src/lib-index/mail-index-sync-update.c

	mail-index-sync-update.c revision 1b3bb8d39686ed24730cbc31cc9a33dc62c8c6c3
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina/* Copyright (C) 2004 Timo Sirainen */
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "lib.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "ioloop.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "buffer.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "file-set-size.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "mmap-util.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "mail-index-view-private.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "mail-index-sync-private.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "mail-transaction-log.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include "mail-transaction-util.h"
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina#include <stdlib.h>
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březinastatic void mail_index_sync_replace_map(struct mail_index_view *view,
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina                    struct mail_index_map *map)
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina{
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    mail_index_unmap(view->index, view->map);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    view->map = map;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    view->map->refcount++;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    mail_index_unmap(view->index, view->index->map);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    view->index->map = map;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    view->index->hdr = &map->hdr;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    map->write_to_disk = TRUE;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina}
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březinastatic void
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březinamail_index_sync_init_expunge_handlers(struct mail_index_sync_map_ctx *ctx)
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina{
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    const mail_index_expunge_handler_t *const *handlers;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina        const struct mail_index_ext *extensions;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    const uint32_t *id_map;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    struct mail_index_expunge_handler eh;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    size_t handlers_count, id_map_size, size;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    uint32_t ext_id;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    handlers = buffer_get_data(ctx->view->index->expunge_handlers,
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina                   &handlers_count);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    handlers_count /= sizeof(*handlers);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    if (handlers_count == 0)
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina        return;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    /* set expunge handlers */
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    memset(&eh, 0, sizeof(eh));
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    if (ctx->expunge_handlers != NULL)
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina        buffer_set_used_size(ctx->expunge_handlers, 0);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    else {
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina        ctx->expunge_handlers =
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina            buffer_create_dynamic(default_pool, 256);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    }
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    extensions = ctx->view->map->extensions->data;
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    id_map = buffer_get_data(ctx->view->map->ext_id_map, &id_map_size);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    id_map_size /= sizeof(*id_map);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    size = I_MIN(handlers_count, id_map_size);
04e870d99e72aa3160bdb6ab05d986fb4005c3edPavel Březina    for (ext_id = 0; ext_id < size; ext_id++) {
        if (handlers[ext_id] == NULL || id_map[ext_id] == (uint32_t)-1)
            continue;

        eh.handler = handlers[ext_id];
        eh.context = &ctx->extra_context[ext_id];
        eh.record_offset = extensions[id_map[ext_id]].record_offset;
        buffer_append(ctx->expunge_handlers, &eh, sizeof(eh));
    }
    ctx->expunge_handlers_set = TRUE;
    ctx->expunge_handlers_used = TRUE;
}

static void
mail_index_sync_deinit_expunge_handlers(struct mail_index_sync_map_ctx *ctx)
{
    const struct mail_index_expunge_handler *eh;
    size_t i, size;

    if (ctx->expunge_handlers == NULL)
        return;

    eh = buffer_get_data(ctx->expunge_handlers, &size);
    size /= sizeof(*eh);

    for (i = 0; i < size; i++) {
        if (eh->context != NULL)
            eh[i].handler(ctx, 0, NULL, eh->context);
    }

    buffer_free(ctx->expunge_handlers);
}

static void mail_index_sync_init_handlers(struct mail_index_sync_map_ctx *ctx)
{
    size_t size;

    if (ctx->view->map->extensions == NULL)
        return;

    /* set space for extra contexts */
    size = sizeof(void *) * (ctx->view->index->extensions->used /
                 sizeof(struct mail_index_ext));
    if (ctx->extra_context_buf == NULL) {
        ctx->extra_context_buf =
            buffer_create_dynamic(default_pool, size);
    } else {
        buffer_set_used_size(ctx->extra_context_buf, 0);
    }
    buffer_append_zero(ctx->extra_context_buf, size);
    ctx->extra_context =
        buffer_get_modifyable_data(ctx->extra_context_buf, NULL);

    ctx->expunge_handlers_set = FALSE;
}

static void mail_index_sync_deinit_handlers(struct mail_index_sync_map_ctx *ctx)
{
        const struct mail_index_sync_handler *sync_handlers;
    size_t i, size;

    if (ctx->extra_context == NULL)
        return;

    sync_handlers = buffer_get_data(ctx->view->index->sync_handlers, &size);
    size /= sizeof(*sync_handlers);

    i_assert(size <= ctx->extra_context_buf->used / sizeof(void *));

    for (i = 0; i < size; i++) {
        if (ctx->extra_context[i] != NULL) {
            sync_handlers[i].callback(ctx, 0, NULL, NULL,
                          &ctx->extra_context[i]);
        }
    }

    buffer_free(ctx->extra_context_buf);
}

static void
mail_index_header_update_counts(struct mail_index_header *hdr,
                uint8_t old_flags, uint8_t new_flags)
{
    if (((old_flags ^ new_flags) & MAIL_RECENT) != 0) {
        /* different recent-flag */
        if ((old_flags & MAIL_RECENT) == 0)
            hdr->recent_messages_count++;
        else if (--hdr->recent_messages_count == 0)
            hdr->first_recent_uid_lowwater = hdr->next_uid;
    }

    if (((old_flags ^ new_flags) & MAIL_SEEN) != 0) {
        /* different seen-flag */
        if ((old_flags & MAIL_SEEN) != 0)
            hdr->seen_messages_count--;
        else if (++hdr->seen_messages_count == hdr->messages_count)
            hdr->first_unseen_uid_lowwater = hdr->next_uid;
    }

    if (((old_flags ^ new_flags) & MAIL_DELETED) != 0) {
        /* different deleted-flag */
        if ((old_flags & MAIL_DELETED) == 0)
            hdr->deleted_messages_count++;
        else if (--hdr->deleted_messages_count == 0)
            hdr->first_deleted_uid_lowwater = hdr->next_uid;
    }
}

static void
mail_index_header_update_lowwaters(struct mail_index_header *hdr,
                   const struct mail_index_record *rec)
{
    if ((rec->flags & MAIL_RECENT) != 0 &&
        rec->uid < hdr->first_recent_uid_lowwater)
        hdr->first_recent_uid_lowwater = rec->uid;
    if ((rec->flags & MAIL_SEEN) == 0 &&
        rec->uid < hdr->first_unseen_uid_lowwater)
        hdr->first_unseen_uid_lowwater = rec->uid;
    if ((rec->flags & MAIL_DELETED) != 0 &&
        rec->uid < hdr->first_deleted_uid_lowwater)
        hdr->first_deleted_uid_lowwater = rec->uid;
}

static int sync_expunge(const struct mail_transaction_expunge *e, void *context)
{
        struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_view *view = ctx->view;
    struct mail_index_map *map = view->map;
    struct mail_index_record *rec;
    uint32_t count, seq, seq1, seq2;
        struct mail_index_expunge_handler *expunge_handlers, *eh;
    size_t i, expunge_handlers_count;

    if (e->uid1 > e->uid2 || e->uid1 == 0) {
        mail_transaction_log_view_set_corrupted(ctx->view->log_view,
                "Invalid UID range in expunge (%u .. %u)",
                e->uid1, e->uid2);
        return -1;
    }

    if (!view->map->write_to_disk) {
        /* expunges have to be atomic. so we'll have to copy
           the mapping, do the changes there and then finally
           replace the whole index file. to avoid extra disk
           I/O we copy the index into memory rather than to
           temporary file */
        map = mail_index_map_to_memory(map, map->hdr.record_size);
        mail_index_sync_replace_map(view, map);
    }
    i_assert(MAIL_INDEX_MAP_IS_IN_MEMORY(map));

    if (mail_index_lookup_uid_range(view, e->uid1, e->uid2,
                    &seq1, &seq2) < 0)
        return -1;

    if (seq1 == 0)
        return 1;

    if (ctx->type != MAIL_INDEX_SYNC_HANDLER_VIEW) {
        if (!ctx->expunge_handlers_set)
            mail_index_sync_init_expunge_handlers(ctx);

        expunge_handlers =
            buffer_get_modifyable_data(ctx->expunge_handlers,
                           &expunge_handlers_count);
        expunge_handlers_count /= sizeof(*expunge_handlers);
    } else {
        /* syncing view - don't call expunge handlers */
        expunge_handlers = NULL;
        expunge_handlers_count = 0;
    }

    for (seq = seq1; seq <= seq2; seq++) {
                rec = MAIL_INDEX_MAP_IDX(map, seq-1);
        mail_index_header_update_counts(&map->hdr, rec->flags, 0);
    }

    for (i = 0; i < expunge_handlers_count; i++) {
        eh = &expunge_handlers[i];

        for (seq = seq1; seq <= seq2; seq++) {
            rec = MAIL_INDEX_MAP_IDX(map, seq-1);
            eh->handler(ctx, seq,
                    PTR_OFFSET(rec, eh->record_offset),
                    eh->context);
        }
    }

    /* @UNSAFE */
    count = seq2 - seq1 + 1;
    memmove(MAIL_INDEX_MAP_IDX(map, seq1-1), MAIL_INDEX_MAP_IDX(map, seq2),
        (map->records_count - seq2) * map->hdr.record_size);

    map->records_count -= count;
    map->hdr.messages_count -= count;
    view->messages_count -= count;

    if (map->buffer != NULL) {
        buffer_set_used_size(map->buffer, map->records_count *
                     map->hdr.record_size);
        map->records = buffer_get_modifyable_data(map->buffer, NULL);
    }
    return 1;
}

static int sync_append(const struct mail_index_record *rec, void *context)
{
        struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_view *view = ctx->view;
    struct mail_index_map *map = view->map;
    void *dest;

    if (rec->uid < map->hdr.next_uid) {
        mail_transaction_log_view_set_corrupted(view->log_view,
            "Append with UID %u, but next_uid = %u",
            rec->uid, map->hdr.next_uid);
        return -1;
    }

    if (MAIL_INDEX_MAP_IS_IN_MEMORY(map)) {
        i_assert(map->records_count * map->hdr.record_size ==
             buffer_get_used_size(map->buffer));
        dest = buffer_append_space_unsafe(map->buffer,
                          map->hdr.record_size);
        map->records = buffer_get_modifyable_data(map->buffer, NULL);
    } else {
        i_assert((map->records_count+1) * map->hdr.record_size <=
             map->mmap_size);
        dest = MAIL_INDEX_MAP_IDX(map, map->records_count);
    }
    memcpy(dest, rec, sizeof(*rec));
    memset(PTR_OFFSET(dest, sizeof(*rec)), 0,
           map->hdr.record_size - sizeof(*rec));

    map->hdr.messages_count++;
    map->hdr.next_uid = rec->uid+1;
    view->messages_count++;
    map->records_count++;

    if ((rec->flags & MAIL_INDEX_MAIL_FLAG_DIRTY) != 0)
        map->hdr.flags |= MAIL_INDEX_HDR_FLAG_HAVE_DIRTY;

    mail_index_header_update_counts(&map->hdr, 0, rec->flags);
    mail_index_header_update_lowwaters(&map->hdr, rec);
    return 1;
}

static int sync_flag_update(const struct mail_transaction_flag_update *u,
                void *context)
{
        struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_view *view = ctx->view;
    struct mail_index_header *hdr;
    struct mail_index_record *rec;
    uint8_t flag_mask, old_flags;
    keywords_mask_t keyword_mask;
    uint32_t i, idx, seq1, seq2;
    int update_keywords;

    if (u->uid1 > u->uid2 || u->uid1 == 0) {
        mail_transaction_log_view_set_corrupted(ctx->view->log_view,
                "Invalid UID range in flag update (%u .. %u)",
                u->uid1, u->uid2);
        return -1;
    }

    if (mail_index_lookup_uid_range(view, u->uid1, u->uid2,
                    &seq1, &seq2) < 0)
        return -1;

    if (seq1 == 0)
        return 1;

    hdr = &view->map->hdr;
    if ((u->add_flags & MAIL_INDEX_MAIL_FLAG_DIRTY) != 0)
        hdr->flags |= MAIL_INDEX_HDR_FLAG_HAVE_DIRTY;

    update_keywords = FALSE;
    for (i = 0; i < INDEX_KEYWORDS_BYTE_COUNT; i++) {
        if (u->add_keywords[i] != 0 ||
            u->remove_keywords[i] != 0)
            update_keywords = TRUE;
        keyword_mask[i] = ~u->remove_keywords[i];
    }
        flag_mask = ~u->remove_flags;

    for (idx = seq1-1; idx < seq2; idx++) {
                rec = MAIL_INDEX_MAP_IDX(view->map, idx);

        old_flags = rec->flags;
        rec->flags = (rec->flags & flag_mask) | u->add_flags;
        if (update_keywords) {
            for (i = 0; i < INDEX_KEYWORDS_BYTE_COUNT; i++) {
                rec->keywords[i] = u->add_keywords[i] |
                    (rec->keywords[i] & keyword_mask[i]);
            }
        }

        mail_index_header_update_counts(hdr, old_flags, rec->flags);
                mail_index_header_update_lowwaters(hdr, rec);
    }
    return 1;
}

static int sync_header_update(const struct mail_transaction_header_update *u,
                  void *context)
{
    struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_map *map = ctx->view->map;

    if (u->offset >= map->hdr.base_header_size ||
        u->offset + u->size > map->hdr.base_header_size) {
        mail_transaction_log_view_set_corrupted(ctx->view->log_view,
            "Header update outside range: %u + %u > %u",
            u->offset, u->size, map->hdr.base_header_size);
        return -1;
    }

    buffer_write(map->hdr_copy_buf, u->offset, u + 1, u->size);
    map->hdr_base = map->hdr_copy_buf->data;

    /* @UNSAFE */
    if ((uint32_t)(u->offset + u->size) <= sizeof(map->hdr)) {
        memcpy(PTR_OFFSET(&map->hdr, u->offset),
               u + 1, u->size);
    } else if (u->offset < sizeof(map->hdr)) {
        memcpy(PTR_OFFSET(&map->hdr, u->offset),
               u + 1, sizeof(map->hdr) - u->offset);
    }
    return 1;
}

static struct mail_index_ext_header *
get_ext_header(struct mail_index_map *map, const struct mail_index_ext *ext)
{
    struct mail_index_ext_header *ext_hdr;
    uint32_t offset;
    void *hdr_base;

    /* do some kludgy jumping to get to it. */
    offset = ext->hdr_offset -
        MAIL_INDEX_HEADER_SIZE_ALIGN(sizeof(*ext_hdr) +
                         strlen(ext->name));

    hdr_base = buffer_get_modifyable_data(map->hdr_copy_buf, NULL);
    ext_hdr = PTR_OFFSET(hdr_base, offset);
    i_assert(memcmp((char *)(ext_hdr + 1),
            ext->name, strlen(ext->name)) == 0);
    return ext_hdr;
}

static int mail_index_ext_align_cmp(const void *p1, const void *p2)
{
    const struct mail_index_ext *const *e1 = p1, *const *e2 = p2;

    return (int)(*e2)->record_align - (int)(*e1)->record_align;
}

static struct mail_index_map *
sync_ext_reorder(struct mail_index_map *map, uint32_t ext_id, uint16_t old_size)
{
    struct mail_index_map *new_map;
    struct mail_index_ext *ext, **sorted;
    struct mail_index_ext_header *ext_hdr;
    uint16_t *old_offsets, min_align;
    uint32_t offset, old_records_count, rec_idx;
    const void *src;
    size_t i, size;

    t_push();
    ext = buffer_get_modifyable_data(map->extensions, &size);
    size /= sizeof(*ext);

    /* @UNSAFE */
    old_offsets = t_new(uint16_t, size);
    sorted = t_new(struct mail_index_ext *, size);
    for (i = 0; i < size; i++) {
        old_offsets[i] = ext[i].record_offset;
        ext[i].record_offset = 0;
        sorted[i] = &ext[i];
    }
    qsort(sorted, size, sizeof(struct mail_index_ext *),
          mail_index_ext_align_cmp);

    /* we simply try to use the extensions with largest alignment
       requirement first. FIXME: if the extension sizes don't match
       alignmentation, this may not give the minimal layout. */
    offset = sizeof(struct mail_index_record);
    for (;;) {
        min_align = (uint16_t)-1;
        for (i = 0; i < size; i++) {
            if (sorted[i]->record_offset == 0) {
                if ((offset % sorted[i]->record_align) == 0)
                    break;
                if (sorted[i]->record_align < min_align)
                    min_align = sorted[i]->record_align;
            }
        }
        if (i == size) {
            if (min_align == (uint16_t)-1) {
                /* all done */
                break;
            }
            /* we have to leave space here */
            i_assert(min_align > 1 && min_align < (uint16_t)-1);
            offset += min_align - (offset % min_align);
        } else {
            sorted[i]->record_offset = offset;
            offset += sorted[i]->record_size;
        }

        i_assert(offset < (uint16_t)-1);
    }

    if ((offset % sizeof(uint32_t)) != 0) {
        /* keep 32bit alignment */
        offset += sizeof(uint32_t) - (offset % sizeof(uint32_t));
    }

    /* create a new mapping without records. a bit kludgy. */
    old_records_count = map->records_count;
    map->records_count = 0;
    new_map = mail_index_map_to_memory(map, offset);
    map->records_count = old_records_count;

    if (old_size > ext[ext_id].record_size) {
        /* we are shrinking the record */
        old_size = ext[ext_id].record_size;
    }

    /* now copy the records to new mapping */
    src = map->records;
    offset = 0;
    for (rec_idx = 0; rec_idx < old_records_count; rec_idx++) {
        buffer_write(new_map->buffer, offset, src,
                 sizeof(struct mail_index_record));
        for (i = 0; i < size; i++) {
            buffer_write(new_map->buffer,
                     offset + ext[i].record_offset,
                     CONST_PTR_OFFSET(src, old_offsets[i]),
                     i == ext_id ? old_size :
                     ext[i].record_size);
        }
        src = CONST_PTR_OFFSET(src, map->hdr.record_size);
        offset += new_map->hdr.record_size;
    }

    if (ext_id == size-1 && ext[ext_id].record_size != old_size &&
        old_records_count != 0) {
        /* we didn't fully write the last record */
        buffer_append_zero(new_map->buffer,
                   ext[ext_id].record_size - old_size);
    }

    new_map->records = buffer_get_modifyable_data(new_map->buffer, NULL);
    new_map->records_count = old_records_count;

    /* update record offsets in headers */
    for (i = 0; i < size; i++) {
                ext_hdr = get_ext_header(new_map, &ext[i]);
        ext_hdr->record_offset = ext[i].record_offset;
    }

    t_pop();
    return new_map;
}

static void
sync_ext_resize(const struct mail_transaction_ext_intro *u, uint32_t ext_id,
        struct mail_index_sync_map_ctx *ctx)
{
    struct mail_index_map *map = ctx->view->map;
    struct mail_index_ext *ext;
    struct mail_index_ext_header *ext_hdr;
    uint32_t old_size, new_size, old_record_size;
    int modified = FALSE;

    ext = buffer_get_modifyable_data(map->extensions, NULL);
    ext += ext_id;

    old_size = MAIL_INDEX_HEADER_SIZE_ALIGN(ext->hdr_size);
    new_size = MAIL_INDEX_HEADER_SIZE_ALIGN(u->hdr_size);

    if (new_size < old_size) {
        /* header shrinked */
        buffer_delete(map->hdr_copy_buf, ext->hdr_offset + new_size,
                  old_size - new_size);
        modified = TRUE;
    } else if (new_size > old_size) {
        /* header grown */
        buffer_insert_zero(map->hdr_copy_buf,
                   ext->hdr_offset + old_size,
                   new_size - old_size);
        modified = TRUE;
    }

    old_record_size = ext->record_size;
    ext->hdr_size = u->hdr_size;
    ext->record_size = u->record_size;
    ext->record_align = u->record_align;

    if (old_record_size != u->record_size)
        modified = TRUE;

    if (modified) {
        map->hdr_base = map->hdr_copy_buf->data;
        map->hdr.header_size = map->hdr_copy_buf->used;

        ext_hdr = get_ext_header(map, ext);
        ext_hdr->reset_id = ext->reset_id;
        ext_hdr->hdr_size = ext->hdr_size;
        ext_hdr->record_offset = ext->record_offset;
        ext_hdr->record_size = ext->record_size;
        ext_hdr->record_align = ext->record_align;
    }

    if (old_record_size != u->record_size) {
        map = sync_ext_reorder(map, ext_id, old_record_size);
        mail_index_sync_replace_map(ctx->view, map);
    }
}

static int sync_ext_intro(const struct mail_transaction_ext_intro *u,
              void *context)
{
    struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_map *map = ctx->view->map;
    struct mail_index_ext_header ext_hdr;
    const struct mail_index_ext *ext;
    const char *name;
    buffer_t *hdr_buf;
    uint32_t ext_id, hdr_offset;

    if (u->ext_id != (uint32_t)-1 &&
        (map->extensions == NULL ||
         u->ext_id >= map->extensions->used / sizeof(*ext))) {
        mail_transaction_log_view_set_corrupted(ctx->view->log_view,
            "Extension introduction for unknown id %u", u->ext_id);
        return -1;
    }

    if (u->ext_id == (uint32_t)-1 && u->name_size == 0) {
        mail_transaction_log_view_set_corrupted(ctx->view->log_view,
            "Extension introduction without id or name");
        return -1;
    }

    t_push();
    if (u->ext_id != (uint32_t)-1) {
        name = NULL;
        ext_id = u->ext_id;
    } else {
        name = t_strndup(u + 1, u->name_size);
        ext_id = mail_index_map_lookup_ext(map, name);
    }

    if (ext_id != (uint32_t)-1) {
        /* exists already */
        ext = map->extensions->data;
        ext += ext_id;

        if (u->reset_id == ext->reset_id) {
            /* check if we need to resize anything */
            sync_ext_resize(u, ext_id, ctx);
            ctx->cur_ext_ignore = FALSE;
        } else {
            /* extension was reset and this transaction hadn't
               yet seen it. ignore this update. */
            ctx->cur_ext_ignore = TRUE;
        }
        t_pop();

        ctx->cur_ext_id = ext_id;
        return 1;
    }

    hdr_buf = map->hdr_copy_buf;
    if (MAIL_INDEX_HEADER_SIZE_ALIGN(hdr_buf->used) != hdr_buf->used) {
        /* we need to add padding between base header and extensions */
        buffer_append_zero(hdr_buf,
                   MAIL_INDEX_HEADER_SIZE_ALIGN(hdr_buf->used) -
                   hdr_buf->used);
    }

    /* register record offset initially using zero,
       sync_ext_reorder() will fix it. */
    hdr_offset = map->hdr_copy_buf->used + sizeof(ext_hdr) + strlen(name);
    hdr_offset = MAIL_INDEX_HEADER_SIZE_ALIGN(hdr_offset);
    ext_id = mail_index_map_register_ext(ctx->view->index, map, name,
                         hdr_offset, u->hdr_size, 0,
                         u->record_size, u->record_align,
                         u->reset_id);

    ext = map->extensions->data;
    ext += ext_id;

    /* <ext_hdr> <name> [padding] [header data] */
    memset(&ext_hdr, 0, sizeof(ext_hdr));
    ext_hdr.name_size = strlen(name);
    ext_hdr.reset_id = ext->reset_id;
    ext_hdr.hdr_size = ext->hdr_size;
    ext_hdr.record_offset = ext->record_offset;
    ext_hdr.record_size = ext->record_size;
    ext_hdr.record_align = ext->record_align;
    buffer_append(hdr_buf, &ext_hdr, sizeof(ext_hdr));
    buffer_append(hdr_buf, name, strlen(name));
    /* header must begin and end in correct alignment */
    buffer_append_zero(hdr_buf,
        MAIL_INDEX_HEADER_SIZE_ALIGN(hdr_buf->used) - hdr_buf->used +
        MAIL_INDEX_HEADER_SIZE_ALIGN(ext->hdr_size));
    i_assert(hdr_buf->used ==
         hdr_offset + MAIL_INDEX_HEADER_SIZE_ALIGN(ext->hdr_size));

    map->hdr.header_size = hdr_buf->used;
    map->hdr_base = map->hdr_copy_buf->data;

    t_pop();

        mail_index_sync_init_handlers(ctx);

    map = sync_ext_reorder(map, ext_id, 0);
    mail_index_sync_replace_map(ctx->view, map);

    ctx->cur_ext_ignore = FALSE;
    ctx->cur_ext_id = ext_id;
    return 1;
}

static int sync_ext_reset(const struct mail_transaction_ext_reset *u,
              void *context)
{
        struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_view *view = ctx->view;
    struct mail_index_map *map = view->map;
    struct mail_index_ext_header *ext_hdr;
        struct mail_index_ext *ext;
    struct mail_index_record *rec;
    uint32_t i;

    if (ctx->cur_ext_id == (uint32_t)-1) {
        mail_transaction_log_view_set_corrupted(view->log_view,
            "Extension reset without intro prefix");
        return -1;
    }
    if (ctx->cur_ext_ignore)
        return 1;

    ext = buffer_get_modifyable_data(map->extensions, NULL);
    ext += ctx->cur_ext_id;
    ext->reset_id = u->new_reset_id;

    memset(buffer_get_space_unsafe(map->hdr_copy_buf, ext->hdr_offset,
                       ext->hdr_size), 0, ext->hdr_size);
    map->hdr_base = map->hdr_copy_buf->data;

    for (i = 0; i < view->messages_count; i++) {
        rec = MAIL_INDEX_MAP_IDX(view->map, i);
        memset(PTR_OFFSET(rec, ext->record_offset), 0,
               ext->record_size);
    }

    ext_hdr = get_ext_header(map, ext);
    ext_hdr->reset_id = u->new_reset_id;

    return 1;
}

static int sync_ext_hdr_update(const struct mail_transaction_ext_hdr_update *u,
                   void *context)
{
        struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_map *map = ctx->view->map;
        const struct mail_index_ext *ext;

    if (ctx->cur_ext_id == (uint32_t)-1) {
        mail_transaction_log_view_set_corrupted(ctx->view->log_view,
            "Extension header update without intro prefix");
        return -1;
    }
    if (ctx->cur_ext_ignore)
        return 1;

    ext = map->extensions->data;
    ext += ctx->cur_ext_id;

    buffer_write(map->hdr_copy_buf, ext->hdr_offset + u->offset,
             u + 1, u->size);
    map->hdr_base = map->hdr_copy_buf->data;
    return 1;
}

static int
sync_ext_rec_update(const struct mail_transaction_ext_rec_update *u,
            void *context)
{
        struct mail_index_sync_map_ctx *ctx = context;
    struct mail_index_view *view = ctx->view;
    struct mail_index_record *rec;
        const struct mail_index_sync_handler *sync_handlers;
    const struct mail_index_ext *ext;
    void *old_data;
    uint32_t seq;
    int ret;

    i_assert(ctx->cur_ext_id != (uint32_t)-1);
    i_assert(!ctx->cur_ext_ignore);

    if (mail_index_lookup_uid_range(view, u->uid, u->uid, &seq, &seq) < 0)
        return -1;

    if (seq == 0)
        return 1;

    ext = view->map->extensions->data;
    ext += ctx->cur_ext_id;

    rec = MAIL_INDEX_MAP_IDX(view->map, seq-1);
    old_data = PTR_OFFSET(rec, ext->record_offset);

    /* @UNSAFE */
    sync_handlers = view->index->sync_handlers->data;
    sync_handlers += ctx->cur_ext_id;

    /* call sync handlers only when we're syncing index (not view) */
    if ((sync_handlers->type & ctx->type) != 0) {
        ret = sync_handlers->callback(ctx, seq, old_data, u + 1,
                    &ctx->extra_context[ctx->cur_ext_id]);
        if (ret <= 0)
            return ret;
    }

    memcpy(old_data, u + 1, ext->record_size);
    return 1;
}

static int mail_index_grow(struct mail_index *index, struct mail_index_map *map,
               unsigned int count)
{
    void *hdr_copy;
    size_t size, hdr_copy_size;

    if (MAIL_INDEX_MAP_IS_IN_MEMORY(map))
        return 0;

    i_assert(map == index->map);

    size = map->hdr.header_size +
        (map->records_count + count) * map->hdr.record_size;
    if (size <= map->mmap_size)
        return 0;

    /* when we grow fast, do it exponentially */
    if (count < index->last_grow_count)
        count = index->last_grow_count;
    if (count < MAIL_INDEX_MAX_POWER_GROW)
        count = nearest_power(count);
    index->last_grow_count = count;

    size = map->hdr.header_size +
        (map->records_count + count) * map->hdr.record_size;
    if (file_set_size(index->fd, (off_t)size) < 0)
        return mail_index_set_syscall_error(index, "file_set_size()");

    /* we only wish to grow the file, but mail_index_map() updates the
       headers as well and may break our modified hdr_copy. so, take
       a backup of it and put it back afterwards */
    t_push();
    i_assert(map->hdr_copy_buf->used == map->hdr.header_size);
        hdr_copy_size = map->hdr_copy_buf->used;
    hdr_copy = t_malloc(hdr_copy_size);
    memcpy(hdr_copy, map->hdr_copy_buf->data, hdr_copy_size);
    memcpy(hdr_copy, &map->hdr, sizeof(map->hdr));

    if (mail_index_map(index, TRUE) <= 0) {
        t_pop();
        return -1;
    }

    map = index->map;
    buffer_reset(map->hdr_copy_buf);
    buffer_append(map->hdr_copy_buf, hdr_copy, hdr_copy_size);

    map->hdr_base = map->hdr_copy_buf->data;
    memcpy(&map->hdr, hdr_copy, sizeof(map->hdr));
    map->records_count = map->hdr.messages_count;

    i_assert(map->mmap_size >= size);
    t_pop();
    return 0;
}

static void
mail_index_update_day_headers(struct mail_index_header *hdr, uint32_t uid)
{
    const int max_days =
        sizeof(hdr->day_first_uid) / sizeof(hdr->day_first_uid[0]);
    struct tm tm;
    time_t stamp;
    int i, days;

    /* get beginning of today */
    tm = *localtime(&ioloop_time);
    tm.tm_hour = 0;
    tm.tm_min = 0;
    tm.tm_sec = 0;
    stamp = mktime(&tm);
    if (stamp == (time_t)-1)
        i_panic("mktime(today) failed");

    if ((time_t)hdr->day_stamp >= stamp)
        return;

    /* get number of days since last message */
    days = (stamp - hdr->day_stamp) / (3600*24);
    if (days > max_days)
        days = max_days;

    /* @UNSAFE: move days forward and fill the missing days with old
       day_first_uid[0]. */
    memcpy(hdr->day_first_uid + days,
           hdr->day_first_uid, max_days - days);
    for (i = 1; i < days; i++)
        hdr->day_first_uid[i] = hdr->day_first_uid[0];

    hdr->day_stamp = stamp;
    hdr->day_first_uid[0] = uid;
}

int mail_index_sync_record(struct mail_index_sync_map_ctx *ctx,
               const struct mail_transaction_header *hdr,
               const void *data)
{
    int ret = 0;

    switch (hdr->type & MAIL_TRANSACTION_TYPE_MASK) {
    case MAIL_TRANSACTION_APPEND: {
        const struct mail_index_record *rec, *end;

        end = CONST_PTR_OFFSET(data, hdr->size);
        for (rec = data; rec < end; rec++) {
            ret = sync_append(rec, ctx);
            if (ret <= 0)
                break;
        }
        break;
    }
    case MAIL_TRANSACTION_EXPUNGE:
    case MAIL_TRANSACTION_EXPUNGE|MAIL_TRANSACTION_EXPUNGE_PROT: {
        const struct mail_transaction_expunge *rec, *end;

        end = CONST_PTR_OFFSET(data, hdr->size);
        for (rec = data; rec < end; rec++) {
            ret = sync_expunge(rec, ctx);
            if (ret <= 0)
                break;
        }
        break;
    }
    case MAIL_TRANSACTION_FLAG_UPDATE: {
        const struct mail_transaction_flag_update *rec, *end;

        end = CONST_PTR_OFFSET(data, hdr->size);
        for (rec = data; rec < end; rec++) {
            ret = sync_flag_update(rec, ctx);
            if (ret <= 0)
                break;
        }
        break;
    }
    case MAIL_TRANSACTION_HEADER_UPDATE: {
        const struct mail_transaction_header_update *rec;
        unsigned int i;

        for (i = 0; i < hdr->size; ) {
            rec = CONST_PTR_OFFSET(data, i);
            ret = sync_header_update(rec, ctx);
            if (ret <= 0)
                break;

            i += sizeof(*rec) + rec->size;
            if ((i % 4) != 0)
                i += 4 - (i % 4);
        }
        break;
    }
    case MAIL_TRANSACTION_EXT_INTRO: {
        const struct mail_transaction_ext_intro *rec = data;
        unsigned int i;

        for (i = 0; i < hdr->size; ) {
            if (i + sizeof(*rec) > hdr->size) {
                /* should be just extra padding */
                break;
            }

            rec = CONST_PTR_OFFSET(data, i);
            ret = sync_ext_intro(rec, ctx);
            if (ret <= 0)
                break;

            i += sizeof(*rec) + rec->name_size;
            if ((i % 4) != 0)
                i += 4 - (i % 4);
        }
        break;
    }
    case MAIL_TRANSACTION_EXT_RESET: {
        const struct mail_transaction_ext_reset *rec = data;
        ret = sync_ext_reset(rec, ctx);
        break;
    }
    case MAIL_TRANSACTION_EXT_HDR_UPDATE: {
        const struct mail_transaction_ext_hdr_update *rec = data;
        unsigned int i;

        for (i = 0; i < hdr->size; ) {
            rec = CONST_PTR_OFFSET(data, i);
            ret = sync_ext_hdr_update(rec, ctx);
            if (ret <= 0)
                break;

            i += sizeof(*rec) + rec->size;
            if ((i % 4) != 0)
                i += 4 - (i % 4);
        }
        break;
    }
    case MAIL_TRANSACTION_EXT_REC_UPDATE: {
        const struct mail_transaction_ext_rec_update *rec, *end;
        const struct mail_index_ext *ext;
        unsigned int record_size;

        if (ctx->cur_ext_id == (uint32_t)-1) {
            mail_transaction_log_view_set_corrupted(
                ctx->view->log_view,
                "Extension record update update "
                "without intro prefix");
            ret = -1;
            break;
        }

        if (ctx->cur_ext_ignore) {
            ret = 1;
            break;
        }

        ext = ctx->view->map->extensions->data;
        record_size = sizeof(*rec) + ext[ctx->cur_ext_id].record_size;

        rec = data;
        end = CONST_PTR_OFFSET(data, hdr->size);
        while (rec < end) {
            ret = sync_ext_rec_update(rec, ctx);
            if (ret <= 0)
                break;

            rec = CONST_PTR_OFFSET(rec, record_size);
        }
        break;
    }
    default:
        i_unreached();
    }

    return ret;
}

void mail_index_sync_map_init(struct mail_index_sync_map_ctx *sync_map_ctx,
                  struct mail_index_view *view,
                  enum mail_index_sync_handler_type type)
{
    memset(sync_map_ctx, 0, sizeof(*sync_map_ctx));
    sync_map_ctx->view = view;
    sync_map_ctx->cur_ext_id = (uint32_t)-1;
    sync_map_ctx->type = type;

    mail_index_sync_init_handlers(sync_map_ctx);
}

void mail_index_sync_map_deinit(struct mail_index_sync_map_ctx *sync_map_ctx)
{
    if (sync_map_ctx->expunge_handlers_used)
        mail_index_sync_deinit_expunge_handlers(sync_map_ctx);
    mail_index_sync_deinit_handlers(sync_map_ctx);
}

int mail_index_sync_update_index(struct mail_index_sync_ctx *sync_ctx,
                 int sync_only_external)
{
    struct mail_index *index = sync_ctx->index;
    struct mail_index_view *view = sync_ctx->view;
    struct mail_index_map *map;
        struct mail_index_sync_map_ctx sync_map_ctx;
    const struct mail_transaction_header *thdr;
    const void *data;
    unsigned int count, old_lock_id;
    uint32_t seq, i, first_append_uid;
    uoff_t offset;
    int ret, had_dirty, skipped, check_ext_offsets;

    mail_index_sync_map_init(&sync_map_ctx, view,
                 MAIL_INDEX_SYNC_HANDLER_INDEX);

    /* we'll have to update view->lock_id to avoid mail_index_view_lock()
       trying to update the file later. */
    old_lock_id = view->lock_id;
    if (mail_index_lock_exclusive(index, &view->lock_id) < 0)
        return -1;
    mail_index_unlock(index, old_lock_id);

    /* NOTE: locking may change index->map so make sure the assignment is
       after locking */
    map = index->map;
    if (MAIL_INDEX_MAP_IS_IN_MEMORY(map))
        map->write_to_disk = TRUE;

    if (map->hdr_base != map->hdr_copy_buf->data) {
        buffer_reset(map->hdr_copy_buf);
        buffer_append(map->hdr_copy_buf, map->hdr_base,
                  map->hdr.header_size);
        map->hdr_base = map->hdr_copy_buf->data;
    }
    i_assert(map->hdr.base_header_size >= sizeof(map->hdr));

    mail_index_unmap(index, view->map);
    view->map = map;
    view->map->refcount++;

    had_dirty = (map->hdr.flags & MAIL_INDEX_HDR_FLAG_HAVE_DIRTY) != 0;
    if (had_dirty)
        map->hdr.flags &= ~MAIL_INDEX_HDR_FLAG_HAVE_DIRTY;

    first_append_uid = 0;
    check_ext_offsets = TRUE;
    while ((ret = mail_transaction_log_view_next(view->log_view, &thdr,
                             &data, &skipped)) > 0) {
        if ((thdr->type & MAIL_TRANSACTION_EXTERNAL) == 0) {
            if (sync_only_external) {
                /* we're syncing only external changes. */
                continue;
            }
        } else if (check_ext_offsets) {
            uint32_t prev_seq;
            uoff_t prev_offset;

            mail_transaction_log_view_get_prev_pos(view->log_view,
                                   &prev_seq,
                                   &prev_offset);
            if (prev_offset < map->hdr.log_file_ext_offset) {
                /* we have already synced this change */
                continue;
            }
            check_ext_offsets = FALSE;
        }

        if ((thdr->type & MAIL_TRANSACTION_APPEND) != 0) {
            const struct mail_index_record *rec = data;

            if (first_append_uid == 0)
                first_append_uid = rec->uid;

            map = view->map;
            count = thdr->size / sizeof(*rec);
            if (mail_index_grow(index, map, count) < 0) {
                ret = -1;
                break;
            }
            if (map != index->map) {
                map = index->map;
                mail_index_unmap(view->index, view->map);
                view->map = map;
                view->map->refcount++;
            }
        }

        if (mail_index_sync_record(&sync_map_ctx, thdr, data) < 0) {
            ret = -1;
            break;
        }
    }
    map = view->map;
        mail_index_sync_map_deinit(&sync_map_ctx);

    if (ret < 0) {
        mail_index_view_unlock(view);
        return -1;
    }

    i_assert(map->records_count == map->hdr.messages_count);
    i_assert(view->messages_count == map->hdr.messages_count);

    mail_transaction_log_get_head(index->log, &seq, &offset);

    map->hdr.log_file_seq = seq;
    if (!sync_only_external)
        map->hdr.log_file_int_offset = offset;
    map->hdr.log_file_ext_offset = offset;

    if (first_append_uid != 0)
        mail_index_update_day_headers(&map->hdr, first_append_uid);

    if ((map->hdr.flags & MAIL_INDEX_HDR_FLAG_HAVE_DIRTY) == 0 &&
        had_dirty) {
        /* do we have dirty flags anymore? */
        const struct mail_index_record *rec;

        for (i = 0; i < map->records_count; i++) {
            rec = MAIL_INDEX_MAP_IDX(map, i);
            if ((rec->flags & MAIL_INDEX_MAIL_FLAG_DIRTY) != 0) {
                map->hdr.flags |=
                    MAIL_INDEX_HDR_FLAG_HAVE_DIRTY;
                break;
            }
        }
    }

    if (!MAIL_INDEX_MAP_IS_IN_MEMORY(map)) {
        map->mmap_used_size = index->hdr->header_size +
            map->records_count * map->hdr.record_size;

        memcpy(map->mmap_base, &map->hdr, sizeof(map->hdr));
        memcpy(PTR_OFFSET(map->mmap_base, sizeof(map->hdr)),
               PTR_OFFSET(map->hdr_base, sizeof(map->hdr)),
               map->hdr.header_size - sizeof(map->hdr));
        if (msync(map->mmap_base, map->mmap_used_size, MS_SYNC) < 0) {
            mail_index_set_syscall_error(index, "msync()");
            ret = -1;
        }
    }
    i_assert(view->map == index->map);

        mail_index_view_unlock(view);
    return ret;
}