Adding upstream version 252.22.upstream/252.22upstream

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

1 files changed, 4255 insertions, 0 deletions

diff --git a/src/libsystemd/sd-journal/journal-file.c b/src/libsystemd/sd-journal/journal-file.c
new file mode 100644
index 0000000..d3a9505
--- /dev/null
+++ b/src/libsystemd/sd-journal/journal-file.c
@@ -0,0 +1,4255 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/fs.h>
+#include <linux/magic.h>
+#include <pthread.h>
+#include <stddef.h>
+#include <sys/mman.h>
+#include <sys/statvfs.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+#include "sd-event.h"
+
+#include "alloc-util.h"
+#include "chattr-util.h"
+#include "compress.h"
+#include "env-util.h"
+#include "fd-util.h"
+#include "format-util.h"
+#include "fs-util.h"
+#include "journal-authenticate.h"
+#include "journal-def.h"
+#include "journal-file.h"
+#include "lookup3.h"
+#include "memory-util.h"
+#include "path-util.h"
+#include "random-util.h"
+#include "set.h"
+#include "sort-util.h"
+#include "stat-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "strv.h"
+#include "sync-util.h"
+#include "xattr-util.h"
+
+#define DEFAULT_DATA_HASH_TABLE_SIZE (2047ULL*sizeof(HashItem))
+#define DEFAULT_FIELD_HASH_TABLE_SIZE (333ULL*sizeof(HashItem))
+
+#define DEFAULT_COMPRESS_THRESHOLD (512ULL)
+#define MIN_COMPRESS_THRESHOLD (8ULL)
+
+/* This is the minimum journal file size */
+#define JOURNAL_FILE_SIZE_MIN (512 * 1024ULL)             /* 512 KiB */
+#define JOURNAL_COMPACT_SIZE_MAX UINT32_MAX               /* 4 GiB */
+
+/* These are the lower and upper bounds if we deduce the max_use value
+ * from the file system size */
+#define MAX_USE_LOWER (1 * 1024 * 1024ULL)                /* 1 MiB */
+#define MAX_USE_UPPER (4 * 1024 * 1024 * 1024ULL)         /* 4 GiB */
+
+/* Those are the lower and upper bounds for the minimal use limit,
+ * i.e. how much we'll use even if keep_free suggests otherwise. */
+#define MIN_USE_LOW (1 * 1024 * 1024ULL)                  /* 1 MiB */
+#define MIN_USE_HIGH (16 * 1024 * 1024ULL)                /* 16 MiB */
+
+/* This is the upper bound if we deduce max_size from max_use */
+#define MAX_SIZE_UPPER (128 * 1024 * 1024ULL)             /* 128 MiB */
+
+/* This is the upper bound if we deduce the keep_free value from the
+ * file system size */
+#define KEEP_FREE_UPPER (4 * 1024 * 1024 * 1024ULL)       /* 4 GiB */
+
+/* This is the keep_free value when we can't determine the system
+ * size */
+#define DEFAULT_KEEP_FREE (1024 * 1024ULL)                /* 1 MB */
+
+/* This is the default maximum number of journal files to keep around. */
+#define DEFAULT_N_MAX_FILES 100
+
+/* n_data was the first entry we added after the initial file format design */
+#define HEADER_SIZE_MIN ALIGN64(offsetof(Header, n_data))
+
+/* How many entries to keep in the entry array chain cache at max */
+#define CHAIN_CACHE_MAX 20
+
+/* How much to increase the journal file size at once each time we allocate something new. */
+#define FILE_SIZE_INCREASE (8 * 1024 * 1024ULL)          /* 8MB */
+
+/* Reread fstat() of the file for detecting deletions at least this often */
+#define LAST_STAT_REFRESH_USEC (5*USEC_PER_SEC)
+
+/* The mmap context to use for the header we pick as one above the last defined typed */
+#define CONTEXT_HEADER _OBJECT_TYPE_MAX
+
+/* Longest hash chain to rotate after */
+#define HASH_CHAIN_DEPTH_MAX 100
+
+#ifdef __clang__
+#  pragma GCC diagnostic ignored "-Waddress-of-packed-member"
+#endif
+
+int journal_file_tail_end_by_pread(JournalFile *f, uint64_t *ret_offset) {
+        uint64_t p;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(ret_offset);
+
+        /* Same as journal_file_tail_end_by_mmap() below, but operates with pread() to avoid the mmap cache
+         * (and thus is thread safe) */
+
+        p = le64toh(f->header->tail_object_offset);
+        if (p == 0)
+                p = le64toh(f->header->header_size);
+        else {
+                Object tail;
+                uint64_t sz;
+
+                r = journal_file_read_object_header(f, OBJECT_UNUSED, p, &tail);
+                if (r < 0)
+                        return r;
+
+                sz = le64toh(tail.object.size);
+                if (sz > UINT64_MAX - sizeof(uint64_t) + 1)
+                        return -EBADMSG;
+
+                sz = ALIGN64(sz);
+                if (p > UINT64_MAX - sz)
+                        return -EBADMSG;
+
+                p += sz;
+        }
+
+        *ret_offset = p;
+
+        return 0;
+}
+
+int journal_file_tail_end_by_mmap(JournalFile *f, uint64_t *ret_offset) {
+        uint64_t p;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(ret_offset);
+
+        /* Same as journal_file_tail_end_by_pread() above, but operates with the usual mmap logic */
+
+        p = le64toh(f->header->tail_object_offset);
+        if (p == 0)
+                p = le64toh(f->header->header_size);
+        else {
+                Object *tail;
+                uint64_t sz;
+
+                r = journal_file_move_to_object(f, OBJECT_UNUSED, p, &tail);
+                if (r < 0)
+                        return r;
+
+                sz = le64toh(READ_NOW(tail->object.size));
+                if (sz > UINT64_MAX - sizeof(uint64_t) + 1)
+                        return -EBADMSG;
+
+                sz = ALIGN64(sz);
+                if (p > UINT64_MAX - sz)
+                        return -EBADMSG;
+
+                p += sz;
+        }
+
+        *ret_offset = p;
+
+        return 0;
+}
+
+int journal_file_set_offline_thread_join(JournalFile *f) {
+        int r;
+
+        assert(f);
+
+        if (f->offline_state == OFFLINE_JOINED)
+                return 0;
+
+        r = pthread_join(f->offline_thread, NULL);
+        if (r)
+                return -r;
+
+        f->offline_state = OFFLINE_JOINED;
+
+        if (mmap_cache_fd_got_sigbus(f->cache_fd))
+                return -EIO;
+
+        return 0;
+}
+
+static int journal_file_set_online(JournalFile *f) {
+        bool wait = true;
+
+        assert(f);
+
+        if (!journal_file_writable(f))
+                return -EPERM;
+
+        if (f->fd < 0 || !f->header)
+                return -EINVAL;
+
+        while (wait) {
+                switch (f->offline_state) {
+                case OFFLINE_JOINED:
+                        /* No offline thread, no need to wait. */
+                        wait = false;
+                        break;
+
+                case OFFLINE_SYNCING: {
+                                OfflineState tmp_state = OFFLINE_SYNCING;
+                                if (!__atomic_compare_exchange_n(&f->offline_state, &tmp_state, OFFLINE_CANCEL,
+                                    false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
+                                        continue;
+                        }
+                        /* Canceled syncing prior to offlining, no need to wait. */
+                        wait = false;
+                        break;
+
+                case OFFLINE_AGAIN_FROM_SYNCING: {
+                                OfflineState tmp_state = OFFLINE_AGAIN_FROM_SYNCING;
+                                if (!__atomic_compare_exchange_n(&f->offline_state, &tmp_state, OFFLINE_CANCEL,
+                                    false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
+                                        continue;
+                        }
+                        /* Canceled restart from syncing, no need to wait. */
+                        wait = false;
+                        break;
+
+                case OFFLINE_AGAIN_FROM_OFFLINING: {
+                                OfflineState tmp_state = OFFLINE_AGAIN_FROM_OFFLINING;
+                                if (!__atomic_compare_exchange_n(&f->offline_state, &tmp_state, OFFLINE_CANCEL,
+                                    false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
+                                        continue;
+                        }
+                        /* Canceled restart from offlining, must wait for offlining to complete however. */
+                        _fallthrough_;
+                default: {
+                        int r;
+
+                        r = journal_file_set_offline_thread_join(f);
+                        if (r < 0)
+                                return r;
+
+                        wait = false;
+                        break;
+                }
+                }
+        }
+
+        if (mmap_cache_fd_got_sigbus(f->cache_fd))
+                return -EIO;
+
+        switch (f->header->state) {
+                case STATE_ONLINE:
+                        return 0;
+
+                case STATE_OFFLINE:
+                        f->header->state = STATE_ONLINE;
+                        (void) fsync(f->fd);
+                        return 0;
+
+                default:
+                        return -EINVAL;
+        }
+}
+
+JournalFile* journal_file_close(JournalFile *f) {
+        if (!f)
+                return NULL;
+
+        if (f->cache_fd)
+                mmap_cache_fd_free(f->cache_fd);
+
+        if (f->close_fd)
+                safe_close(f->fd);
+        free(f->path);
+
+        ordered_hashmap_free_free(f->chain_cache);
+
+#if HAVE_COMPRESSION
+        free(f->compress_buffer);
+#endif
+
+#if HAVE_GCRYPT
+        if (f->fss_file)
+                munmap(f->fss_file, PAGE_ALIGN(f->fss_file_size));
+        else
+                free(f->fsprg_state);
+
+        free(f->fsprg_seed);
+
+        if (f->hmac)
+                gcry_md_close(f->hmac);
+#endif
+
+        return mfree(f);
+}
+
+static bool keyed_hash_requested(void) {
+        int r;
+
+        r = getenv_bool("SYSTEMD_JOURNAL_KEYED_HASH");
+        if (r >= 0)
+                return r;
+        if (r != -ENXIO)
+                log_debug_errno(r, "Failed to parse $SYSTEMD_JOURNAL_KEYED_HASH environment variable, ignoring: %m");
+
+        return true;
+}
+
+static bool compact_mode_requested(void) {
+        int r;
+
+        r = getenv_bool("SYSTEMD_JOURNAL_COMPACT");
+        if (r >= 0)
+                return r;
+        if (r != -ENXIO)
+                log_debug_errno(r, "Failed to parse $SYSTEMD_JOURNAL_COMPACT environment variable, ignoring: %m");
+
+        return true;
+}
+
+static int journal_file_init_header(JournalFile *f, JournalFileFlags file_flags, JournalFile *template) {
+        Header h = {};
+        ssize_t k;
+        bool seal = false;
+        int r;
+
+        assert(f);
+
+#if HAVE_GCRYPT
+        /* Try to load the FSPRG state, and if we can't, then just don't do sealing */
+        seal = FLAGS_SET(file_flags, JOURNAL_SEAL) && journal_file_fss_load(f) >= 0;
+#endif
+
+        memcpy(h.signature, HEADER_SIGNATURE, 8);
+        h.header_size = htole64(ALIGN64(sizeof(h)));
+
+        h.incompatible_flags |= htole32(
+                        FLAGS_SET(file_flags, JOURNAL_COMPRESS) *
+                        COMPRESSION_TO_HEADER_INCOMPATIBLE_FLAG(DEFAULT_COMPRESSION) |
+                        keyed_hash_requested() * HEADER_INCOMPATIBLE_KEYED_HASH |
+                        compact_mode_requested() * HEADER_INCOMPATIBLE_COMPACT);
+
+        h.compatible_flags = htole32(seal * HEADER_COMPATIBLE_SEALED);
+
+        r = sd_id128_randomize(&h.file_id);
+        if (r < 0)
+                return r;
+
+        if (template) {
+                h.seqnum_id = template->header->seqnum_id;
+                h.tail_entry_seqnum = template->header->tail_entry_seqnum;
+        } else
+                h.seqnum_id = h.file_id;
+
+        k = pwrite(f->fd, &h, sizeof(h), 0);
+        if (k < 0)
+                return -errno;
+
+        if (k != sizeof(h))
+                return -EIO;
+
+        return 0;
+}
+
+static int journal_file_refresh_header(JournalFile *f) {
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        r = sd_id128_get_machine(&f->header->machine_id);
+        if (IN_SET(r, -ENOENT, -ENOMEDIUM, -ENOPKG))
+                /* We don't have a machine-id, let's continue without */
+                zero(f->header->machine_id);
+        else if (r < 0)
+                return r;
+
+        r = sd_id128_get_boot(&f->header->boot_id);
+        if (r < 0)
+                return r;
+
+        r = journal_file_set_online(f);
+
+        /* Sync the online state to disk; likely just created a new file, also sync the directory this file
+         * is located in. */
+        (void) fsync_full(f->fd);
+
+        return r;
+}
+
+static bool warn_wrong_flags(const JournalFile *f, bool compatible) {
+        const uint32_t any = compatible ? HEADER_COMPATIBLE_ANY : HEADER_INCOMPATIBLE_ANY,
+                supported = compatible ? HEADER_COMPATIBLE_SUPPORTED : HEADER_INCOMPATIBLE_SUPPORTED;
+        const char *type = compatible ? "compatible" : "incompatible";
+        uint32_t flags;
+
+        assert(f);
+        assert(f->header);
+
+        flags = le32toh(compatible ? f->header->compatible_flags : f->header->incompatible_flags);
+
+        if (flags & ~supported) {
+                if (flags & ~any)
+                        log_debug("Journal file %s has unknown %s flags 0x%"PRIx32,
+                                  f->path, type, flags & ~any);
+                flags = (flags & any) & ~supported;
+                if (flags) {
+                        const char* strv[6];
+                        size_t n = 0;
+                        _cleanup_free_ char *t = NULL;
+
+                        if (compatible) {
+                                if (flags & HEADER_COMPATIBLE_SEALED)
+                                        strv[n++] = "sealed";
+                        } else {
+                                if (flags & HEADER_INCOMPATIBLE_COMPRESSED_XZ)
+                                        strv[n++] = "xz-compressed";
+                                if (flags & HEADER_INCOMPATIBLE_COMPRESSED_LZ4)
+                                        strv[n++] = "lz4-compressed";
+                                if (flags & HEADER_INCOMPATIBLE_COMPRESSED_ZSTD)
+                                        strv[n++] = "zstd-compressed";
+                                if (flags & HEADER_INCOMPATIBLE_KEYED_HASH)
+                                        strv[n++] = "keyed-hash";
+                                if (flags & HEADER_INCOMPATIBLE_COMPACT)
+                                        strv[n++] = "compact";
+                        }
+                        strv[n] = NULL;
+                        assert(n < ELEMENTSOF(strv));
+
+                        t = strv_join((char**) strv, ", ");
+                        log_debug("Journal file %s uses %s %s %s disabled at compilation time.",
+                                  f->path, type, n > 1 ? "flags" : "flag", strnull(t));
+                }
+                return true;
+        }
+
+        return false;
+}
+
+static int journal_file_verify_header(JournalFile *f) {
+        uint64_t arena_size, header_size;
+
+        assert(f);
+        assert(f->header);
+
+        if (memcmp(f->header->signature, HEADER_SIGNATURE, 8))
+                return -EBADMSG;
+
+        /* In both read and write mode we refuse to open files with incompatible
+         * flags we don't know. */
+        if (warn_wrong_flags(f, false))
+                return -EPROTONOSUPPORT;
+
+        /* When open for writing we refuse to open files with compatible flags, too. */
+        if (journal_file_writable(f) && warn_wrong_flags(f, true))
+                return -EPROTONOSUPPORT;
+
+        if (f->header->state >= _STATE_MAX)
+                return -EBADMSG;
+
+        header_size = le64toh(READ_NOW(f->header->header_size));
+
+        /* The first addition was n_data, so check that we are at least this large */
+        if (header_size < HEADER_SIZE_MIN)
+                return -EBADMSG;
+
+        if (JOURNAL_HEADER_SEALED(f->header) && !JOURNAL_HEADER_CONTAINS(f->header, n_entry_arrays))
+                return -EBADMSG;
+
+        arena_size = le64toh(READ_NOW(f->header->arena_size));
+
+        if (UINT64_MAX - header_size < arena_size || header_size + arena_size > (uint64_t) f->last_stat.st_size)
+                return -ENODATA;
+
+        if (le64toh(f->header->tail_object_offset) > header_size + arena_size)
+                return -ENODATA;
+
+        if (!VALID64(le64toh(f->header->data_hash_table_offset)) ||
+            !VALID64(le64toh(f->header->field_hash_table_offset)) ||
+            !VALID64(le64toh(f->header->tail_object_offset)) ||
+            !VALID64(le64toh(f->header->entry_array_offset)))
+                return -ENODATA;
+
+        if (journal_file_writable(f)) {
+                sd_id128_t machine_id;
+                uint8_t state;
+                int r;
+
+                r = sd_id128_get_machine(&machine_id);
+                if (r < 0)
+                        return r;
+
+                if (!sd_id128_equal(machine_id, f->header->machine_id))
+                        return -EHOSTDOWN;
+
+                state = f->header->state;
+
+                if (state == STATE_ARCHIVED)
+                        return -ESHUTDOWN; /* Already archived */
+                else if (state == STATE_ONLINE)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBUSY),
+                                               "Journal file %s is already online. Assuming unclean closing.",
+                                               f->path);
+                else if (state != STATE_OFFLINE)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBUSY),
+                                               "Journal file %s has unknown state %i.",
+                                               f->path, state);
+
+                if (f->header->field_hash_table_size == 0 || f->header->data_hash_table_size == 0)
+                        return -EBADMSG;
+
+                /* Don't permit appending to files from the future. Because otherwise the realtime timestamps wouldn't
+                 * be strictly ordered in the entries in the file anymore, and we can't have that since it breaks
+                 * bisection. */
+                if (le64toh(f->header->tail_entry_realtime) > now(CLOCK_REALTIME))
+                        return log_debug_errno(SYNTHETIC_ERRNO(ETXTBSY),
+                                               "Journal file %s is from the future, refusing to append new data to it that'd be older.",
+                                               f->path);
+        }
+
+        return 0;
+}
+
+int journal_file_fstat(JournalFile *f) {
+        int r;
+
+        assert(f);
+        assert(f->fd >= 0);
+
+        if (fstat(f->fd, &f->last_stat) < 0)
+                return -errno;
+
+        f->last_stat_usec = now(CLOCK_MONOTONIC);
+
+        /* Refuse dealing with files that aren't regular */
+        r = stat_verify_regular(&f->last_stat);
+        if (r < 0)
+                return r;
+
+        /* Refuse appending to files that are already deleted */
+        if (f->last_stat.st_nlink <= 0)
+                return -EIDRM;
+
+        return 0;
+}
+
+static int journal_file_allocate(JournalFile *f, uint64_t offset, uint64_t size) {
+        uint64_t old_size, new_size, old_header_size, old_arena_size;
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        /* We assume that this file is not sparse, and we know that for sure, since we always call
+         * posix_fallocate() ourselves */
+
+        if (size > PAGE_ALIGN_DOWN(UINT64_MAX) - offset)
+                return -EINVAL;
+
+        if (mmap_cache_fd_got_sigbus(f->cache_fd))
+                return -EIO;
+
+        old_header_size = le64toh(READ_NOW(f->header->header_size));
+        old_arena_size = le64toh(READ_NOW(f->header->arena_size));
+        if (old_arena_size > PAGE_ALIGN_DOWN(UINT64_MAX) - old_header_size)
+                return -EBADMSG;
+
+        old_size = old_header_size + old_arena_size;
+
+        new_size = MAX(PAGE_ALIGN(offset + size), old_header_size);
+
+        if (new_size <= old_size) {
+
+                /* We already pre-allocated enough space, but before
+                 * we write to it, let's check with fstat() if the
+                 * file got deleted, in order make sure we don't throw
+                 * away the data immediately. Don't check fstat() for
+                 * all writes though, but only once ever 10s. */
+
+                if (f->last_stat_usec + LAST_STAT_REFRESH_USEC > now(CLOCK_MONOTONIC))
+                        return 0;
+
+                return journal_file_fstat(f);
+        }
+
+        /* Allocate more space. */
+
+        if (f->metrics.max_size > 0 && new_size > f->metrics.max_size)
+                return -E2BIG;
+
+        /* Refuse to go over 4G in compact mode so offsets can be stored in 32-bit. */
+        if (JOURNAL_HEADER_COMPACT(f->header) && new_size > UINT32_MAX)
+                return -E2BIG;
+
+        if (new_size > f->metrics.min_size && f->metrics.keep_free > 0) {
+                struct statvfs svfs;
+
+                if (fstatvfs(f->fd, &svfs) >= 0) {
+                        uint64_t available;
+
+                        available = LESS_BY((uint64_t) svfs.f_bfree * (uint64_t) svfs.f_bsize, f->metrics.keep_free);
+
+                        if (new_size - old_size > available)
+                                return -E2BIG;
+                }
+        }
+
+        /* Increase by larger blocks at once */
+        new_size = DIV_ROUND_UP(new_size, FILE_SIZE_INCREASE) * FILE_SIZE_INCREASE;
+        if (f->metrics.max_size > 0 && new_size > f->metrics.max_size)
+                new_size = f->metrics.max_size;
+
+        /* Note that the glibc fallocate() fallback is very
+           inefficient, hence we try to minimize the allocation area
+           as we can. */
+        r = posix_fallocate_loop(f->fd, old_size, new_size - old_size);
+        if (r < 0)
+                return r;
+
+        f->header->arena_size = htole64(new_size - old_header_size);
+
+        return journal_file_fstat(f);
+}
+
+static unsigned type_to_context(ObjectType type) {
+        /* One context for each type, plus one catch-all for the rest */
+        assert_cc(_OBJECT_TYPE_MAX <= MMAP_CACHE_MAX_CONTEXTS);
+        assert_cc(CONTEXT_HEADER < MMAP_CACHE_MAX_CONTEXTS);
+        return type > OBJECT_UNUSED && type < _OBJECT_TYPE_MAX ? type : 0;
+}
+
+static int journal_file_move_to(
+                JournalFile *f,
+                ObjectType type,
+                bool keep_always,
+                uint64_t offset,
+                uint64_t size,
+                void **ret) {
+
+        int r;
+
+        assert(f);
+        assert(ret);
+
+        /* This function may clear, overwrite, or alter previously cached entries. After this function has
+         * been called, all objects except for one obtained by this function are invalidated and must be
+         * re-read before use. */
+
+        if (size <= 0)
+                return -EINVAL;
+
+        if (size > UINT64_MAX - offset)
+                return -EBADMSG;
+
+        /* Avoid SIGBUS on invalid accesses */
+        if (offset + size > (uint64_t) f->last_stat.st_size) {
+                /* Hmm, out of range? Let's refresh the fstat() data
+                 * first, before we trust that check. */
+
+                r = journal_file_fstat(f);
+                if (r < 0)
+                        return r;
+
+                if (offset + size > (uint64_t) f->last_stat.st_size)
+                        return -EADDRNOTAVAIL;
+        }
+
+        return mmap_cache_fd_get(f->cache_fd, type_to_context(type), keep_always, offset, size, &f->last_stat, ret);
+}
+
+static uint64_t minimum_header_size(JournalFile *f, Object *o) {
+
+        static const uint64_t table[] = {
+                [OBJECT_DATA]             = sizeof(DataObject),
+                [OBJECT_FIELD]            = sizeof(FieldObject),
+                [OBJECT_ENTRY]            = sizeof(EntryObject),
+                [OBJECT_DATA_HASH_TABLE]  = sizeof(HashTableObject),
+                [OBJECT_FIELD_HASH_TABLE] = sizeof(HashTableObject),
+                [OBJECT_ENTRY_ARRAY]      = sizeof(EntryArrayObject),
+                [OBJECT_TAG]              = sizeof(TagObject),
+        };
+
+        assert(f);
+        assert(o);
+
+        if (o->object.type == OBJECT_DATA)
+                return journal_file_data_payload_offset(f);
+
+        if (o->object.type >= ELEMENTSOF(table) || table[o->object.type] <= 0)
+                return sizeof(ObjectHeader);
+
+        return table[o->object.type];
+}
+
+static int check_object_header(JournalFile *f, Object *o, ObjectType type, uint64_t offset) {
+        uint64_t s;
+
+        assert(f);
+        assert(o);
+
+        s = le64toh(READ_NOW(o->object.size));
+        if (s == 0)
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to move to uninitialized object: %" PRIu64,
+                                       offset);
+
+        if (s < sizeof(ObjectHeader))
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to move to overly short object: %" PRIu64,
+                                       offset);
+
+        if (o->object.type <= OBJECT_UNUSED)
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to move to object with invalid type: %" PRIu64,
+                                       offset);
+
+        if (type > OBJECT_UNUSED && o->object.type != type)
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to move to object of unexpected type: %" PRIu64,
+                                       offset);
+
+        if (s < minimum_header_size(f, o))
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to move to truncated object: %" PRIu64,
+                                       offset);
+
+        return 0;
+}
+
+/* Lightweight object checks. We want this to be fast, so that we won't
+ * slowdown every journal_file_move_to_object() call too much. */
+static int check_object(JournalFile *f, Object *o, uint64_t offset) {
+        assert(f);
+        assert(o);
+
+        switch (o->object.type) {
+
+        case OBJECT_DATA:
+                if ((le64toh(o->data.entry_offset) == 0) ^ (le64toh(o->data.n_entries) == 0))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Bad n_entries: %" PRIu64 ": %" PRIu64,
+                                               le64toh(o->data.n_entries),
+                                               offset);
+
+                if (le64toh(o->object.size) <= journal_file_data_payload_offset(f))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Bad object size (<= %zu): %" PRIu64 ": %" PRIu64,
+                                               journal_file_data_payload_offset(f),
+                                               le64toh(o->object.size),
+                                               offset);
+
+                if (!VALID64(le64toh(o->data.next_hash_offset)) ||
+                    !VALID64(le64toh(o->data.next_field_offset)) ||
+                    !VALID64(le64toh(o->data.entry_offset)) ||
+                    !VALID64(le64toh(o->data.entry_array_offset)))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid offset, next_hash_offset=" OFSfmt ", next_field_offset=" OFSfmt ", entry_offset=" OFSfmt ", entry_array_offset=" OFSfmt ": %" PRIu64,
+                                               le64toh(o->data.next_hash_offset),
+                                               le64toh(o->data.next_field_offset),
+                                               le64toh(o->data.entry_offset),
+                                               le64toh(o->data.entry_array_offset),
+                                               offset);
+
+                break;
+
+        case OBJECT_FIELD:
+                if (le64toh(o->object.size) <= offsetof(Object, field.payload))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Bad field size (<= %zu): %" PRIu64 ": %" PRIu64,
+                                               offsetof(Object, field.payload),
+                                               le64toh(o->object.size),
+                                               offset);
+
+                if (!VALID64(le64toh(o->field.next_hash_offset)) ||
+                    !VALID64(le64toh(o->field.head_data_offset)))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid offset, next_hash_offset=" OFSfmt ", head_data_offset=" OFSfmt ": %" PRIu64,
+                                               le64toh(o->field.next_hash_offset),
+                                               le64toh(o->field.head_data_offset),
+                                               offset);
+                break;
+
+        case OBJECT_ENTRY: {
+                uint64_t sz;
+
+                sz = le64toh(READ_NOW(o->object.size));
+                if (sz < offsetof(Object, entry.items) ||
+                    (sz - offsetof(Object, entry.items)) % journal_file_entry_item_size(f) != 0)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Bad entry size (<= %zu): %" PRIu64 ": %" PRIu64,
+                                               offsetof(Object, entry.items),
+                                               sz,
+                                               offset);
+
+                if ((sz - offsetof(Object, entry.items)) / journal_file_entry_item_size(f) <= 0)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid number items in entry: %" PRIu64 ": %" PRIu64,
+                                               (sz - offsetof(Object, entry.items)) / journal_file_entry_item_size(f),
+                                               offset);
+
+                if (le64toh(o->entry.seqnum) <= 0)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid entry seqnum: %" PRIx64 ": %" PRIu64,
+                                               le64toh(o->entry.seqnum),
+                                               offset);
+
+                if (!VALID_REALTIME(le64toh(o->entry.realtime)))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid entry realtime timestamp: %" PRIu64 ": %" PRIu64,
+                                               le64toh(o->entry.realtime),
+                                               offset);
+
+                if (!VALID_MONOTONIC(le64toh(o->entry.monotonic)))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid entry monotonic timestamp: %" PRIu64 ": %" PRIu64,
+                                               le64toh(o->entry.monotonic),
+                                               offset);
+
+                break;
+        }
+
+        case OBJECT_DATA_HASH_TABLE:
+        case OBJECT_FIELD_HASH_TABLE: {
+                uint64_t sz;
+
+                sz = le64toh(READ_NOW(o->object.size));
+                if (sz < offsetof(Object, hash_table.items) ||
+                    (sz - offsetof(Object, hash_table.items)) % sizeof(HashItem) != 0 ||
+                    (sz - offsetof(Object, hash_table.items)) / sizeof(HashItem) <= 0)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid %s hash table size: %" PRIu64 ": %" PRIu64,
+                                               o->object.type == OBJECT_DATA_HASH_TABLE ? "data" : "field",
+                                               sz,
+                                               offset);
+
+                break;
+        }
+
+        case OBJECT_ENTRY_ARRAY: {
+                uint64_t sz, next;
+
+                sz = le64toh(READ_NOW(o->object.size));
+                if (sz < offsetof(Object, entry_array.items) ||
+                    (sz - offsetof(Object, entry_array.items)) % journal_file_entry_array_item_size(f) != 0 ||
+                    (sz - offsetof(Object, entry_array.items)) / journal_file_entry_array_item_size(f) <= 0)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid object entry array size: %" PRIu64 ": %" PRIu64,
+                                               sz,
+                                               offset);
+                /* Here, we request that the offset of each entry array object is in strictly increasing order. */
+                next = le64toh(o->entry_array.next_entry_array_offset);
+                if (!VALID64(next) || (next > 0 && next <= offset))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid object entry array next_entry_array_offset: %" PRIu64 ": %" PRIu64,
+                                               next,
+                                               offset);
+
+                break;
+        }
+
+        case OBJECT_TAG:
+                if (le64toh(o->object.size) != sizeof(TagObject))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid object tag size: %" PRIu64 ": %" PRIu64,
+                                               le64toh(o->object.size),
+                                               offset);
+
+                if (!VALID_EPOCH(le64toh(o->tag.epoch)))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid object tag epoch: %" PRIu64 ": %" PRIu64,
+                                               le64toh(o->tag.epoch), offset);
+
+                break;
+        }
+
+        return 0;
+}
+
+int journal_file_move_to_object(JournalFile *f, ObjectType type, uint64_t offset, Object **ret) {
+        int r;
+        Object *o;
+
+        assert(f);
+
+        /* Even if this function fails, it may clear, overwrite, or alter previously cached entries. After
+         * this function has been called, all objects except for one obtained by this function are
+         * invalidated and must be re-read before use.. */
+
+        /* Objects may only be located at multiple of 64 bit */
+        if (!VALID64(offset))
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to move to object at non-64bit boundary: %" PRIu64,
+                                       offset);
+
+        /* Object may not be located in the file header */
+        if (offset < le64toh(f->header->header_size))
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to move to object located in file header: %" PRIu64,
+                                       offset);
+
+        r = journal_file_move_to(f, type, false, offset, sizeof(ObjectHeader), (void**) &o);
+        if (r < 0)
+                return r;
+
+        r = check_object_header(f, o, type, offset);
+        if (r < 0)
+                return r;
+
+        r = journal_file_move_to(f, type, false, offset, le64toh(READ_NOW(o->object.size)), (void**) &o);
+        if (r < 0)
+                return r;
+
+        r = check_object_header(f, o, type, offset);
+        if (r < 0)
+                return r;
+
+        r = check_object(f, o, offset);
+        if (r < 0)
+                return r;
+
+        if (ret)
+                *ret = o;
+
+        return 0;
+}
+
+int journal_file_read_object_header(JournalFile *f, ObjectType type, uint64_t offset, Object *ret) {
+        ssize_t n;
+        Object o;
+        int r;
+
+        assert(f);
+
+        /* Objects may only be located at multiple of 64 bit */
+        if (!VALID64(offset))
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to read object at non-64bit boundary: %" PRIu64,
+                                       offset);
+
+        /* Object may not be located in the file header */
+        if (offset < le64toh(f->header->header_size))
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "Attempt to read object located in file header: %" PRIu64,
+                                       offset);
+
+        /* This will likely read too much data but it avoids having to call pread() twice. */
+        n = pread(f->fd, &o, sizeof(o), offset);
+        if (n < 0)
+                return log_debug_errno(errno, "Failed to read journal file at offset: %" PRIu64,
+                                       offset);
+
+        if ((size_t) n < sizeof(o.object))
+                return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Failed to read short object at offset: %" PRIu64,
+                                       offset);
+
+        r = check_object_header(f, &o, type, offset);
+        if (r < 0)
+                return r;
+
+        if ((size_t) n < minimum_header_size(f, &o))
+                return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+                                       "Short read while reading object: %" PRIu64,
+                                       offset);
+
+        r = check_object(f, &o, offset);
+        if (r < 0)
+                return r;
+
+        if (ret)
+                *ret = o;
+
+        return 0;
+}
+
+static uint64_t journal_file_entry_seqnum(
+                JournalFile *f,
+                uint64_t *seqnum) {
+
+        uint64_t ret;
+
+        assert(f);
+        assert(f->header);
+
+        /* Picks a new sequence number for the entry we are about to add and returns it. */
+
+        ret = le64toh(f->header->tail_entry_seqnum) + 1;
+
+        if (seqnum) {
+                /* If an external seqnum counter was passed, we update both the local and the external one,
+                 * and set it to the maximum of both */
+
+                if (*seqnum + 1 > ret)
+                        ret = *seqnum + 1;
+
+                *seqnum = ret;
+        }
+
+        f->header->tail_entry_seqnum = htole64(ret);
+
+        if (f->header->head_entry_seqnum == 0)
+                f->header->head_entry_seqnum = htole64(ret);
+
+        return ret;
+}
+
+int journal_file_append_object(
+                JournalFile *f,
+                ObjectType type,
+                uint64_t size,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        int r;
+        uint64_t p;
+        Object *o;
+
+        assert(f);
+        assert(f->header);
+        assert(type > OBJECT_UNUSED && type < _OBJECT_TYPE_MAX);
+        assert(size >= sizeof(ObjectHeader));
+
+        r = journal_file_set_online(f);
+        if (r < 0)
+                return r;
+
+        r = journal_file_tail_end_by_mmap(f, &p);
+        if (r < 0)
+                return r;
+
+        r = journal_file_allocate(f, p, size);
+        if (r < 0)
+                return r;
+
+        r = journal_file_move_to(f, type, false, p, size, (void**) &o);
+        if (r < 0)
+                return r;
+
+        o->object = (ObjectHeader) {
+                .type = type,
+                .size = htole64(size),
+        };
+
+        f->header->tail_object_offset = htole64(p);
+        f->header->n_objects = htole64(le64toh(f->header->n_objects) + 1);
+
+        if (ret_object)
+                *ret_object = o;
+
+        if (ret_offset)
+                *ret_offset = p;
+
+        return 0;
+}
+
+static int journal_file_setup_data_hash_table(JournalFile *f) {
+        uint64_t s, p;
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        /* We estimate that we need 1 hash table entry per 768 bytes
+           of journal file and we want to make sure we never get
+           beyond 75% fill level. Calculate the hash table size for
+           the maximum file size based on these metrics. */
+
+        s = (f->metrics.max_size * 4 / 768 / 3) * sizeof(HashItem);
+        if (s < DEFAULT_DATA_HASH_TABLE_SIZE)
+                s = DEFAULT_DATA_HASH_TABLE_SIZE;
+
+        log_debug("Reserving %"PRIu64" entries in data hash table.", s / sizeof(HashItem));
+
+        r = journal_file_append_object(f,
+                                       OBJECT_DATA_HASH_TABLE,
+                                       offsetof(Object, hash_table.items) + s,
+                                       &o, &p);
+        if (r < 0)
+                return r;
+
+        memzero(o->hash_table.items, s);
+
+        f->header->data_hash_table_offset = htole64(p + offsetof(Object, hash_table.items));
+        f->header->data_hash_table_size = htole64(s);
+
+        return 0;
+}
+
+static int journal_file_setup_field_hash_table(JournalFile *f) {
+        uint64_t s, p;
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        /* We use a fixed size hash table for the fields as this
+         * number should grow very slowly only */
+
+        s = DEFAULT_FIELD_HASH_TABLE_SIZE;
+        log_debug("Reserving %"PRIu64" entries in field hash table.", s / sizeof(HashItem));
+
+        r = journal_file_append_object(f,
+                                       OBJECT_FIELD_HASH_TABLE,
+                                       offsetof(Object, hash_table.items) + s,
+                                       &o, &p);
+        if (r < 0)
+                return r;
+
+        memzero(o->hash_table.items, s);
+
+        f->header->field_hash_table_offset = htole64(p + offsetof(Object, hash_table.items));
+        f->header->field_hash_table_size = htole64(s);
+
+        return 0;
+}
+
+int journal_file_map_data_hash_table(JournalFile *f) {
+        uint64_t s, p;
+        void *t;
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        if (f->data_hash_table)
+                return 0;
+
+        p = le64toh(f->header->data_hash_table_offset);
+        s = le64toh(f->header->data_hash_table_size);
+
+        r = journal_file_move_to(f,
+                                 OBJECT_DATA_HASH_TABLE,
+                                 true,
+                                 p, s,
+                                 &t);
+        if (r < 0)
+                return r;
+
+        f->data_hash_table = t;
+        return 0;
+}
+
+int journal_file_map_field_hash_table(JournalFile *f) {
+        uint64_t s, p;
+        void *t;
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        if (f->field_hash_table)
+                return 0;
+
+        p = le64toh(f->header->field_hash_table_offset);
+        s = le64toh(f->header->field_hash_table_size);
+
+        r = journal_file_move_to(f,
+                                 OBJECT_FIELD_HASH_TABLE,
+                                 true,
+                                 p, s,
+                                 &t);
+        if (r < 0)
+                return r;
+
+        f->field_hash_table = t;
+        return 0;
+}
+
+static int journal_file_link_field(
+                JournalFile *f,
+                Object *o,
+                uint64_t offset,
+                uint64_t hash) {
+
+        uint64_t p, h, m;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(f->field_hash_table);
+        assert(o);
+        assert(offset > 0);
+
+        if (o->object.type != OBJECT_FIELD)
+                return -EINVAL;
+
+        m = le64toh(READ_NOW(f->header->field_hash_table_size)) / sizeof(HashItem);
+        if (m <= 0)
+                return -EBADMSG;
+
+        /* This might alter the window we are looking at */
+        o->field.next_hash_offset = o->field.head_data_offset = 0;
+
+        h = hash % m;
+        p = le64toh(f->field_hash_table[h].tail_hash_offset);
+        if (p == 0)
+                f->field_hash_table[h].head_hash_offset = htole64(offset);
+        else {
+                r = journal_file_move_to_object(f, OBJECT_FIELD, p, &o);
+                if (r < 0)
+                        return r;
+
+                o->field.next_hash_offset = htole64(offset);
+        }
+
+        f->field_hash_table[h].tail_hash_offset = htole64(offset);
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_fields))
+                f->header->n_fields = htole64(le64toh(f->header->n_fields) + 1);
+
+        return 0;
+}
+
+static int journal_file_link_data(
+                JournalFile *f,
+                Object *o,
+                uint64_t offset,
+                uint64_t hash) {
+
+        uint64_t p, h, m;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(f->data_hash_table);
+        assert(o);
+        assert(offset > 0);
+
+        if (o->object.type != OBJECT_DATA)
+                return -EINVAL;
+
+        m = le64toh(READ_NOW(f->header->data_hash_table_size)) / sizeof(HashItem);
+        if (m <= 0)
+                return -EBADMSG;
+
+        /* This might alter the window we are looking at */
+        o->data.next_hash_offset = o->data.next_field_offset = 0;
+        o->data.entry_offset = o->data.entry_array_offset = 0;
+        o->data.n_entries = 0;
+
+        h = hash % m;
+        p = le64toh(f->data_hash_table[h].tail_hash_offset);
+        if (p == 0)
+                /* Only entry in the hash table is easy */
+                f->data_hash_table[h].head_hash_offset = htole64(offset);
+        else {
+                /* Move back to the previous data object, to patch in
+                 * pointer */
+
+                r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
+                if (r < 0)
+                        return r;
+
+                o->data.next_hash_offset = htole64(offset);
+        }
+
+        f->data_hash_table[h].tail_hash_offset = htole64(offset);
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_data))
+                f->header->n_data = htole64(le64toh(f->header->n_data) + 1);
+
+        return 0;
+}
+
+static int get_next_hash_offset(
+                JournalFile *f,
+                uint64_t *p,
+                le64_t *next_hash_offset,
+                uint64_t *depth,
+                le64_t *header_max_depth) {
+
+        uint64_t nextp;
+
+        assert(f);
+        assert(p);
+        assert(next_hash_offset);
+        assert(depth);
+
+        nextp = le64toh(READ_NOW(*next_hash_offset));
+        if (nextp > 0) {
+                if (nextp <= *p) /* Refuse going in loops */
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Detected hash item loop in %s, refusing.", f->path);
+
+                (*depth)++;
+
+                /* If the depth of this hash chain is larger than all others we have seen so far, record it */
+                if (header_max_depth && journal_file_writable(f))
+                        *header_max_depth = htole64(MAX(*depth, le64toh(*header_max_depth)));
+        }
+
+        *p = nextp;
+        return 0;
+}
+
+int journal_file_find_field_object_with_hash(
+                JournalFile *f,
+                const void *field,
+                uint64_t size,
+                uint64_t hash,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t p, osize, h, m, depth = 0;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(field);
+        assert(size > 0);
+
+        /* If the field hash table is empty, we can't find anything */
+        if (le64toh(f->header->field_hash_table_size) <= 0)
+                return 0;
+
+        /* Map the field hash table, if it isn't mapped yet. */
+        r = journal_file_map_field_hash_table(f);
+        if (r < 0)
+                return r;
+
+        osize = offsetof(Object, field.payload) + size;
+
+        m = le64toh(READ_NOW(f->header->field_hash_table_size)) / sizeof(HashItem);
+        if (m <= 0)
+                return -EBADMSG;
+
+        h = hash % m;
+        p = le64toh(f->field_hash_table[h].head_hash_offset);
+        while (p > 0) {
+                Object *o;
+
+                r = journal_file_move_to_object(f, OBJECT_FIELD, p, &o);
+                if (r < 0)
+                        return r;
+
+                if (le64toh(o->field.hash) == hash &&
+                    le64toh(o->object.size) == osize &&
+                    memcmp(o->field.payload, field, size) == 0) {
+
+                        if (ret_object)
+                                *ret_object = o;
+                        if (ret_offset)
+                                *ret_offset = p;
+
+                        return 1;
+                }
+
+                r = get_next_hash_offset(
+                                f,
+                                &p,
+                                &o->field.next_hash_offset,
+                                &depth,
+                                JOURNAL_HEADER_CONTAINS(f->header, field_hash_chain_depth) ? &f->header->field_hash_chain_depth : NULL);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+uint64_t journal_file_hash_data(
+                JournalFile *f,
+                const void *data,
+                size_t sz) {
+
+        assert(f);
+        assert(f->header);
+        assert(data || sz == 0);
+
+        /* We try to unify our codebase on siphash, hence new-styled journal files utilizing the keyed hash
+         * function use siphash. Old journal files use the Jenkins hash. */
+
+        if (JOURNAL_HEADER_KEYED_HASH(f->header))
+                return siphash24(data, sz, f->header->file_id.bytes);
+
+        return jenkins_hash64(data, sz);
+}
+
+int journal_file_find_field_object(
+                JournalFile *f,
+                const void *field,
+                uint64_t size,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        assert(f);
+        assert(field);
+        assert(size > 0);
+
+        return journal_file_find_field_object_with_hash(
+                        f,
+                        field, size,
+                        journal_file_hash_data(f, field, size),
+                        ret_object, ret_offset);
+}
+
+int journal_file_find_data_object_with_hash(
+                JournalFile *f,
+                const void *data,
+                uint64_t size,
+                uint64_t hash,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t p, h, m, depth = 0;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(data || size == 0);
+
+        /* If there's no data hash table, then there's no entry. */
+        if (le64toh(f->header->data_hash_table_size) <= 0)
+                return 0;
+
+        /* Map the data hash table, if it isn't mapped yet. */
+        r = journal_file_map_data_hash_table(f);
+        if (r < 0)
+                return r;
+
+        m = le64toh(READ_NOW(f->header->data_hash_table_size)) / sizeof(HashItem);
+        if (m <= 0)
+                return -EBADMSG;
+
+        h = hash % m;
+        p = le64toh(f->data_hash_table[h].head_hash_offset);
+
+        while (p > 0) {
+                Object *o;
+                void *d;
+                size_t rsize;
+
+                r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
+                if (r < 0)
+                        return r;
+
+                if (le64toh(o->data.hash) != hash)
+                        goto next;
+
+                r = journal_file_data_payload(f, o, p, NULL, 0, 0, &d, &rsize);
+                if (r < 0)
+                        return r;
+                assert(r > 0); /* journal_file_data_payload() always returns > 0 if no field is provided. */
+
+                if (memcmp_nn(data, size, d, rsize) == 0) {
+                         if (ret_object)
+                                *ret_object = o;
+
+                        if (ret_offset)
+                                *ret_offset = p;
+
+                        return 1;
+                }
+
+        next:
+                r = get_next_hash_offset(
+                                f,
+                                &p,
+                                &o->data.next_hash_offset,
+                                &depth,
+                                JOURNAL_HEADER_CONTAINS(f->header, data_hash_chain_depth) ? &f->header->data_hash_chain_depth : NULL);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+int journal_file_find_data_object(
+                JournalFile *f,
+                const void *data,
+                uint64_t size,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        assert(f);
+        assert(data || size == 0);
+
+        return journal_file_find_data_object_with_hash(
+                        f,
+                        data, size,
+                        journal_file_hash_data(f, data, size),
+                        ret_object, ret_offset);
+}
+
+bool journal_field_valid(const char *p, size_t l, bool allow_protected) {
+        /* We kinda enforce POSIX syntax recommendations for
+           environment variables here, but make a couple of additional
+           requirements.
+
+           http://pubs.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap08.html */
+
+        assert(p);
+
+        if (l == SIZE_MAX)
+                l = strlen(p);
+
+        /* No empty field names */
+        if (l <= 0)
+                return false;
+
+        /* Don't allow names longer than 64 chars */
+        if (l > 64)
+                return false;
+
+        /* Variables starting with an underscore are protected */
+        if (!allow_protected && p[0] == '_')
+                return false;
+
+        /* Don't allow digits as first character */
+        if (ascii_isdigit(p[0]))
+                return false;
+
+        /* Only allow A-Z0-9 and '_' */
+        for (const char *a = p; a < p + l; a++)
+                if ((*a < 'A' || *a > 'Z') &&
+                    !ascii_isdigit(*a) &&
+                    *a != '_')
+                        return false;
+
+        return true;
+}
+
+static int journal_file_append_field(
+                JournalFile *f,
+                const void *field,
+                uint64_t size,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t hash, p;
+        uint64_t osize;
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(field);
+        assert(size > 0);
+
+        if (!journal_field_valid(field, size, true))
+                return -EBADMSG;
+
+        hash = journal_file_hash_data(f, field, size);
+
+        r = journal_file_find_field_object_with_hash(f, field, size, hash, ret_object, ret_offset);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                return 0;
+
+        osize = offsetof(Object, field.payload) + size;
+        r = journal_file_append_object(f, OBJECT_FIELD, osize, &o, &p);
+        if (r < 0)
+                return r;
+
+        o->field.hash = htole64(hash);
+        memcpy(o->field.payload, field, size);
+
+        r = journal_file_link_field(f, o, p, hash);
+        if (r < 0)
+                return r;
+
+        /* The linking might have altered the window, so let's only pass the offset to hmac which will
+         * move to the object again if needed. */
+
+#if HAVE_GCRYPT
+        r = journal_file_hmac_put_object(f, OBJECT_FIELD, NULL, p);
+        if (r < 0)
+                return r;
+#endif
+
+        if (ret_object) {
+                r = journal_file_move_to_object(f, OBJECT_FIELD, p, ret_object);
+                if (r < 0)
+                        return r;
+        }
+
+        if (ret_offset)
+                *ret_offset = p;
+
+        return 0;
+}
+
+static Compression maybe_compress_payload(JournalFile *f, uint8_t *dst, const uint8_t *src, uint64_t size, size_t *rsize) {
+        Compression compression = COMPRESSION_NONE;
+
+        assert(f);
+        assert(f->header);
+
+#if HAVE_COMPRESSION
+        if (JOURNAL_FILE_COMPRESS(f) && size >= f->compress_threshold_bytes) {
+                compression = compress_blob(src, size, dst, size - 1, rsize);
+                if (compression > 0)
+                        log_debug("Compressed data object %"PRIu64" -> %zu using %s",
+                                  size, *rsize, compression_to_string(compression));
+                else
+                        /* Compression didn't work, we don't really care why, let's continue without compression */
+                        compression = COMPRESSION_NONE;
+        }
+#endif
+
+        return compression;
+}
+
+static int journal_file_append_data(
+                JournalFile *f,
+                const void *data,
+                uint64_t size,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t hash, p, osize;
+        Object *o, *fo;
+        size_t rsize = 0;
+        Compression c;
+        const void *eq;
+        int r;
+
+        assert(f);
+
+        if (!data || size == 0)
+                return -EINVAL;
+
+        hash = journal_file_hash_data(f, data, size);
+
+        r = journal_file_find_data_object_with_hash(f, data, size, hash, ret_object, ret_offset);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                return 0;
+
+        eq = memchr(data, '=', size);
+        if (!eq)
+                return -EINVAL;
+
+        osize = journal_file_data_payload_offset(f) + size;
+        r = journal_file_append_object(f, OBJECT_DATA, osize, &o, &p);
+        if (r < 0)
+                return r;
+
+        o->data.hash = htole64(hash);
+
+        c = maybe_compress_payload(f, journal_file_data_payload_field(f, o), data, size, &rsize);
+
+        if (c != COMPRESSION_NONE) {
+                o->object.size = htole64(journal_file_data_payload_offset(f) + rsize);
+                o->object.flags |= COMPRESSION_TO_OBJECT_FLAG(c);
+        } else
+                memcpy_safe(journal_file_data_payload_field(f, o), data, size);
+
+        r = journal_file_link_data(f, o, p, hash);
+        if (r < 0)
+                return r;
+
+        /* The linking might have altered the window, so let's refresh our pointer. */
+        r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
+        if (r < 0)
+                return r;
+
+#if HAVE_GCRYPT
+        r = journal_file_hmac_put_object(f, OBJECT_DATA, o, p);
+        if (r < 0)
+                return r;
+#endif
+
+        /* Create field object ... */
+        r = journal_file_append_field(f, data, (uint8_t*) eq - (uint8_t*) data, &fo, NULL);
+        if (r < 0)
+                return r;
+
+        /* ... and link it in. */
+        o->data.next_field_offset = fo->field.head_data_offset;
+        fo->field.head_data_offset = le64toh(p);
+
+        if (ret_object)
+                *ret_object = o;
+
+        if (ret_offset)
+                *ret_offset = p;
+
+        return 0;
+}
+
+static int maybe_decompress_payload(
+                JournalFile *f,
+                uint8_t *payload,
+                uint64_t size,
+                Compression compression,
+                const char *field,
+                size_t field_length,
+                size_t data_threshold,
+                void **ret_data,
+                size_t *ret_size) {
+
+        assert(f);
+
+        /* We can't read objects larger than 4G on a 32bit machine */
+        if ((uint64_t) (size_t) size != size)
+                return -E2BIG;
+
+        if (compression != COMPRESSION_NONE) {
+#if HAVE_COMPRESSION
+                size_t rsize;
+                int r;
+
+                if (field) {
+                        r = decompress_startswith(compression, payload, size, &f->compress_buffer, field,
+                                                  field_length, '=');
+                        if (r < 0)
+                                return log_debug_errno(r,
+                                                       "Cannot decompress %s object of length %" PRIu64 ": %m",
+                                                       compression_to_string(compression),
+                                                       size);
+                        if (r == 0) {
+                                if (ret_data)
+                                        *ret_data = NULL;
+                                if (ret_size)
+                                        *ret_size = 0;
+                                return 0;
+                        }
+                }
+
+                r = decompress_blob(compression, payload, size, &f->compress_buffer, &rsize, 0);
+                if (r < 0)
+                        return r;
+
+                if (ret_data)
+                        *ret_data = f->compress_buffer;
+                if (ret_size)
+                        *ret_size = rsize;
+#else
+                return -EPROTONOSUPPORT;
+#endif
+        } else {
+                if (field && (size < field_length + 1 || memcmp(payload, field, field_length) != 0 || payload[field_length] != '=')) {
+                        if (ret_data)
+                                *ret_data = NULL;
+                        if (ret_size)
+                                *ret_size = 0;
+                        return 0;
+                }
+
+                if (ret_data)
+                        *ret_data = payload;
+                if (ret_size)
+                        *ret_size = (size_t) size;
+        }
+
+        return 1;
+}
+
+int journal_file_data_payload(
+                JournalFile *f,
+                Object *o,
+                uint64_t offset,
+                const char *field,
+                size_t field_length,
+                size_t data_threshold,
+                void **ret_data,
+                size_t *ret_size) {
+
+        uint64_t size;
+        Compression c;
+        int r;
+
+        assert(f);
+        assert(!field == (field_length == 0)); /* These must be specified together. */
+
+        if (!o) {
+                r = journal_file_move_to_object(f, OBJECT_DATA, offset, &o);
+                if (r < 0)
+                        return r;
+        }
+
+        size = le64toh(READ_NOW(o->object.size));
+        if (size < journal_file_data_payload_offset(f))
+                return -EBADMSG;
+
+        size -= journal_file_data_payload_offset(f);
+
+        c = COMPRESSION_FROM_OBJECT(o);
+        if (c < 0)
+                return -EPROTONOSUPPORT;
+
+        return maybe_decompress_payload(f, journal_file_data_payload_field(f, o), size, c, field,
+                                        field_length, data_threshold, ret_data, ret_size);
+}
+
+uint64_t journal_file_entry_n_items(JournalFile *f, Object *o) {
+        uint64_t sz;
+
+        assert(f);
+        assert(o);
+
+        if (o->object.type != OBJECT_ENTRY)
+                return 0;
+
+        sz = le64toh(READ_NOW(o->object.size));
+        if (sz < offsetof(Object, entry.items))
+                return 0;
+
+        return (sz - offsetof(Object, entry.items)) / journal_file_entry_item_size(f);
+}
+
+uint64_t journal_file_entry_array_n_items(JournalFile *f, Object *o) {
+        uint64_t sz;
+
+        assert(f);
+        assert(o);
+
+        if (o->object.type != OBJECT_ENTRY_ARRAY)
+                return 0;
+
+        sz = le64toh(READ_NOW(o->object.size));
+        if (sz < offsetof(Object, entry_array.items))
+                return 0;
+
+        return (sz - offsetof(Object, entry_array.items)) / journal_file_entry_array_item_size(f);
+}
+
+uint64_t journal_file_hash_table_n_items(Object *o) {
+        uint64_t sz;
+
+        assert(o);
+
+        if (!IN_SET(o->object.type, OBJECT_DATA_HASH_TABLE, OBJECT_FIELD_HASH_TABLE))
+                return 0;
+
+        sz = le64toh(READ_NOW(o->object.size));
+        if (sz < offsetof(Object, hash_table.items))
+                return 0;
+
+        return (sz - offsetof(Object, hash_table.items)) / sizeof(HashItem);
+}
+
+static void write_entry_array_item(JournalFile *f, Object *o, uint64_t i, uint64_t p) {
+        assert(f);
+        assert(o);
+
+        if (JOURNAL_HEADER_COMPACT(f->header)) {
+                assert(p <= UINT32_MAX);
+                o->entry_array.items.compact[i] = htole32(p);
+        } else
+                o->entry_array.items.regular[i] = htole64(p);
+}
+
+static int link_entry_into_array(
+                JournalFile *f,
+                le64_t *first,
+                le64_t *idx,
+                le32_t *tail,
+                le32_t *tidx,
+                uint64_t p) {
+
+        uint64_t n = 0, ap = 0, q, i, a, hidx;
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(first);
+        assert(idx);
+        assert(p > 0);
+
+        a = tail ? le32toh(*tail) : le64toh(*first);
+        hidx = le64toh(READ_NOW(*idx));
+        i = tidx ? le32toh(READ_NOW(*tidx)) : hidx;
+
+        while (a > 0) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &o);
+                if (r < 0)
+                        return r;
+
+                n = journal_file_entry_array_n_items(f, o);
+                if (i < n) {
+                        write_entry_array_item(f, o, i, p);
+                        *idx = htole64(hidx + 1);
+                        if (tidx)
+                                *tidx = htole32(le32toh(*tidx) + 1);
+                        return 0;
+                }
+
+                i -= n;
+                ap = a;
+                a = le64toh(o->entry_array.next_entry_array_offset);
+        }
+
+        if (hidx > n)
+                n = (hidx+1) * 2;
+        else
+                n = n * 2;
+
+        if (n < 4)
+                n = 4;
+
+        r = journal_file_append_object(f, OBJECT_ENTRY_ARRAY,
+                                       offsetof(Object, entry_array.items) + n * journal_file_entry_array_item_size(f),
+                                       &o, &q);
+        if (r < 0)
+                return r;
+
+#if HAVE_GCRYPT
+        r = journal_file_hmac_put_object(f, OBJECT_ENTRY_ARRAY, o, q);
+        if (r < 0)
+                return r;
+#endif
+
+        write_entry_array_item(f, o, i, p);
+
+        if (ap == 0)
+                *first = htole64(q);
+        else {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, ap, &o);
+                if (r < 0)
+                        return r;
+
+                o->entry_array.next_entry_array_offset = htole64(q);
+        }
+
+        if (tail)
+                *tail = htole32(q);
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_entry_arrays))
+                f->header->n_entry_arrays = htole64(le64toh(f->header->n_entry_arrays) + 1);
+
+        *idx = htole64(hidx + 1);
+        if (tidx)
+                *tidx = htole32(1);
+
+        return 0;
+}
+
+static int link_entry_into_array_plus_one(
+                JournalFile *f,
+                le64_t *extra,
+                le64_t *first,
+                le64_t *idx,
+                le32_t *tail,
+                le32_t *tidx,
+                uint64_t p) {
+
+        uint64_t hidx;
+        int r;
+
+        assert(f);
+        assert(extra);
+        assert(first);
+        assert(idx);
+        assert(p > 0);
+
+        hidx = le64toh(READ_NOW(*idx));
+        if (hidx == UINT64_MAX)
+                return -EBADMSG;
+        if (hidx == 0)
+                *extra = htole64(p);
+        else {
+                le64_t i;
+
+                i = htole64(hidx - 1);
+                r = link_entry_into_array(f, first, &i, tail, tidx, p);
+                if (r < 0)
+                        return r;
+        }
+
+        *idx = htole64(hidx + 1);
+        return 0;
+}
+
+static int journal_file_link_entry_item(JournalFile *f, uint64_t offset, uint64_t p) {
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(offset > 0);
+
+        r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
+        if (r < 0)
+                return r;
+
+        return link_entry_into_array_plus_one(f,
+                                              &o->data.entry_offset,
+                                              &o->data.entry_array_offset,
+                                              &o->data.n_entries,
+                                              JOURNAL_HEADER_COMPACT(f->header) ? &o->data.compact.tail_entry_array_offset : NULL,
+                                              JOURNAL_HEADER_COMPACT(f->header) ? &o->data.compact.tail_entry_array_n_entries : NULL,
+                                              offset);
+}
+
+static int journal_file_link_entry(
+                JournalFile *f,
+                Object *o,
+                uint64_t offset,
+                const EntryItem items[],
+                size_t n_items) {
+
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(o);
+        assert(offset > 0);
+
+        if (o->object.type != OBJECT_ENTRY)
+                return -EINVAL;
+
+        __atomic_thread_fence(__ATOMIC_SEQ_CST);
+
+        /* Link up the entry itself */
+        r = link_entry_into_array(f,
+                                  &f->header->entry_array_offset,
+                                  &f->header->n_entries,
+                                  JOURNAL_HEADER_CONTAINS(f->header, tail_entry_array_offset) ? &f->header->tail_entry_array_offset : NULL,
+                                  JOURNAL_HEADER_CONTAINS(f->header, tail_entry_array_n_entries) ? &f->header->tail_entry_array_n_entries : NULL,
+                                  offset);
+        if (r < 0)
+                return r;
+
+        /* log_debug("=> %s seqnr=%"PRIu64" n_entries=%"PRIu64, f->path, o->entry.seqnum, f->header->n_entries); */
+
+        if (f->header->head_entry_realtime == 0)
+                f->header->head_entry_realtime = o->entry.realtime;
+
+        f->header->tail_entry_realtime = o->entry.realtime;
+        f->header->tail_entry_monotonic = o->entry.monotonic;
+
+        /* Link up the items */
+        for (uint64_t i = 0; i < n_items; i++) {
+                int k;
+
+                /* If we fail to link an entry item because we can't allocate a new entry array, don't fail
+                 * immediately but try to link the other entry items since it might still be possible to link
+                 * those if they don't require a new entry array to be allocated. */
+
+                k = journal_file_link_entry_item(f, offset, items[i].object_offset);
+                if (k == -E2BIG)
+                        r = k;
+                else if (k < 0)
+                        return k;
+        }
+
+        return r;
+}
+
+static void write_entry_item(JournalFile *f, Object *o, uint64_t i, const EntryItem *item) {
+        assert(f);
+        assert(o);
+        assert(item);
+
+        if (JOURNAL_HEADER_COMPACT(f->header)) {
+                assert(item->object_offset <= UINT32_MAX);
+                o->entry.items.compact[i].object_offset = htole32(item->object_offset);
+        } else {
+                o->entry.items.regular[i].object_offset = htole64(item->object_offset);
+                o->entry.items.regular[i].hash = htole64(item->hash);
+        }
+}
+
+static int journal_file_append_entry_internal(
+                JournalFile *f,
+                const dual_timestamp *ts,
+                const sd_id128_t *boot_id,
+                uint64_t xor_hash,
+                const EntryItem items[],
+                size_t n_items,
+                uint64_t *seqnum,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t np;
+        uint64_t osize;
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(ts);
+        assert(items || n_items == 0);
+
+        osize = offsetof(Object, entry.items) + (n_items * journal_file_entry_item_size(f));
+
+        r = journal_file_append_object(f, OBJECT_ENTRY, osize, &o, &np);
+        if (r < 0)
+                return r;
+
+        o->entry.seqnum = htole64(journal_file_entry_seqnum(f, seqnum));
+        o->entry.realtime = htole64(ts->realtime);
+        o->entry.monotonic = htole64(ts->monotonic);
+        o->entry.xor_hash = htole64(xor_hash);
+        if (boot_id)
+                f->header->boot_id = *boot_id;
+        o->entry.boot_id = f->header->boot_id;
+
+        for (size_t i = 0; i < n_items; i++)
+                write_entry_item(f, o, i, &items[i]);
+
+#if HAVE_GCRYPT
+        r = journal_file_hmac_put_object(f, OBJECT_ENTRY, o, np);
+        if (r < 0)
+                return r;
+#endif
+
+        r = journal_file_link_entry(f, o, np, items, n_items);
+        if (r < 0)
+                return r;
+
+        if (ret_object)
+                *ret_object = o;
+
+        if (ret_offset)
+                *ret_offset = np;
+
+        return r;
+}
+
+void journal_file_post_change(JournalFile *f) {
+        assert(f);
+
+        if (f->fd < 0)
+                return;
+
+        /* inotify() does not receive IN_MODIFY events from file
+         * accesses done via mmap(). After each access we hence
+         * trigger IN_MODIFY by truncating the journal file to its
+         * current size which triggers IN_MODIFY. */
+
+        __atomic_thread_fence(__ATOMIC_SEQ_CST);
+
+        if (ftruncate(f->fd, f->last_stat.st_size) < 0)
+                log_debug_errno(errno, "Failed to truncate file to its own size: %m");
+}
+
+static int post_change_thunk(sd_event_source *timer, uint64_t usec, void *userdata) {
+        assert(userdata);
+
+        journal_file_post_change(userdata);
+
+        return 1;
+}
+
+static void schedule_post_change(JournalFile *f) {
+        sd_event *e;
+        int r;
+
+        assert(f);
+        assert(f->post_change_timer);
+
+        assert_se(e = sd_event_source_get_event(f->post_change_timer));
+
+        /* If we are already going down, post the change immediately. */
+        if (IN_SET(sd_event_get_state(e), SD_EVENT_EXITING, SD_EVENT_FINISHED))
+                goto fail;
+
+        r = sd_event_source_get_enabled(f->post_change_timer, NULL);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to get ftruncate timer state: %m");
+                goto fail;
+        }
+        if (r > 0)
+                return;
+
+        r = sd_event_source_set_time_relative(f->post_change_timer, f->post_change_timer_period);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to set time for scheduling ftruncate: %m");
+                goto fail;
+        }
+
+        r = sd_event_source_set_enabled(f->post_change_timer, SD_EVENT_ONESHOT);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to enable scheduled ftruncate: %m");
+                goto fail;
+        }
+
+        return;
+
+fail:
+        /* On failure, let's simply post the change immediately. */
+        journal_file_post_change(f);
+}
+
+/* Enable coalesced change posting in a timer on the provided sd_event instance */
+int journal_file_enable_post_change_timer(JournalFile *f, sd_event *e, usec_t t) {
+        _cleanup_(sd_event_source_unrefp) sd_event_source *timer = NULL;
+        int r;
+
+        assert(f);
+        assert_return(!f->post_change_timer, -EINVAL);
+        assert(e);
+        assert(t);
+
+        /* If we are already going down, we cannot install the timer.
+         * In such case, the caller needs to call journal_file_post_change() explicitly. */
+        if (IN_SET(sd_event_get_state(e), SD_EVENT_EXITING, SD_EVENT_FINISHED))
+                return 0;
+
+        r = sd_event_add_time(e, &timer, CLOCK_MONOTONIC, 0, 0, post_change_thunk, f);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_enabled(timer, SD_EVENT_OFF);
+        if (r < 0)
+                return r;
+
+        f->post_change_timer = TAKE_PTR(timer);
+        f->post_change_timer_period = t;
+
+        return 1;
+}
+
+static int entry_item_cmp(const EntryItem *a, const EntryItem *b) {
+        return CMP(ASSERT_PTR(a)->object_offset, ASSERT_PTR(b)->object_offset);
+}
+
+static size_t remove_duplicate_entry_items(EntryItem items[], size_t n) {
+        size_t j = 1;
+
+        assert(items || n == 0);
+
+        if (n <= 1)
+                return n;
+
+        for (size_t i = 1; i < n; i++)
+                if (items[i].object_offset != items[j - 1].object_offset)
+                        items[j++] = items[i];
+
+        return j;
+}
+
+int journal_file_append_entry(
+                JournalFile *f,
+                const dual_timestamp *ts,
+                const sd_id128_t *boot_id,
+                const struct iovec iovec[],
+                unsigned n_iovec,
+                uint64_t *seqnum,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        _cleanup_free_ EntryItem *items_alloc = NULL;
+        EntryItem *items;
+        uint64_t xor_hash = 0;
+        struct dual_timestamp _ts;
+        int r;
+
+        assert(f);
+        assert(f->header);
+        assert(iovec);
+        assert(n_iovec > 0);
+
+        if (ts) {
+                if (!VALID_REALTIME(ts->realtime))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid realtime timestamp %" PRIu64 ", refusing entry.",
+                                               ts->realtime);
+                if (!VALID_MONOTONIC(ts->monotonic))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                               "Invalid monotomic timestamp %" PRIu64 ", refusing entry.",
+                                               ts->monotonic);
+        } else {
+                dual_timestamp_get(&_ts);
+                ts = &_ts;
+        }
+
+#if HAVE_GCRYPT
+        r = journal_file_maybe_append_tag(f, ts->realtime);
+        if (r < 0)
+                return r;
+#endif
+
+        if (n_iovec < ALLOCA_MAX / sizeof(EntryItem) / 2)
+                items = newa(EntryItem, n_iovec);
+        else {
+                items_alloc = new(EntryItem, n_iovec);
+                if (!items_alloc)
+                        return -ENOMEM;
+
+                items = items_alloc;
+        }
+
+        for (size_t i = 0; i < n_iovec; i++) {
+                uint64_t p;
+                Object *o;
+
+                r = journal_file_append_data(f, iovec[i].iov_base, iovec[i].iov_len, &o, &p);
+                if (r < 0)
+                        return r;
+
+                /* When calculating the XOR hash field, we need to take special care if the "keyed-hash"
+                 * journal file flag is on. We use the XOR hash field to quickly determine the identity of a
+                 * specific record, and give records with otherwise identical position (i.e. match in seqno,
+                 * timestamp, …) a stable ordering. But for that we can't have it that the hash of the
+                 * objects in each file is different since they are keyed. Hence let's calculate the Jenkins
+                 * hash here for that. This also has the benefit that cursors for old and new journal files
+                 * are completely identical (they include the XOR hash after all). For classic Jenkins-hash
+                 * files things are easier, we can just take the value from the stored record directly. */
+
+                if (JOURNAL_HEADER_KEYED_HASH(f->header))
+                        xor_hash ^= jenkins_hash64(iovec[i].iov_base, iovec[i].iov_len);
+                else
+                        xor_hash ^= le64toh(o->data.hash);
+
+                items[i] = (EntryItem) {
+                        .object_offset = p,
+                        .hash = le64toh(o->data.hash),
+                };
+        }
+
+        /* Order by the position on disk, in order to improve seek
+         * times for rotating media. */
+        typesafe_qsort(items, n_iovec, entry_item_cmp);
+        n_iovec = remove_duplicate_entry_items(items, n_iovec);
+
+        r = journal_file_append_entry_internal(f, ts, boot_id, xor_hash, items, n_iovec, seqnum, ret_object, ret_offset);
+
+        /* If the memory mapping triggered a SIGBUS then we return an
+         * IO error and ignore the error code passed down to us, since
+         * it is very likely just an effect of a nullified replacement
+         * mapping page */
+
+        if (mmap_cache_fd_got_sigbus(f->cache_fd))
+                r = -EIO;
+
+        if (f->post_change_timer)
+                schedule_post_change(f);
+        else
+                journal_file_post_change(f);
+
+        return r;
+}
+
+typedef struct ChainCacheItem {
+        uint64_t first; /* the array at the beginning of the chain */
+        uint64_t array; /* the cached array */
+        uint64_t begin; /* the first item in the cached array */
+        uint64_t total; /* the total number of items in all arrays before this one in the chain */
+        uint64_t last_index; /* the last index we looked at, to optimize locality when bisecting */
+} ChainCacheItem;
+
+static void chain_cache_put(
+                OrderedHashmap *h,
+                ChainCacheItem *ci,
+                uint64_t first,
+                uint64_t array,
+                uint64_t begin,
+                uint64_t total,
+                uint64_t last_index) {
+
+        assert(h);
+
+        if (!ci) {
+                /* If the chain item to cache for this chain is the
+                 * first one it's not worth caching anything */
+                if (array == first)
+                        return;
+
+                if (ordered_hashmap_size(h) >= CHAIN_CACHE_MAX) {
+                        ci = ordered_hashmap_steal_first(h);
+                        assert(ci);
+                } else {
+                        ci = new(ChainCacheItem, 1);
+                        if (!ci)
+                                return;
+                }
+
+                ci->first = first;
+
+                if (ordered_hashmap_put(h, &ci->first, ci) < 0) {
+                        free(ci);
+                        return;
+                }
+        } else
+                assert(ci->first == first);
+
+        ci->array = array;
+        ci->begin = begin;
+        ci->total = total;
+        ci->last_index = last_index;
+}
+
+static int bump_array_index(uint64_t *i, direction_t direction, uint64_t n) {
+        assert(i);
+
+        /* Increase or decrease the specified index, in the right direction. */
+
+        if (direction == DIRECTION_DOWN) {
+                if (*i >= n - 1)
+                        return 0;
+
+                (*i)++;
+        } else {
+                if (*i <= 0)
+                        return 0;
+
+                (*i)--;
+        }
+
+        return 1;
+}
+
+static int bump_entry_array(
+                JournalFile *f,
+                Object *o,
+                uint64_t offset,
+                uint64_t first,
+                direction_t direction,
+                uint64_t *ret) {
+
+        uint64_t p, q = 0;
+        int r;
+
+        assert(f);
+        assert(offset);
+        assert(ret);
+
+        if (direction == DIRECTION_DOWN) {
+                assert(o);
+                *ret = le64toh(o->entry_array.next_entry_array_offset);
+                return 0;
+        }
+
+        /* Entry array chains are a singly linked list, so to find the previous array in the chain, we have
+         * to start iterating from the top. */
+
+        p = first;
+
+        while (p > 0 && p != offset) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, p, &o);
+                if (r < 0)
+                        return r;
+
+                q = p;
+                p = le64toh(o->entry_array.next_entry_array_offset);
+        }
+
+        /* If we can't find the previous entry array in the entry array chain, we're likely dealing with a
+         * corrupted journal file. */
+        if (p == 0)
+                return -EBADMSG;
+
+        *ret = q;
+
+        return 0;
+}
+
+static int generic_array_get(
+                JournalFile *f,
+                uint64_t first,
+                uint64_t i,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t p = 0, a, t = 0, k;
+        ChainCacheItem *ci;
+        Object *o;
+        int r;
+
+        assert(f);
+
+        /* FIXME: fix return value assignment on success. */
+
+        a = first;
+
+        /* Try the chain cache first */
+        ci = ordered_hashmap_get(f->chain_cache, &first);
+        if (ci && i > ci->total) {
+                a = ci->array;
+                i -= ci->total;
+                t = ci->total;
+        }
+
+        while (a > 0) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &o);
+                if (IN_SET(r, -EBADMSG, -EADDRNOTAVAIL)) {
+                        /* If there's corruption and we're going downwards, let's pretend we reached the
+                         * final entry in the entry array chain. */
+
+                        if (direction == DIRECTION_DOWN)
+                                return 0;
+
+                        /* If there's corruption and we're going upwards, move back to the previous entry
+                         * array and start iterating entries from there. */
+
+                        r = bump_entry_array(f, NULL, a, first, DIRECTION_UP, &a);
+                        if (r < 0)
+                                return r;
+
+                        i = UINT64_MAX;
+
+                        break;
+                }
+                if (r < 0)
+                        return r;
+
+                k = journal_file_entry_array_n_items(f, o);
+                if (i < k)
+                        break;
+
+                i -= k;
+                t += k;
+                a = le64toh(o->entry_array.next_entry_array_offset);
+        }
+
+        /* If we've found the right location, now look for the first non-corrupt entry object (in the right
+         * direction). */
+
+        while (a > 0) {
+                /* In the first iteration of the while loop, we reuse i, k and o from the previous while
+                 * loop. */
+                if (i == UINT64_MAX) {
+                        r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &o);
+                        if (r < 0)
+                                return r;
+
+                        k = journal_file_entry_array_n_items(f, o);
+                        if (k == 0)
+                                break;
+
+                        i = direction == DIRECTION_DOWN ? 0 : k - 1;
+                }
+
+                do {
+                        p = journal_file_entry_array_item(f, o, i);
+
+                        r = journal_file_move_to_object(f, OBJECT_ENTRY, p, ret_object);
+                        if (r >= 0) {
+                                /* Let's cache this item for the next invocation */
+                                chain_cache_put(f->chain_cache, ci, first, a, journal_file_entry_array_item(f, o, 0), t, i);
+
+                                if (ret_offset)
+                                        *ret_offset = p;
+
+                                return 1;
+                        }
+                        if (!IN_SET(r, -EADDRNOTAVAIL, -EBADMSG))
+                                return r;
+
+                        /* OK, so this entry is borked. Most likely some entry didn't get synced to
+                        * disk properly, let's see if the next one might work for us instead. */
+                        log_debug_errno(r, "Entry item %" PRIu64 " is bad, skipping over it.", i);
+                } while (bump_array_index(&i, direction, k) > 0);
+
+                r = bump_entry_array(f, o, a, first, direction, &a);
+                if (r < 0)
+                        return r;
+
+                t += k;
+                i = UINT64_MAX;
+        }
+
+        return 0;
+}
+
+static int generic_array_get_plus_one(
+                JournalFile *f,
+                uint64_t extra,
+                uint64_t first,
+                uint64_t i,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        int r;
+
+        assert(f);
+
+        /* FIXME: fix return value assignment on success. */
+
+        if (i == 0) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, extra, ret_object);
+                if (IN_SET(r, -EADDRNOTAVAIL, -EBADMSG))
+                        return generic_array_get(f, first, 0, direction, ret_object, ret_offset);
+                if (r < 0)
+                        return r;
+
+                if (ret_offset)
+                        *ret_offset = extra;
+
+                return 1;
+        }
+
+        return generic_array_get(f, first, i - 1, direction, ret_object, ret_offset);
+}
+
+enum {
+        TEST_FOUND,
+        TEST_LEFT,
+        TEST_RIGHT
+};
+
+static int generic_array_bisect(
+                JournalFile *f,
+                uint64_t first,
+                uint64_t n,
+                uint64_t needle,
+                int (*test_object)(JournalFile *f, uint64_t p, uint64_t needle),
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset,
+                uint64_t *ret_idx) {
+
+        /* Given an entry array chain, this function finds the object "closest" to the given needle in the
+         * chain, taking into account the provided direction. A function can be provided to determine how
+         * an object is matched against the given needle.
+         *
+         * Given a journal file, the offset of an object and the needle, the test_object() function should
+         * return TEST_LEFT if the needle is located earlier in the entry array chain, TEST_RIGHT if the
+         * needle is located later in the entry array chain and TEST_FOUND if the object matches the needle.
+         * If test_object() returns TEST_FOUND for a specific object, that object's information will be used
+         * to populate the return values of this function. If test_object() never returns TEST_FOUND, the
+         * return values are populated with the details of one of the objects closest to the needle. If the
+         * direction is DIRECTION_UP, the earlier object is used. Otherwise, the later object is used.
+         */
+
+        uint64_t a, p, t = 0, i = 0, last_p = 0, last_index = UINT64_MAX;
+        bool subtract_one = false;
+        Object *array = NULL;
+        ChainCacheItem *ci;
+        int r;
+
+        assert(f);
+        assert(test_object);
+
+        /* Start with the first array in the chain */
+        a = first;
+
+        ci = ordered_hashmap_get(f->chain_cache, &first);
+        if (ci && n > ci->total && ci->begin != 0) {
+                /* Ah, we have iterated this bisection array chain
+                 * previously! Let's see if we can skip ahead in the
+                 * chain, as far as the last time. But we can't jump
+                 * backwards in the chain, so let's check that
+                 * first. */
+
+                r = test_object(f, ci->begin, needle);
+                if (r < 0)
+                        return r;
+
+                if (r == TEST_LEFT) {
+                        /* OK, what we are looking for is right of the
+                         * begin of this EntryArray, so let's jump
+                         * straight to previously cached array in the
+                         * chain */
+
+                        a = ci->array;
+                        n -= ci->total;
+                        t = ci->total;
+                        last_index = ci->last_index;
+                }
+        }
+
+        while (a > 0) {
+                uint64_t left, right, k, lp;
+
+                r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &array);
+                if (r < 0)
+                        return r;
+
+                k = journal_file_entry_array_n_items(f, array);
+                right = MIN(k, n);
+                if (right <= 0)
+                        return 0;
+
+                i = right - 1;
+                lp = p = journal_file_entry_array_item(f, array, i);
+                if (p <= 0)
+                        r = -EBADMSG;
+                else
+                        r = test_object(f, p, needle);
+                if (r == -EBADMSG) {
+                        log_debug_errno(r, "Encountered invalid entry while bisecting, cutting algorithm short. (1)");
+                        n = i;
+                        continue;
+                }
+                if (r < 0)
+                        return r;
+
+                if (r == TEST_FOUND)
+                        r = direction == DIRECTION_DOWN ? TEST_RIGHT : TEST_LEFT;
+
+                if (r == TEST_RIGHT) {
+                        left = 0;
+                        right -= 1;
+
+                        if (last_index != UINT64_MAX) {
+                                assert(last_index <= right);
+
+                                /* If we cached the last index we
+                                 * looked at, let's try to not to jump
+                                 * too wildly around and see if we can
+                                 * limit the range to look at early to
+                                 * the immediate neighbors of the last
+                                 * index we looked at. */
+
+                                if (last_index > 0) {
+                                        uint64_t x = last_index - 1;
+
+                                        p = journal_file_entry_array_item(f, array, x);
+                                        if (p <= 0)
+                                                return -EBADMSG;
+
+                                        r = test_object(f, p, needle);
+                                        if (r < 0)
+                                                return r;
+
+                                        if (r == TEST_FOUND)
+                                                r = direction == DIRECTION_DOWN ? TEST_RIGHT : TEST_LEFT;
+
+                                        if (r == TEST_RIGHT)
+                                                right = x;
+                                        else
+                                                left = x + 1;
+                                }
+
+                                if (last_index < right) {
+                                        uint64_t y = last_index + 1;
+
+                                        p = journal_file_entry_array_item(f, array, y);
+                                        if (p <= 0)
+                                                return -EBADMSG;
+
+                                        r = test_object(f, p, needle);
+                                        if (r < 0)
+                                                return r;
+
+                                        if (r == TEST_FOUND)
+                                                r = direction == DIRECTION_DOWN ? TEST_RIGHT : TEST_LEFT;
+
+                                        if (r == TEST_RIGHT)
+                                                right = y;
+                                        else
+                                                left = y + 1;
+                                }
+                        }
+
+                        for (;;) {
+                                if (left == right) {
+                                        if (direction == DIRECTION_UP)
+                                                subtract_one = true;
+
+                                        i = left;
+                                        goto found;
+                                }
+
+                                assert(left < right);
+                                i = (left + right) / 2;
+
+                                p = journal_file_entry_array_item(f, array, i);
+                                if (p <= 0)
+                                        r = -EBADMSG;
+                                else
+                                        r = test_object(f, p, needle);
+                                if (r == -EBADMSG) {
+                                        log_debug_errno(r, "Encountered invalid entry while bisecting, cutting algorithm short. (2)");
+                                        right = n = i;
+                                        continue;
+                                }
+                                if (r < 0)
+                                        return r;
+
+                                if (r == TEST_FOUND)
+                                        r = direction == DIRECTION_DOWN ? TEST_RIGHT : TEST_LEFT;
+
+                                if (r == TEST_RIGHT)
+                                        right = i;
+                                else
+                                        left = i + 1;
+                        }
+                }
+
+                if (k >= n) {
+                        if (direction == DIRECTION_UP) {
+                                i = n;
+                                subtract_one = true;
+                                goto found;
+                        }
+
+                        return 0;
+                }
+
+                last_p = lp;
+
+                n -= k;
+                t += k;
+                last_index = UINT64_MAX;
+                a = le64toh(array->entry_array.next_entry_array_offset);
+        }
+
+        return 0;
+
+found:
+        if (subtract_one && t == 0 && i == 0)
+                return 0;
+
+        /* Let's cache this item for the next invocation */
+        chain_cache_put(f->chain_cache, ci, first, a, journal_file_entry_array_item(f, array, 0), t, subtract_one ? (i > 0 ? i-1 : UINT64_MAX) : i);
+
+        if (subtract_one && i == 0)
+                p = last_p;
+        else if (subtract_one)
+                p = journal_file_entry_array_item(f, array, i - 1);
+        else
+                p = journal_file_entry_array_item(f, array, i);
+
+        if (ret_object) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, p, ret_object);
+                if (r < 0)
+                        return r;
+        }
+
+        if (ret_offset)
+                *ret_offset = p;
+
+        if (ret_idx)
+                *ret_idx = t + i + (subtract_one ? -1 : 0);
+
+        return 1;
+}
+
+static int generic_array_bisect_plus_one(
+                JournalFile *f,
+                uint64_t extra,
+                uint64_t first,
+                uint64_t n,
+                uint64_t needle,
+                int (*test_object)(JournalFile *f, uint64_t p, uint64_t needle),
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset,
+                uint64_t *ret_idx) {
+
+        int r;
+        bool step_back = false;
+
+        assert(f);
+        assert(test_object);
+
+        if (n <= 0)
+                return 0;
+
+        /* This bisects the array in object 'first', but first checks
+         * an extra  */
+        r = test_object(f, extra, needle);
+        if (r < 0)
+                return r;
+
+        if (r == TEST_FOUND)
+                r = direction == DIRECTION_DOWN ? TEST_RIGHT : TEST_LEFT;
+
+        /* if we are looking with DIRECTION_UP then we need to first
+           see if in the actual array there is a matching entry, and
+           return the last one of that. But if there isn't any we need
+           to return this one. Hence remember this, and return it
+           below. */
+        if (r == TEST_LEFT)
+                step_back = direction == DIRECTION_UP;
+
+        if (r == TEST_RIGHT) {
+                if (direction == DIRECTION_DOWN)
+                        goto found;
+                else
+                        return 0;
+        }
+
+        r = generic_array_bisect(f, first, n-1, needle, test_object, direction, ret_object, ret_offset, ret_idx);
+
+        if (r == 0 && step_back)
+                goto found;
+
+        if (r > 0 && ret_idx)
+                (*ret_idx)++;
+
+        return r;
+
+found:
+        if (ret_object) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, extra, ret_object);
+                if (r < 0)
+                        return r;
+        }
+
+        if (ret_offset)
+                *ret_offset = extra;
+
+        if (ret_idx)
+                *ret_idx = 0;
+
+        return 1;
+}
+
+_pure_ static int test_object_offset(JournalFile *f, uint64_t p, uint64_t needle) {
+        assert(f);
+        assert(p > 0);
+
+        if (p == needle)
+                return TEST_FOUND;
+        else if (p < needle)
+                return TEST_LEFT;
+        else
+                return TEST_RIGHT;
+}
+
+int journal_file_move_to_entry_by_offset(
+                JournalFile *f,
+                uint64_t p,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        assert(f);
+        assert(f->header);
+
+        return generic_array_bisect(
+                        f,
+                        le64toh(f->header->entry_array_offset),
+                        le64toh(f->header->n_entries),
+                        p,
+                        test_object_offset,
+                        direction,
+                        ret_object, ret_offset, NULL);
+}
+
+static int test_object_seqnum(JournalFile *f, uint64_t p, uint64_t needle) {
+        uint64_t sq;
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(p > 0);
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, p, &o);
+        if (r < 0)
+                return r;
+
+        sq = le64toh(READ_NOW(o->entry.seqnum));
+        if (sq == needle)
+                return TEST_FOUND;
+        else if (sq < needle)
+                return TEST_LEFT;
+        else
+                return TEST_RIGHT;
+}
+
+int journal_file_move_to_entry_by_seqnum(
+                JournalFile *f,
+                uint64_t seqnum,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        assert(f);
+        assert(f->header);
+
+        return generic_array_bisect(
+                        f,
+                        le64toh(f->header->entry_array_offset),
+                        le64toh(f->header->n_entries),
+                        seqnum,
+                        test_object_seqnum,
+                        direction,
+                        ret_object, ret_offset, NULL);
+}
+
+static int test_object_realtime(JournalFile *f, uint64_t p, uint64_t needle) {
+        Object *o;
+        uint64_t rt;
+        int r;
+
+        assert(f);
+        assert(p > 0);
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, p, &o);
+        if (r < 0)
+                return r;
+
+        rt = le64toh(READ_NOW(o->entry.realtime));
+        if (rt == needle)
+                return TEST_FOUND;
+        else if (rt < needle)
+                return TEST_LEFT;
+        else
+                return TEST_RIGHT;
+}
+
+int journal_file_move_to_entry_by_realtime(
+                JournalFile *f,
+                uint64_t realtime,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        assert(f);
+        assert(f->header);
+
+        return generic_array_bisect(
+                        f,
+                        le64toh(f->header->entry_array_offset),
+                        le64toh(f->header->n_entries),
+                        realtime,
+                        test_object_realtime,
+                        direction,
+                        ret_object, ret_offset, NULL);
+}
+
+static int test_object_monotonic(JournalFile *f, uint64_t p, uint64_t needle) {
+        Object *o;
+        uint64_t m;
+        int r;
+
+        assert(f);
+        assert(p > 0);
+
+        r = journal_file_move_to_object(f, OBJECT_ENTRY, p, &o);
+        if (r < 0)
+                return r;
+
+        m = le64toh(READ_NOW(o->entry.monotonic));
+        if (m == needle)
+                return TEST_FOUND;
+        else if (m < needle)
+                return TEST_LEFT;
+        else
+                return TEST_RIGHT;
+}
+
+static int find_data_object_by_boot_id(
+                JournalFile *f,
+                sd_id128_t boot_id,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        char t[STRLEN("_BOOT_ID=") + 32 + 1] = "_BOOT_ID=";
+
+        assert(f);
+
+        sd_id128_to_string(boot_id, t + 9);
+        return journal_file_find_data_object(f, t, sizeof(t) - 1, ret_object, ret_offset);
+}
+
+int journal_file_move_to_entry_by_monotonic(
+                JournalFile *f,
+                sd_id128_t boot_id,
+                uint64_t monotonic,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        Object *o;
+        int r;
+
+        assert(f);
+
+        r = find_data_object_by_boot_id(f, boot_id, &o, NULL);
+        if (r <= 0)
+                return r;
+
+        return generic_array_bisect_plus_one(
+                        f,
+                        le64toh(o->data.entry_offset),
+                        le64toh(o->data.entry_array_offset),
+                        le64toh(o->data.n_entries),
+                        monotonic,
+                        test_object_monotonic,
+                        direction,
+                        ret_object, ret_offset, NULL);
+}
+
+void journal_file_reset_location(JournalFile *f) {
+        assert(f);
+
+        f->location_type = LOCATION_HEAD;
+        f->current_offset = 0;
+        f->current_seqnum = 0;
+        f->current_realtime = 0;
+        f->current_monotonic = 0;
+        zero(f->current_boot_id);
+        f->current_xor_hash = 0;
+}
+
+void journal_file_save_location(JournalFile *f, Object *o, uint64_t offset) {
+        assert(f);
+        assert(o);
+
+        f->location_type = LOCATION_SEEK;
+        f->current_offset = offset;
+        f->current_seqnum = le64toh(o->entry.seqnum);
+        f->current_realtime = le64toh(o->entry.realtime);
+        f->current_monotonic = le64toh(o->entry.monotonic);
+        f->current_boot_id = o->entry.boot_id;
+        f->current_xor_hash = le64toh(o->entry.xor_hash);
+}
+
+int journal_file_compare_locations(JournalFile *af, JournalFile *bf) {
+        int r;
+
+        assert(af);
+        assert(af->header);
+        assert(bf);
+        assert(bf->header);
+        assert(af->location_type == LOCATION_SEEK);
+        assert(bf->location_type == LOCATION_SEEK);
+
+        /* If contents, timestamps and seqnum match, these entries are
+         * identical. */
+        if (sd_id128_equal(af->current_boot_id, bf->current_boot_id) &&
+            af->current_monotonic == bf->current_monotonic &&
+            af->current_realtime == bf->current_realtime &&
+            af->current_xor_hash == bf->current_xor_hash &&
+            sd_id128_equal(af->header->seqnum_id, bf->header->seqnum_id) &&
+            af->current_seqnum == bf->current_seqnum)
+                return 0;
+
+        if (sd_id128_equal(af->header->seqnum_id, bf->header->seqnum_id)) {
+
+                /* If this is from the same seqnum source, compare
+                 * seqnums */
+                r = CMP(af->current_seqnum, bf->current_seqnum);
+                if (r != 0)
+                        return r;
+
+                /* Wow! This is weird, different data but the same
+                 * seqnums? Something is borked, but let's make the
+                 * best of it and compare by time. */
+        }
+
+        if (sd_id128_equal(af->current_boot_id, bf->current_boot_id)) {
+
+                /* If the boot id matches, compare monotonic time */
+                r = CMP(af->current_monotonic, bf->current_monotonic);
+                if (r != 0)
+                        return r;
+        }
+
+        /* Otherwise, compare UTC time */
+        r = CMP(af->current_realtime, bf->current_realtime);
+        if (r != 0)
+                return r;
+
+        /* Finally, compare by contents */
+        return CMP(af->current_xor_hash, bf->current_xor_hash);
+}
+
+static bool check_properly_ordered(uint64_t new_offset, uint64_t old_offset, direction_t direction) {
+
+        /* Consider it an error if any of the two offsets is uninitialized */
+        if (old_offset == 0 || new_offset == 0)
+                return false;
+
+        /* If we go down, the new offset must be larger than the old one. */
+        return direction == DIRECTION_DOWN ?
+                new_offset > old_offset  :
+                new_offset < old_offset;
+}
+
+int journal_file_next_entry(
+                JournalFile *f,
+                uint64_t p,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t i, n, ofs;
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        /* FIXME: fix return value assignment. */
+
+        n = le64toh(READ_NOW(f->header->n_entries));
+        if (n <= 0)
+                return 0;
+
+        if (p == 0)
+                i = direction == DIRECTION_DOWN ? 0 : n - 1;
+        else {
+                r = generic_array_bisect(f,
+                                         le64toh(f->header->entry_array_offset),
+                                         le64toh(f->header->n_entries),
+                                         p,
+                                         test_object_offset,
+                                         DIRECTION_DOWN,
+                                         NULL, NULL,
+                                         &i);
+                if (r <= 0)
+                        return r;
+
+                r = bump_array_index(&i, direction, n);
+                if (r <= 0)
+                        return r;
+        }
+
+        /* And jump to it */
+        r = generic_array_get(f, le64toh(f->header->entry_array_offset), i, direction, ret_object, &ofs);
+        if (r <= 0)
+                return r;
+
+        /* Ensure our array is properly ordered. */
+        if (p > 0 && !check_properly_ordered(ofs, p, direction))
+                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
+                                       "%s: entry array not properly ordered at entry %" PRIu64,
+                                       f->path, i);
+
+        if (ret_offset)
+                *ret_offset = ofs;
+
+        return 1;
+}
+
+int journal_file_next_entry_for_data(
+                JournalFile *f,
+                Object *d,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t i, n, ofs;
+        int r;
+
+        assert(f);
+        assert(d);
+        assert(d->object.type == OBJECT_DATA);
+
+        /* FIXME: fix return value assignment. */
+
+        n = le64toh(READ_NOW(d->data.n_entries));
+        if (n <= 0)
+                return n;
+
+        i = direction == DIRECTION_DOWN ? 0 : n - 1;
+
+        r = generic_array_get_plus_one(f,
+                                       le64toh(d->data.entry_offset),
+                                       le64toh(d->data.entry_array_offset),
+                                       i,
+                                       direction,
+                                       ret_object, &ofs);
+        if (r <= 0)
+                return r;
+
+        if (ret_offset)
+                *ret_offset = ofs;
+
+        return 1;
+}
+
+int journal_file_move_to_entry_by_offset_for_data(
+                JournalFile *f,
+                Object *d,
+                uint64_t p,
+                direction_t direction,
+                Object **ret, uint64_t *ret_offset) {
+
+        assert(f);
+        assert(d);
+        assert(d->object.type == OBJECT_DATA);
+
+        return generic_array_bisect_plus_one(
+                        f,
+                        le64toh(d->data.entry_offset),
+                        le64toh(d->data.entry_array_offset),
+                        le64toh(d->data.n_entries),
+                        p,
+                        test_object_offset,
+                        direction,
+                        ret, ret_offset, NULL);
+}
+
+int journal_file_move_to_entry_by_monotonic_for_data(
+                JournalFile *f,
+                Object *d,
+                sd_id128_t boot_id,
+                uint64_t monotonic,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        uint64_t b, z, entry_offset, entry_array_offset, n_entries;
+        Object *o;
+        int r;
+
+        assert(f);
+        assert(d);
+        assert(d->object.type == OBJECT_DATA);
+
+        /* Save all the required data before the data object gets invalidated. */
+        entry_offset = le64toh(READ_NOW(d->data.entry_offset));
+        entry_array_offset = le64toh(READ_NOW(d->data.entry_array_offset));
+        n_entries = le64toh(READ_NOW(d->data.n_entries));
+
+        /* First, seek by time */
+        r = find_data_object_by_boot_id(f, boot_id, &o, &b);
+        if (r <= 0)
+                return r;
+
+        r = generic_array_bisect_plus_one(f,
+                                          le64toh(o->data.entry_offset),
+                                          le64toh(o->data.entry_array_offset),
+                                          le64toh(o->data.n_entries),
+                                          monotonic,
+                                          test_object_monotonic,
+                                          direction,
+                                          NULL, &z, NULL);
+        if (r <= 0)
+                return r;
+
+        /* And now, continue seeking until we find an entry that
+         * exists in both bisection arrays */
+
+        r = journal_file_move_to_object(f, OBJECT_DATA, b, &o);
+        if (r < 0)
+                return r;
+
+        for (;;) {
+                uint64_t p, q;
+
+                r = generic_array_bisect_plus_one(f,
+                                                  entry_offset,
+                                                  entry_array_offset,
+                                                  n_entries,
+                                                  z,
+                                                  test_object_offset,
+                                                  direction,
+                                                  NULL, &p, NULL);
+                if (r <= 0)
+                        return r;
+
+                r = generic_array_bisect_plus_one(f,
+                                                  le64toh(o->data.entry_offset),
+                                                  le64toh(o->data.entry_array_offset),
+                                                  le64toh(o->data.n_entries),
+                                                  p,
+                                                  test_object_offset,
+                                                  direction,
+                                                  NULL, &q, NULL);
+
+                if (r <= 0)
+                        return r;
+
+                if (p == q) {
+                        if (ret_object) {
+                                r = journal_file_move_to_object(f, OBJECT_ENTRY, q, ret_object);
+                                if (r < 0)
+                                        return r;
+                        }
+
+                        if (ret_offset)
+                                *ret_offset = q;
+
+                        return 1;
+                }
+
+                z = q;
+        }
+}
+
+int journal_file_move_to_entry_by_seqnum_for_data(
+                JournalFile *f,
+                Object *d,
+                uint64_t seqnum,
+                direction_t direction,
+                Object **ret_object,
+                uint64_t *ret_offset) {
+
+        assert(f);
+        assert(d);
+        assert(d->object.type == OBJECT_DATA);
+
+        return generic_array_bisect_plus_one(
+                        f,
+                        le64toh(d->data.entry_offset),
+                        le64toh(d->data.entry_array_offset),
+                        le64toh(d->data.n_entries),
+                        seqnum,
+                        test_object_seqnum,
+                        direction,
+                        ret_object, ret_offset, NULL);
+}
+
+int journal_file_move_to_entry_by_realtime_for_data(
+                JournalFile *f,
+                Object *d,
+                uint64_t realtime,
+                direction_t direction,
+                Object **ret, uint64_t *ret_offset) {
+
+        assert(f);
+        assert(d);
+        assert(d->object.type == OBJECT_DATA);
+
+        return generic_array_bisect_plus_one(
+                        f,
+                        le64toh(d->data.entry_offset),
+                        le64toh(d->data.entry_array_offset),
+                        le64toh(d->data.n_entries),
+                        realtime,
+                        test_object_realtime,
+                        direction,
+                        ret, ret_offset, NULL);
+}
+
+void journal_file_dump(JournalFile *f) {
+        Object *o;
+        uint64_t p;
+        int r;
+
+        assert(f);
+        assert(f->header);
+
+        journal_file_print_header(f);
+
+        p = le64toh(READ_NOW(f->header->header_size));
+        while (p != 0) {
+                const char *s;
+                Compression c;
+
+                r = journal_file_move_to_object(f, OBJECT_UNUSED, p, &o);
+                if (r < 0)
+                        goto fail;
+
+                s = journal_object_type_to_string(o->object.type);
+
+                switch (o->object.type) {
+
+                case OBJECT_ENTRY:
+                        assert(s);
+
+                        printf("Type: %s seqnum=%"PRIu64" monotonic=%"PRIu64" realtime=%"PRIu64"\n",
+                               s,
+                               le64toh(o->entry.seqnum),
+                               le64toh(o->entry.monotonic),
+                               le64toh(o->entry.realtime));
+                        break;
+
+                case OBJECT_TAG:
+                        assert(s);
+
+                        printf("Type: %s seqnum=%"PRIu64" epoch=%"PRIu64"\n",
+                               s,
+                               le64toh(o->tag.seqnum),
+                               le64toh(o->tag.epoch));
+                        break;
+
+                default:
+                        if (s)
+                                printf("Type: %s \n", s);
+                        else
+                                printf("Type: unknown (%i)", o->object.type);
+
+                        break;
+                }
+
+                c = COMPRESSION_FROM_OBJECT(o);
+                if (c > COMPRESSION_NONE)
+                        printf("Flags: %s\n",
+                               compression_to_string(c));
+
+                if (p == le64toh(f->header->tail_object_offset))
+                        p = 0;
+                else
+                        p += ALIGN64(le64toh(o->object.size));
+        }
+
+        return;
+fail:
+        log_error("File corrupt");
+}
+
+/* Note: the lifetime of the compound literal is the immediately surrounding block. */
+#define FORMAT_TIMESTAMP_SAFE(t) (FORMAT_TIMESTAMP(t) ?: " --- ")
+
+void journal_file_print_header(JournalFile *f) {
+        struct stat st;
+
+        assert(f);
+        assert(f->header);
+
+        printf("File path: %s\n"
+               "File ID: %s\n"
+               "Machine ID: %s\n"
+               "Boot ID: %s\n"
+               "Sequential number ID: %s\n"
+               "State: %s\n"
+               "Compatible flags:%s%s\n"
+               "Incompatible flags:%s%s%s%s%s%s\n"
+               "Header size: %"PRIu64"\n"
+               "Arena size: %"PRIu64"\n"
+               "Data hash table size: %"PRIu64"\n"
+               "Field hash table size: %"PRIu64"\n"
+               "Rotate suggested: %s\n"
+               "Head sequential number: %"PRIu64" (%"PRIx64")\n"
+               "Tail sequential number: %"PRIu64" (%"PRIx64")\n"
+               "Head realtime timestamp: %s (%"PRIx64")\n"
+               "Tail realtime timestamp: %s (%"PRIx64")\n"
+               "Tail monotonic timestamp: %s (%"PRIx64")\n"
+               "Objects: %"PRIu64"\n"
+               "Entry objects: %"PRIu64"\n",
+               f->path,
+               SD_ID128_TO_STRING(f->header->file_id),
+               SD_ID128_TO_STRING(f->header->machine_id),
+               SD_ID128_TO_STRING(f->header->boot_id),
+               SD_ID128_TO_STRING(f->header->seqnum_id),
+               f->header->state == STATE_OFFLINE ? "OFFLINE" :
+               f->header->state == STATE_ONLINE ? "ONLINE" :
+               f->header->state == STATE_ARCHIVED ? "ARCHIVED" : "UNKNOWN",
+               JOURNAL_HEADER_SEALED(f->header) ? " SEALED" : "",
+               (le32toh(f->header->compatible_flags) & ~HEADER_COMPATIBLE_ANY) ? " ???" : "",
+               JOURNAL_HEADER_COMPRESSED_XZ(f->header) ? " COMPRESSED-XZ" : "",
+               JOURNAL_HEADER_COMPRESSED_LZ4(f->header) ? " COMPRESSED-LZ4" : "",
+               JOURNAL_HEADER_COMPRESSED_ZSTD(f->header) ? " COMPRESSED-ZSTD" : "",
+               JOURNAL_HEADER_KEYED_HASH(f->header) ? " KEYED-HASH" : "",
+               JOURNAL_HEADER_COMPACT(f->header) ? " COMPACT" : "",
+               (le32toh(f->header->incompatible_flags) & ~HEADER_INCOMPATIBLE_ANY) ? " ???" : "",
+               le64toh(f->header->header_size),
+               le64toh(f->header->arena_size),
+               le64toh(f->header->data_hash_table_size) / sizeof(HashItem),
+               le64toh(f->header->field_hash_table_size) / sizeof(HashItem),
+               yes_no(journal_file_rotate_suggested(f, 0, LOG_DEBUG)),
+               le64toh(f->header->head_entry_seqnum), le64toh(f->header->head_entry_seqnum),
+               le64toh(f->header->tail_entry_seqnum), le64toh(f->header->tail_entry_seqnum),
+               FORMAT_TIMESTAMP_SAFE(le64toh(f->header->head_entry_realtime)), le64toh(f->header->head_entry_realtime),
+               FORMAT_TIMESTAMP_SAFE(le64toh(f->header->tail_entry_realtime)), le64toh(f->header->tail_entry_realtime),
+               FORMAT_TIMESPAN(le64toh(f->header->tail_entry_monotonic), USEC_PER_MSEC), le64toh(f->header->tail_entry_monotonic),
+               le64toh(f->header->n_objects),
+               le64toh(f->header->n_entries));
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_data))
+                printf("Data objects: %"PRIu64"\n"
+                       "Data hash table fill: %.1f%%\n",
+                       le64toh(f->header->n_data),
+                       100.0 * (double) le64toh(f->header->n_data) / ((double) (le64toh(f->header->data_hash_table_size) / sizeof(HashItem))));
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_fields))
+                printf("Field objects: %"PRIu64"\n"
+                       "Field hash table fill: %.1f%%\n",
+                       le64toh(f->header->n_fields),
+                       100.0 * (double) le64toh(f->header->n_fields) / ((double) (le64toh(f->header->field_hash_table_size) / sizeof(HashItem))));
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_tags))
+                printf("Tag objects: %"PRIu64"\n",
+                       le64toh(f->header->n_tags));
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_entry_arrays))
+                printf("Entry array objects: %"PRIu64"\n",
+                       le64toh(f->header->n_entry_arrays));
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, field_hash_chain_depth))
+                printf("Deepest field hash chain: %" PRIu64"\n",
+                       f->header->field_hash_chain_depth);
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, data_hash_chain_depth))
+                printf("Deepest data hash chain: %" PRIu64"\n",
+                       f->header->data_hash_chain_depth);
+
+        if (fstat(f->fd, &st) >= 0)
+                printf("Disk usage: %s\n", FORMAT_BYTES((uint64_t) st.st_blocks * 512ULL));
+}
+
+static int journal_file_warn_btrfs(JournalFile *f) {
+        unsigned attrs;
+        int r;
+
+        assert(f);
+
+        /* Before we write anything, check if the COW logic is turned
+         * off on btrfs. Given our write pattern that is quite
+         * unfriendly to COW file systems this should greatly improve
+         * performance on COW file systems, such as btrfs, at the
+         * expense of data integrity features (which shouldn't be too
+         * bad, given that we do our own checksumming). */
+
+        r = fd_is_fs_type(f->fd, BTRFS_SUPER_MAGIC);
+        if (r < 0)
+                return log_warning_errno(r, "Failed to determine if journal is on btrfs: %m");
+        if (!r)
+                return 0;
+
+        r = read_attr_fd(f->fd, &attrs);
+        if (r < 0)
+                return log_warning_errno(r, "Failed to read file attributes: %m");
+
+        if (attrs & FS_NOCOW_FL) {
+                log_debug("Detected btrfs file system with copy-on-write disabled, all is good.");
+                return 0;
+        }
+
+        log_notice("Creating journal file %s on a btrfs file system, and copy-on-write is enabled. "
+                   "This is likely to slow down journal access substantially, please consider turning "
+                   "off the copy-on-write file attribute on the journal directory, using chattr +C.", f->path);
+
+        return 1;
+}
+
+static void journal_default_metrics(JournalMetrics *m, int fd, bool compact) {
+        struct statvfs ss;
+        uint64_t fs_size = 0;
+
+        assert(m);
+        assert(fd >= 0);
+
+        if (fstatvfs(fd, &ss) >= 0)
+                fs_size = ss.f_frsize * ss.f_blocks;
+        else
+                log_debug_errno(errno, "Failed to determine disk size: %m");
+
+        if (m->max_use == UINT64_MAX) {
+
+                if (fs_size > 0)
+                        m->max_use = CLAMP(PAGE_ALIGN(fs_size / 10), /* 10% of file system size */
+                                           MAX_USE_LOWER, MAX_USE_UPPER);
+                else
+                        m->max_use = MAX_USE_LOWER;
+        } else {
+                m->max_use = PAGE_ALIGN(m->max_use);
+
+                if (m->max_use != 0 && m->max_use < JOURNAL_FILE_SIZE_MIN*2)
+                        m->max_use = JOURNAL_FILE_SIZE_MIN*2;
+        }
+
+        if (m->min_use == UINT64_MAX) {
+                if (fs_size > 0)
+                        m->min_use = CLAMP(PAGE_ALIGN(fs_size / 50), /* 2% of file system size */
+                                           MIN_USE_LOW, MIN_USE_HIGH);
+                else
+                        m->min_use = MIN_USE_LOW;
+        }
+
+        if (m->min_use > m->max_use)
+                m->min_use = m->max_use;
+
+        if (m->max_size == UINT64_MAX)
+                m->max_size = MIN(PAGE_ALIGN(m->max_use / 8), /* 8 chunks */
+                                  MAX_SIZE_UPPER);
+        else
+                m->max_size = PAGE_ALIGN(m->max_size);
+
+        if (compact && m->max_size > JOURNAL_COMPACT_SIZE_MAX)
+                m->max_size = JOURNAL_COMPACT_SIZE_MAX;
+
+        if (m->max_size != 0) {
+                if (m->max_size < JOURNAL_FILE_SIZE_MIN)
+                        m->max_size = JOURNAL_FILE_SIZE_MIN;
+
+                if (m->max_use != 0 && m->max_size*2 > m->max_use)
+                        m->max_use = m->max_size*2;
+        }
+
+        if (m->min_size == UINT64_MAX)
+                m->min_size = JOURNAL_FILE_SIZE_MIN;
+        else
+                m->min_size = CLAMP(PAGE_ALIGN(m->min_size),
+                                    JOURNAL_FILE_SIZE_MIN,
+                                    m->max_size ?: UINT64_MAX);
+
+        if (m->keep_free == UINT64_MAX) {
+                if (fs_size > 0)
+                        m->keep_free = MIN(PAGE_ALIGN(fs_size / 20), /* 5% of file system size */
+                                           KEEP_FREE_UPPER);
+                else
+                        m->keep_free = DEFAULT_KEEP_FREE;
+        }
+
+        if (m->n_max_files == UINT64_MAX)
+                m->n_max_files = DEFAULT_N_MAX_FILES;
+
+        log_debug("Fixed min_use=%s max_use=%s max_size=%s min_size=%s keep_free=%s n_max_files=%" PRIu64,
+                  FORMAT_BYTES(m->min_use),
+                  FORMAT_BYTES(m->max_use),
+                  FORMAT_BYTES(m->max_size),
+                  FORMAT_BYTES(m->min_size),
+                  FORMAT_BYTES(m->keep_free),
+                  m->n_max_files);
+}
+
+int journal_file_open(
+                int fd,
+                const char *fname,
+                int open_flags,
+                JournalFileFlags file_flags,
+                mode_t mode,
+                uint64_t compress_threshold_bytes,
+                JournalMetrics *metrics,
+                MMapCache *mmap_cache,
+                JournalFile *template,
+                JournalFile **ret) {
+
+        bool newly_created = false;
+        JournalFile *f;
+        void *h;
+        int r;
+
+        assert(fd >= 0 || fname);
+        assert(mmap_cache);
+        assert(ret);
+
+        if (!IN_SET((open_flags & O_ACCMODE), O_RDONLY, O_RDWR))
+                return -EINVAL;
+
+        if ((open_flags & O_ACCMODE) == O_RDONLY && FLAGS_SET(open_flags, O_CREAT))
+                return -EINVAL;
+
+        if (fname && (open_flags & O_CREAT) && !endswith(fname, ".journal"))
+                return -EINVAL;
+
+        f = new(JournalFile, 1);
+        if (!f)
+                return -ENOMEM;
+
+        *f = (JournalFile) {
+                .fd = fd,
+                .mode = mode,
+                .open_flags = open_flags,
+                .compress_threshold_bytes = compress_threshold_bytes == UINT64_MAX ?
+                                            DEFAULT_COMPRESS_THRESHOLD :
+                                            MAX(MIN_COMPRESS_THRESHOLD, compress_threshold_bytes),
+        };
+
+        if (fname) {
+                f->path = strdup(fname);
+                if (!f->path) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+        } else {
+                assert(fd >= 0);
+
+                /* If we don't know the path, fill in something explanatory and vaguely useful */
+                if (asprintf(&f->path, "/proc/self/%i", fd) < 0) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+        }
+
+        f->chain_cache = ordered_hashmap_new(&uint64_hash_ops);
+        if (!f->chain_cache) {
+                r = -ENOMEM;
+                goto fail;
+        }
+
+        if (f->fd < 0) {
+                /* We pass O_NONBLOCK here, so that in case somebody pointed us to some character device node or FIFO
+                 * or so, we likely fail quickly than block for long. For regular files O_NONBLOCK has no effect, hence
+                 * it doesn't hurt in that case. */
+
+                f->fd = openat_report_new(AT_FDCWD, f->path, f->open_flags|O_CLOEXEC|O_NONBLOCK, f->mode, &newly_created);
+                if (f->fd < 0) {
+                        r = f->fd;
+                        goto fail;
+                }
+
+                /* fds we opened here by us should also be closed by us. */
+                f->close_fd = true;
+
+                r = fd_nonblock(f->fd, false);
+                if (r < 0)
+                        goto fail;
+
+                if (!newly_created) {
+                        r = journal_file_fstat(f);
+                        if (r < 0)
+                                goto fail;
+                }
+        } else {
+                r = journal_file_fstat(f);
+                if (r < 0)
+                        goto fail;
+
+                /* If we just got the fd passed in, we don't really know if we created the file anew */
+                newly_created = f->last_stat.st_size == 0 && journal_file_writable(f);
+        }
+
+        f->cache_fd = mmap_cache_add_fd(mmap_cache, f->fd, prot_from_flags(open_flags));
+        if (!f->cache_fd) {
+                r = -ENOMEM;
+                goto fail;
+        }
+
+        if (newly_created) {
+                (void) journal_file_warn_btrfs(f);
+
+                /* Let's attach the creation time to the journal file, so that the vacuuming code knows the age of this
+                 * file even if the file might end up corrupted one day... Ideally we'd just use the creation time many
+                 * file systems maintain for each file, but the API to query this is very new, hence let's emulate this
+                 * via extended attributes. If extended attributes are not supported we'll just skip this, and rely
+                 * solely on mtime/atime/ctime of the file. */
+                (void) fd_setcrtime(f->fd, 0);
+
+                r = journal_file_init_header(f, file_flags, template);
+                if (r < 0)
+                        goto fail;
+
+                r = journal_file_fstat(f);
+                if (r < 0)
+                        goto fail;
+        }
+
+        if (f->last_stat.st_size < (off_t) HEADER_SIZE_MIN) {
+                r = -ENODATA;
+                goto fail;
+        }
+
+        r = mmap_cache_fd_get(f->cache_fd, CONTEXT_HEADER, true, 0, PAGE_ALIGN(sizeof(Header)), &f->last_stat, &h);
+        if (r == -EINVAL) {
+                /* Some file systems (jffs2 or p9fs) don't support mmap() properly (or only read-only
+                 * mmap()), and return EINVAL in that case. Let's propagate that as a more recognizable error
+                 * code. */
+                r = -EAFNOSUPPORT;
+                goto fail;
+        }
+        if (r < 0)
+                goto fail;
+
+        f->header = h;
+
+        if (!newly_created) {
+                r = journal_file_verify_header(f);
+                if (r < 0)
+                        goto fail;
+        }
+
+#if HAVE_GCRYPT
+        if (!newly_created && journal_file_writable(f) && JOURNAL_HEADER_SEALED(f->header)) {
+                r = journal_file_fss_load(f);
+                if (r < 0)
+                        goto fail;
+        }
+#endif
+
+        if (journal_file_writable(f)) {
+                if (metrics) {
+                        journal_default_metrics(metrics, f->fd, JOURNAL_HEADER_COMPACT(f->header));
+                        f->metrics = *metrics;
+                } else if (template)
+                        f->metrics = template->metrics;
+
+                r = journal_file_refresh_header(f);
+                if (r < 0)
+                        goto fail;
+        }
+
+#if HAVE_GCRYPT
+        r = journal_file_hmac_setup(f);
+        if (r < 0)
+                goto fail;
+#endif
+
+        if (newly_created) {
+                r = journal_file_setup_field_hash_table(f);
+                if (r < 0)
+                        goto fail;
+
+                r = journal_file_setup_data_hash_table(f);
+                if (r < 0)
+                        goto fail;
+
+#if HAVE_GCRYPT
+                r = journal_file_append_first_tag(f);
+                if (r < 0)
+                        goto fail;
+#endif
+        }
+
+        if (mmap_cache_fd_got_sigbus(f->cache_fd)) {
+                r = -EIO;
+                goto fail;
+        }
+
+        if (template && template->post_change_timer) {
+                r = journal_file_enable_post_change_timer(
+                                f,
+                                sd_event_source_get_event(template->post_change_timer),
+                                template->post_change_timer_period);
+
+                if (r < 0)
+                        goto fail;
+        }
+
+        /* The file is opened now successfully, thus we take possession of any passed in fd. */
+        f->close_fd = true;
+
+        if (DEBUG_LOGGING) {
+                static int last_seal = -1, last_compress = -1, last_keyed_hash = -1;
+                static uint64_t last_bytes = UINT64_MAX;
+
+                if (last_seal != JOURNAL_HEADER_SEALED(f->header) ||
+                    last_keyed_hash != JOURNAL_HEADER_KEYED_HASH(f->header) ||
+                    last_compress != JOURNAL_FILE_COMPRESS(f) ||
+                    last_bytes != f->compress_threshold_bytes) {
+
+                        log_debug("Journal effective settings seal=%s keyed_hash=%s compress=%s compress_threshold_bytes=%s",
+                                  yes_no(JOURNAL_HEADER_SEALED(f->header)), yes_no(JOURNAL_HEADER_KEYED_HASH(f->header)),
+                                  yes_no(JOURNAL_FILE_COMPRESS(f)), FORMAT_BYTES(f->compress_threshold_bytes));
+                        last_seal = JOURNAL_HEADER_SEALED(f->header);
+                        last_keyed_hash = JOURNAL_HEADER_KEYED_HASH(f->header);
+                        last_compress = JOURNAL_FILE_COMPRESS(f);
+                        last_bytes = f->compress_threshold_bytes;
+                }
+        }
+
+        *ret = f;
+        return 0;
+
+fail:
+        if (f->cache_fd && mmap_cache_fd_got_sigbus(f->cache_fd))
+                r = -EIO;
+
+        (void) journal_file_close(f);
+
+        if (newly_created && fd < 0)
+                (void) unlink(fname);
+
+        return r;
+}
+
+int journal_file_archive(JournalFile *f, char **ret_previous_path) {
+        _cleanup_free_ char *p = NULL;
+
+        assert(f);
+
+        if (!journal_file_writable(f))
+                return -EINVAL;
+
+        /* Is this a journal file that was passed to us as fd? If so, we synthesized a path name for it, and we refuse
+         * rotation, since we don't know the actual path, and couldn't rename the file hence. */
+        if (path_startswith(f->path, "/proc/self/fd"))
+                return -EINVAL;
+
+        if (!endswith(f->path, ".journal"))
+                return -EINVAL;
+
+        if (asprintf(&p, "%.*s@" SD_ID128_FORMAT_STR "-%016"PRIx64"-%016"PRIx64".journal",
+                     (int) strlen(f->path) - 8, f->path,
+                     SD_ID128_FORMAT_VAL(f->header->seqnum_id),
+                     le64toh(f->header->head_entry_seqnum),
+                     le64toh(f->header->head_entry_realtime)) < 0)
+                return -ENOMEM;
+
+        /* Try to rename the file to the archived version. If the file already was deleted, we'll get ENOENT, let's
+         * ignore that case. */
+        if (rename(f->path, p) < 0 && errno != ENOENT)
+                return -errno;
+
+        /* Sync the rename to disk */
+        (void) fsync_directory_of_file(f->fd);
+
+        if (ret_previous_path)
+                *ret_previous_path = f->path;
+        else
+                free(f->path);
+
+        f->path = TAKE_PTR(p);
+
+        /* Set as archive so offlining commits w/state=STATE_ARCHIVED. Previously we would set old_file->header->state
+         * to STATE_ARCHIVED directly here, but journal_file_set_offline() short-circuits when state != STATE_ONLINE,
+         * which would result in the rotated journal never getting fsync() called before closing.  Now we simply queue
+         * the archive state by setting an archive bit, leaving the state as STATE_ONLINE so proper offlining
+         * occurs. */
+        f->archive = true;
+
+        return 0;
+}
+
+int journal_file_dispose(int dir_fd, const char *fname) {
+        _cleanup_free_ char *p = NULL;
+
+        assert(fname);
+
+        /* Renames a journal file to *.journal~, i.e. to mark it as corrupted or otherwise uncleanly shutdown. Note that
+         * this is done without looking into the file or changing any of its contents. The idea is that this is called
+         * whenever something is suspicious and we want to move the file away and make clear that it is not accessed
+         * for writing anymore. */
+
+        if (!endswith(fname, ".journal"))
+                return -EINVAL;
+
+        if (asprintf(&p, "%.*s@%016" PRIx64 "-%016" PRIx64 ".journal~",
+                     (int) strlen(fname) - 8, fname,
+                     now(CLOCK_REALTIME),
+                     random_u64()) < 0)
+                return -ENOMEM;
+
+        if (renameat(dir_fd, fname, dir_fd, p) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int journal_file_copy_entry(JournalFile *from, JournalFile *to, Object *o, uint64_t p) {
+        _cleanup_free_ EntryItem *items_alloc = NULL;
+        EntryItem *items;
+        uint64_t n, m = 0, xor_hash = 0;
+        sd_id128_t boot_id;
+        dual_timestamp ts;
+        int r;
+
+        assert(from);
+        assert(to);
+        assert(o);
+        assert(p > 0);
+
+        if (!journal_file_writable(to))
+                return -EPERM;
+
+        ts = (dual_timestamp) {
+                .monotonic = le64toh(o->entry.monotonic),
+                .realtime = le64toh(o->entry.realtime),
+        };
+        boot_id = o->entry.boot_id;
+
+        n = journal_file_entry_n_items(from, o);
+        if (n == 0)
+                return 0;
+
+        if (n < ALLOCA_MAX / sizeof(EntryItem) / 2)
+                items = newa(EntryItem, n);
+        else {
+                items_alloc = new(EntryItem, n);
+                if (!items_alloc)
+                        return -ENOMEM;
+
+                items = items_alloc;
+        }
+
+        for (uint64_t i = 0; i < n; i++) {
+                uint64_t h, q;
+                void *data;
+                size_t l;
+                Object *u;
+
+                q = journal_file_entry_item_object_offset(from, o, i);
+                r = journal_file_data_payload(from, NULL, q, NULL, 0, 0, &data, &l);
+                if (IN_SET(r, -EADDRNOTAVAIL, -EBADMSG)) {
+                        log_debug_errno(r, "Entry item %"PRIu64" data object is bad, skipping over it: %m", i);
+                        goto next;
+                }
+                if (r < 0)
+                        return r;
+                assert(r > 0);
+
+                if (l == 0)
+                        return -EBADMSG;
+
+                r = journal_file_append_data(to, data, l, &u, &h);
+                if (r < 0)
+                        return r;
+
+                if (JOURNAL_HEADER_KEYED_HASH(to->header))
+                        xor_hash ^= jenkins_hash64(data, l);
+                else
+                        xor_hash ^= le64toh(u->data.hash);
+
+                items[m++] = (EntryItem) {
+                        .object_offset = h,
+                        .hash = le64toh(u->data.hash),
+                };
+
+        next:
+                /* The above journal_file_data_payload() may clear or overwrite cached object. Hence, we need
+                 * to re-read the object from the cache. */
+                r = journal_file_move_to_object(from, OBJECT_ENTRY, p, &o);
+                if (r < 0)
+                        return r;
+        }
+
+        if (m == 0)
+                return 0;
+
+        r = journal_file_append_entry_internal(to, &ts, &boot_id, xor_hash, items, m, NULL, NULL, NULL);
+
+        if (mmap_cache_fd_got_sigbus(to->cache_fd))
+                return -EIO;
+
+        return r;
+}
+
+void journal_reset_metrics(JournalMetrics *m) {
+        assert(m);
+
+        /* Set everything to "pick automatic values". */
+
+        *m = (JournalMetrics) {
+                .min_use = UINT64_MAX,
+                .max_use = UINT64_MAX,
+                .min_size = UINT64_MAX,
+                .max_size = UINT64_MAX,
+                .keep_free = UINT64_MAX,
+                .n_max_files = UINT64_MAX,
+        };
+}
+
+int journal_file_get_cutoff_realtime_usec(JournalFile *f, usec_t *ret_from, usec_t *ret_to) {
+        assert(f);
+        assert(f->header);
+        assert(ret_from || ret_to);
+
+        if (ret_from) {
+                if (f->header->head_entry_realtime == 0)
+                        return -ENOENT;
+
+                *ret_from = le64toh(f->header->head_entry_realtime);
+        }
+
+        if (ret_to) {
+                if (f->header->tail_entry_realtime == 0)
+                        return -ENOENT;
+
+                *ret_to = le64toh(f->header->tail_entry_realtime);
+        }
+
+        return 1;
+}
+
+int journal_file_get_cutoff_monotonic_usec(JournalFile *f, sd_id128_t boot_id, usec_t *ret_from, usec_t *ret_to) {
+        Object *o;
+        uint64_t p;
+        int r;
+
+        assert(f);
+        assert(ret_from || ret_to);
+
+        /* FIXME: fix return value assignment on success with 0. */
+
+        r = find_data_object_by_boot_id(f, boot_id, &o, &p);
+        if (r <= 0)
+                return r;
+
+        if (le64toh(o->data.n_entries) <= 0)
+                return 0;
+
+        if (ret_from) {
+                r = journal_file_move_to_object(f, OBJECT_ENTRY, le64toh(o->data.entry_offset), &o);
+                if (r < 0)
+                        return r;
+
+                *ret_from = le64toh(o->entry.monotonic);
+        }
+
+        if (ret_to) {
+                r = journal_file_move_to_object(f, OBJECT_DATA, p, &o);
+                if (r < 0)
+                        return r;
+
+                r = generic_array_get_plus_one(f,
+                                               le64toh(o->data.entry_offset),
+                                               le64toh(o->data.entry_array_offset),
+                                               le64toh(o->data.n_entries) - 1,
+                                               DIRECTION_UP,
+                                               &o, NULL);
+                if (r <= 0)
+                        return r;
+
+                *ret_to = le64toh(o->entry.monotonic);
+        }
+
+        return 1;
+}
+
+bool journal_file_rotate_suggested(JournalFile *f, usec_t max_file_usec, int log_level) {
+        assert(f);
+        assert(f->header);
+
+        /* If we gained new header fields we gained new features,
+         * hence suggest a rotation */
+        if (le64toh(f->header->header_size) < sizeof(Header)) {
+                log_full(log_level, "%s uses an outdated header, suggesting rotation.", f->path);
+                return true;
+        }
+
+        /* Let's check if the hash tables grew over a certain fill level (75%, borrowing this value from
+         * Java's hash table implementation), and if so suggest a rotation. To calculate the fill level we
+         * need the n_data field, which only exists in newer versions. */
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_data))
+                if (le64toh(f->header->n_data) * 4ULL > (le64toh(f->header->data_hash_table_size) / sizeof(HashItem)) * 3ULL) {
+                        log_full(log_level,
+                                 "Data hash table of %s has a fill level at %.1f (%"PRIu64" of %"PRIu64" items, %llu file size, %"PRIu64" bytes per hash table item), suggesting rotation.",
+                                 f->path,
+                                 100.0 * (double) le64toh(f->header->n_data) / ((double) (le64toh(f->header->data_hash_table_size) / sizeof(HashItem))),
+                                 le64toh(f->header->n_data),
+                                 le64toh(f->header->data_hash_table_size) / sizeof(HashItem),
+                                 (unsigned long long) f->last_stat.st_size,
+                                 f->last_stat.st_size / le64toh(f->header->n_data));
+                        return true;
+                }
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_fields))
+                if (le64toh(f->header->n_fields) * 4ULL > (le64toh(f->header->field_hash_table_size) / sizeof(HashItem)) * 3ULL) {
+                        log_full(log_level,
+                                 "Field hash table of %s has a fill level at %.1f (%"PRIu64" of %"PRIu64" items), suggesting rotation.",
+                                 f->path,
+                                 100.0 * (double) le64toh(f->header->n_fields) / ((double) (le64toh(f->header->field_hash_table_size) / sizeof(HashItem))),
+                                 le64toh(f->header->n_fields),
+                                 le64toh(f->header->field_hash_table_size) / sizeof(HashItem));
+                        return true;
+                }
+
+        /* If there are too many hash collisions somebody is most likely playing games with us. Hence, if our
+         * longest chain is longer than some threshold, let's suggest rotation. */
+        if (JOURNAL_HEADER_CONTAINS(f->header, data_hash_chain_depth) &&
+            le64toh(f->header->data_hash_chain_depth) > HASH_CHAIN_DEPTH_MAX) {
+                log_full(log_level,
+                         "Data hash table of %s has deepest hash chain of length %" PRIu64 ", suggesting rotation.",
+                         f->path, le64toh(f->header->data_hash_chain_depth));
+                return true;
+        }
+
+        if (JOURNAL_HEADER_CONTAINS(f->header, field_hash_chain_depth) &&
+            le64toh(f->header->field_hash_chain_depth) > HASH_CHAIN_DEPTH_MAX) {
+                log_full(log_level,
+                         "Field hash table of %s has deepest hash chain of length at %" PRIu64 ", suggesting rotation.",
+                         f->path, le64toh(f->header->field_hash_chain_depth));
+                return true;
+        }
+
+        /* Are the data objects properly indexed by field objects? */
+        if (JOURNAL_HEADER_CONTAINS(f->header, n_data) &&
+            JOURNAL_HEADER_CONTAINS(f->header, n_fields) &&
+            le64toh(f->header->n_data) > 0 &&
+            le64toh(f->header->n_fields) == 0) {
+                log_full(log_level,
+                         "Data objects of %s are not indexed by field objects, suggesting rotation.",
+                         f->path);
+                return true;
+        }
+
+        if (max_file_usec > 0) {
+                usec_t t, h;
+
+                h = le64toh(f->header->head_entry_realtime);
+                t = now(CLOCK_REALTIME);
+
+                if (h > 0 && t > h + max_file_usec) {
+                        log_full(log_level,
+                                 "Oldest entry in %s is older than the configured file retention duration (%s), suggesting rotation.",
+                                 f->path, FORMAT_TIMESPAN(max_file_usec, USEC_PER_SEC));
+                        return true;
+                }
+        }
+
+        return false;
+}
+
+static const char * const journal_object_type_table[] = {
+        [OBJECT_UNUSED] = "unused",
+        [OBJECT_DATA] = "data",
+        [OBJECT_FIELD] = "field",
+        [OBJECT_ENTRY] = "entry",
+        [OBJECT_DATA_HASH_TABLE] = "data hash table",
+        [OBJECT_FIELD_HASH_TABLE] = "field hash table",
+        [OBJECT_ENTRY_ARRAY] = "entry array",
+        [OBJECT_TAG] = "tag",
+};
+
+DEFINE_STRING_TABLE_LOOKUP_TO_STRING(journal_object_type, ObjectType);