src/lib-index/mail-index.c

	mail-index.c revision 3c24d47ad5ff02ea00684233bef314ef2eefda4a
2605N/A/* Copyright (C) 2003-2004 Timo Sirainen */
2605N/A
2605N/A#include "lib.h"
2605N/A#include "buffer.h"
2605N/A#include "file-lock.h"
2605N/A#include "mmap-util.h"
2605N/A#include "read-full.h"
2605N/A#include "write-full.h"
2605N/A#include "mail-index-private.h"
2605N/A#include "mail-transaction-log.h"
2605N/A
2605N/A#include <stdio.h>
2605N/A#include <stddef.h>
2605N/A#include <time.h>
2605N/A#include <sys/stat.h>
2605N/A
2605N/Astatic int mail_index_try_open_only(struct mail_index *index);
2605N/A
2605N/Astruct mail_index *mail_index_alloc(const char *dir, const char *prefix)
2605N/A{
2605N/A    struct mail_index *index;
2605N/A
6033N/A    index = i_new(struct mail_index, 1);
2605N/A    index->dir = i_strdup(dir);
4070N/A    index->prefix = i_strdup(prefix);
2605N/A    index->fd = -1;
2605N/A
2605N/A    index->extra_records_pool =
6033N/A        pool_alloconly_create("extra_record_pool", 256);
6033N/A    index->extra_records_buf =
6033N/A        buffer_create_dynamic(index->extra_records_pool,
2605N/A                      64, (size_t)-1);
2605N/A    index->record_size = sizeof(struct mail_index_record);
2605N/A
6033N/A    index->mode = 0600;
2605N/A    index->gid = (gid_t)-1;
2605N/A    return index;
2605N/A}
4070N/A
2605N/Avoid mail_index_free(struct mail_index *index)
6033N/A{
3661N/A    mail_index_close(index);
3996N/A    pool_unref(index->extra_records_pool);
3996N/A
3996N/A    i_free(index->error);
2605N/A    i_free(index->dir);
2605N/A    i_free(index->prefix);
2605N/A    i_free(index);
2605N/A}
2605N/A
4623N/Auint32_t mail_index_register_record_extra(struct mail_index *index,
2605N/A                      const char *name, uint16_t size)
4070N/A{
2605N/A    struct mail_index_extra_record_info info;
4070N/A    size_t buf_size;
2605N/A    unsigned int i;
4070N/A
4070N/A    /* see if it's there already */
4070N/A    for (i = 0; i < index->extra_records_count; i++) {
4070N/A        if (strcmp(index->extra_records[i].name, name) == 0) {
4070N/A            i_assert(index->extra_records[i].size == size);
2605N/A            return i;
2605N/A        }
4070N/A    }
4070N/A
4070N/A    i_assert(size % 4 == 0);
4070N/A    i_assert(!index->opened);
4070N/A    i_assert(index->record_size + size <= 65535);
4070N/A
4070N/A    if (index->extra_records_count >= MAIL_INDEX_MAX_EXTRA_RECORDS) {
2605N/A        i_panic("Maximum extra record count reached, "
2605N/A            "you'll need to recompile with larger limit. "
2605N/A            "MAIL_INDEX_MAX_EXTRA_RECORDS = %d",
2605N/A            MAIL_INDEX_MAX_EXTRA_RECORDS);
2605N/A    }
2605N/A
2605N/A    memset(&info, 0, sizeof(info));
2605N/A    info.name = p_strdup(index->extra_records_pool, name);
4312N/A    info.size = size;
4623N/A    info.offset = index->record_size;
6033N/A
4623N/A    buffer_append(index->extra_records_buf, &info, sizeof(info));
4623N/A    index->extra_records =
4623N/A        buffer_get_data(index->extra_records_buf, &buf_size);
6033N/A    index->extra_records_count = buf_size / sizeof(info);
6033N/A
6033N/A    index->record_size += size;
6033N/A    return index->extra_records_count-1;
6033N/A}
4623N/A
4623N/Astatic int mail_index_check_header(struct mail_index *index,
6033N/A                   struct mail_index_map *map)
3996N/A{
    const struct mail_index_header *hdr = map->hdr;
    unsigned char compat_data[sizeof(hdr->compat_data)];

    memset(compat_data, 0, sizeof(compat_data));
#ifndef WORDS_BIGENDIAN
    compat_data[0] = MAIL_INDEX_COMPAT_LITTLE_ENDIAN;
#endif
    compat_data[1] = sizeof(uoff_t);
    compat_data[2] = sizeof(time_t);

    if (hdr->major_version != MAIL_INDEX_MAJOR_VERSION) {
        /* major version change - handle silently(?) */
        return -1;
    }
    if (memcmp(hdr->compat_data, compat_data, sizeof(compat_data)) != 0) {
        /* architecture change - handle silently(?) */
        return -1;
    }

    if ((map->hdr->flags & MAIL_INDEX_HDR_FLAG_CORRUPTED) != 0) {
        /* we've already complained about it */
        return -1;
    }

    /* following some extra checks that only take a bit of CPU */
    if (hdr->uid_validity == 0 && hdr->next_uid != 1) {
        mail_index_set_error(index, "Corrupted index file %s: "
                     "uid_validity = 0, next_uid = %u",
                     index->filepath, hdr->next_uid);
        return -1;
    }

    if (hdr->keywords_mask_size != sizeof(keywords_mask_t)) {
        mail_index_set_error(index, "Corrupted index file %s: "
                     "keywords_mask_size mismatch: %d != %d",
                     index->filepath, hdr->keywords_mask_size,
                     (int)sizeof(keywords_mask_t));
        return -1;
    }

    if (hdr->record_size != index->record_size) {
        mail_index_set_error(index, "Corrupted index file %s: "
                     "record_size mismatch: %d != %d",
                     index->filepath, hdr->record_size,
                     (int)index->record_size);
        return -1;
    }

    if (hdr->next_uid == 0)
        return 0;

    if (hdr->recent_messages_count > hdr->messages_count ||
        hdr->seen_messages_count > hdr->messages_count ||
        hdr->deleted_messages_count > hdr->messages_count)
        return 0;
    if (hdr->first_recent_uid_lowwater > hdr->next_uid ||
        hdr->first_unseen_uid_lowwater > hdr->next_uid ||
        hdr->first_deleted_uid_lowwater > hdr->next_uid)
        return 0;

    return 1;
}

static void mail_index_map_clear(struct mail_index *index,
                 struct mail_index_map *map)
{
    if (map->buffer != NULL) {
        i_assert(map->mmap_base == NULL);
        buffer_free(map->buffer);
        map->buffer = NULL;
    } else if (map->mmap_base != NULL) {
        i_assert(map->buffer == NULL);
        if (munmap(map->mmap_base, map->mmap_size) < 0)
            mail_index_set_syscall_error(index, "munmap()");
        map->mmap_base = NULL;
    }

    if (map->refcount > 0) {
        map->mmap_size = 0;
        map->mmap_used_size = 0;
        map->hdr = NULL;
        map->records = NULL;
        map->records_count = 0;
    }
}

void mail_index_unmap(struct mail_index *index, struct mail_index_map *map)
{
    if (--map->refcount > 0)
        return;

    i_assert(map->refcount == 0);
    mail_index_map_clear(index, map);
    i_free(map);
}

static void mail_index_unmap_forced(struct mail_index *index,
                    struct mail_index_map *map)
{
    mail_index_map_clear(index, map);
    mail_index_unmap(index, map);
}

static int mail_index_mmap(struct mail_index *index, struct mail_index_map *map)
{
    const struct mail_index_header *hdr;
    unsigned int records_count;

    i_assert(!map->write_to_disk);

    if (map->buffer != NULL) {
        /* we had temporarily used a buffer, eg. for updating index */
        buffer_free(map->buffer);
        map->buffer = NULL;
    }

    map->mmap_base = index->lock_type != F_WRLCK ?
        mmap_ro_file(index->fd, &map->mmap_size) :
        mmap_rw_file(index->fd, &map->mmap_size);
    if (map->mmap_base == MAP_FAILED) {
        map->mmap_base = NULL;
        mail_index_set_syscall_error(index, "mmap()");
        return -1;
    }

    if (map->mmap_size < MAIL_INDEX_HEADER_MIN_SIZE) {
        mail_index_set_error(index, "Corrupted index file %s: "
                     "File too small (%"PRIuSIZE_T")",
                     index->filepath, map->mmap_size);
        return 0;
    }

    hdr = map->mmap_base;
    map->hdr = hdr;
    map->mmap_used_size = hdr->header_size +
        hdr->messages_count * index->record_size;

    if (map->mmap_used_size > map->mmap_size) {
        records_count = (map->mmap_size - hdr->header_size) /
            index->record_size;
        mail_index_set_error(index, "Corrupted index file %s: "
                     "messages_count too large (%u > %u)",
                     index->filepath, hdr->messages_count,
                     records_count);
        return 0;
    }

    if (map->hdr->base_header_size < sizeof(*map->hdr)) {
        /* header smaller than ours, make a copy so our newer headers
           won't have garbage in them */
        memcpy(&map->hdr_copy, map->hdr, map->hdr->base_header_size);
        map->hdr = &map->hdr_copy;
    }

    map->records = PTR_OFFSET(map->mmap_base, map->hdr->header_size);
    map->records_count = map->hdr->messages_count;
    return 1;
}

static int mail_index_read_map(struct mail_index *index,
                   struct mail_index_map *map)
{
    struct mail_index_header hdr;
    void *data = NULL;
    ssize_t ret;
    size_t pos, records_size;

    i_assert(map->mmap_base == NULL);

    memset(&hdr, 0, sizeof(hdr));

    ret = 1;
    for (pos = 0; ret > 0 && pos < sizeof(hdr); ) {
        ret = pread(index->fd, PTR_OFFSET(&hdr, pos),
                sizeof(hdr) - pos, pos);
        if (ret > 0)
            pos += ret;
    }
    if (ret >= 0 && pos >= MAIL_INDEX_HEADER_MIN_SIZE) {
        records_size = hdr.messages_count * index->record_size;

        if (map->buffer == NULL) {
            map->buffer = buffer_create_dynamic(default_pool,
                                records_size,
                                (size_t)-1);
        }

        /* @UNSAFE */
        buffer_set_used_size(map->buffer, 0);
        data = buffer_append_space_unsafe(map->buffer, records_size);

        ret = pread_full(index->fd, data, records_size,
                 hdr.header_size);
    }

    if (ret < 0) {
        if (errno == ESTALE)
            return 0;
        mail_index_set_syscall_error(index, "pread_full()");
        return -1;
    }
    if (ret == 0) {
        mail_index_set_error(index,
            "Unexpected EOF while reading index file");
        return -1;
    }

    map->records = data;
    map->records_count = hdr.messages_count;

    map->hdr_copy = hdr;
    map->hdr = &map->hdr_copy;
    return 1;
}

static int mail_index_read_map_with_retry(struct mail_index *index,
                      struct mail_index_map *map)
{
    int i, ret;

    for (i = 0; i < MAIL_INDEX_ESTALE_RETRY_COUNT; i++) {
        ret = mail_index_read_map(index, map);
        if (ret != 0)
            return ret;

        /* ESTALE - reopen index file */
        if (close(index->fd) < 0)
            mail_index_set_syscall_error(index, "close()");
        index->fd = -1;

        ret = mail_index_try_open_only(index);
        if (ret <= 0) {
            if (ret == 0) {
                /* the file was lost */
                errno = ENOENT;
                mail_index_set_syscall_error(index, "open()");
            }
            return -1;
        }
    }

    /* Too many ESTALE retries */
    mail_index_set_syscall_error(index, "read_map()");
    return -1;
}

int mail_index_map(struct mail_index *index, int force)
{
    const struct mail_index_header *hdr;
    struct mail_index_map *map;
    size_t used_size;
    int ret;

    map = index->map;
    if (map == NULL) {
        map = i_new(struct mail_index_map, 1);
        map->refcount = 1;
    } else if (MAIL_INDEX_MAP_IS_IN_MEMORY(map)) {
        if (map->write_to_disk) {
            /* we have modified this mapping and it's waiting to
               be written to disk once we drop exclusive lock.
               mapping couldn't have changed, so do nothing. */
            return 1;
        }
        /* FIXME: we need to re-read header */
    } else if (map->mmap_base != NULL) {
        /* see if re-mmaping is needed (file has grown) */
        i_assert(map->buffer == NULL);
        hdr = map->mmap_base;

        /* always check corrupted-flag to avoid errors later */
        if ((map->hdr->flags & MAIL_INDEX_HDR_FLAG_CORRUPTED) != 0)
            return -1;

        used_size = hdr->header_size +
            hdr->messages_count * index->record_size;
        if (map->mmap_size >= used_size && !force) {
            map->records_count = hdr->messages_count;
            return 1;
        }

        if (munmap(map->mmap_base, map->mmap_size) < 0)
            mail_index_set_syscall_error(index, "munmap()");
        map->mmap_base = NULL;
    }

    index->hdr = NULL;
    index->map = NULL;

    if (!index->mmap_disable) {
        if ((ret = mail_index_mmap(index, map)) <= 0) {
            mail_index_unmap_forced(index, map);
            return ret;
        }
    } else {
        if (mail_index_read_map_with_retry(index, map) < 0) {
            mail_index_unmap_forced(index, map);
            return -1;
        }
    }

    ret = mail_index_check_header(index, map);
    if (ret < 0) {
        mail_index_unmap_forced(index, map);
        return 0;
    }
    if (ret == 0)
        index->fsck = TRUE;

    map->log_file_seq = map->hdr->log_file_seq;
    map->log_file_offset = map->hdr->log_file_offset;

    index->hdr = map->hdr;
    index->map = map;
    return 1;
}

struct mail_index_map *
mail_index_map_to_memory(struct mail_index *index, struct mail_index_map *map)
{
    const struct mail_index_header *hdr;
    struct mail_index_map *mem_map;
    size_t size;

    if (MAIL_INDEX_MAP_IS_IN_MEMORY(map)) {
        map->refcount++;
        return map;
    }

        size = map->records_count * index->record_size;

    mem_map = i_new(struct mail_index_map, 1);
    mem_map->refcount = 1;
    mem_map->buffer = buffer_create_dynamic(default_pool, size, (size_t)-1);
    buffer_append(mem_map->buffer, map->records, size);

    mem_map->records = buffer_get_modifyable_data(mem_map->buffer, NULL);
    mem_map->records_count = map->records_count;

    hdr = map->mmap_base;
    memcpy(&mem_map->hdr_copy, map->mmap_base,
           I_MIN(hdr->base_header_size, sizeof(mem_map->hdr_copy)));
    mem_map->hdr = &mem_map->hdr_copy;
    return mem_map;
}

static int mail_index_try_open_only(struct mail_index *index)
{
    int i;

    for (i = 0; i < 3; i++) {
        index->fd = open(index->filepath, O_RDWR);
        if (index->fd == -1 && errno == EACCES) {
            index->fd = open(index->filepath, O_RDONLY);
            index->readonly = TRUE;
        }
        if (index->fd != -1 || errno != ESTALE)
            break;

        /* May happen with some OSes with NFS. Try again, although
           there's still a race condition with another computer
           creating the index file again. However, we can't try forever
           as ESTALE happens also if index directory has been deleted
           from server.. */
    }
    if (index->fd == -1) {
        if (errno != ENOENT)
            return mail_index_set_syscall_error(index, "open()");

        /* have to create it */
        return 0;
    }
    return 1;
}

static int
mail_index_try_open(struct mail_index *index, unsigned int *lock_id_r)
{
    unsigned int lock_id;
    int ret;

    if (lock_id_r != NULL)
        *lock_id_r = 0;

    ret = mail_index_try_open_only(index);
    if (ret <= 0)
        return ret;

    if (mail_index_lock_shared(index, FALSE, &lock_id) < 0)
        return -1;
    ret = mail_index_map(index, FALSE);
    if (ret == 0) {
        /* it's corrupted - recreate it */
        mail_index_unlock(index, lock_id);
        if (lock_id_r != NULL)
            *lock_id_r = 0;

        (void)close(index->fd);
        index->fd = -1;
    } else {
        if (lock_id_r != NULL)
            *lock_id_r = lock_id;
        else
            mail_index_unlock(index, lock_id);
    }
    return ret;
}

int mail_index_write_header(struct mail_index *index,
                const struct mail_index_header *hdr)
{
    if (!MAIL_INDEX_MAP_IS_IN_MEMORY(index->map)) {
        memcpy(index->map->mmap_base, hdr, sizeof(*hdr));
        if (msync(index->map->mmap_base, sizeof(*hdr), MS_SYNC) < 0)
            return mail_index_set_syscall_error(index, "msync()");
    } else {
        if (pwrite_full(index->fd, hdr, sizeof(*hdr), 0) < 0) {
            mail_index_set_syscall_error(index, "pwrite_full()");
            return -1;
        }

        index->map->hdr_copy = *hdr;
        index->hdr = &index->map->hdr_copy;
    }

    return 0;
}

int mail_index_create_tmp_file(struct mail_index *index, const char **path_r)
{
    const char *path;
    int fd;

    path = *path_r = t_strconcat(index->filepath, ".tmp", NULL);
    fd = open(path, O_RDWR|O_CREAT|O_TRUNC, index->mode);
    if (fd == -1)
        return mail_index_file_set_syscall_error(index, path, "open()");

    if (index->gid != (gid_t)-1 &&
        fchown(index->fd, (uid_t)-1, index->gid) < 0) {
        mail_index_file_set_syscall_error(index, path, "fchown()");
        return -1;
    }

    return fd;
}

static int mail_index_create(struct mail_index *index,
                 struct mail_index_header *hdr)
{
    const char *path;
    uint32_t seq;
    uoff_t offset;
    int ret;

    /* log file lock protects index creation */
    if (mail_transaction_log_sync_lock(index->log, &seq, &offset) < 0)
        return -1;

    ret = mail_index_try_open(index, NULL);
    if (ret != 0) {
        mail_transaction_log_sync_unlock(index->log);
        return ret;
    }

    /* create it fully in index.tmp first */
    index->fd = mail_index_create_tmp_file(index, &path);
    if (index->fd == -1)
        ret = -1;
    else if (write_full(index->fd, hdr, sizeof(*hdr)) < 0) {
        mail_index_file_set_syscall_error(index, path, "write_full()");
        ret = -1;
    } else {
        ret = mail_index_map(index, FALSE);
    }

    if (ret == 0) {
        /* it's corrupted even while we just created it,
           should never happen unless someone pokes the file directly */
        mail_index_set_error(index,
            "Newly created index file is corrupted: %s", path);
        ret = -1;
    }

    if (ret < 0) {
        if (unlink(path) < 0 && errno != ENOENT) {
            mail_index_file_set_syscall_error(index, path,
                              "unlink()");
        }
    } else {
        /* make it visible to others */
        if (rename(path, index->filepath) < 0) {
            mail_index_set_error(index, "rename(%s, %s) failed: %m",
                         path, index->filepath);
            ret = -1;
        }
    }

    mail_transaction_log_sync_unlock(index->log);
    return ret;
}

static void mail_index_header_init(struct mail_index *index,
                   struct mail_index_header *hdr)
{
    time_t now = time(NULL);

    memset(hdr, 0, sizeof(*hdr));

    hdr->major_version = MAIL_INDEX_MAJOR_VERSION;
    hdr->minor_version = MAIL_INDEX_MINOR_VERSION;
    hdr->base_header_size = sizeof(*hdr);
    hdr->header_size = sizeof(*hdr);
    hdr->record_size = index->record_size;
    hdr->keywords_mask_size = sizeof(keywords_mask_t);

#ifndef WORDS_BIGENDIAN
    hdr->compat_data[0] = MAIL_INDEX_COMPAT_LITTLE_ENDIAN;
#endif
    hdr->compat_data[1] = sizeof(uoff_t);
    hdr->compat_data[2] = sizeof(time_t);

    hdr->indexid = now;

    hdr->next_uid = 1;
}

static int mail_index_open_files(struct mail_index *index,
                 enum mail_index_open_flags flags)
{
    struct mail_index_header hdr;
    unsigned int lock_id = 0;
    int ret;

    ret = mail_index_try_open(index, &lock_id);
    if (ret > 0)
        hdr = *index->hdr;
    else if (ret == 0) {
        /* doesn't exist, or corrupted */
        if ((flags & MAIL_INDEX_OPEN_FLAG_CREATE) == 0)
            return 0;
        mail_index_header_init(index, &hdr);
        index->hdr = &hdr;
    } else if (ret < 0)
        return -1;

    index->indexid = hdr.indexid;

    index->log = mail_transaction_log_open_or_create(index);
    if (index->log == NULL)
        return -1;

    if (lock_id != 0)
        mail_index_unlock(index, lock_id);
    return index->fd != -1 ? 1 : mail_index_create(index, &hdr);
}

int mail_index_open(struct mail_index *index, enum mail_index_open_flags flags)
{
    int i = 0, ret;

    if (index->opened)
        return 0;

    index->filepath = i_strconcat(index->dir, "/", index->prefix, NULL);

    do {
        index->shared_lock_count = 0;
        index->excl_lock_count = 0;
        index->lock_type = F_UNLCK;
        index->lock_id = 2;

        index->nodiskspace = FALSE;
        index->index_lock_timeout = FALSE;
        index->log_locked = FALSE;
        index->mmap_disable =
            (flags & MAIL_INDEX_OPEN_FLAG_MMAP_DISABLE) != 0;
        index->mmap_no_write =
            (flags & MAIL_INDEX_OPEN_FLAG_MMAP_NO_WRITE) != 0;
        index->fcntl_locks_disable =
            (flags & MAIL_INDEX_OPEN_FLAG_FCNTL_LOCKS_DISABLE) != 0;
        index->readonly = FALSE;

        ret = mail_index_open_files(index, flags);
        if (ret <= 0)
            break;

        index->opened = TRUE;
        if (index->fsck) {
            index->fsck = FALSE;
            ret = mail_index_fsck(index);
            if (ret == 0) {
                /* completely broken, reopen */
                if (i++ < 3)
                    continue;
                /* too many tries */
                ret = -1;
            }
        }
        break;
    } while (1);

    if (ret <= 0)
        mail_index_close(index);

    return ret;
}

void mail_index_close(struct mail_index *index)
{
    if (index->log != NULL) {
        mail_transaction_log_close(index->log);
        index->log = NULL;
    }

    if (index->map != NULL) {
        mail_index_unmap(index, index->map);
        index->map = NULL;
    }

    if (index->fd != -1) {
        if (close(index->fd) < 0)
            mail_index_set_syscall_error(index, "close()");
        index->fd = -1;
    }

    i_free(index->copy_lock_path);
    index->copy_lock_path = NULL;
    i_free(index->filepath);
    index->filepath = NULL;

    index->indexid = 0;
    index->opened = FALSE;
}

int mail_index_reopen(struct mail_index *index, int fd)
{
    struct mail_index_map *old_map;
    unsigned int old_shared_locks, old_lock_id, lock_id = 0;
    int ret, old_fd, old_lock_type;

    old_map = index->map;
    old_fd = index->fd;

    index->map = NULL;
    index->hdr = NULL;

    /* new file, new locks. the old fd can keep it's locks, they don't
       matter anymore as no-one's going to modify the file. */
    old_lock_type = index->lock_type;
    old_lock_id = index->lock_id;
    old_shared_locks = index->shared_lock_count;

    if (index->lock_type == F_RDLCK)
        index->lock_type = F_UNLCK;
    index->lock_id += 2;
    index->shared_lock_count = 0;

    if (fd != -1) {
        index->fd = fd;
        ret = 0;
    } else {
        i_assert(index->excl_lock_count == 0);
        ret = mail_index_try_open_only(index);
        if (ret > 0)
            ret = mail_index_lock_shared(index, FALSE, &lock_id);
        else if (ret == 0) {
            /* index file is lost */
            ret = -1;
        }
    }

    if (ret == 0) {
        if (mail_index_map(index, FALSE) <= 0)
            ret = -1;
    }

    if (lock_id != 0)
        mail_index_unlock(index, lock_id);

    if (ret == 0) {
        mail_index_unmap(index, old_map);
        if (close(old_fd) < 0)
            mail_index_set_syscall_error(index, "close()");
    } else {
        if (index->map != NULL)
            mail_index_unmap(index, index->map);
        if (index->fd != -1) {
            if (close(index->fd) < 0)
                mail_index_set_syscall_error(index, "close()");
        }

        index->map = old_map;
        index->hdr = index->map->hdr;
        index->fd = old_fd;
        index->lock_type = old_lock_type;
        index->lock_id = old_lock_id;
        index->shared_lock_count = old_shared_locks;
    }
    return ret;
}

int mail_index_refresh(struct mail_index *index)
{
    struct stat st1, st2;

    if (fstat(index->fd, &st1) < 0)
        return mail_index_set_syscall_error(index, "fstat()");
    if (stat(index->filepath, &st2) < 0) {
        mail_index_set_syscall_error(index, "stat()");
        if (errno != ENOENT)
            return -1;

        /* lost it? recreate */
        (void)mail_index_mark_corrupted(index);
        return -1;
    }

    if (st1.st_ino != st2.st_ino ||
        !CMP_DEV_T(st1.st_dev, st2.st_dev)) {
        if (mail_index_reopen(index, -1) < 0)
            return -1;
        return 1;
    } else {
        return 0;
    }
}

struct mail_cache *mail_index_get_cache(struct mail_index *index)
{
    return index->cache;
}

int mail_index_set_error(struct mail_index *index, const char *fmt, ...)
{
    va_list va;

    i_free(index->error);

    if (fmt == NULL)
        index->error = NULL;
    else {
        va_start(va, fmt);
        index->error = i_strdup_vprintf(fmt, va);
        va_end(va);

        i_error("%s", index->error);
    }

    return -1;
}

void mail_index_set_inconsistent(struct mail_index *index)
{
    index->indexid = 0;
}

void mail_index_mark_corrupted(struct mail_index *index)
{
    struct mail_index_header hdr;

    mail_index_set_inconsistent(index);

    if (index->readonly)
        return;

    /* make sure we can write the header */
    if (!MAIL_INDEX_MAP_IS_IN_MEMORY(index->map)) {
        if (mprotect(index->map->mmap_base, sizeof(hdr),
                 PROT_READ | PROT_WRITE) < 0) {
            mail_index_set_syscall_error(index, "mprotect()");
            return;
        }
    }

    hdr = *index->hdr;
    hdr.flags |= MAIL_INDEX_HDR_FLAG_CORRUPTED;
    if (mail_index_write_header(index, &hdr) == 0) {
        if (fsync(index->fd) < 0)
            mail_index_set_syscall_error(index, "fsync()");
    }
}

int mail_index_set_syscall_error(struct mail_index *index,
                 const char *function)
{
    i_assert(function != NULL);

    if (ENOSPACE(errno)) {
        index->nodiskspace = TRUE;
        return -1;
    }

    return mail_index_set_error(index, "%s failed with index file %s: %m",
                    function, index->filepath);
}

int mail_index_file_set_syscall_error(struct mail_index *index,
                      const char *filepath,
                      const char *function)
{
    i_assert(filepath != NULL);
    i_assert(function != NULL);

    if (ENOSPACE(errno)) {
        index->nodiskspace = TRUE;
        return -1;
    }

    return mail_index_set_error(index, "%s failed with file %s: %m",
                    function, filepath);
}

enum mail_index_error mail_index_get_last_error(struct mail_index *index)
{
    if (index->nodiskspace)
        return MAIL_INDEX_ERROR_DISKSPACE;
    if (index->error != NULL)
        return MAIL_INDEX_ERROR_INTERNAL;

    return MAIL_INDEX_ERROR_NONE;
}

const char *mail_index_get_error_message(struct mail_index *index)
{
    return index->error;
}

void mail_index_reset_error(struct mail_index *index)
{
    if (index->error != NULL) {
        i_free(index->error);
        index->error = NULL;
    }

    index->nodiskspace = FALSE;
        index->index_lock_timeout = FALSE;
}

int mail_index_is_in_memory(struct mail_index *index)
{
    return FALSE; // FIXME
}