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

	mail-index-sync-ext.c revision c3c41a923c7ac19679e8ff797530869dbef7e018
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen/* Copyright (C) 2004 Timo Sirainen */
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen#include "lib.h"
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen#include "buffer.h"
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen#include "mail-index-view-private.h"
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen#include "mail-index-sync-private.h"
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen#include "mail-transaction-log.h"
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen#include <stdlib.h>
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenvoid mail_index_sync_init_expunge_handlers(struct mail_index_sync_map_ctx *ctx)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen{
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    const mail_index_expunge_handler_t *const *handlers;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        const struct mail_index_ext *extensions;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    const uint32_t *id_map;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    struct mail_index_expunge_handler eh;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size_t handlers_count, id_map_size, size;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    uint32_t idx_ext_id, map_ext_id;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    handlers = buffer_get_data(ctx->view->index->expunge_handlers,
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen                   &handlers_count);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    handlers_count /= sizeof(*handlers);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    if (handlers_count == 0)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        return;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    /* set expunge handlers */
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    memset(&eh, 0, sizeof(eh));
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    if (ctx->expunge_handlers != NULL)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        buffer_set_used_size(ctx->expunge_handlers, 0);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    else {
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        ctx->expunge_handlers =
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen            buffer_create_dynamic(default_pool, 256);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    }
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    extensions = ctx->view->map->extensions->data;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    id_map = buffer_get_data(ctx->view->map->ext_id_map, &id_map_size);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    id_map_size /= sizeof(*id_map);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size = I_MIN(handlers_count, id_map_size);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    for (idx_ext_id = 0; idx_ext_id < size; idx_ext_id++) {
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        map_ext_id = id_map[idx_ext_id];
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        if (handlers[idx_ext_id] == NULL || map_ext_id == (uint32_t)-1)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen            continue;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        eh.handler = handlers[idx_ext_id];
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        eh.context = &ctx->extra_context[map_ext_id];
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        eh.record_offset = extensions[map_ext_id].record_offset;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        buffer_append(ctx->expunge_handlers, &eh, sizeof(eh));
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    }
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    ctx->expunge_handlers_set = TRUE;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    ctx->expunge_handlers_used = TRUE;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen}
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenvoid
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenmail_index_sync_deinit_expunge_handlers(struct mail_index_sync_map_ctx *ctx)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen{
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    const struct mail_index_expunge_handler *eh;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size_t i, size;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    if (ctx->expunge_handlers == NULL)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        return;
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    eh = buffer_get_data(ctx->expunge_handlers, &size);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size /= sizeof(*eh);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    for (i = 0; i < size; i++) {
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        if (eh->context != NULL)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen            eh[i].handler(ctx, 0, NULL, eh->context);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    }
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    buffer_free(ctx->expunge_handlers);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen}
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenvoid mail_index_sync_init_handlers(struct mail_index_sync_map_ctx *ctx)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen{
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size_t size;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    if (ctx->view->map->extensions == NULL)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        return;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    /* set space for extra contexts */
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size = sizeof(void *) * (ctx->view->index->extensions->used /
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen                 sizeof(struct mail_index_ext));
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    if (ctx->extra_context_buf == NULL) {
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen        ctx->extra_context_buf =
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen            buffer_create_dynamic(default_pool, size);
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    } else {
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen        buffer_set_used_size(ctx->extra_context_buf, 0);
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    }
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    buffer_append_zero(ctx->extra_context_buf, size);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    ctx->extra_context =
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        buffer_get_modifyable_data(ctx->extra_context_buf, NULL);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    ctx->expunge_handlers_set = FALSE;
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen}
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainenvoid mail_index_sync_deinit_handlers(struct mail_index_sync_map_ctx *ctx)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen{
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    const struct mail_index_sync_handler *sync_handlers;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    const struct mail_index_ext *ext;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size_t i, synch_size, size;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    if (ctx->extra_context == NULL)
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen        return;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    sync_handlers = buffer_get_data(ctx->view->index->sync_handlers,
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen                    &synch_size);
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    synch_size /= sizeof(*sync_handlers);
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    i_assert(synch_size <= ctx->extra_context_buf->used / sizeof(void *));
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen
eef20a55e19a239244b14963d716cf0d070fe1bbTimo Sirainen    ext = buffer_get_data(ctx->view->map->extensions, &size);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    size /= sizeof(*ext);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    i_assert(size <= synch_size);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    /* sync_handlers[] is ordered by index->extensions while
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen       extra_context is ordered by map->extensions. */
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    for (i = 0; i < size; i++) {
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        if (ctx->extra_context[i] != NULL) {
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen            sync_handlers[ext[i].index_idx].
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen                callback(ctx, 0, NULL, NULL,
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen                     &ctx->extra_context[i]);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        }
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    }
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    buffer_free(ctx->extra_context_buf);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen}
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenstatic struct mail_index_ext_header *
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenget_ext_header(struct mail_index_map *map, const struct mail_index_ext *ext)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen{
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    struct mail_index_ext_header *ext_hdr;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    uint32_t offset;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    void *hdr_base;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    /* do some kludgy jumping to get to it. */
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    offset = ext->hdr_offset -
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen        MAIL_INDEX_HEADER_SIZE_ALIGN(sizeof(*ext_hdr) +
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen                         strlen(ext->name));
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    hdr_base = buffer_get_modifyable_data(map->hdr_copy_buf, NULL);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    ext_hdr = PTR_OFFSET(hdr_base, offset);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    i_assert(memcmp((char *)(ext_hdr + 1),
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen            ext->name, strlen(ext->name)) == 0);
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    return ext_hdr;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen}
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenstatic int mail_index_ext_align_cmp(const void *p1, const void *p2)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen{
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    const struct mail_index_ext *const *e1 = p1, *const *e2 = p2;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen    return (int)(*e2)->record_align - (int)(*e1)->record_align;
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen}
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainenstatic struct mail_index_map *
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainensync_ext_reorder(struct mail_index_map *map, uint32_t ext_id, uint16_t old_size)
83942ac160cdfb922c3a2f29ddfae2a13ebf8b5dTimo Sirainen{
    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_clone(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 (new_map->buffer->used !=
        old_records_count * new_map->hdr.record_size) {
        /* we didn't fully write the last record */
        size_t space = old_records_count * new_map->hdr.record_size -
            new_map->buffer->used;
        i_assert(space < new_map->hdr.record_size);
        buffer_append_zero(new_map->buffer, space);
    }

    new_map->records = buffer_get_modifyable_data(new_map->buffer, NULL);
    new_map->records_count = old_records_count;
    i_assert(new_map->records_count == new_map->hdr.messages_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, map);
    }
}

int mail_index_sync_ext_intro(struct mail_index_sync_map_ctx *ctx,
                  const struct mail_transaction_ext_intro *u)
{
    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, map);

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

int mail_index_sync_ext_reset(struct mail_index_sync_map_ctx *ctx,
                  const struct mail_transaction_ext_reset *u)
{
    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->map->records_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;
}

int
mail_index_sync_ext_hdr_update(struct mail_index_sync_map_ctx *ctx,
                   const struct mail_transaction_ext_hdr_update *u)
{
    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;
}

int
mail_index_sync_ext_rec_update(struct mail_index_sync_map_ctx *ctx,
                   const struct mail_transaction_ext_rec_update *u)
{
    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);

    sync_handlers = view->index->sync_handlers->data;
    sync_handlers += ext->index_idx;

    /* 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;
    }

    /* @UNSAFE */
    memcpy(old_data, u + 1, ext->record_size);
    return 1;
}