compress.h>
+#include <dns/db.h>
+#include <dns/dbiterator.h>
+#include <dns/diff.h>
+#include <dns/fixedname.h>
+#include <dns/journal.h>
+#include <dns/log.h>
+#include <dns/rdataset.h>
+#include <dns/rdatasetiter.h>
+#include <dns/result.h>
+#include <dns/soa.h>
+
+/*! \file
+ * \brief Journaling.
+ *
+ * A journal file consists of
+ *
+ *   \li A fixed-size header of type journal_rawheader_t.
+ *
+ *   \li The index.  This is an unordered array of index entries
+ *     of type journal_rawpos_t giving the locations
+ *     of some arbitrary subset of the journal's addressable
+ *     transactions.  The index entries are used as hints to
+ *     speed up the process of locating a transaction with a given
+ *     serial number.  Unused index entries have an "offset"
+ *     field of zero.  The size of the index can vary between
+ *     journal files, but does not change during the lifetime
+ *     of a file.  The size can be zero.
+ *
+ *   \li The journal data.  This  consists of one or more transactions.
+ *     Each transaction begins with a transaction header of type
+ *     journal_rawxhdr_t.  The transaction header is followed by a
+ *     sequence of RRs, similar in structure to an IXFR difference
+ *     sequence (RFC1995).  That is, the pre-transaction SOA,
+ *     zero or more other deleted RRs, the post-transaction SOA,
+ *     and zero or more other added RRs.  Unlike in IXFR, each RR
+ *     is prefixed with a 32-bit length.
+ *
+ *     The journal data part grows as new transactions are
+ *     appended to the file.  Only those transactions
+ *     whose serial number is current-(2^31-1) to current
+ *     are considered "addressable" and may be pointed
+ *     to from the header or index.  They may be preceded
+ *     by old transactions that are no longer addressable,
+ *     and they may be followed by transactions that were
+ *     appended to the journal but never committed by updating
+ *     the "end" position in the header.  The latter will
+ *     be overwritten when new transactions are added.
+ */
+/*%
+ * When true, accept IXFR difference sequences where the
+ * SOA serial number does not change (BIND 8 sends such
+ * sequences).
+ */
+static bool bind8_compat = true; /* XXX config */
+
+/**************************************************************************/
+/*
+ * Miscellaneous utilities.
+ */
+
+#define JOURNAL_COMMON_LOGARGS \
+	dns_lctx, DNS_LOGCATEGORY_GENERAL, DNS_LOGMODULE_JOURNAL
+
+#define JOURNAL_DEBUG_LOGARGS(n) \
+	JOURNAL_COMMON_LOGARGS, ISC_LOG_DEBUG(n)
+
+/*%
+ * It would be non-sensical (or at least obtuse) to use FAIL() with an
+ * ISC_R_SUCCESS code, but the test is there to keep the Solaris compiler
+ * from complaining about "end-of-loop code not reached".
+ */
+#define FAIL(code) \
+	do { result = (code);					\
+		if (result != ISC_R_SUCCESS) goto failure;	\
+	} while (0)
+
+#define CHECK(op) \
+	do { result = (op); 					\
+		if (result != ISC_R_SUCCESS) goto failure; 	\
+	} while (0)
+
+#define JOURNAL_SERIALSET	0x01U
+
+static isc_result_t index_to_disk(dns_journal_t *);
+
+static inline uint32_t
+decode_uint32(unsigned char *p) {
+	return ((p[0] << 24) +
+		(p[1] << 16) +
+		(p[2] <<  8) +
+		(p[3] <<  0));
+}
+
+static inline void
+encode_uint32(uint32_t val, unsigned char *p) {
+	p[0] = (uint8_t)(val >> 24);
+	p[1] = (uint8_t)(val >> 16);
+	p[2] = (uint8_t)(val >>  8);
+	p[3] = (uint8_t)(val >>  0);
+}
+
+isc_result_t
+dns_db_createsoatuple(dns_db_t *db, dns_dbversion_t *ver, isc_mem_t *mctx,
+		      dns_diffop_t op, dns_difftuple_t **tp)
+{
+	isc_result_t result;
+	dns_dbnode_t *node;
+	dns_rdataset_t rdataset;
+	dns_rdata_t rdata = DNS_RDATA_INIT;
+	dns_fixedname_t fixed;
+	dns_name_t *zonename;
+
+	zonename = dns_fixedname_initname(&fixed);
+	dns_name_copy(dns_db_origin(db), zonename, NULL);
+
+	node = NULL;
+	result = dns_db_findnode(db, zonename, false, &node);
+	if (result != ISC_R_SUCCESS)
+		goto nonode;
+
+	dns_rdataset_init(&rdataset);
+	result = dns_db_findrdataset(db, node, ver, dns_rdatatype_soa, 0,
+				     (isc_stdtime_t)0, &rdataset, NULL);
+	if (result != ISC_R_SUCCESS)
+		goto freenode;
+
+	result = dns_rdataset_first(&rdataset);
+	if (result != ISC_R_SUCCESS)
+		goto freenode;
+
+	dns_rdataset_current(&rdataset, &rdata);
+	dns_rdataset_getownercase(&rdataset, zonename);
+
+	result = dns_difftuple_create(mctx, op, zonename, rdataset.ttl,
+				      &rdata, tp);
+
+	dns_rdataset_disassociate(&rdataset);
+	dns_db_detachnode(db, &node);
+	return (result);
+
+ freenode:
+	dns_db_detachnode(db, &node);
+ nonode:
+	UNEXPECTED_ERROR(__FILE__, __LINE__, "missing SOA");
+	return (result);
+}
+
+/* Journaling */
+
+/*%
+ * On-disk representation of a "pointer" to a journal entry.
+ * These are used in the journal header to locate the beginning
+ * and end of the journal, and in the journal index to locate
+ * other transactions.
+ */
+typedef struct {
+	unsigned char	serial[4];  /*%< SOA serial before update. */
+	/*
+	 * XXXRTH  Should offset be 8 bytes?
+	 * XXXDCL ... probably, since isc_offset_t is 8 bytes on many OSs.
+	 * XXXAG  ... but we will not be able to seek >2G anyway on many
+	 *            platforms as long as we are using fseek() rather
+	 *            than lseek().
+	 */
+	unsigned char	offset[4];  /*%< Offset from beginning of file. */
+} journal_rawpos_t;
+
+
+/*%
+ * The header is of a fixed size, with some spare room for future
+ * extensions.
+ */
+#define JOURNAL_HEADER_SIZE 64 /* Bytes. */
+
+/*%
+ * The on-disk representation of the journal header.
+ * All numbers are stored in big-endian order.
+ */
+typedef union {
+	struct {
+		/*% File format version ID. */
+		unsigned char 		format[16];
+		/*% Position of the first addressable transaction */
+		journal_rawpos_t 	begin;
+		/*% Position of the next (yet nonexistent) transaction. */
+		journal_rawpos_t 	end;
+		/*% Number of index entries following the header. */
+		unsigned char 		index_size[4];
+		/*% Source serial number. */
+		unsigned char           sourceserial[4];
+		unsigned char           flags;
+	} h;
+	/* Pad the header to a fixed size. */
+	unsigned char pad[JOURNAL_HEADER_SIZE];
+} journal_rawheader_t;
+
+/*%
+ * The on-disk representation of the transaction header.
+ * There is one of these at the beginning of each transaction.
+ */
+typedef struct {
+	unsigned char	size[4]; 	/*%< In bytes, excluding header. */
+	unsigned char	serial0[4];	/*%< SOA serial before update. */
+	unsigned char	serial1[4];	/*%< SOA serial after update. */
+} journal_rawxhdr_t;
+
+/*%
+ * The on-disk representation of the RR header.
+ * There is one of these at the beginning of each RR.
+ */
+typedef struct {
+	unsigned char	size[4]; 	/*%< In bytes, excluding header. */
+} journal_rawrrhdr_t;
+
+/*%
+ * The in-core representation of the journal header.
+ */
+typedef struct {
+	uint32_t	serial;
+	isc_offset_t	offset;
+} journal_pos_t;
+
+#define POS_VALID(pos) 		((pos).offset != 0)
+#define POS_INVALIDATE(pos) 	((pos).offset = 0, (pos).serial = 0)
+
+typedef struct {
+	unsigned char 	format[16];
+	journal_pos_t 	begin;
+	journal_pos_t 	end;
+	uint32_t	index_size;
+	uint32_t	sourceserial;
+	bool	serialset;
+} journal_header_t;
+
+/*%
+ * The in-core representation of the transaction header.
+ */
+
+typedef struct {
+	uint32_t	size;
+	uint32_t	serial0;
+	uint32_t	serial1;
+} journal_xhdr_t;
+
+/*%
+ * The in-core representation of the RR header.
+ */
+typedef struct {
+	uint32_t	size;
+} journal_rrhdr_t;
+
+
+/*%
+ * Initial contents to store in the header of a newly created
+ * journal file.
+ *
+ * The header starts with the magic string ";BIND LOG V9\n"
+ * to identify the file as a BIND 9 journal file.  An ASCII
+ * identification string is used rather than a binary magic
+ * number to be consistent with BIND 8 (BIND 8 journal files
+ * are ASCII text files).
+ */
+
+static journal_header_t
+initial_journal_header = { ";BIND LOG V9\n", { 0, 0 }, { 0, 0 }, 0, 0, 0 };
+
+#define JOURNAL_EMPTY(h) ((h)->begin.offset == (h)->end.offset)
+
+typedef enum {
+	JOURNAL_STATE_INVALID,
+	JOURNAL_STATE_READ,
+	JOURNAL_STATE_WRITE,
+	JOURNAL_STATE_TRANSACTION,
+	JOURNAL_STATE_INLINE
+} journal_state_t;
+
+struct dns_journal {
+	unsigned int		magic;		/*%< JOUR */
+	isc_mem_t		*mctx;		/*%< Memory context */
+	journal_state_t		state;
+	char 			*filename;	/*%< Journal file name */
+	FILE *			fp;		/*%< File handle */
+	isc_offset_t		offset;		/*%< Current file offset */
+	journal_header_t 	header;		/*%< In-core journal header */
+	unsigned char		*rawindex;	/*%< In-core buffer for journal index in on-disk format */
+	journal_pos_t		*index;		/*%< In-core journal index */
+
+	/*% Current transaction state (when writing). */
+	struct {
+		unsigned int	n_soa;		/*%< Number of SOAs seen */
+		journal_pos_t	pos[2];		/*%< Begin/end position */
+	} x;
+
+	/*% Iteration state (when reading). */
+	struct {
+		/* These define the part of the journal we iterate over. */
+		journal_pos_t bpos;		/*%< Position before first, */
+		journal_pos_t epos;		/*%< and after last transaction */
+		/* The rest is iterator state. */
+		uint32_t current_serial;	/*%< Current SOA serial */
+		isc_buffer_t source;		/*%< Data from disk */
+		isc_buffer_t target;		/*%< Data from _fromwire check */
+		dns_decompress_t dctx;		/*%< Dummy decompression ctx */
+		dns_name_t name;		/*%< Current domain name */
+		dns_rdata_t rdata;		/*%< Current rdata */
+		uint32_t ttl;		/*%< Current TTL */
+		unsigned int xsize;		/*%< Size of transaction data */
+		unsigned int xpos;		/*%< Current position in it */
+		isc_result_t result;		/*%< Result of last call */
+	} it;
+};
+
+#define DNS_JOURNAL_MAGIC	ISC_MAGIC('J', 'O', 'U', 'R')
+#define DNS_JOURNAL_VALID(t)	ISC_MAGIC_VALID(t, DNS_JOURNAL_MAGIC)
+
+static void
+journal_pos_decode(journal_rawpos_t *raw, journal_pos_t *cooked) {
+	cooked->serial = decode_uint32(raw->serial);
+	cooked->offset = decode_uint32(raw->offset);
+}
+
+static void
+journal_pos_encode(journal_rawpos_t *raw, journal_pos_t *cooked) {
+	encode_uint32(cooked->serial, raw->serial);
+	encode_uint32(cooked->offset, raw->offset);
+}
+
+static void
+journal_header_decode(journal_rawheader_t *raw, journal_header_t *cooked) {
+	INSIST(sizeof(cooked->format) == sizeof(raw->h.format));
+	memmove(cooked->format, raw->h.format, sizeof(cooked->format));
+	journal_pos_decode(&raw->h.begin, &cooked->begin);
+	journal_pos_decode(&raw->h.end, &cooked->end);
+	cooked->index_size = decode_uint32(raw->h.index_size);
+	cooked->sourceserial = decode_uint32(raw->h.sourceserial);
+	cooked->serialset = (raw->h.flags & JOURNAL_SERIALSET);
+}
+
+static void
+journal_header_encode(journal_header_t *cooked, journal_rawheader_t *raw) {
+	unsigned char flags = 0;
+
+	INSIST(sizeof(cooked->format) == sizeof(raw->h.format));
+	memset(raw->pad, 0, sizeof(raw->pad));
+	memmove(raw->h.format, cooked->format, sizeof(raw->h.format));
+	journal_pos_encode(&raw->h.begin, &cooked->begin);
+	journal_pos_encode(&raw->h.end, &cooked->end);
+	encode_uint32(cooked->index_size, raw->h.index_size);
+	encode_uint32(cooked->sourceserial, raw->h.sourceserial);
+	if (cooked->serialset)
+		flags |= JOURNAL_SERIALSET;
+	raw->h.flags = flags;
+}
+
+/*
+ * Journal file I/O subroutines, with error checking and reporting.
+ */
+static isc_result_t
+journal_seek(dns_journal_t *j, uint32_t offset) {
+	isc_result_t result;
+
+	result = isc_stdio_seek(j->fp, (off_t)offset, SEEK_SET);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: seek: %s", j->filename,
+			      isc_result_totext(result));
+		return (ISC_R_UNEXPECTED);
+	}
+	j->offset = offset;
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+journal_read(dns_journal_t *j, void *mem, size_t nbytes) {
+	isc_result_t result;
+
+	result = isc_stdio_read(mem, 1, nbytes, j->fp, NULL);
+	if (result != ISC_R_SUCCESS) {
+		if (result == ISC_R_EOF)
+			return (ISC_R_NOMORE);
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: read: %s",
+			      j->filename, isc_result_totext(result));
+		return (ISC_R_UNEXPECTED);
+	}
+	j->offset += (isc_offset_t)nbytes;
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+journal_write(dns_journal_t *j, void *mem, size_t nbytes) {
+	isc_result_t result;
+
+	result = isc_stdio_write(mem, 1, nbytes, j->fp, NULL);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: write: %s",
+			      j->filename, isc_result_totext(result));
+		return (ISC_R_UNEXPECTED);
+	}
+	j->offset += (isc_offset_t)nbytes;
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+journal_fsync(dns_journal_t *j) {
+	isc_result_t result;
+	result = isc_stdio_flush(j->fp);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: flush: %s",
+			      j->filename, isc_result_totext(result));
+		return (ISC_R_UNEXPECTED);
+	}
+	result = isc_stdio_sync(j->fp);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: fsync: %s",
+			      j->filename, isc_result_totext(result));
+		return (ISC_R_UNEXPECTED);
+	}
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * Read/write a transaction header at the current file position.
+ */
+
+static isc_result_t
+journal_read_xhdr(dns_journal_t *j, journal_xhdr_t *xhdr) {
+	journal_rawxhdr_t raw;
+	isc_result_t result;
+	result = journal_read(j, &raw, sizeof(raw));
+	if (result != ISC_R_SUCCESS)
+		return (result);
+	xhdr->size = decode_uint32(raw.size);
+	xhdr->serial0 = decode_uint32(raw.serial0);
+	xhdr->serial1 = decode_uint32(raw.serial1);
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+journal_write_xhdr(dns_journal_t *j, uint32_t size,
+		   uint32_t serial0, uint32_t serial1)
+{
+	journal_rawxhdr_t raw;
+	encode_uint32(size, raw.size);
+	encode_uint32(serial0, raw.serial0);
+	encode_uint32(serial1, raw.serial1);
+	return (journal_write(j, &raw, sizeof(raw)));
+}
+
+
+/*
+ * Read an RR header at the current file position.
+ */
+
+static isc_result_t
+journal_read_rrhdr(dns_journal_t *j, journal_rrhdr_t *rrhdr) {
+	journal_rawrrhdr_t raw;
+	isc_result_t result;
+	result = journal_read(j, &raw, sizeof(raw));
+	if (result != ISC_R_SUCCESS)
+		return (result);
+	rrhdr->size = decode_uint32(raw.size);
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+journal_file_create(isc_mem_t *mctx, const char *filename) {
+	FILE *fp = NULL;
+	isc_result_t result;
+	journal_header_t header;
+	journal_rawheader_t rawheader;
+	int index_size = 56; /* XXX configurable */
+	int size;
+	void *mem; /* Memory for temporary index image. */
+
+	INSIST(sizeof(journal_rawheader_t) == JOURNAL_HEADER_SIZE);
+
+	result = isc_stdio_open(filename, "wb", &fp);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: create: %s",
+			      filename, isc_result_totext(result));
+		return (ISC_R_UNEXPECTED);
+	}
+
+	header = initial_journal_header;
+	header.index_size = index_size;
+	journal_header_encode(&header, &rawheader);
+
+	size = sizeof(journal_rawheader_t) +
+		index_size * sizeof(journal_rawpos_t);
+
+	mem = isc_mem_get(mctx, size);
+	if (mem == NULL) {
+		(void)isc_stdio_close(fp);
+		(void)isc_file_remove(filename);
+		return (ISC_R_NOMEMORY);
+	}
+	memset(mem, 0, size);
+	memmove(mem, &rawheader, sizeof(rawheader));
+
+	result = isc_stdio_write(mem, 1, (size_t) size, fp, NULL);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+				 "%s: write: %s",
+				 filename, isc_result_totext(result));
+		(void)isc_stdio_close(fp);
+		(void)isc_file_remove(filename);
+		isc_mem_put(mctx, mem, size);
+		return (ISC_R_UNEXPECTED);
+	}
+	isc_mem_put(mctx, mem, size);
+
+	result = isc_stdio_close(fp);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+				 "%s: close: %s",
+				 filename, isc_result_totext(result));
+		(void)isc_file_remove(filename);
+		return (ISC_R_UNEXPECTED);
+	}
+
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+journal_open(isc_mem_t *mctx, const char *filename, bool writable,
+	     bool create, dns_journal_t **journalp)
+{
+	FILE *fp = NULL;
+	isc_result_t result;
+	journal_rawheader_t rawheader;
+	dns_journal_t *j;
+
+	INSIST(journalp != NULL && *journalp == NULL);
+	j = isc_mem_get(mctx, sizeof(*j));
+	if (j == NULL)
+		return (ISC_R_NOMEMORY);
+
+	j->mctx = NULL;
+	isc_mem_attach(mctx, &j->mctx);
+	j->state = JOURNAL_STATE_INVALID;
+	j->fp = NULL;
+	j->filename = isc_mem_strdup(mctx, filename);
+	j->index = NULL;
+	j->rawindex = NULL;
+
+	if (j->filename == NULL)
+		FAIL(ISC_R_NOMEMORY);
+
+	result = isc_stdio_open(j->filename, writable ? "rb+" : "rb", &fp);
+
+	if (result == ISC_R_FILENOTFOUND) {
+		if (create) {
+			isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_DEBUG(1),
+				      "journal file %s does not exist, "
+				      "creating it", j->filename);
+			CHECK(journal_file_create(mctx, filename));
+			/*
+			 * Retry.
+			 */
+			result = isc_stdio_open(j->filename, "rb+", &fp);
+		} else {
+			FAIL(ISC_R_NOTFOUND);
+		}
+	}
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: open: %s",
+			      j->filename, isc_result_totext(result));
+		FAIL(ISC_R_UNEXPECTED);
+	}
+
+	j->fp = fp;
+
+	/*
+	 * Set magic early so that seek/read can succeed.
+	 */
+	j->magic = DNS_JOURNAL_MAGIC;
+
+	CHECK(journal_seek(j, 0));
+	CHECK(journal_read(j, &rawheader, sizeof(rawheader)));
+
+	if (memcmp(rawheader.h.format, initial_journal_header.format,
+		   sizeof(initial_journal_header.format)) != 0) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+				 "%s: journal format not recognized",
+				 j->filename);
+		FAIL(ISC_R_UNEXPECTED);
+	}
+	journal_header_decode(&rawheader, &j->header);
+
+	/*
+	 * If there is an index, read the raw index into a dynamically
+	 * allocated buffer and then convert it into a cooked index.
+	 */
+	if (j->header.index_size != 0) {
+		unsigned int i;
+		unsigned int rawbytes;
+		unsigned char *p;
+
+		rawbytes = j->header.index_size * sizeof(journal_rawpos_t);
+		j->rawindex = isc_mem_get(mctx, rawbytes);
+		if (j->rawindex == NULL)
+			FAIL(ISC_R_NOMEMORY);
+
+		CHECK(journal_read(j, j->rawindex, rawbytes));
+
+		j->index = isc_mem_get(mctx, j->header.index_size *
+				       sizeof(journal_pos_t));
+		if (j->index == NULL)
+			FAIL(ISC_R_NOMEMORY);
+
+		p = j->rawindex;
+		for (i = 0; i < j->header.index_size; i++) {
+			j->index[i].serial = decode_uint32(p);
+			p += 4;
+			j->index[i].offset = decode_uint32(p);
+			p += 4;
+		}
+		INSIST(p == j->rawindex + rawbytes);
+	}
+	j->offset = -1; /* Invalid, must seek explicitly. */
+
+	/*
+	 * Initialize the iterator.
+	 */
+	dns_name_init(&j->it.name, NULL);
+	dns_rdata_init(&j->it.rdata);
+
+	/*
+	 * Set up empty initial buffers for unchecked and checked
+	 * wire format RR data.  They will be reallocated
+	 * later.
+	 */
+	isc_buffer_init(&j->it.source, NULL, 0);
+	isc_buffer_init(&j->it.target, NULL, 0);
+	dns_decompress_init(&j->it.dctx, -1, DNS_DECOMPRESS_NONE);
+
+	j->state =
+		writable ? JOURNAL_STATE_WRITE : JOURNAL_STATE_READ;
+
+	*journalp = j;
+	return (ISC_R_SUCCESS);
+
+ failure:
+	j->magic = 0;
+	if (j->rawindex != NULL)
+		isc_mem_put(j->mctx, j->rawindex, j->header.index_size *
+			    sizeof(journal_rawpos_t));
+	if (j->index != NULL)
+		isc_mem_put(j->mctx, j->index, j->header.index_size *
+			    sizeof(journal_pos_t));
+	if (j->filename != NULL)
+		isc_mem_free(j->mctx, j->filename);
+	if (j->fp != NULL)
+		(void)isc_stdio_close(j->fp);
+	isc_mem_putanddetach(&j->mctx, j, sizeof(*j));
+	return (result);
+}
+
+isc_result_t
+dns_journal_open(isc_mem_t *mctx, const char *filename, unsigned int mode,
+		 dns_journal_t **journalp)
+{
+	isc_result_t result;
+	size_t namelen;
+	char backup[1024];
+	bool writable, create;
+
+	create = (mode & DNS_JOURNAL_CREATE);
+	writable = (mode & (DNS_JOURNAL_WRITE|DNS_JOURNAL_CREATE));
+
+	result = journal_open(mctx, filename, writable, create, journalp);
+	if (result == ISC_R_NOTFOUND) {
+		namelen = strlen(filename);
+		if (namelen > 4U && strcmp(filename + namelen - 4, ".jnl") == 0)
+			namelen -= 4;
+
+		result = isc_string_printf(backup, sizeof(backup), "%.*s.jbk",
+					   (int)namelen, filename);
+		if (result != ISC_R_SUCCESS)
+			return (result);
+		result = journal_open(mctx, backup, writable, writable,
+				      journalp);
+	}
+	return (result);
+}
+
+/*
+ * A comparison function defining the sorting order for
+ * entries in the IXFR-style journal file.
+ *
+ * The IXFR format requires that deletions are sorted before
+ * additions, and within either one, SOA records are sorted
+ * before others.
+ *
+ * Also sort the non-SOA records by type as a courtesy to the
+ * server receiving the IXFR - it may help reduce the amount of
+ * rdataset merging it has to do.
+ */
+static int
+ixfr_order(const void *av, const void *bv) {
+	dns_difftuple_t const * const *ap = av;
+	dns_difftuple_t const * const *bp = bv;
+	dns_difftuple_t const *a = *ap;
+	dns_difftuple_t const *b = *bp;
+	int r;
+	int bop = 0, aop = 0;
+
+	switch (a->op) {
+	case DNS_DIFFOP_DEL:
+	case DNS_DIFFOP_DELRESIGN:
+		aop = 1;
+		break;
+	case DNS_DIFFOP_ADD:
+	case DNS_DIFFOP_ADDRESIGN:
+		aop = 0;
+		break;
+	default:
+		INSIST(0);
+	}
+
+	switch (b->op) {
+	case DNS_DIFFOP_DEL:
+	case DNS_DIFFOP_DELRESIGN:
+		bop = 1;
+		break;
+	case DNS_DIFFOP_ADD:
+	case DNS_DIFFOP_ADDRESIGN:
+		bop = 0;
+		break;
+	default:
+		INSIST(0);
+	}
+
+	r = bop - aop;
+	if (r != 0)
+		return (r);
+
+	r = (b->rdata.type == dns_rdatatype_soa) -
+		(a->rdata.type == dns_rdatatype_soa);
+	if (r != 0)
+		return (r);
+
+	r = (a->rdata.type - b->rdata.type);
+	return (r);
+}
+
+/*
+ * Advance '*pos' to the next journal transaction.
+ *
+ * Requires:
+ *	*pos refers to a valid journal transaction.
+ *
+ * Ensures:
+ *	When ISC_R_SUCCESS is returned,
+ *	*pos refers to the next journal transaction.
+ *
+ * Returns one of:
+ *
+ *    ISC_R_SUCCESS
+ *    ISC_R_NOMORE 	*pos pointed at the last transaction
+ *    Other results due to file errors are possible.
+ */
+static isc_result_t
+journal_next(dns_journal_t *j, journal_pos_t *pos) {
+	isc_result_t result;
+	journal_xhdr_t xhdr;
+	REQUIRE(DNS_JOURNAL_VALID(j));
+
+	result = journal_seek(j, pos->offset);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	if (pos->serial == j->header.end.serial)
+		return (ISC_R_NOMORE);
+	/*
+	 * Read the header of the current transaction.
+	 * This will return ISC_R_NOMORE if we are at EOF.
+	 */
+	result = journal_read_xhdr(j, &xhdr);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	/*
+	 * Check serial number consistency.
+	 */
+	if (xhdr.serial0 != pos->serial) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: journal file corrupt: "
+			      "expected serial %u, got %u",
+			      j->filename, pos->serial, xhdr.serial0);
+		return (ISC_R_UNEXPECTED);
+	}
+
+	/*
+	 * Check for offset wraparound.
+	 */
+	if ((isc_offset_t)(pos->offset + sizeof(journal_rawxhdr_t) + xhdr.size)
+	    < pos->offset) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: offset too large", j->filename);
+		return (ISC_R_UNEXPECTED);
+	}
+
+	pos->offset += sizeof(journal_rawxhdr_t) + xhdr.size;
+	pos->serial = xhdr.serial1;
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * If the index of the journal 'j' contains an entry "better"
+ * than '*best_guess', replace '*best_guess' with it.
+ *
+ * "Better" means having a serial number closer to 'serial'
+ * but not greater than 'serial'.
+ */
+static void
+index_find(dns_journal_t *j, uint32_t serial, journal_pos_t *best_guess) {
+	unsigned int i;
+	if (j->index == NULL)
+		return;
+	for (i = 0; i < j->header.index_size; i++) {
+		if (POS_VALID(j->index[i]) &&
+		    DNS_SERIAL_GE(serial, j->index[i].serial) &&
+		    DNS_SERIAL_GT(j->index[i].serial, best_guess->serial))
+			*best_guess = j->index[i];
+	}
+}
+
+/*
+ * Add a new index entry.  If there is no room, make room by removing
+ * the odd-numbered entries and compacting the others into the first
+ * half of the index.  This decimates old index entries exponentially
+ * over time, so that the index always contains a much larger fraction
+ * of recent serial numbers than of old ones.  This is deliberate -
+ * most index searches are for outgoing IXFR, and IXFR tends to request
+ * recent versions more often than old ones.
+ */
+static void
+index_add(dns_journal_t *j, journal_pos_t *pos) {
+	unsigned int i;
+	if (j->index == NULL)
+		return;
+	/*
+	 * Search for a vacant position.
+	 */
+	for (i = 0; i < j->header.index_size; i++) {
+		if (! POS_VALID(j->index[i]))
+			break;
+	}
+	if (i == j->header.index_size) {
+		unsigned int k = 0;
+		/*
+		 * Found no vacant position.  Make some room.
+		 */
+		for (i = 0; i < j->header.index_size; i += 2) {
+			j->index[k++] = j->index[i];
+		}
+		i = k; /* 'i' identifies the first vacant position. */
+		while (k < j->header.index_size) {
+			POS_INVALIDATE(j->index[k]);
+			k++;
+		}
+	}
+	INSIST(i < j->header.index_size);
+	INSIST(! POS_VALID(j->index[i]));
+
+	/*
+	 * Store the new index entry.
+	 */
+	j->index[i] = *pos;
+}
+
+/*
+ * Invalidate any existing index entries that could become
+ * ambiguous when a new transaction with number 'serial' is added.
+ */
+static void
+index_invalidate(dns_journal_t *j, uint32_t serial) {
+	unsigned int i;
+	if (j->index == NULL)
+		return;
+	for (i = 0; i < j->header.index_size; i++) {
+		if (! DNS_SERIAL_GT(serial, j->index[i].serial))
+			POS_INVALIDATE(j->index[i]);
+	}
+}
+
+/*
+ * Try to find a transaction with initial serial number 'serial'
+ * in the journal 'j'.
+ *
+ * If found, store its position at '*pos' and return ISC_R_SUCCESS.
+ *
+ * If 'serial' is current (= the ending serial number of the
+ * last transaction in the journal), set '*pos' to
+ * the position immediately following the last transaction and
+ * return ISC_R_SUCCESS.
+ *
+ * If 'serial' is within the range of addressable serial numbers
+ * covered by the journal but that particular serial number is missing
+ * (from the journal, not just from the index), return ISC_R_NOTFOUND.
+ *
+ * If 'serial' is outside the range of addressable serial numbers
+ * covered by the journal, return ISC_R_RANGE.
+ *
+ */
+static isc_result_t
+journal_find(dns_journal_t *j, uint32_t serial, journal_pos_t *pos) {
+	isc_result_t result;
+	journal_pos_t current_pos;
+	REQUIRE(DNS_JOURNAL_VALID(j));
+
+	if (DNS_SERIAL_GT(j->header.begin.serial, serial))
+		return (ISC_R_RANGE);
+	if (DNS_SERIAL_GT(serial, j->header.end.serial))
+		return (ISC_R_RANGE);
+	if (serial == j->header.end.serial) {
+		*pos = j->header.end;
+		return (ISC_R_SUCCESS);
+	}
+
+	current_pos = j->header.begin;
+	index_find(j, serial, &current_pos);
+
+	while (current_pos.serial != serial) {
+		if (DNS_SERIAL_GT(current_pos.serial, serial))
+			return (ISC_R_NOTFOUND);
+		result = journal_next(j, &current_pos);
+		if (result != ISC_R_SUCCESS)
+			return (result);
+	}
+	*pos = current_pos;
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+dns_journal_begin_transaction(dns_journal_t *j) {
+	uint32_t offset;
+	isc_result_t result;
+	journal_rawxhdr_t hdr;
+
+	REQUIRE(DNS_JOURNAL_VALID(j));
+	REQUIRE(j->state == JOURNAL_STATE_WRITE ||
+		j->state == JOURNAL_STATE_INLINE);
+
+	/*
+	 * Find the file offset where the new transaction should
+	 * be written, and seek there.
+	 */
+	if (JOURNAL_EMPTY(&j->header)) {
+		offset = sizeof(journal_rawheader_t) +
+			j->header.index_size * sizeof(journal_rawpos_t);
+	} else {
+		offset = j->header.end.offset;
+	}
+	j->x.pos[0].offset = offset;
+	j->x.pos[1].offset = offset; /* Initial value, will be incremented. */
+	j->x.n_soa = 0;
+
+	CHECK(journal_seek(j, offset));
+
+	/*
+	 * Write a dummy transaction header of all zeroes to reserve
+	 * space.  It will be filled in when the transaction is
+	 * finished.
+	 */
+	memset(&hdr, 0, sizeof(hdr));
+	CHECK(journal_write(j, &hdr, sizeof(hdr)));
+	j->x.pos[1].offset = j->offset;
+
+	j->state = JOURNAL_STATE_TRANSACTION;
+	result = ISC_R_SUCCESS;
+ failure:
+	return (result);
+}
+
+isc_result_t
+dns_journal_writediff(dns_journal_t *j, dns_diff_t *diff) {
+	dns_difftuple_t *t;
+	isc_buffer_t buffer;
+	void *mem = NULL;
+	uint64_t size;
+	isc_result_t result;
+	isc_region_t used;
+
+	REQUIRE(DNS_DIFF_VALID(diff));
+	REQUIRE(j->state == JOURNAL_STATE_TRANSACTION);
+
+	isc_log_write(JOURNAL_DEBUG_LOGARGS(3), "writing to journal");
+	(void)dns_diff_print(diff, NULL);
+
+	/*
+	 * Pass 1: determine the buffer size needed, and
+	 * keep track of SOA serial numbers.
+	 */
+	size = 0;
+	for (t = ISC_LIST_HEAD(diff->tuples); t != NULL;
+	     t = ISC_LIST_NEXT(t, link))
+	{
+		if (t->rdata.type == dns_rdatatype_soa) {
+			if (j->x.n_soa < 2)
+				j->x.pos[j->x.n_soa].serial =
+					dns_soa_getserial(&t->rdata);
+			j->x.n_soa++;
+		}
+		size += sizeof(journal_rawrrhdr_t);
+		size += t->name.length; /* XXX should have access macro? */
+		size += 10;
+		size += t->rdata.length;
+	}
+
+	if (size >= INT32_MAX) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "dns_journal_writediff: %s: journal entry "
+			      "too big to be stored: %" PRIu64 " bytes",
+			      j->filename, size);
+		return (ISC_R_NOSPACE);
+	}
+
+	mem = isc_mem_get(j->mctx, size);
+	if (mem == NULL)
+		return (ISC_R_NOMEMORY);
+
+	isc_buffer_init(&buffer, mem, size);
+
+	/*
+	 * Pass 2.  Write RRs to buffer.
+	 */
+	for (t = ISC_LIST_HEAD(diff->tuples); t != NULL;
+	     t = ISC_LIST_NEXT(t, link))
+	{
+		/*
+		 * Write the RR header.
+		 */
+		isc_buffer_putuint32(&buffer, t->name.length + 10 +
+				     t->rdata.length);
+		/*
+		 * Write the owner name, RR header, and RR data.
+		 */
+		isc_buffer_putmem(&buffer, t->name.ndata, t->name.length);
+		isc_buffer_putuint16(&buffer, t->rdata.type);
+		isc_buffer_putuint16(&buffer, t->rdata.rdclass);
+		isc_buffer_putuint32(&buffer, t->ttl);
+		INSIST(t->rdata.length < 65536);
+		isc_buffer_putuint16(&buffer, (uint16_t)t->rdata.length);
+		INSIST(isc_buffer_availablelength(&buffer) >= t->rdata.length);
+		isc_buffer_putmem(&buffer, t->rdata.data, t->rdata.length);
+	}
+
+	isc_buffer_usedregion(&buffer, &used);
+	INSIST(used.length == size);
+
+	j->x.pos[1].offset += used.length;
+
+	/*
+	 * Write the buffer contents to the journal file.
+	 */
+	CHECK(journal_write(j, used.base, used.length));
+
+	result = ISC_R_SUCCESS;
+
+ failure:
+	if (mem != NULL)
+		isc_mem_put(j->mctx, mem, size);
+	return (result);
+
+}
+
+isc_result_t
+dns_journal_commit(dns_journal_t *j) {
+	isc_result_t result;
+	journal_rawheader_t rawheader;
+	uint64_t total;
+
+	REQUIRE(DNS_JOURNAL_VALID(j));
+	REQUIRE(j->state == JOURNAL_STATE_TRANSACTION ||
+		j->state == JOURNAL_STATE_INLINE);
+
+	/*
+	 * Just write out a updated header.
+	 */
+	if (j->state == JOURNAL_STATE_INLINE) {
+		CHECK(journal_fsync(j));
+		journal_header_encode(&j->header, &rawheader);
+		CHECK(journal_seek(j, 0));
+		CHECK(journal_write(j, &rawheader, sizeof(rawheader)));
+		CHECK(journal_fsync(j));
+		j->state = JOURNAL_STATE_WRITE;
+		return (ISC_R_SUCCESS);
+	}
+
+	/*
+	 * Perform some basic consistency checks.
+	 */
+	if (j->x.n_soa != 2) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: malformed transaction: %d SOAs",
+			      j->filename, j->x.n_soa);
+		return (ISC_R_UNEXPECTED);
+	}
+	if (! (DNS_SERIAL_GT(j->x.pos[1].serial, j->x.pos[0].serial) ||
+	       (bind8_compat &&
+		j->x.pos[1].serial == j->x.pos[0].serial)))
+	{
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: malformed transaction: serial number "
+			      "would decrease", j->filename);
+		return (ISC_R_UNEXPECTED);
+	}
+	if (! JOURNAL_EMPTY(&j->header)) {
+		if (j->x.pos[0].serial != j->header.end.serial) {
+			isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+					 "malformed transaction: "
+					 "%s last serial %u != "
+					 "transaction first serial %u",
+					 j->filename,
+					 j->header.end.serial,
+					 j->x.pos[0].serial);
+			return (ISC_R_UNEXPECTED);
+		}
+	}
+
+	/*
+	 * We currently don't support huge journal entries.
+	 */
+	total = j->x.pos[1].offset - j->x.pos[0].offset;
+	if (total >= INT32_MAX) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			     "transaction too big to be stored in journal: "
+			     "%" PRIu64 "b (max is %" PRIu64 "b)", total,
+			     (uint64_t)INT32_MAX);
+		return (ISC_R_UNEXPECTED);
+	}
+
+	/*
+	 * Some old journal entries may become non-addressable
+	 * when we increment the current serial number.  Purge them
+	 * by stepping header.begin forward to the first addressable
+	 * transaction.  Also purge them from the index.
+	 */
+	if (! JOURNAL_EMPTY(&j->header)) {
+		while (! DNS_SERIAL_GT(j->x.pos[1].serial,
+				       j->header.begin.serial)) {
+			CHECK(journal_next(j, &j->header.begin));
+		}
+		index_invalidate(j, j->x.pos[1].serial);
+	}
+#ifdef notyet
+	if (DNS_SERIAL_GT(last_dumped_serial, j->x.pos[1].serial)) {
+		force_dump(...);
+	}
+#endif
+
+	/*
+	 * Commit the transaction data to stable storage.
+	 */
+	CHECK(journal_fsync(j));
+
+	if (j->state == JOURNAL_STATE_TRANSACTION) {
+		isc_offset_t offset;
+		offset = (j->x.pos[1].offset - j->x.pos[0].offset) -
+				 sizeof(journal_rawxhdr_t);
+		/*
+		 * Update the transaction header.
+		 */
+		CHECK(journal_seek(j, j->x.pos[0].offset));
+		CHECK(journal_write_xhdr(j, offset, j->x.pos[0].serial,
+					 j->x.pos[1].serial));
+	}
+
+	/*
+	 * Update the journal header.
+	 */
+	if (JOURNAL_EMPTY(&j->header))
+		j->header.begin = j->x.pos[0];
+	j->header.end = j->x.pos[1];
+	journal_header_encode(&j->header, &rawheader);
+	CHECK(journal_seek(j, 0));
+	CHECK(journal_write(j, &rawheader, sizeof(rawheader)));
+
+	/*
+	 * Update the index.
+	 */
+	index_add(j, &j->x.pos[0]);
+
+	/*
+	 * Convert the index into on-disk format and write
+	 * it to disk.
+	 */
+	CHECK(index_to_disk(j));
+
+	/*
+	 * Commit the header to stable storage.
+	 */
+	CHECK(journal_fsync(j));
+
+	/*
+	 * We no longer have a transaction open.
+	 */
+	j->state = JOURNAL_STATE_WRITE;
+
+	result = ISC_R_SUCCESS;
+
+ failure:
+	return (result);
+}
+
+isc_result_t
+dns_journal_write_transaction(dns_journal_t *j, dns_diff_t *diff) {
+	isc_result_t result;
+	CHECK(dns_diff_sort(diff, ixfr_order));
+	CHECK(dns_journal_begin_transaction(j));
+	CHECK(dns_journal_writediff(j, diff));
+	CHECK(dns_journal_commit(j));
+	result = ISC_R_SUCCESS;
+ failure:
+	return (result);
+}
+
+void
+dns_journal_destroy(dns_journal_t **journalp) {
+	dns_journal_t *j = *journalp;
+	REQUIRE(DNS_JOURNAL_VALID(j));
+
+	j->it.result = ISC_R_FAILURE;
+	dns_name_invalidate(&j->it.name);
+	dns_decompress_invalidate(&j->it.dctx);
+	if (j->rawindex != NULL)
+		isc_mem_put(j->mctx, j->rawindex, j->header.index_size *
+			    sizeof(journal_rawpos_t));
+	if (j->index != NULL)
+		isc_mem_put(j->mctx, j->index, j->header.index_size *
+			    sizeof(journal_pos_t));
+	if (j->it.target.base != NULL)
+		isc_mem_put(j->mctx, j->it.target.base, j->it.target.length);
+	if (j->it.source.base != NULL)
+		isc_mem_put(j->mctx, j->it.source.base, j->it.source.length);
+	if (j->filename != NULL)
+		isc_mem_free(j->mctx, j->filename);
+	if (j->fp != NULL)
+		(void)isc_stdio_close(j->fp);
+	j->magic = 0;
+	isc_mem_putanddetach(&j->mctx, j, sizeof(*j));
+	*journalp = NULL;
+}
+
+/*
+ * Roll the open journal 'j' into the database 'db'.
+ * A new database version will be created.
+ */
+
+/* XXX Share code with incoming IXFR? */
+
+static isc_result_t
+roll_forward(dns_journal_t *j, dns_db_t *db, unsigned int options) {
+	isc_buffer_t source;		/* Transaction data from disk */
+	isc_buffer_t target;		/* Ditto after _fromwire check */
+	uint32_t db_serial;		/* Database SOA serial */
+	uint32_t end_serial;	/* Last journal SOA serial */
+	isc_result_t result;
+	dns_dbversion_t *ver = NULL;
+	journal_pos_t pos;
+	dns_diff_t diff;
+	unsigned int n_soa = 0;
+	unsigned int n_put = 0;
+	dns_diffop_t op;
+
+	REQUIRE(DNS_JOURNAL_VALID(j));
+	REQUIRE(DNS_DB_VALID(db));
+
+	dns_diff_init(j->mctx, &diff);
+
+	/*
+	 * Set up empty initial buffers for unchecked and checked
+	 * wire format transaction data.  They will be reallocated
+	 * later.
+	 */
+	isc_buffer_init(&source, NULL, 0);
+	isc_buffer_init(&target, NULL, 0);
+
+	/*
+	 * Create the new database version.
+	 */
+	CHECK(dns_db_newversion(db, &ver));
+
+	/*
+	 * Get the current database SOA serial number.
+	 */
+	CHECK(dns_db_getsoaserial(db, ver, &db_serial));
+
+	/*
+	 * Locate a journal entry for the current database serial.
+	 */
+	CHECK(journal_find(j, db_serial, &pos));
+	/*
+	 * XXX do more drastic things, like marking zone stale,
+	 * if this fails?
+	 */
+	/*
+	 * XXXRTH  The zone code should probably mark the zone as bad and
+	 *         scream loudly into the log if this is a dynamic update
+	 *	   log reply that failed.
+	 */
+
+	end_serial = dns_journal_last_serial(j);
+	if (db_serial == end_serial)
+		CHECK(DNS_R_UPTODATE);
+
+	CHECK(dns_journal_iter_init(j, db_serial, end_serial));
+
+	for (result = dns_journal_first_rr(j);
+	     result == ISC_R_SUCCESS;
+	     result = dns_journal_next_rr(j))
+	{
+		dns_name_t *name;
+		uint32_t ttl;
+		dns_rdata_t *rdata;
+		dns_difftuple_t *tuple = NULL;
+
+		name = NULL;
+		rdata = NULL;
+		dns_journal_current_rr(j, &name, &ttl, &rdata);
+
+		if (rdata->type == dns_rdatatype_soa) {
+			n_soa++;
+			if (n_soa == 2)
+				db_serial = j->it.current_serial;
+		}
+
+		if (n_soa == 3)
+			n_soa = 1;
+		if (n_soa == 0) {
+			isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+					 "%s: journal file corrupt: missing "
+					 "initial SOA", j->filename);
+			FAIL(ISC_R_UNEXPECTED);
+		}
+		if ((options & DNS_JOURNALOPT_RESIGN) != 0)
+			op = (n_soa == 1) ? DNS_DIFFOP_DELRESIGN :
+					    DNS_DIFFOP_ADDRESIGN;
+		else
+			op = (n_soa == 1) ? DNS_DIFFOP_DEL : DNS_DIFFOP_ADD;
+
+		CHECK(dns_difftuple_create(diff.mctx, op, name, ttl, rdata,
+					   &tuple));
+		dns_diff_append(&diff, &tuple);
+
+		if (++n_put > 100)  {
+			isc_log_write(JOURNAL_DEBUG_LOGARGS(3),
+				      "%s: applying diff to database (%u)",
+				      j->filename, db_serial);
+			(void)dns_diff_print(&diff, NULL);
+			CHECK(dns_diff_apply(&diff, db, ver));
+			dns_diff_clear(&diff);
+			n_put = 0;
+		}
+	}
+	if (result == ISC_R_NOMORE)
+		result = ISC_R_SUCCESS;
+	CHECK(result);
+
+	if (n_put != 0) {
+		isc_log_write(JOURNAL_DEBUG_LOGARGS(3),
+			      "%s: applying final diff to database (%u)",
+			      j->filename, db_serial);
+		(void)dns_diff_print(&diff, NULL);
+		CHECK(dns_diff_apply(&diff, db, ver));
+		dns_diff_clear(&diff);
+	}
+
+ failure:
+	if (ver != NULL)
+		dns_db_closeversion(db, &ver, result == ISC_R_SUCCESS ?
+				    true : false);
+
+	if (source.base != NULL)
+		isc_mem_put(j->mctx, source.base, source.length);
+	if (target.base != NULL)
+		isc_mem_put(j->mctx, target.base, target.length);
+
+	dns_diff_clear(&diff);
+
+	INSIST(ver == NULL);
+
+	return (result);
+}
+
+isc_result_t
+dns_journal_rollforward(isc_mem_t *mctx, dns_db_t *db, unsigned int options,
+			const char *filename)
+{
+	dns_journal_t *j;
+	isc_result_t result;
+
+	REQUIRE(DNS_DB_VALID(db));
+	REQUIRE(filename != NULL);
+
+	j = NULL;
+	result = dns_journal_open(mctx, filename, DNS_JOURNAL_READ, &j);
+	if (result == ISC_R_NOTFOUND) {
+		isc_log_write(JOURNAL_DEBUG_LOGARGS(3),
+			      "no journal file, but that's OK");
+		return (DNS_R_NOJOURNAL);
+	}
+	if (result != ISC_R_SUCCESS)
+		return (result);
+	if (JOURNAL_EMPTY(&j->header))
+		result = DNS_R_UPTODATE;
+	else
+		result = roll_forward(j, db, options);
+
+	dns_journal_destroy(&j);
+
+	return (result);
+}
+
+isc_result_t
+dns_journal_print(isc_mem_t *mctx, const char *filename, FILE *file) {
+	dns_journal_t *j;
+	isc_buffer_t source;		/* Transaction data from disk */
+	isc_buffer_t target;		/* Ditto after _fromwire check */
+	uint32_t start_serial;		/* Database SOA serial */
+	uint32_t end_serial;	/* Last journal SOA serial */
+	isc_result_t result;
+	dns_diff_t diff;
+	unsigned int n_soa = 0;
+	unsigned int n_put = 0;
+
+	REQUIRE(filename != NULL);
+
+	j = NULL;
+	result = dns_journal_open(mctx, filename, DNS_JOURNAL_READ, &j);
+	if (result == ISC_R_NOTFOUND) {
+		isc_log_write(JOURNAL_DEBUG_LOGARGS(3), "no journal file");
+		return (DNS_R_NOJOURNAL);
+	}
+
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "journal open failure: %s: %s",
+			      isc_result_totext(result), filename);
+		return (result);
+	}
+
+	if (j->header.serialset)
+		fprintf(file, "Source serial = %u\n", j->header.sourceserial);
+	dns_diff_init(j->mctx, &diff);
+
+	/*
+	 * Set up empty initial buffers for unchecked and checked
+	 * wire format transaction data.  They will be reallocated
+	 * later.
+	 */
+	isc_buffer_init(&source, NULL, 0);
+	isc_buffer_init(&target, NULL, 0);
+
+	start_serial = dns_journal_first_serial(j);
+	end_serial = dns_journal_last_serial(j);
+
+	CHECK(dns_journal_iter_init(j, start_serial, end_serial));
+
+	for (result = dns_journal_first_rr(j);
+	     result == ISC_R_SUCCESS;
+	     result = dns_journal_next_rr(j))
+	{
+		dns_name_t *name;
+		uint32_t ttl;
+		dns_rdata_t *rdata;
+		dns_difftuple_t *tuple = NULL;
+
+		name = NULL;
+		rdata = NULL;
+		dns_journal_current_rr(j, &name, &ttl, &rdata);
+
+		if (rdata->type == dns_rdatatype_soa)
+			n_soa++;
+
+		if (n_soa == 3)
+			n_soa = 1;
+		if (n_soa == 0) {
+			isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+				      "%s: journal file corrupt: missing "
+				      "initial SOA", j->filename);
+			FAIL(ISC_R_UNEXPECTED);
+		}
+		CHECK(dns_difftuple_create(diff.mctx, n_soa == 1 ?
+					   DNS_DIFFOP_DEL : DNS_DIFFOP_ADD,
+					   name, ttl, rdata, &tuple));
+		dns_diff_append(&diff, &tuple);
+
+		if (++n_put > 100)  {
+			result = dns_diff_print(&diff, file);
+			dns_diff_clear(&diff);
+			n_put = 0;
+			if (result != ISC_R_SUCCESS)
+				break;
+		}
+	}
+	if (result == ISC_R_NOMORE)
+		result = ISC_R_SUCCESS;
+	CHECK(result);
+
+	if (n_put != 0) {
+		result = dns_diff_print(&diff, file);
+		dns_diff_clear(&diff);
+	}
+	goto cleanup;
+
+ failure:
+	isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+		      "%s: cannot print: journal file corrupt", j->filename);
+
+ cleanup:
+	if (source.base != NULL)
+		isc_mem_put(j->mctx, source.base, source.length);
+	if (target.base != NULL)
+		isc_mem_put(j->mctx, target.base, target.length);
+
+	dns_diff_clear(&diff);
+	dns_journal_destroy(&j);
+
+	return (result);
+}
+
+/**************************************************************************/
+/*
+ * Miscellaneous accessors.
+ */
+uint32_t
+dns_journal_first_serial(dns_journal_t *j) {
+	return (j->header.begin.serial);
+}
+
+uint32_t
+dns_journal_last_serial(dns_journal_t *j) {
+	return (j->header.end.serial);
+}
+
+void
+dns_journal_set_sourceserial(dns_journal_t *j, uint32_t sourceserial) {
+
+	REQUIRE(j->state == JOURNAL_STATE_WRITE ||
+		j->state == JOURNAL_STATE_INLINE ||
+		j->state == JOURNAL_STATE_TRANSACTION);
+
+	j->header.sourceserial = sourceserial;
+	j->header.serialset = true;
+	if (j->state == JOURNAL_STATE_WRITE)
+		j->state = JOURNAL_STATE_INLINE;
+}
+
+bool
+dns_journal_get_sourceserial(dns_journal_t *j, uint32_t *sourceserial) {
+	REQUIRE(sourceserial != NULL);
+
+	if (!j->header.serialset)
+		return (false);
+	*sourceserial = j->header.sourceserial;
+	return (true);
+}
+
+/**************************************************************************/
+/*
+ * Iteration support.
+ *
+ * When serving an outgoing IXFR, we transmit a part the journal starting
+ * at the serial number in the IXFR request and ending at the serial
+ * number that is current when the IXFR request arrives.  The ending
+ * serial number is not necessarily at the end of the journal:
+ * the journal may grow while the IXFR is in progress, but we stop
+ * when we reach the serial number that was current when the IXFR started.
+ */
+
+static isc_result_t read_one_rr(dns_journal_t *j);
+
+/*
+ * Make sure the buffer 'b' is has at least 'size' bytes
+ * allocated, and clear it.
+ *
+ * Requires:
+ *	Either b->base is NULL, or it points to b->length bytes of memory
+ *	previously allocated by isc_mem_get().
+ */
+
+static isc_result_t
+size_buffer(isc_mem_t *mctx, isc_buffer_t *b, unsigned size) {
+	if (b->length < size) {
+		void *mem = isc_mem_get(mctx, size);
+		if (mem == NULL)
+			return (ISC_R_NOMEMORY);
+		if (b->base != NULL)
+			isc_mem_put(mctx, b->base, b->length);
+		b->base = mem;
+		b->length = size;
+	}
+	isc_buffer_clear(b);
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+dns_journal_iter_init(dns_journal_t *j,
+		      uint32_t begin_serial, uint32_t end_serial)
+{
+	isc_result_t result;
+
+	CHECK(journal_find(j, begin_serial, &j->it.bpos));
+	INSIST(j->it.bpos.serial == begin_serial);
+
+	CHECK(journal_find(j, end_serial, &j->it.epos));
+	INSIST(j->it.epos.serial == end_serial);
+
+	result = ISC_R_SUCCESS;
+ failure:
+	j->it.result = result;
+	return (j->it.result);
+}
+
+
+isc_result_t
+dns_journal_first_rr(dns_journal_t *j) {
+	isc_result_t result;
+
+	/*
+	 * Seek to the beginning of the first transaction we are
+	 * interested in.
+	 */
+	CHECK(journal_seek(j, j->it.bpos.offset));
+	j->it.current_serial = j->it.bpos.serial;
+
+	j->it.xsize = 0;  /* We have no transaction data yet... */
+	j->it.xpos = 0;	  /* ...and haven't used any of it. */
+
+	return (read_one_rr(j));
+
+ failure:
+	return (result);
+}
+
+static isc_result_t
+read_one_rr(dns_journal_t *j) {
+	isc_result_t result;
+
+	dns_rdatatype_t rdtype;
+	dns_rdataclass_t rdclass;
+	unsigned int rdlen;
+	uint32_t ttl;
+	journal_xhdr_t xhdr;
+	journal_rrhdr_t rrhdr;
+
+	if (j->offset > j->it.epos.offset) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+			      "%s: journal corrupt: possible integer overflow",
+			      j->filename);
+		return (ISC_R_UNEXPECTED);
+	}
+	if (j->offset == j->it.epos.offset)
+		return (ISC_R_NOMORE);
+	if (j->it.xpos == j->it.xsize) {
+		/*
+		 * We are at a transaction boundary.
+		 * Read another transaction header.
+		 */
+		CHECK(journal_read_xhdr(j, &xhdr));
+		if (xhdr.size == 0) {
+			isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+				      "%s: journal corrupt: empty transaction",
+				      j->filename);
+			FAIL(ISC_R_UNEXPECTED);
+		}
+		if (xhdr.serial0 != j->it.current_serial) {
+			isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+					 "%s: journal file corrupt: "
+					 "expected serial %u, got %u",
+					 j->filename,
+					 j->it.current_serial, xhdr.serial0);
+			FAIL(ISC_R_UNEXPECTED);
+		}
+		j->it.xsize = xhdr.size;
+		j->it.xpos = 0;
+	}
+	/*
+	 * Read an RR.
+	 */
+	CHECK(journal_read_rrhdr(j, &rrhdr));
+	/*
+	 * Perform a sanity check on the journal RR size.
+	 * The smallest possible RR has a 1-byte owner name
+	 * and a 10-byte header.  The largest possible
+	 * RR has 65535 bytes of data, a header, and a maximum-
+	 * size owner name, well below 70 k total.
+	 */
+	if (rrhdr.size < 1+10 || rrhdr.size > 70000) {
+		isc_log_write(JOURNAL_COMMON_LOGARGS, ISC_LOG_ERROR,
+				 "%s: journal corrupt: impossible RR size "
+				 "(%d bytes)", j->filename, rrhdr.size);
+		FAIL(ISC_R_UNEXPECTED);
+	}
+
+	CHECK(size_buffer(j->mctx, &j->it.source, rrhdr.size));
+	CHECK(journal_read(j, j->it.source.base, rrhdr.size));
+	isc_buffer_add(&j->it.source, rrhdr.size);
+
+	/*
+	 * The target buffer is made the same size
+	 * as the source buffer, with the assumption that when
+	 * no compression in present, the output of dns_*_fromwire()
+	 * is no larger than the input.
+	 */
+	CHECK(size_buffer(j->mctx, &j->it.target, rrhdr.size));
+
+	/*
+	 * Parse the owner name.  We don't know where it
+	 * ends yet, so we make the entire "remaining"
+	 * part of the buffer "active".
+	 */
+	isc_buffer_setactive(&j->it.source,
+			     j->it.source.used - j->it.source.current);
+	CHECK(dns_name_fromwire(&j->it.name, &j->it.source,
+				&j->it.dctx, 0, &j->it.target));
+
+	/*
+	 * Check that the RR header is there, and parse it.
+	 */
+	if (isc_buffer_remaininglength(&j->it.source) < 10)
+		FAIL(DNS_R_FORMERR);
+
+	rdtype = isc_buffer_getuint16(&j->it.source);
+	rdclass = isc_buffer_getuint16(&j->it.source);
+	ttl = isc_buffer_getuint32(&j->it.source);
+	rdlen = isc_buffer_getuint16(&j->it.source);
+
+	/*
+	 * Parse the rdata.
+	 */
+	if (isc_buffer_remaininglength(&j->it.source) != rdlen)
+		FAIL(DNS_R_FORMERR);
+	isc_buffer_setactive(&j->it.source, rdlen);
+	dns_rdata_reset(&j->it.rdata);
+	CHECK(dns_rdata_fromwire(&j->it.rdata, rdclass,
+				 rdtype, &j->it.source, &j->it.dctx,
+				 0, &j->it.target));
+	j->it.ttl = ttl;
+
+	j->it.xpos += sizeof(journal_rawrrhdr_t) + rrhdr.size;
+	if (rdtype == dns_rdatatype_soa) {
+		/* XXX could do additional consistency checks here */
+		j->it.current_serial = dns_soa_getserial(&j->it.rdata);
+	}
+
+	result = ISC_R_SUCCESS;
+
+ failure:
+	j->it.result = result;
+	return (result);
+}
+
+isc_result_t
+dns_journal_next_rr(dns_journal_t *j) {
+	j->it.result = read_one_rr(j);
+	return (j->it.result);
+}
+
+void
+dns_journal_current_rr(dns_journal_t *j, dns_name_t **name, uint32_t *ttl,
+		   dns_rdata_t **rdata)
+{
+	REQUIRE(j->it.result == ISC_R_SUCCESS);
+	*name = &j->it.name;
+	*ttl = j->it.ttl;
+	*rdata = &j->it.rdata;
+}
+
+/**************************************************************************/
+/*
+ * Generating diffs from databases
+ */
+
+/*
+ * Construct a diff containing all the RRs at the current name of the
+ * database iterator 'dbit' in database 'db', version 'ver'.
+ * Set '*name' to the current name, and append the diff to 'diff'.
+ * All new tuples will have the operation 'op'.
+ *
+ * Requires: 'name' must have buffer large enough to hold the name.
+ * Typically, a dns_fixedname_t would be used.
+ */
+static isc_result_t
+get_name_diff(dns_db_t *db, dns_dbversion_t *ver, isc_stdtime_t now,
+	      dns_dbiterator_t *dbit, dns_name_t *name, dns_diffop_t op,
+	      dns_diff_t *diff)
+{
+	isc_result_t result;
+	dns_dbnode_t *node = NULL;
+	dns_rdatasetiter_t *rdsiter = NULL;
+	dns_difftuple_t *tuple = NULL;
+
+	result = dns_dbiterator_current(dbit, &node, name);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	result = dns_db_allrdatasets(db, node, ver, now, &rdsiter);
+	if (result != ISC_R_SUCCESS)
+		goto cleanup_node;
+
+	for (result = dns_rdatasetiter_first(rdsiter);
+	     result == ISC_R_SUCCESS;
+	     result = dns_rdatasetiter_next(rdsiter))
+	{
+		dns_rdataset_t rdataset;
+
+		dns_rdataset_init(&rdataset);
+		dns_rdatasetiter_current(rdsiter, &rdataset);
+
+		for (result = dns_rdataset_first(&rdataset);
+		     result == ISC_R_SUCCESS;
+		     result = dns_rdataset_next(&rdataset))
+		{
+			dns_rdata_t rdata = DNS_RDATA_INIT;
+			dns_rdataset_current(&rdataset, &rdata);
+			result = dns_difftuple_create(diff->mctx, op, name,
+						      rdataset.ttl, &rdata,
+						      &tuple);
+			if (result != ISC_R_SUCCESS) {
+				dns_rdataset_disassociate(&rdataset);
+				goto cleanup_iterator;
+			}
+			dns_diff_append(diff, &tuple);
+		}
+		dns_rdataset_disassociate(&rdataset);
+		if (result != ISC_R_NOMORE)
+			goto cleanup_iterator;
+	}
+	if (result != ISC_R_NOMORE)
+		goto cleanup_iterator;
+
+	result = ISC_R_SUCCESS;
+
+ cleanup_iterator:
+	dns_rdatasetiter_destroy(&rdsiter);
+
+ cleanup_node:
+	dns_db_detachnode(db, &node);
+
+	return (result);
+}
+
+/*
+ * Comparison function for use by dns_diff_subtract when sorting
+ * the diffs to be subtracted.  The sort keys are the rdata type
+ * and the rdata itself.  The owner name is ignored, because
+ * it is known to be the same for all tuples.
+ */
+static int
+rdata_order(const void *av, const void *bv) {
+	dns_difftuple_t const * const *ap = av;
+	dns_difftuple_t const * const *bp = bv;
+	dns_difftuple_t const *a = *ap;
+	dns_difftuple_t const *b = *bp;
+	int r;
+	r = (b->rdata.type - a->rdata.type);
+	if (r != 0)
+		return (r);
+	r = dns_rdata_compare(&a->rdata, &b->rdata);
+	return (r);
+}
+
+static isc_result_t
+dns_diff_subtract(dns_diff_t diff[2], dns_diff_t *r) {
+	isc_result_t result;
+	dns_difftuple_t *p[2];
+	int i, t;
+	bool append;
+
+	CHECK(dns_diff_sort(&diff[0], rdata_order));
+	CHECK(dns_diff_sort(&diff[1], rdata_order));
+
+	for (;;) {
+		p[0] = ISC_LIST_HEAD(diff[0].tuples);
+		p[1] = ISC_LIST_HEAD(diff[1].tuples);
+		if (p[0] == NULL && p[1] == NULL)
+			break;
+
+		for (i = 0; i < 2; i++)
+			if (p[!i] == NULL) {
+				ISC_LIST_UNLINK(diff[i].tuples, p[i], link);
+				ISC_LIST_APPEND(r->tuples, p[i], link);
+				goto next;
+			}
+		t = rdata_order(&p[0], &p[1]);
+		if (t < 0) {
+			ISC_LIST_UNLINK(diff[0].tuples, p[0], link);
+			ISC_LIST_APPEND(r->tuples, p[0], link);
+			goto next;
+		}
+		if (t > 0) {
+			ISC_LIST_UNLINK(diff[1].tuples, p[1], link);
+			ISC_LIST_APPEND(r->tuples, p[1], link);
+			goto next;
+		}
+		INSIST(t == 0);
+		/*
+		 * Identical RRs in both databases; skip them both
+		 * if the ttl differs.
+		 */
+		append = (p[0]->ttl != p[1]->ttl);
+		for (i = 0; i < 2; i++) {
+			ISC_LIST_UNLINK(diff[i].tuples, p[i], link);
+			if (append) {
+				ISC_LIST_APPEND(r->tuples, p[i], link);
+			} else {
+				dns_difftuple_free(&p[i]);
+			}
+		}
+	next: ;
+	}
+	result = ISC_R_SUCCESS;
+ failure:
+	return (result);
+}
+
+static isc_result_t
+diff_namespace(dns_db_t *dba, dns_dbversion_t *dbvera,
+	       dns_db_t *dbb, dns_dbversion_t *dbverb,
+	       unsigned int options, dns_diff_t *resultdiff)
+{
+	dns_db_t *db[2];
+	dns_dbversion_t *ver[2];
+	dns_dbiterator_t *dbit[2] = { NULL, NULL };
+	bool have[2] = { false, false };
+	dns_fixedname_t fixname[2];
+	isc_result_t result, itresult[2];
+	dns_diff_t diff[2];
+	int i, t;
+
+	db[0] = dba, db[1] = dbb;
+	ver[0] = dbvera, ver[1] = dbverb;
+
+	dns_diff_init(resultdiff->mctx, &diff[0]);
+	dns_diff_init(resultdiff->mctx, &diff[1]);
+
+	dns_fixedname_init(&fixname[0]);
+	dns_fixedname_init(&fixname[1]);
+
+	result = dns_db_createiterator(db[0], options, &dbit[0]);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+	result = dns_db_createiterator(db[1], options, &dbit[1]);
+	if (result != ISC_R_SUCCESS)
+		goto cleanup_iterator;
+
+	itresult[0] = dns_dbiterator_first(dbit[0]);
+	itresult[1] = dns_dbiterator_first(dbit[1]);
+
+	for (;;) {
+		for (i = 0; i < 2; i++) {
+			if (! have[i] && itresult[i] == ISC_R_SUCCESS) {
+				CHECK(get_name_diff(db[i], ver[i], 0, dbit[i],
+					    dns_fixedname_name(&fixname[i]),
+					    i == 0 ?
+					    DNS_DIFFOP_ADD :
+					    DNS_DIFFOP_DEL,
+					    &diff[i]));
+				itresult[i] = dns_dbiterator_next(dbit[i]);
+				have[i] = true;
+			}
+		}
+
+		if (! have[0] && ! have[1]) {
+			INSIST(ISC_LIST_EMPTY(diff[0].tuples));
+			INSIST(ISC_LIST_EMPTY(diff[1].tuples));
+			break;
+		}
+
+		for (i = 0; i < 2; i++) {
+			if (! have[!i]) {
+				ISC_LIST_APPENDLIST(resultdiff->tuples,
+						    diff[i].tuples, link);
+				INSIST(ISC_LIST_EMPTY(diff[i].tuples));
+				have[i] = false;
+				goto next;
+			}
+		}
+
+		t = dns_name_compare(dns_fixedname_name(&fixname[0]),
+				     dns_fixedname_name(&fixname[1]));
+		if (t < 0) {
+			ISC_LIST_APPENDLIST(resultdiff->tuples,
+					    diff[0].tuples, link);
+			INSIST(ISC_LIST_EMPTY(diff[0].tuples));
+			have[0] = false;
+			continue;
+		}
+		if (t > 0) {
+			ISC_LIST_APPENDLIST(resultdiff->tuples,
+					    diff[1].tuples, link);
+			INSIST(ISC_LIST_EMPTY(diff[1].tuples));
+			have[1] = false;
+			continue;
+		}
+		INSIST(t == 0);
+		CHECK(dns_diff_subtract(diff, resultdiff));
+		INSIST(ISC_LIST_EMPTY(diff[0].tuples));
+		INSIST(ISC_LIST_EMPTY(diff[1].tuples));
+		have[0] = have[1] = false;
+	next: ;
+	}
+	if (itresult[0] != ISC_R_NOMORE)
+		FAIL(itresult[0]);
+	if (itresult[1] != ISC_R_NOMORE)
+		FAIL(itresult[1]);
+
+	INSIST(ISC_LIST_EMPTY(diff[0].tuples));
+	INSIST(ISC_LIST_EMPTY(diff[1].tuples));
+
+ failure:
+	dns_dbiterator_destroy(&dbit[1]);
+
+ cleanup_iterator:
+	dns_dbiterator_destroy(&dbit[0]);
+	dns_diff_clear(&diff[0]);
+	dns_diff_clear(&diff[1]);
+	return (result);
+}
+
+/*
+ * Compare the databases 'dba' and 'dbb' and generate a journal
+ * entry containing the changes to make 'dba' from 'dbb' (note
+ * the order).  This journal entry will consist of a single,
+ * possibly very large transaction.
+ */
+isc_result_t
+dns_db_diff(isc_mem_t *mctx, dns_db_t *dba, dns_dbversion_t *dbvera,
+	    dns_db_t *dbb, dns_dbversion_t *dbverb, const char *filename)
+{
+	isc_result_t result;
+	dns_diff_t diff;
+
+	dns_diff_init(mctx, &diff);
+
+	result = dns_db_diffx(&diff, dba, dbvera, dbb, dbverb, filename);
+
+	dns_diff_clear(&diff);
+
+	return (result);
+}
+
+isc_result_t
+dns_db_diffx(dns_diff_t *diff, dns_db_t *dba, dns_dbversion_t *dbvera,
+	     dns_db_t *dbb, dns_dbversion_t *dbverb, const char *filename)
+{
+	isc_result_t result;
+	dns_journal_t *journal = NULL;
+
+	if (filename != NULL) {
+		result = dns_journal_open(diff->mctx, filename,
+					  DNS_JOURNAL_CREATE, &journal);
+		if (result != ISC_R_SUCCESS)
+			return (result);
+	}
+
+	CHECK(diff_namespace(dba, dbvera, dbb, dbverb, DNS_DB_NONSEC3, diff));
+	CHECK(diff_namespace(dba, dbvera, dbb, dbverb, DNS_DB_NSEC3ONLY, diff));
+
+	if (journal != NULL) {
+		if (ISC_LIST_EMPTY(diff->tuples))
+			isc_log_write(JOURNAL_DEBUG_LOGARGS(3), "no changes");
+		else
+			CHECK(dns_journal_write_transaction(journal, diff));
+	}
+
+ failure:
+	if (journal != NULL)
+		dns_journal_destroy(&journal);
+	return (result);
+}
+
+isc_result_t
+dns_journal_compact(isc_mem_t *mctx, char *filename, uint32_t serial,
+		    uint32_t target_size)
+{
+	unsigned int i;
+	journal_pos_t best_guess;
+	journal_pos_t current_pos;
+	dns_journal_t *j1 = NULL;
+	dns_journal_t *j2 = NULL;
+	journal_rawheader_t rawheader;
+	unsigned int copy_length;
+	size_t namelen;
+	char *buf = NULL;
+	unsigned int size = 0;
+	isc_result_t result;
+	unsigned int indexend;
+	char newname[1024];
+	char backup[1024];
+	bool is_backup = false;
+
+	REQUIRE(filename != NULL);
+
+	namelen = strlen(filename);
+	if (namelen > 4U && strcmp(filename + namelen - 4, ".jnl") == 0)
+		namelen -= 4;
+
+	result = isc_string_printf(newname, sizeof(newname), "%.*s.jnw",
+				   (int)namelen, filename);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	result = isc_string_printf(backup, sizeof(backup), "%.*s.jbk",
+				   (int)namelen, filename);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	result = journal_open(mctx, filename, false, false, &j1);
+	if (result == ISC_R_NOTFOUND) {
+		is_backup = true;
+		result = journal_open(mctx, backup, false, false, &j1);
+	}
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	if (JOURNAL_EMPTY(&j1->header)) {
+		dns_journal_destroy(&j1);
+		return (ISC_R_SUCCESS);
+	}
+
+	if (DNS_SERIAL_GT(j1->header.begin.serial, serial) ||
+	    DNS_SERIAL_GT(serial, j1->header.end.serial)) {
+		dns_journal_destroy(&j1);
+		return (ISC_R_RANGE);
+	}
+
+	/*
+	 * Cope with very small target sizes.
+	 */
+	indexend = sizeof(journal_rawheader_t) +
+		   j1->header.index_size * sizeof(journal_rawpos_t);
+	if (target_size < indexend * 2)
+		target_size = target_size/2 + indexend;
+
+	/*
+	 * See if there is any work to do.
+	 */
+	if ((uint32_t) j1->header.end.offset < target_size) {
+		dns_journal_destroy(&j1);
+		return (ISC_R_SUCCESS);
+	}
+
+	CHECK(journal_open(mctx, newname, true, true, &j2));
+
+	/*
+	 * Remove overhead so space test below can succeed.
+	 */
+	if (target_size >= indexend)
+		target_size -= indexend;
+
+	/*
+	 * Find if we can create enough free space.
+	 */
+	best_guess = j1->header.begin;
+	for (i = 0; i < j1->header.index_size; i++) {
+		if (POS_VALID(j1->index[i]) &&
+		    DNS_SERIAL_GE(serial, j1->index[i].serial) &&
+		    ((uint32_t)(j1->header.end.offset - j1->index[i].offset)
+		     >= target_size / 2) &&
+		    j1->index[i].offset > best_guess.offset)
+			best_guess = j1->index[i];
+	}
+
+	current_pos = best_guess;
+	while (current_pos.serial != serial) {
+		CHECK(journal_next(j1, &current_pos));
+		if (current_pos.serial == j1->header.end.serial)
+			break;
+
+		if (DNS_SERIAL_GE(serial, current_pos.serial) &&
+		   ((uint32_t)(j1->header.end.offset - current_pos.offset)
+		     >= (target_size / 2)) &&
+		    current_pos.offset > best_guess.offset)
+			best_guess = current_pos;
+		else
+			break;
+	}
+
+	INSIST(best_guess.serial != j1->header.end.serial);
+	if (best_guess.serial != serial)
+		CHECK(journal_next(j1, &best_guess));
+
+	/*
+	 * We should now be roughly half target_size provided
+	 * we did not reach 'serial'.  If not we will just copy
+	 * all uncommitted deltas regardless of the size.
+	 */
+	copy_length = j1->header.end.offset - best_guess.offset;
+
+	if (copy_length != 0) {
+		/*
+		 * Copy best_guess to end into space just freed.
+		 */
+		size = 64*1024;
+		if (copy_length < size)
+			size = copy_length;
+		buf = isc_mem_get(mctx, size);
+		if (buf == NULL) {
+			result = ISC_R_NOMEMORY;
+			goto failure;
+		}
+
+		CHECK(journal_seek(j1, best_guess.offset));
+		CHECK(journal_seek(j2, indexend));
+		for (i = 0; i < copy_length; i += size) {
+			unsigned int len = (copy_length - i) > size ? size :
+							 (copy_length - i);
+			CHECK(journal_read(j1, buf, len));
+			CHECK(journal_write(j2, buf, len));
+		}
+
+		CHECK(journal_fsync(j2));
+
+		/*
+		 * Compute new header.
+		 */
+		j2->header.begin.serial = best_guess.serial;
+		j2->header.begin.offset = indexend;
+		j2->header.end.serial = j1->header.end.serial;
+		j2->header.end.offset = indexend + copy_length;
+		j2->header.sourceserial = j1->header.sourceserial;
+		j2->header.serialset = j1->header.serialset;
+
+		/*
+		 * Update the journal header.
+		 */
+		journal_header_encode(&j2->header, &rawheader);
+		CHECK(journal_seek(j2, 0));
+		CHECK(journal_write(j2, &rawheader, sizeof(rawheader)));
+		CHECK(journal_fsync(j2));
+
+		/*
+		 * Build new index.
+		 */
+		current_pos = j2->header.begin;
+		while (current_pos.serial != j2->header.end.serial) {
+			index_add(j2, &current_pos);
+			CHECK(journal_next(j2, &current_pos));
+		}
+
+		/*
+		 * Write index.
+		 */
+		CHECK(index_to_disk(j2));
+		CHECK(journal_fsync(j2));
+
+		indexend = j2->header.end.offset;
+		POST(indexend);
+	}
+
+	/*
+	 * Close both journals before trying to rename files (this is
+	 * necessary on WIN32).
+	 */
+	dns_journal_destroy(&j1);
+	dns_journal_destroy(&j2);
+
+	/*
+	 * With a UFS file system this should just succeed and be atomic.
+	 * Any IXFR outs will just continue and the old journal will be
+	 * removed on final close.
+	 *
+	 * With MSDOS / NTFS we need to do a two stage rename, triggered
+	 * by EEXIST.  (If any IXFR's are running in other threads, however,
+	 * this will fail, and the journal will not be compacted.  But
+	 * if so, hopefully they'll be finished by the next time we
+	 * compact.)
+	 */
+	if (rename(newname, filename) == -1) {
+		if (errno == EEXIST && !is_backup) {
+			result = isc_file_remove(backup);
+			if (result != ISC_R_SUCCESS &&
+			    result != ISC_R_FILENOTFOUND)
+				goto failure;
+			if (rename(filename, backup) == -1)
+				goto maperrno;
+			if (rename(newname, filename) == -1)
+				goto maperrno;
+			(void)isc_file_remove(backup);
+		} else {
+ maperrno:
+			result = ISC_R_FAILURE;
+			goto failure;
+		}
+	}
+
+	result = ISC_R_SUCCESS;
+
+ failure:
+	(void)isc_file_remove(newname);
+	if (buf != NULL)
+		isc_mem_put(mctx, buf, size);
+	if (j1 != NULL)
+		dns_journal_destroy(&j1);
+	if (j2 != NULL)
+		dns_journal_destroy(&j2);
+	return (result);
+}
+
+static isc_result_t
+index_to_disk(dns_journal_t *j) {
+	isc_result_t result = ISC_R_SUCCESS;
+
+	if (j->header.index_size != 0) {
+		unsigned int i;
+		unsigned char *p;
+		unsigned int rawbytes;
+
+		rawbytes = j->header.index_size * sizeof(journal_rawpos_t);
+
+		p = j->rawindex;
+		for (i = 0; i < j->header.index_size; i++) {
+			encode_uint32(j->index[i].serial, p);
+			p += 4;
+			encode_uint32(j->index[i].offset, p);
+			p += 4;
+		}
+		INSIST(p == j->rawindex + rawbytes);
+
+		CHECK(journal_seek(j, sizeof(journal_rawheader_t)));
+		CHECK(journal_write(j, j->rawindex, rawbytes));
+	}
+failure:
+	return (result);
+}