src/lib-index/mail-transaction-log.c

	mail-transaction-log.c revision 437b1d7e0a91ed93ff66a9056d0aac16ae23603c
5e0ce63bb65db34d7f48b34bbb5545fa791781c4Timo Sirainen/* Copyright (C) 2003-2007 Timo Sirainen */
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include "lib.h"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include "ioloop.h"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include "buffer.h"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include "file-dotlock.h"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include "nfs-workarounds.h"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include "close-keep-errno.h"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include "mmap-util.h"
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen#include "mail-index-private.h"
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen#include "mail-transaction-log-private.h"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include <stddef.h>
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include <stdio.h>
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#include <sys/stat.h>
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen/* this lock should never exist for a long time.. */
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#define LOG_DOTLOCK_TIMEOUT 60
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#define LOG_DOTLOCK_STALE_TIMEOUT 60
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#define MAIL_TRANSACTION_LOG_SUFFIX ".log"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#define LOG_NEW_DOTLOCK_SUFFIX ".newlock"
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenstatic void
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainenmail_transaction_log_set_head(struct mail_transaction_log *log,
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen                  struct mail_transaction_log_file *file)
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    i_assert(log->head != file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    file->refcount++;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    log->head = file;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen}
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenstruct mail_transaction_log *
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenmail_transaction_log_alloc(struct mail_index *index)
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    struct mail_transaction_log *log;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    log = i_new(struct mail_transaction_log, 1);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    log->index = index;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    log->dotlock_settings.use_excl_lock = index->use_excl_dotlocks;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    log->dotlock_settings.timeout = LOG_DOTLOCK_TIMEOUT;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    log->dotlock_settings.stale_timeout = LOG_DOTLOCK_STALE_TIMEOUT;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    log->new_dotlock_settings = log->dotlock_settings;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    log->new_dotlock_settings.lock_suffix = LOG_NEW_DOTLOCK_SUFFIX;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    return log;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen}
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainenint mail_transaction_log_open(struct mail_transaction_log *log)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    struct mail_transaction_log_file *file;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    const char *path;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    int ret;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    if (log->open_file != NULL)
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen        mail_transaction_log_file_free(&log->open_file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen    if (MAIL_INDEX_IS_IN_MEMORY(log->index))
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen        return 0;
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen    path = t_strconcat(log->index->filepath,
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen               MAIL_TRANSACTION_LOG_SUFFIX, NULL);
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen    file = mail_transaction_log_file_alloc(log, path);
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen    if ((ret = mail_transaction_log_file_open(file, FALSE)) <= 0) {
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        /* leave the file for _create() */
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        log->open_file = file;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen        return ret;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    }
f923659c0e5298263d80622c99f4dc4132b4675bTimo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    mail_transaction_log_set_head(log, file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    return 1;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen}
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenint mail_transaction_log_create(struct mail_transaction_log *log)
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    struct mail_transaction_log_file *file;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    const char *path;
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen
af81f402ddc897c74c1e85abd02879612ce44882Timo Sirainen    if (MAIL_INDEX_IS_IN_MEMORY(log->index)) {
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file = mail_transaction_log_file_alloc_in_memory(log);
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen        mail_transaction_log_set_head(log, file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        return 0;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    }
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen    path = t_strconcat(log->index->filepath,
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen               MAIL_TRANSACTION_LOG_SUFFIX, NULL);
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen    file = mail_transaction_log_file_alloc(log, path);
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen    if (log->open_file != NULL) {
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen        /* remember what file we tried to open. if someone else created
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen           a new file, use it instead of recreating it */
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->st_ino = log->open_file->st_ino;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->st_dev = log->open_file->st_dev;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->last_size = log->open_file->last_size;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->last_mtime = log->open_file->last_mtime;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        mail_transaction_log_file_free(&log->open_file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    }
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    if (mail_transaction_log_file_create(file) < 0)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        mail_transaction_log_file_free(&file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    mail_transaction_log_set_head(log, file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    return 1;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen}
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenvoid mail_transaction_log_close(struct mail_transaction_log *log)
b3142c8e513bc78da821fa70f479016148fa95e5Timo Sirainen{
af81f402ddc897c74c1e85abd02879612ce44882Timo Sirainen    mail_transaction_log_views_close(log);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    if (log->open_file != NULL)
b3142c8e513bc78da821fa70f479016148fa95e5Timo Sirainen        mail_transaction_log_file_free(&log->open_file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    if (log->head != NULL)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        log->head->refcount--;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    mail_transaction_logs_clean(log);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    i_assert(log->files == NULL);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen}
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenvoid mail_transaction_log_free(struct mail_transaction_log **_log)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    struct mail_transaction_log *log = *_log;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    *_log = NULL;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    mail_transaction_log_close(log);
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    log->index->log = NULL;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    i_free(log);
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen}
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainenvoid mail_transaction_log_move_to_memory(struct mail_transaction_log *log)
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    if (log->head != NULL)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        mail_transaction_log_file_move_to_memory(log->head);
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen}
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenvoid mail_transaction_logs_clean(struct mail_transaction_log *log)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen{
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    struct mail_transaction_log_file *file, *next;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    for (file = log->files; file != NULL; file = next) {
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        next = file->next;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
b3142c8e513bc78da821fa70f479016148fa95e5Timo Sirainen        i_assert(file->refcount >= 0);
b3142c8e513bc78da821fa70f479016148fa95e5Timo Sirainen        if (file->refcount == 0)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen            mail_transaction_log_file_free(&file);
b3142c8e513bc78da821fa70f479016148fa95e5Timo Sirainen    }
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen}
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen#define LOG_WANT_ROTATE(file) \
b3142c8e513bc78da821fa70f479016148fa95e5Timo Sirainen    (((file)->sync_offset > MAIL_TRANSACTION_LOG_ROTATE_MIN_SIZE && \
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen      (time_t)(file)->hdr.create_stamp < \
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen       ioloop_time - MAIL_TRANSACTION_LOG_ROTATE_TIME) || \
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen     ((file)->sync_offset > MAIL_TRANSACTION_LOG_ROTATE_MAX_SIZE))
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainenbool mail_transaction_log_want_rotate(struct mail_transaction_log *log)
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    return LOG_WANT_ROTATE(log->head);
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen}
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainenint mail_transaction_log_rotate(struct mail_transaction_log *log)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen{
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    struct mail_transaction_log_file *file;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    const char *path = log->head->filepath;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen    struct stat st;
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    i_assert(log->head->locked);
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen    if (MAIL_INDEX_IS_IN_MEMORY(log->index))
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file = mail_transaction_log_file_alloc_in_memory(log);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    else {
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen                /* we're locked, we shouldn't need to worry about ESTALE
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen                   problems in here. */
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        if (fstat(log->head->fd, &st) < 0) {
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen            mail_index_file_set_syscall_error(log->index,
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen                file->filepath, "fstat()");
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen            return -1;
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen        }
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen        file = mail_transaction_log_file_alloc(log, path);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->st_dev = st.st_dev;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->st_ino = st.st_ino;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->last_mtime = st.st_mtime;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        file->last_size = st.st_size;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        if (mail_transaction_log_file_create(file) < 0) {
c0435c854a0e7246373b9752d163095cc4fbe985Timo Sirainen            mail_transaction_log_file_free(&file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen            return -1;
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen        }
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    }
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    if (--log->head->refcount == 0)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        mail_transaction_logs_clean(log);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    else
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen        mail_transaction_log_file_unlock(log->head);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    mail_transaction_log_set_head(log, file);
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen    return 0;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen}
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainenstatic int mail_transaction_log_refresh(struct mail_transaction_log *log)
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen{
dd62b77c932d1b518f2a3e4bf80e36542becc256Timo Sirainen        struct mail_transaction_log_file *file;
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen    struct stat st;
03f5c621d06d6b6d77a145196c9633a7aa64dc78Timo Sirainen    const char *path;
ecc81625167ed96c04c02aa190a1ea5baa65b474Timo Sirainen
    i_assert(log->head != NULL);

    if (MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(log->head))
        return 0;

    path = t_strconcat(log->index->filepath,
               MAIL_TRANSACTION_LOG_SUFFIX, NULL);
    if (nfs_safe_stat(path, &st) < 0) {
        if (errno != ENOENT) {
            mail_index_file_set_syscall_error(log->index, path,
                              "stat()");
            return -1;
        }
        return -1;
    } else {
        if (log->head->st_ino == st.st_ino &&
            CMP_DEV_T(log->head->st_dev, st.st_dev)) {
            /* same file */
            return 0;
        }
    }

    file = mail_transaction_log_file_alloc(log, path);
    if (mail_transaction_log_file_open(file, FALSE) <= 0) {
        mail_transaction_log_file_free(&file);
        return -1;
    }

    i_assert(!file->locked);

    if (--log->head->refcount == 0)
        mail_transaction_logs_clean(log);
    mail_transaction_log_set_head(log, file);
    return 0;
}

void mail_transaction_log_get_mailbox_sync_pos(struct mail_transaction_log *log,
                           uint32_t *file_seq_r,
                           uoff_t *file_offset_r)
{
    *file_seq_r = log->head->hdr.file_seq;
    *file_offset_r = log->head->mailbox_sync_max_offset;
}

void mail_transaction_log_set_mailbox_sync_pos(struct mail_transaction_log *log,
                           uint32_t file_seq,
                           uoff_t file_offset)
{
    i_assert(file_seq == log->head->hdr.file_seq);
    i_assert(file_offset >= log->head->mailbox_sync_saved_offset);

    if (file_offset >= log->head->mailbox_sync_max_offset)
        log->head->mailbox_sync_max_offset = file_offset;
}

int mail_transaction_log_find_file(struct mail_transaction_log *log,
                   uint32_t file_seq,
                   struct mail_transaction_log_file **file_r)
{
    struct mail_transaction_log_file *file;
    const char *path;
    int ret;

    if (file_seq > log->head->hdr.file_seq) {
        /* see if the .log file has been recreated */
        if (log->head->locked) {
            /* transaction log is locked. there's no way a newer
               file exists. */
            return 0;
        }

        if (mail_transaction_log_refresh(log) < 0)
            return -1;
        if (file_seq > log->head->hdr.file_seq)
            return 0;
    }

    for (file = log->files; file != NULL; file = file->next) {
        if (file->hdr.file_seq == file_seq) {
            *file_r = file;
            return 1;
        }
    }

    if (MAIL_INDEX_IS_IN_MEMORY(log->index))
        return 0;

    /* see if we have it in log.2 file */
    path = t_strconcat(log->index->filepath,
               MAIL_TRANSACTION_LOG_SUFFIX".2", NULL);
    file = mail_transaction_log_file_alloc(log, path);
    if ((ret = mail_transaction_log_file_open(file, TRUE)) <= 0)
        return ret;

    /* but is it what we expected? */
    if (file->hdr.file_seq != file_seq)
        return 0;

    *file_r = file;
    return 1;
}

int mail_transaction_log_lock_head(struct mail_transaction_log *log)
{
    struct mail_transaction_log_file *file;
    int ret = 0;

    /* we want to get the head file locked. this is a bit racy,
       since by the time we have it locked a new log file may have been
       created.

       creating new log file requires locking the head file, so if we
       can lock it and don't see another file, we can be sure no-one is
       creating a new log at the moment */

    for (;;) {
        file = log->head;
        if (mail_transaction_log_file_lock(file) < 0)
            return -1;

        file->refcount++;
        ret = mail_transaction_log_refresh(log);
        if (--file->refcount == 0) {
            mail_transaction_logs_clean(log);
            file = NULL;
        }

        if (ret == 0 && log->head == file) {
            /* success */
            break;
        }

        if (file != NULL)
            mail_transaction_log_file_unlock(file);

        if (ret < 0)
            break;

        /* try again */
    }

    return ret;
}

int mail_transaction_log_sync_lock(struct mail_transaction_log *log,
                   uint32_t *file_seq_r, uoff_t *file_offset_r)
{
    i_assert(!log->index->log_locked);

    if (mail_transaction_log_lock_head(log) < 0)
        return -1;

    /* update sync_offset */
    if (mail_transaction_log_file_map(log->head, log->head->sync_offset,
                      (uoff_t)-1) <= 0) {
        mail_transaction_log_file_unlock(log->head);
        return -1;
    }

    log->index->log_locked = TRUE;
    *file_seq_r = log->head->hdr.file_seq;
    *file_offset_r = log->head->sync_offset;
    return 0;
}

void mail_transaction_log_sync_unlock(struct mail_transaction_log *log)
{
    i_assert(log->index->log_locked);

    log->index->log_locked = FALSE;
    mail_transaction_log_file_unlock(log->head);
}

void mail_transaction_log_get_head(struct mail_transaction_log *log,
                   uint32_t *file_seq_r, uoff_t *file_offset_r)
{
    i_assert(log->index->log_locked);

    *file_seq_r = log->head->hdr.file_seq;
    *file_offset_r = log->head->sync_offset;
}

bool mail_transaction_log_is_head_prev(struct mail_transaction_log *log,
                       uint32_t file_seq, uoff_t file_offset)
{
    return log->head->hdr.prev_file_seq == file_seq &&
        log->head->hdr.prev_file_offset == file_offset;
}