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

	mail-transaction-log-file.c revision e0f4fbf127b192667c62af7875c4f2ca294b6c7a
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen/* Copyright (c) 2003-2017 Dovecot authors, see the included COPYING file */
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#include "lib.h"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#include "array.h"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#include "ioloop.h"
e074ffeaee1ce283bd42f167c6810e3d013f8218Timo Sirainen#include "file-dotlock.h"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#include "nfs-workarounds.h"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#include "read-full.h"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#include "write-full.h"
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen#include "mmap-util.h"
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen#include "mail-index-private.h"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#include "mail-index-modseq.h"
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen#include "mail-transaction-log-private.h"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#define LOG_PREFETCH IO_BLOCK_SIZE
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#define MEMORY_LOG_NAME "(in-memory transaction log file)"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen#define LOG_NEW_DOTLOCK_SUFFIX ".newlock"
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenstatic int
797de45dcf6e24642ab347d5033beb92034b779dTimo Sirainenmail_transaction_log_file_sync(struct mail_transaction_log_file *file,
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen                   bool *retry_r);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainenstatic void
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainenlog_file_set_syscall_error(struct mail_transaction_log_file *file,
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen               const char *function)
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen{
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    mail_index_file_set_syscall_error(file->log->index,
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen                      file->filepath, function);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen}
797de45dcf6e24642ab347d5033beb92034b779dTimo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenstatic void
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainenmail_transaction_log_mark_corrupted(struct mail_transaction_log_file *file)
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen{
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen    unsigned int offset =
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen        offsetof(struct mail_transaction_log_header, indexid);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    int flags;
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen
797de45dcf6e24642ab347d5033beb92034b779dTimo Sirainen    if (MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(file) ||
8afe3f0e832b8b3483b692205bbd59c0110a20fdTimo Sirainen        file->log->index->readonly)
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen        return;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    /* indexid=0 marks the log file as corrupted. we opened the file with
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen       O_APPEND, and now we need to drop it for pwrite() to work (at least
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen       in Linux) */
797de45dcf6e24642ab347d5033beb92034b779dTimo Sirainen    flags = fcntl(file->fd, F_GETFL, 0);
720692523ece4a549f7c589508d5693ee310f6b3Timo Sirainen    if (flags < 0) {
720692523ece4a549f7c589508d5693ee310f6b3Timo Sirainen        mail_index_file_set_syscall_error(file->log->index,
720692523ece4a549f7c589508d5693ee310f6b3Timo Sirainen            file->filepath, "fcntl(F_GETFL)");
4b8459c6c24b79d4ed5974ab6e3289a3f2b701c0Timo Sirainen        return;
720692523ece4a549f7c589508d5693ee310f6b3Timo Sirainen    }
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen    if (fcntl(file->fd, F_SETFL, flags & ~O_APPEND) < 0) {
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        mail_index_file_set_syscall_error(file->log->index,
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen            file->filepath, "fcntl(F_SETFL)");
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen        return;
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen    }
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    if (pwrite_full(file->fd, &file->hdr.indexid,
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen            sizeof(file->hdr.indexid), offset) < 0) {
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        mail_index_file_set_syscall_error(file->log->index,
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen                          file->filepath, "pwrite()");
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen    }
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen}
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenvoid
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenmail_transaction_log_file_set_corrupted(struct mail_transaction_log_file *file,
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen                    const char *fmt, ...)
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen{
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen    va_list va;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    file->corrupted = TRUE;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    file->hdr.indexid = 0;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    mail_transaction_log_mark_corrupted(file);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    va_start(va, fmt);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    T_BEGIN {
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen        mail_index_set_error(file->log->index,
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen            "Corrupted transaction log file %s seq %u: %s "
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen            "(sync_offset=%"PRIuUOFF_T")",
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen            file->filepath, file->hdr.file_seq,
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen            t_strdup_vprintf(fmt, va), file->sync_offset);
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen    } T_END;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    va_end(va);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen}
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenstruct mail_transaction_log_file *
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenmail_transaction_log_file_alloc(struct mail_transaction_log *log,
193f5296d2a6b847970c222d8a261b89aae46331Timo Sirainen                const char *path)
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen{
193f5296d2a6b847970c222d8a261b89aae46331Timo Sirainen    struct mail_transaction_log_file *file;
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    file = i_new(struct mail_transaction_log_file, 1);
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    file->log = log;
6ef7e31619edfaa17ed044b45861d106a86191efTimo Sirainen    file->filepath = i_strdup(path);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    file->fd = -1;
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    return file;
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen}
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenvoid mail_transaction_log_file_free(struct mail_transaction_log_file **_file)
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen{
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    struct mail_transaction_log_file *file = *_file;
965e13eea8dc7f1da3769ab0c4667e36d0f33192Timo Sirainen    struct mail_transaction_log_file **p;
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen    int old_errno = errno;
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    *_file = NULL;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    i_assert(!file->locked);
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    for (p = &file->log->files; *p != NULL; p = &(*p)->next) {
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        if (*p == file) {
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen            *p = file->next;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen            break;
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        }
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    }
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    if (file == file->log->head)
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        file->log->head = NULL;
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    if (file->buffer != NULL)
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        buffer_free(&file->buffer);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    if (file->mmap_base != NULL) {
193f5296d2a6b847970c222d8a261b89aae46331Timo Sirainen        if (munmap(file->mmap_base, file->mmap_size) < 0)
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen            log_file_set_syscall_error(file, "munmap()");
193f5296d2a6b847970c222d8a261b89aae46331Timo Sirainen    }
08f24237ccc177f5b3a09b24d8a725fa47e1ee32Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    if (file->fd != -1) {
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        if (close(file->fd) < 0)
6ef7e31619edfaa17ed044b45861d106a86191efTimo Sirainen            log_file_set_syscall_error(file, "close()");
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    }
8d80659e504ffb34bb0c6a633184fece35751b18Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    i_free(file->filepath);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        i_free(file);
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen        errno = old_errno;
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen}
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenstatic void
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainenmail_transaction_log_file_skip_to_head(struct mail_transaction_log_file *file)
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen{
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen    struct mail_transaction_log *log = file->log;
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen    struct mail_index_map *map = log->index->map;
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen    const struct mail_index_modseq_header *modseq_hdr;
745f2c7424d88e368eff0a3a7650b352a9d1f0ddTimo Sirainen    uoff_t head_offset;
f05b9dd37f830576ca7d32ec7071bf87906df3d2Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    if (map == NULL || file->hdr.file_seq != map->hdr.log_file_seq ||
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        map->hdr.log_file_head_offset == 0)
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        return;
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen    /* we can get a valid log offset from index file. initialize
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen       sync_offset from it so we don't have to read the whole log
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen       file from beginning. */
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    head_offset = map->hdr.log_file_head_offset;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    modseq_hdr = mail_index_map_get_modseq_header(map);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    if (head_offset < file->hdr.hdr_size) {
797de45dcf6e24642ab347d5033beb92034b779dTimo Sirainen        mail_index_set_error(log->index,
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen                     "%s: log_file_head_offset too small",
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen                     log->index->filepath);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        file->sync_offset = file->hdr.hdr_size;
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen        file->sync_highest_modseq = file->hdr.initial_modseq;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    } else if (modseq_hdr == NULL && file->hdr.initial_modseq == 0) {
35565557e05721a761132cec2ba1d93acacb6c14Timo Sirainen        /* modseqs not used yet */
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen        file->sync_offset = head_offset;
6ef7e31619edfaa17ed044b45861d106a86191efTimo Sirainen        file->sync_highest_modseq = 0;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    } else if (modseq_hdr == NULL ||
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen           modseq_hdr->log_seq != file->hdr.file_seq) {
20a3870db4f78717574ee94bca1512994391b2abTimo Sirainen        /* highest_modseq not synced, start from beginning */
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        file->sync_offset = file->hdr.hdr_size;
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen        file->sync_highest_modseq = file->hdr.initial_modseq;
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen    } else if (modseq_hdr->log_offset > head_offset) {
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        mail_index_set_error(log->index,
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen                     "%s: modseq_hdr.log_offset too large",
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen                     log->index->filepath);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        file->sync_offset = file->hdr.hdr_size;
20a3870db4f78717574ee94bca1512994391b2abTimo Sirainen        file->sync_highest_modseq = file->hdr.initial_modseq;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    } else {
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen        /* start from where we last stopped tracking modseqs */
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        file->sync_offset = modseq_hdr->log_offset;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        file->sync_highest_modseq = modseq_hdr->highest_modseq;
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen    }
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen    if (file->hdr.file_seq == log->index->map->hdr.log_file_seq) {
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen        file->saved_tail_offset =
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen            log->index->map->hdr.log_file_tail_offset;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        file->saved_tail_sync_offset = file->saved_tail_offset;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    }
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen    if (file->saved_tail_offset > file->max_tail_offset)
dba5754de32284b3149ddd5c9bb1701b05707752Timo Sirainen        file->max_tail_offset = file->saved_tail_offset;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen}
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenstatic void
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainenmail_transaction_log_file_add_to_list(struct mail_transaction_log_file *file)
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen{
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    struct mail_transaction_log_file **p;
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen    bool retry;
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen    file->sync_offset = file->hdr.hdr_size;
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen    file->sync_highest_modseq = file->hdr.initial_modseq;
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen    mail_transaction_log_file_skip_to_head(file);
8d59f06c9422fa49b538e23ffb06eddb23c6add2Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    /* insert it to correct position */
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    for (p = &file->log->files; *p != NULL; p = &(*p)->next) {
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        if ((*p)->hdr.file_seq > file->hdr.file_seq)
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen            break;
a912d084eb8024ce35462c9fd2d50b86b13d8d33Timo Sirainen        i_assert((*p)->hdr.file_seq < file->hdr.file_seq);
a912d084eb8024ce35462c9fd2d50b86b13d8d33Timo Sirainen    }
a912d084eb8024ce35462c9fd2d50b86b13d8d33Timo Sirainen
dcc76bb1e1bb287e3e71e6a39a7ca207fab0eaa8Timo Sirainen    file->next = *p;
a912d084eb8024ce35462c9fd2d50b86b13d8d33Timo Sirainen    *p = file;
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen    if (file->buffer != NULL) {
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        /* if we read any unfinished data, make sure the buffer gets
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen           truncated. */
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        (void)mail_transaction_log_file_sync(file, &retry);
c014f12e8268bf37ca2997e632ad7c22b8d04a84Timo Sirainen        buffer_set_used_size(file->buffer,
                     file->sync_offset - file->buffer_offset);
    }
}

static int
mail_transaction_log_init_hdr(struct mail_transaction_log *log,
                  struct mail_transaction_log_header *hdr)
{
    struct mail_index *index = log->index;
    struct mail_transaction_log_file *file;

    i_assert(index->indexid != 0);

    i_zero(hdr);
    hdr->major_version = MAIL_TRANSACTION_LOG_MAJOR_VERSION;
    hdr->minor_version = MAIL_TRANSACTION_LOG_MINOR_VERSION;
    hdr->hdr_size = sizeof(struct mail_transaction_log_header);
    hdr->indexid = log->index->indexid;
    hdr->create_stamp = ioloop_time;
#if !WORDS_BIGENDIAN
    hdr->compat_flags |= MAIL_INDEX_COMPAT_LITTLE_ENDIAN;
#endif

    if (index->fd != -1) {
        /* not creating index - make sure we have latest header */
        if (!index->mapping) {
            if (mail_index_map(index,
                       MAIL_INDEX_SYNC_HANDLER_HEAD) <= 0)
                return -1;
        } else {
            /* if we got here from mapping, the .log file is
               corrupted. use whatever values we got from index
               file */
        }
    }
    if (index->map != NULL) {
        hdr->prev_file_seq = index->map->hdr.log_file_seq;
        hdr->prev_file_offset = index->map->hdr.log_file_head_offset;
        hdr->file_seq = index->map->hdr.log_file_seq + 1;
        hdr->initial_modseq =
            mail_index_map_modseq_get_highest(index->map);
    } else {
        hdr->file_seq = 1;
    }
    if (hdr->initial_modseq == 0) {
        /* modseq tracking in log files is required for many reasons
           nowadays, even if per-message modseqs aren't enabled in
           dovecot.index. */
        hdr->initial_modseq = 1;
    }

    if (log->head != NULL) {
        /* make sure the sequence always increases to avoid crashes
           later. this catches the buggy case where two processes
           happen to replace the same log file. */
        for (file = log->head->next; file != NULL; file = file->next) {
            if (hdr->file_seq <= file->hdr.file_seq)
                hdr->file_seq = file->hdr.file_seq + 1;
        }

        if (hdr->file_seq <= log->head->hdr.file_seq) {
            /* make sure the sequence grows */
            hdr->file_seq = log->head->hdr.file_seq+1;
        }
        if (hdr->initial_modseq < log->head->sync_highest_modseq) {
            /* this should be always up-to-date */
            hdr->initial_modseq = log->head->sync_highest_modseq;
        }
    }
    return 0;
}

struct mail_transaction_log_file *
mail_transaction_log_file_alloc_in_memory(struct mail_transaction_log *log)
{
    struct mail_transaction_log_file *file;

    file = mail_transaction_log_file_alloc(log, MEMORY_LOG_NAME);
    if (mail_transaction_log_init_hdr(log, &file->hdr) < 0) {
        i_free(file);
        return NULL;
    }

    file->buffer = buffer_create_dynamic(default_pool, 4096);
    file->buffer_offset = sizeof(file->hdr);

    mail_transaction_log_file_add_to_list(file);
    return file;
}

static int
mail_transaction_log_file_dotlock(struct mail_transaction_log_file *file)
{
    struct dotlock_settings dotlock_set;
    int ret;

    if (file->log->dotlock_count > 0)
        ret = 1;
    else {
        mail_transaction_log_get_dotlock_set(file->log, &dotlock_set);
        ret = file_dotlock_create(&dotlock_set, file->filepath, 0,
                      &file->log->dotlock);
    }
    if (ret > 0) {
        file->log->dotlock_count++;
        file->locked = TRUE;
        file->lock_created = time(NULL);
        return 0;
    }
    if (ret < 0) {
        log_file_set_syscall_error(file, "file_dotlock_create()");
        return -1;
    }

    mail_index_set_error(file->log->index,
                 "Timeout (%us) while waiting for "
                 "dotlock for transaction log file %s",
                 dotlock_set.timeout, file->filepath);
    file->log->index->index_lock_timeout = TRUE;
    return -1;
}

static int
mail_transaction_log_file_undotlock(struct mail_transaction_log_file *file)
{
    int ret;

    if (--file->log->dotlock_count > 0)
        return 0;

    ret = file_dotlock_delete(&file->log->dotlock);
    if (ret < 0) {
        log_file_set_syscall_error(file, "file_dotlock_delete()");
        return -1;
    }

    if (ret == 0) {
        mail_index_set_error(file->log->index,
            "Dotlock was lost for transaction log file %s",
            file->filepath);
        return -1;
    }
    return 0;
}

int mail_transaction_log_file_lock(struct mail_transaction_log_file *file)
{
    unsigned int lock_timeout_secs;
    int ret;

    if (file->locked)
        return 0;

    if (MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(file)) {
        file->locked = TRUE;
        return 0;
    }

    if (file->log->index->lock_method == FILE_LOCK_METHOD_DOTLOCK)
        return mail_transaction_log_file_dotlock(file);

    if (file->log->index->readonly) {
        mail_index_set_error(file->log->index,
            "Index is read-only, can't write-lock %s",
            file->filepath);
        return -1;
    }

    i_assert(file->file_lock == NULL);
    lock_timeout_secs = I_MIN(MAIL_TRANSACTION_LOG_LOCK_TIMEOUT,
                  file->log->index->max_lock_timeout_secs);
    ret = mail_index_lock_fd(file->log->index, file->filepath, file->fd,
                 F_WRLCK, lock_timeout_secs,
                 &file->file_lock);
    if (ret > 0) {
        file->locked = TRUE;
        file->lock_created = time(NULL);
        return 0;
    }
    if (ret < 0) {
        log_file_set_syscall_error(file, "mail_index_wait_lock_fd()");
        return -1;
    }

    mail_index_set_error(file->log->index,
        "Timeout (%us) while waiting for lock for "
        "transaction log file %s%s",
        lock_timeout_secs, file->filepath,
        file_lock_find(file->fd, file->log->index->lock_method, F_WRLCK));
    file->log->index->index_lock_timeout = TRUE;
    return -1;
}

void mail_transaction_log_file_unlock(struct mail_transaction_log_file *file,
                      const char *lock_reason)
{
    unsigned int lock_time;

    if (!file->locked)
        return;

    file->locked = FALSE;
    file->locked_sync_offset_updated = FALSE;

    if (MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(file))
        return;

    lock_time = time(NULL) - file->lock_created;
    if (lock_time >= MAIL_TRANSACTION_LOG_LOCK_WARN_SECS && lock_reason != NULL) {
        i_warning("Transaction log file %s was locked for %u seconds (%s)",
              file->filepath, lock_time, lock_reason);
    }

    if (file->log->index->lock_method == FILE_LOCK_METHOD_DOTLOCK) {
        (void)mail_transaction_log_file_undotlock(file);
        return;
    }

    file_unlock(&file->file_lock);
}

static ssize_t
mail_transaction_log_file_read_header(struct mail_transaction_log_file *file)
{
    void *dest;
    size_t pos, dest_size;
    ssize_t ret;

    i_assert(file->buffer == NULL && file->mmap_base == NULL);

    i_zero(&file->hdr);
    if (file->last_size < mmap_get_page_size() && file->last_size > 0) {
        /* just read the entire transaction log to memory.
           note that if some of the data hasn't been fully committed
           yet (hdr.size=0), the buffer must be truncated later */
        file->buffer = buffer_create_dynamic(default_pool, 4096);
        file->buffer_offset = 0;
        dest_size = file->last_size;
        dest = buffer_append_space_unsafe(file->buffer, dest_size);
    } else {
        /* read only the header */
        dest = &file->hdr;
        dest_size = sizeof(file->hdr);
    }

    /* it's not necessarily an error to read less than wanted header size,
       since older versions of the log format used smaller headers. */
        pos = 0;
    do {
        ret = pread(file->fd, PTR_OFFSET(dest, pos),
                dest_size - pos, pos);
        if (ret > 0)
            pos += ret;
    } while (ret > 0 && pos < dest_size);

    if (file->buffer != NULL) {
        buffer_set_used_size(file->buffer, pos);
        memcpy(&file->hdr, file->buffer->data,
               I_MIN(pos, sizeof(file->hdr)));
    }

    return ret < 0 ? -1 : (ssize_t)pos;
}

static int
mail_transaction_log_file_fail_dupe(struct mail_transaction_log_file *file)
{
    int ret;

    /* mark the old file corrupted. we can't safely remove
       it from the list however, so return failure. */
    file->hdr.indexid = 0;
    if (strcmp(file->filepath, file->log->head->filepath) != 0) {
        /* only mark .2 corrupted, just to make sure we don't lose any
           changes from .log in case we're somehow wrong */
        mail_transaction_log_mark_corrupted(file);
        ret = 0;
    } else {
        ret = -1;
    }
    if (!file->corrupted) {
        file->corrupted = TRUE;
        mail_index_set_error(file->log->index,
                     "Transaction log %s: "
                     "duplicate transaction log sequence (%u)",
                     file->filepath, file->hdr.file_seq);
    }
    return ret;
}

static int
mail_transaction_log_file_read_hdr(struct mail_transaction_log_file *file,
                   bool ignore_estale)
{
        struct mail_transaction_log_file *f;
    int ret;

    i_assert(!MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(file));

    if (file->corrupted)
        return 0;

    ret = mail_transaction_log_file_read_header(file);
    if (ret < 0) {
                if (errno != ESTALE || !ignore_estale)
            log_file_set_syscall_error(file, "pread()");
        return -1;
    }
    if (file->hdr.major_version != MAIL_TRANSACTION_LOG_MAJOR_VERSION) {
        /* incompatible version - fix silently */
        return 0;
    }
    if (ret < MAIL_TRANSACTION_LOG_HEADER_MIN_SIZE) {
        mail_transaction_log_file_set_corrupted(file,
            "unexpected end of file while reading header");
        return 0;
    }

    const unsigned int hdr_version =
        MAIL_TRANSACTION_LOG_HDR_VERSION(&file->hdr);
    if (MAIL_TRANSACTION_LOG_VERSION_HAVE(hdr_version, COMPAT_FLAGS)) {
        /* we have compatibility flags */
        enum mail_index_header_compat_flags compat_flags = 0;

#if !WORDS_BIGENDIAN
        compat_flags |= MAIL_INDEX_COMPAT_LITTLE_ENDIAN;
#endif
        if (file->hdr.compat_flags != compat_flags) {
            /* architecture change */
            mail_index_set_error(file->log->index,
                         "Rebuilding index file %s: "
                         "CPU architecture changed",
                         file->log->index->filepath);
            return 0;
        }
    }
    if (file->hdr.hdr_size < MAIL_TRANSACTION_LOG_HEADER_MIN_SIZE) {
        mail_transaction_log_file_set_corrupted(file,
            "Header size too small");
        return 0;
    }
    if (file->hdr.hdr_size < sizeof(file->hdr)) {
        /* @UNSAFE: smaller than we expected - zero out the fields we
           shouldn't have filled */
        memset(PTR_OFFSET(&file->hdr, file->hdr.hdr_size), 0,
               sizeof(file->hdr) - file->hdr.hdr_size);
    }

    if (file->hdr.indexid == 0) {
        /* corrupted */
        file->corrupted = TRUE;
        mail_index_set_error(file->log->index,
            "Transaction log file %s: marked corrupted",
            file->filepath);
        return 0;
    }
    if (file->hdr.indexid != file->log->index->indexid) {
        if (file->log->index->indexid != 0 &&
            !file->log->index->initial_create) {
            /* index file was probably just rebuilt and we don't
               know about it yet */
            mail_transaction_log_file_set_corrupted(file,
                "indexid changed %u -> %u",
                file->log->index->indexid, file->hdr.indexid);
            return 0;
        }

        /* creating index file. since transaction log is created
           first, use the indexid in it to create the main index
           to avoid races. */
        file->log->index->indexid = file->hdr.indexid;
    }

    /* make sure we already don't have a file with the same sequence
       opened. it shouldn't happen unless the old log file was
       corrupted. */
    for (f = file->log->files; f != NULL; f = f->next) {
        if (f->hdr.file_seq == file->hdr.file_seq) {
            if (strcmp(f->filepath, f->log->head->filepath) != 0) {
                /* old "f" is the .log.2 */
                return mail_transaction_log_file_fail_dupe(f);
            } else {
                /* new "file" is probably the .log.2 */
                return mail_transaction_log_file_fail_dupe(file);
            }
        }
    }

    file->sync_highest_modseq = file->hdr.initial_modseq;
    return 1;
}

static int
mail_transaction_log_file_stat(struct mail_transaction_log_file *file,
                   bool ignore_estale)
{
    struct stat st;

    if (fstat(file->fd, &st) < 0) {
                if (!ESTALE_FSTAT(errno) || !ignore_estale)
            log_file_set_syscall_error(file, "fstat()");
        return -1;
    }

    file->st_dev = st.st_dev;
    file->st_ino = st.st_ino;
    file->last_mtime = st.st_mtime;
    file->last_size = st.st_size;
    return 0;
}

static bool
mail_transaction_log_file_is_dupe(struct mail_transaction_log_file *file)
{
    struct mail_transaction_log_file *tmp;

    for (tmp = file->log->files; tmp != NULL; tmp = tmp->next) {
        if (tmp->st_ino == file->st_ino &&
            CMP_DEV_T(tmp->st_dev, file->st_dev))
            return TRUE;
    }
    return FALSE;
}

static void log_write_ext_hdr_init_data(struct mail_index *index, buffer_t *buf)
{
    const struct mail_index_registered_ext *rext;
    struct mail_transaction_header *hdr;
    struct mail_transaction_ext_intro *intro;
    struct mail_transaction_ext_hdr_update *ext_hdr;
    unsigned int hdr_offset;

    rext = array_idx(&index->extensions, index->ext_hdr_init_id);

    /* introduce the extension */
    hdr_offset = buf->used;
    hdr = buffer_append_space_unsafe(buf, sizeof(*hdr));
    hdr->type = MAIL_TRANSACTION_EXT_INTRO;

    intro = buffer_append_space_unsafe(buf, sizeof(*intro));
    intro->ext_id = (uint32_t)-1;
    intro->hdr_size = rext->hdr_size;
    intro->record_size = rext->record_size;
    intro->record_align = rext->record_align;
    intro->name_size = strlen(rext->name);
    buffer_append(buf, rext->name, intro->name_size);
    if (buf->used % 4 != 0)
        buffer_append_zero(buf, 4 - buf->used % 4);

    hdr = buffer_get_space_unsafe(buf, hdr_offset, sizeof(*hdr));
    hdr->size = mail_index_uint32_to_offset(buf->used - hdr_offset);

    /* add the extension header data */
    hdr_offset = buf->used;
    hdr = buffer_append_space_unsafe(buf, sizeof(*hdr));
    hdr->type = MAIL_TRANSACTION_EXT_HDR_UPDATE;

    ext_hdr = buffer_append_space_unsafe(buf, sizeof(*ext_hdr));
    ext_hdr->size = rext->hdr_size;
    buffer_append(buf, index->ext_hdr_init_data, rext->hdr_size);

    hdr = buffer_get_space_unsafe(buf, hdr_offset, sizeof(*hdr));
    hdr->size = mail_index_uint32_to_offset(buf->used - hdr_offset);
}

static int
mail_transaction_log_file_create2(struct mail_transaction_log_file *file,
                  int new_fd, bool reset,
                  struct dotlock **dotlock)
{
    struct mail_index *index = file->log->index;
    struct stat st;
    const char *path2;
    buffer_t *writebuf;
    int fd, ret;
    bool rename_existing, need_lock;

    need_lock = file->log->head != NULL && file->log->head->locked;

    if (fcntl(new_fd, F_SETFL, O_APPEND) < 0) {
        log_file_set_syscall_error(file, "fcntl(O_APPEND)");
        return -1;
    }

    if (file->log->nfs_flush) {
        /* although we check also mtime and file size below, it's done
           only to fix broken log files. we don't bother flushing
           attribute cache just for that. */
        nfs_flush_file_handle_cache(file->filepath);
    }

    /* log creation is locked now - see if someone already created it.
       note that if we're rotating, we need to keep the log locked until
       the file has been rewritten. and because fcntl() locks are stupid,
       if we go and open()+close() the file and we had it already opened,
       its locks are lost. so we use stat() to check if the file has been
       recreated, although it almost never is. */
    if (reset)
        rename_existing = FALSE;
    else if (nfs_safe_stat(file->filepath, &st) < 0) {
        if (errno != ENOENT) {
            log_file_set_syscall_error(file, "stat()");
            return -1;
        }
        rename_existing = FALSE;
    } else if (st.st_ino == file->st_ino &&
           CMP_DEV_T(st.st_dev, file->st_dev) &&
           /* inode/dev checks are enough when we're rotating the file,
              but not when we're replacing a broken log file */
           st.st_mtime == file->last_mtime &&
           (uoff_t)st.st_size == file->last_size) {
        /* no-one else recreated the file */
        rename_existing = TRUE;
    } else {
        /* recreated. use the file if its header is ok */
        fd = nfs_safe_open(file->filepath, O_RDWR | O_APPEND);
        if (fd == -1) {
            if (errno != ENOENT) {
                log_file_set_syscall_error(file, "open()");
                return -1;
            }
        } else {
            file->fd = fd;
            file->last_size = 0;
            if (mail_transaction_log_file_read_hdr(file,
                                   FALSE) > 0 &&
                mail_transaction_log_file_stat(file, FALSE) == 0) {
                /* yes, it was ok */
                file_dotlock_delete(dotlock);
                mail_transaction_log_file_add_to_list(file);
                return 0;
            }
            file->fd = -1;
            if (close(fd) < 0)
                log_file_set_syscall_error(file, "close()");
        }
        rename_existing = FALSE;
    }

    if (index->fd == -1 && !rename_existing) {
        /* creating the initial index */
        reset = TRUE;
    }

    if (mail_transaction_log_init_hdr(file->log, &file->hdr) < 0)
        return -1;

    if (reset) {
        /* don't reset modseqs. if we're reseting due to rebuilding
           indexes we'll probably want to keep uidvalidity and in such
           cases we really don't want to shrink modseqs. */
        file->hdr.prev_file_seq = 0;
        file->hdr.prev_file_offset = 0;
    }

    writebuf = buffer_create_dynamic(pool_datastack_create(), 128);
    buffer_append(writebuf, &file->hdr, sizeof(file->hdr));

    if (index->ext_hdr_init_data != NULL && reset)
        log_write_ext_hdr_init_data(index, writebuf);
    if (write_full(new_fd, writebuf->data, writebuf->used) < 0) {
        log_file_set_syscall_error(file, "write_full()");
        return -1;
    }

    if (file->log->index->fsync_mode == FSYNC_MODE_ALWAYS) {
        /* the header isn't important, so don't bother calling
           fdatasync() unless it's required */
        if (fdatasync(new_fd) < 0) {
            log_file_set_syscall_error(file, "fdatasync()");
            return -1;
        }
    }

    file->fd = new_fd;
    ret = mail_transaction_log_file_stat(file, FALSE);

    if (need_lock && ret == 0) {
        /* we'll need to preserve the lock */
        if (mail_transaction_log_file_lock(file) < 0)
            ret = -1;
    }

    /* if we return -1 the dotlock deletion code closes the fd */
    file->fd = -1;
    if (ret < 0)
        return -1;

    /* keep two log files */
    if (rename_existing) {
        /* rename() would be nice and easy way to do this, except then
           there's a race condition between the rename and
           file_dotlock_replace(). during that time the log file
           doesn't exist, which could cause problems. */
        path2 = t_strconcat(file->filepath, ".2", NULL);
        if (i_unlink_if_exists(path2) < 0) {
            /* try to link() anyway */
        }
        if (nfs_safe_link(file->filepath, path2, FALSE) < 0 &&
            errno != ENOENT && errno != EEXIST) {
                        mail_index_set_error(index, "link(%s, %s) failed: %m",
                         file->filepath, path2);
            /* ignore the error. we don't care that much about the
               second log file and we're going to overwrite this
               first one. */
        }
        /* NOTE: here's a race condition where both .log and .log.2
           point to the same file. our reading code should ignore that
           though by comparing the inodes. */
    }

    if (file_dotlock_replace(dotlock,
                 DOTLOCK_REPLACE_FLAG_DONT_CLOSE_FD) <= 0) {
        /* need to unlock to avoid assert-crash in
           mail_transaction_log_file_free() */
        mail_transaction_log_file_unlock(file, "creation failed");
        return -1;
    }

    /* success */
    file->fd = new_fd;
    mail_transaction_log_file_add_to_list(file);

    i_assert(!need_lock || file->locked);
    return 1;
}

int mail_transaction_log_file_create(struct mail_transaction_log_file *file,
                     bool reset)
{
    struct mail_index *index = file->log->index;
    struct dotlock_settings new_dotlock_set;
    struct dotlock *dotlock;
    mode_t old_mask;
    int fd, ret;

    i_assert(!MAIL_INDEX_IS_IN_MEMORY(index));

    if (file->log->index->readonly) {
        mail_index_set_error(index,
            "Can't create log file %s: Index is read-only",
            file->filepath);
        return -1;
    }

    if (index->indexid == 0) {
        mail_index_set_error(index,
            "Can't create log file %s: Index is marked corrupted",
            file->filepath);
        return -1;
    }

    mail_transaction_log_get_dotlock_set(file->log, &new_dotlock_set);
    new_dotlock_set.lock_suffix = LOG_NEW_DOTLOCK_SUFFIX;

    /* With dotlocking we might already have path.lock created, so this
       filename has to be different. */
    old_mask = umask(index->mode ^ 0666);
    fd = file_dotlock_open(&new_dotlock_set, file->filepath, 0, &dotlock);
    umask(old_mask);

    if (fd == -1) {
        log_file_set_syscall_error(file, "file_dotlock_open()");
        return -1;
    }
    mail_index_fchown(index, fd, file_dotlock_get_lock_path(dotlock));

        /* either fd gets used or the dotlock gets deleted and returned fd
           is for the existing file */
    ret = mail_transaction_log_file_create2(file, fd, reset, &dotlock);
    if (ret < 0) {
        if (dotlock != NULL)
            file_dotlock_delete(&dotlock);
        return -1;
    }
    return ret;
}

int mail_transaction_log_file_open(struct mail_transaction_log_file *file,
                   const char **reason_r)
{
    struct mail_index *index = file->log->index;
        unsigned int i;
    bool ignore_estale;
    int ret;

        for (i = 0;; i++) {
        if (!index->readonly) {
            file->fd = nfs_safe_open(file->filepath,
                         O_RDWR | O_APPEND);
        } else {
            file->fd = nfs_safe_open(file->filepath, O_RDONLY);
        }
        if (file->fd == -1 && errno == EACCES) {
            file->fd = nfs_safe_open(file->filepath, O_RDONLY);
            index->readonly = TRUE;
        }
        if (file->fd == -1) {
            if (errno == ENOENT) {
                *reason_r = "File doesn't exist";
                return 0;
            }

            log_file_set_syscall_error(file, "open()");
            *reason_r = t_strdup_printf("open() failed: %m");
            return -1;
                }

        ignore_estale = i < MAIL_INDEX_ESTALE_RETRY_COUNT;
        if (mail_transaction_log_file_stat(file, ignore_estale) < 0)
            ret = -1;
        else if (mail_transaction_log_file_is_dupe(file)) {
            /* probably our already opened .log file has been
               renamed to .log.2 and we're trying to reopen it.
               also possible that hit a race condition where .log
               and .log.2 are linked. */
            *reason_r = "File is already open";
            return 0;
        } else {
            ret = mail_transaction_log_file_read_hdr(file,
                                 ignore_estale);
        }
        if (ret > 0) {
            /* success */
            break;
        }

        if (ret == 0) {
            /* corrupted */
            if (index->readonly) {
                /* don't delete */
            } else {
                i_unlink_if_exists(file->filepath);
            }
            *reason_r = "File is corrupted";
            return 0;
        }
        if (errno != ESTALE ||
            i == MAIL_INDEX_ESTALE_RETRY_COUNT) {
            /* syscall error */
            *reason_r = t_strdup_printf("fstat() failed: %m");
            return -1;
        }

        /* ESTALE - try again */
        if (file->buffer != NULL)
            buffer_free(&file->buffer);
        }

    mail_transaction_log_file_add_to_list(file);
    return 1;
}

static int
log_file_track_mailbox_sync_offset_hdr(struct mail_transaction_log_file *file,
                       const void *data, unsigned int trans_size)
{
    const struct mail_transaction_header_update *u = data;
    const struct mail_index_header *ihdr;
    const unsigned int size = trans_size - sizeof(struct mail_transaction_header);
    const unsigned int offset_pos =
        offsetof(struct mail_index_header, log_file_tail_offset);
    const unsigned int offset_size = sizeof(ihdr->log_file_tail_offset);
    uint32_t tail_offset;

    i_assert(offset_size == sizeof(tail_offset));

    if (size < sizeof(*u) || size < sizeof(*u) + u->size) {
        mail_transaction_log_file_set_corrupted(file,
            "header update extends beyond record size");
        return -1;
    }

    if (u->offset <= offset_pos &&
        u->offset + u->size >= offset_pos + offset_size) {
        memcpy(&tail_offset,
               CONST_PTR_OFFSET(u + 1, offset_pos - u->offset),
               sizeof(tail_offset));

        if (tail_offset < file->saved_tail_offset) {
            /* ignore shrinking tail offsets */
            return 1;
        } else if (tail_offset > file->sync_offset + trans_size) {
            mail_transaction_log_file_set_corrupted(file,
                "log_file_tail_offset %u goes past sync offset %"PRIuUOFF_T,
                tail_offset, file->sync_offset + trans_size);
        } else {
            file->saved_tail_offset = tail_offset;
            if (tail_offset > file->max_tail_offset)
                file->max_tail_offset = tail_offset;
            return 1;
        }
    }
    return 0;
}

void mail_transaction_update_modseq(const struct mail_transaction_header *hdr,
                    const void *data, uint64_t *cur_modseq)
{
    uint32_t trans_size;

    trans_size = mail_index_offset_to_uint32(hdr->size);
    i_assert(trans_size != 0);

    if (*cur_modseq != 0) {
        /* tracking modseqs */
    } else if ((hdr->type & MAIL_TRANSACTION_TYPE_MASK) ==
           MAIL_TRANSACTION_EXT_INTRO) {
        /* modseqs not tracked yet. see if this is a modseq
           extension introduction. */
        const struct mail_transaction_ext_intro *intro = data;
        const unsigned int modseq_ext_len =
            strlen(MAIL_INDEX_MODSEQ_EXT_NAME);

        if (intro->name_size == modseq_ext_len &&
            memcmp(intro + 1, MAIL_INDEX_MODSEQ_EXT_NAME,
               modseq_ext_len) == 0) {
            /* modseq tracking started */
            *cur_modseq += 1;
        }
        return;
    } else {
        /* not tracking modseqs */
        return;
    }

    /* NOTE: keep in sync with mail_index_transaction_get_highest_modseq() */
    switch (hdr->type & MAIL_TRANSACTION_TYPE_MASK) {
    case MAIL_TRANSACTION_EXPUNGE | MAIL_TRANSACTION_EXPUNGE_PROT:
    case MAIL_TRANSACTION_EXPUNGE_GUID | MAIL_TRANSACTION_EXPUNGE_PROT:
        if ((hdr->type & MAIL_TRANSACTION_EXTERNAL) == 0) {
            /* ignore expunge requests */
            break;
        }
    case MAIL_TRANSACTION_APPEND:
    case MAIL_TRANSACTION_FLAG_UPDATE:
    case MAIL_TRANSACTION_KEYWORD_UPDATE:
    case MAIL_TRANSACTION_KEYWORD_RESET:
    case MAIL_TRANSACTION_ATTRIBUTE_UPDATE:
        /* these changes increase modseq */
        *cur_modseq += 1;
        break;
    case MAIL_TRANSACTION_MODSEQ_UPDATE: {
        const struct mail_transaction_modseq_update *rec, *end;

        end = CONST_PTR_OFFSET(data, trans_size - sizeof(*hdr));
        for (rec = data; rec < end; rec++) {
            uint64_t modseq = ((uint64_t)rec->modseq_high32 << 32) |
                rec->modseq_low32;
            if (*cur_modseq < modseq)
                *cur_modseq = modseq;
        }
    }
    }
}

static struct modseq_cache *
modseq_cache_hit(struct mail_transaction_log_file *file, unsigned int idx)
{
    struct modseq_cache cache;

    if (idx > 0) {
        /* @UNSAFE: move it to top */
        cache = file->modseq_cache[idx];
        memmove(file->modseq_cache + 1, file->modseq_cache,
            sizeof(*file->modseq_cache) * idx);
        file->modseq_cache[0] = cache;
    }
    return &file->modseq_cache[0];
}

static struct modseq_cache *
modseq_cache_get_offset(struct mail_transaction_log_file *file, uoff_t offset)
{
    unsigned int i, best = UINT_MAX;

    for (i = 0; i < N_ELEMENTS(file->modseq_cache); i++) {
        if (offset < file->modseq_cache[i].offset)
            continue;

        if (file->modseq_cache[i].offset == 0)
            return NULL;

        if (offset == file->modseq_cache[i].offset) {
            /* exact cache hit */
            return modseq_cache_hit(file, i);
        }

        if (best == UINT_MAX ||
            file->modseq_cache[i].offset <
            file->modseq_cache[best].offset)
            best = i;
    }
    if (best == UINT_MAX)
        return NULL;
    return &file->modseq_cache[best];
}

static struct modseq_cache *
modseq_cache_get_modseq(struct mail_transaction_log_file *file, uint64_t modseq)
{
    unsigned int i, best = UINT_MAX;

    for (i = 0; i < N_ELEMENTS(file->modseq_cache); i++) {
        if (modseq < file->modseq_cache[i].highest_modseq)
            continue;

        if (file->modseq_cache[i].offset == 0)
            return NULL;

        if (modseq == file->modseq_cache[i].highest_modseq) {
            /* exact cache hit */
            return modseq_cache_hit(file, i);
        }

        if (best == UINT_MAX ||
            file->modseq_cache[i].highest_modseq <
            file->modseq_cache[best].highest_modseq)
            best = i;
    }
    if (best == UINT_MAX)
        return NULL;
    return &file->modseq_cache[best];
}

static int
log_get_synced_record(struct mail_transaction_log_file *file, uoff_t *offset,
              const struct mail_transaction_header **hdr_r)
{
    const struct mail_transaction_header *hdr;
    uint32_t trans_size;

    hdr = CONST_PTR_OFFSET(file->buffer->data,
                   *offset - file->buffer_offset);

    /* we've already synced this record at some point. it should
       be valid. */
    trans_size = mail_index_offset_to_uint32(hdr->size);
    if (trans_size < sizeof(*hdr) ||
        *offset - file->buffer_offset + trans_size > file->buffer->used) {
        mail_transaction_log_file_set_corrupted(file,
            "Transaction log corrupted unexpectedly at "
            "%"PRIuUOFF_T": Invalid size %u (type=%x)",
            *offset, trans_size, hdr->type);
        return -1;
    }
    *offset += trans_size;
    *hdr_r = hdr;
    return 0;
}

int mail_transaction_log_file_get_highest_modseq_at(
        struct mail_transaction_log_file *file,
        uoff_t offset, uint64_t *highest_modseq_r)
{
    const struct mail_transaction_header *hdr;
    struct modseq_cache *cache;
    uoff_t cur_offset;
    uint64_t cur_modseq;
    int ret;

    i_assert(offset <= file->sync_offset);

    if (offset == file->sync_offset) {
        *highest_modseq_r = file->sync_highest_modseq;
        return 0;
    }

    cache = modseq_cache_get_offset(file, offset);
    if (cache == NULL) {
        /* nothing usable in cache - scan from beginning */
        cur_offset = file->hdr.hdr_size;
        cur_modseq = file->hdr.initial_modseq;
    } else if (cache->offset == offset) {
        /* exact cache hit */
        *highest_modseq_r = cache->highest_modseq;
        return 0;
    } else {
        /* use cache to skip over some records */
        cur_offset = cache->offset;
        cur_modseq = cache->highest_modseq;
    }

    ret = mail_transaction_log_file_map(file, cur_offset, offset);
    if (ret <= 0) {
        if (ret < 0)
            return -1;
        mail_index_set_error(file->log->index,
            "%s: Transaction log corrupted, can't get modseq",
            file->filepath);
        return -1;
    }

    i_assert(cur_offset >= file->buffer_offset);
    i_assert(cur_offset + file->buffer->used >= offset);
    while (cur_offset < offset) {
        if (log_get_synced_record(file, &cur_offset, &hdr) < 0)
            return- 1;
        mail_transaction_update_modseq(hdr, hdr + 1, &cur_modseq);
    }

    /* @UNSAFE: cache the value */
    memmove(file->modseq_cache + 1, file->modseq_cache,
        sizeof(*file->modseq_cache) *
        (N_ELEMENTS(file->modseq_cache) - 1));
    file->modseq_cache[0].offset = cur_offset;
    file->modseq_cache[0].highest_modseq = cur_modseq;

    *highest_modseq_r = cur_modseq;
    return 0;
}

int mail_transaction_log_file_get_modseq_next_offset(
        struct mail_transaction_log_file *file,
        uint64_t modseq, uoff_t *next_offset_r)
{
    const struct mail_transaction_header *hdr;
    struct modseq_cache *cache;
    uoff_t cur_offset;
    uint64_t cur_modseq;
    int ret;

    if (modseq == file->sync_highest_modseq) {
        *next_offset_r = file->sync_offset;
        return 0;
    }
    if (modseq == file->hdr.initial_modseq) {
        *next_offset_r = file->hdr.hdr_size;
        return 0;
    }

    cache = modseq_cache_get_modseq(file, modseq);
    if (cache == NULL) {
        /* nothing usable in cache - scan from beginning */
        cur_offset = file->hdr.hdr_size;
        cur_modseq = file->hdr.initial_modseq;
    } else if (cache->highest_modseq == modseq) {
        /* exact cache hit */
        *next_offset_r = cache->offset;
        return 0;
    } else {
        /* use cache to skip over some records */
        cur_offset = cache->offset;
        cur_modseq = cache->highest_modseq;
    }

    /* make sure we've read until end of file. this is especially important
       with non-head logs which might only have been opened without being
       synced. */
    ret = mail_transaction_log_file_map(file, cur_offset, (uoff_t)-1);
    if (ret <= 0) {
        if (ret < 0)
            return -1;
        mail_index_set_error(file->log->index,
            "%s: Transaction log corrupted, can't get modseq",
            file->filepath);
        return -1;
    }

    /* check sync_highest_modseq again in case sync_offset was updated */
    if (modseq >= file->sync_highest_modseq) {
        *next_offset_r = file->sync_offset;
        return 0;
    }

    i_assert(cur_offset >= file->buffer_offset);
    while (cur_offset < file->sync_offset) {
        if (log_get_synced_record(file, &cur_offset, &hdr) < 0)
            return -1;
        mail_transaction_update_modseq(hdr, hdr + 1, &cur_modseq);
        if (cur_modseq >= modseq)
            break;
    }
    if (cur_offset == file->sync_offset) {
        /* if we got to sync_offset, cur_modseq should be
           sync_highest_modseq */
        mail_index_set_error(file->log->index,
            "%s: Transaction log changed unexpectedly, "
            "can't get modseq", file->filepath);
        return -1;
    }

    /* @UNSAFE: cache the value */
    memmove(file->modseq_cache + 1, file->modseq_cache,
        sizeof(*file->modseq_cache) *
        (N_ELEMENTS(file->modseq_cache) - 1));
    file->modseq_cache[0].offset = cur_offset;
    file->modseq_cache[0].highest_modseq = cur_modseq;

    *next_offset_r = cur_offset;
    return 0;
}

static int
log_file_track_sync(struct mail_transaction_log_file *file,
            const struct mail_transaction_header *hdr,
            unsigned int trans_size)
{
    const void *data = hdr + 1;
    int ret;

    mail_transaction_update_modseq(hdr, hdr + 1,
                       &file->sync_highest_modseq);
    if ((hdr->type & MAIL_TRANSACTION_EXTERNAL) == 0)
        return 1;

    /* external transactions: */
    switch (hdr->type & MAIL_TRANSACTION_TYPE_MASK) {
    case MAIL_TRANSACTION_HEADER_UPDATE:
        /* see if this updates mailbox_sync_offset */
        ret = log_file_track_mailbox_sync_offset_hdr(file, data,
                                 trans_size);
        if (ret != 0)
            return ret < 0 ? -1 : 1;
        break;
    case MAIL_TRANSACTION_INDEX_DELETED:
        if (file->sync_offset < file->index_undeleted_offset)
            break;
        file->log->index->index_deleted = TRUE;
        file->log->index->index_delete_requested = FALSE;
        file->index_deleted_offset = file->sync_offset + trans_size;
        break;
    case MAIL_TRANSACTION_INDEX_UNDELETED:
        if (file->sync_offset < file->index_deleted_offset)
            break;
        file->log->index->index_deleted = FALSE;
        file->log->index->index_delete_requested = FALSE;
        file->index_undeleted_offset = file->sync_offset + trans_size;
        break;
    case MAIL_TRANSACTION_BOUNDARY: {
        const struct mail_transaction_boundary *boundary =
            (const void *)(hdr + 1);
        size_t wanted_buffer_size;

        wanted_buffer_size = file->sync_offset - file->buffer_offset +
            boundary->size;
        if (wanted_buffer_size > file->buffer->used) {
            /* the full transaction hasn't been written yet */
            return 0;
        }
        break;
    }
    }

    if (file->max_tail_offset == file->sync_offset) {
        /* external transactions aren't synced to mailbox. we can
           update mailbox sync offset to skip this transaction to
           avoid re-reading it at the next sync. */
        file->max_tail_offset += trans_size;
    }
    return 1;
}

static int
mail_transaction_log_file_sync(struct mail_transaction_log_file *file,
                   bool *retry_r)
{
        const struct mail_transaction_header *hdr;
    const void *data;
    struct stat st;
    size_t size, avail;
    uint32_t trans_size = 0;
    int ret;

    i_assert(file->sync_offset >= file->buffer_offset);

    *retry_r = FALSE;

    data = buffer_get_data(file->buffer, &size);
    if (file->buffer_offset + size < file->sync_offset) {
        mail_transaction_log_file_set_corrupted(file,
            "log file shrank (%"PRIuUOFF_T" < %"PRIuUOFF_T")",
            file->buffer_offset + (uoff_t)size, file->sync_offset);
        /* fix the sync_offset to avoid crashes later on */
        file->sync_offset = file->buffer_offset + size;
        return 0;
    }
    while (file->sync_offset - file->buffer_offset + sizeof(*hdr) <= size) {
        hdr = CONST_PTR_OFFSET(data, file->sync_offset -
                       file->buffer_offset);
        trans_size = mail_index_offset_to_uint32(hdr->size);
        if (trans_size == 0) {
            /* unfinished */
            return 1;
        }
        if (trans_size < sizeof(*hdr)) {
            mail_transaction_log_file_set_corrupted(file,
                "hdr.size too small (%u)", trans_size);
            return 0;
        }

        if (file->sync_offset - file->buffer_offset + trans_size > size)
            break;

        /* transaction has been fully written */
        if ((ret = log_file_track_sync(file, hdr, trans_size)) <= 0) {
            if (ret < 0)
                return 0;
            break;
        }

        file->sync_offset += trans_size;
    }

    if (file->mmap_base != NULL && !file->locked) {
        /* Now that all the mmaped pages have page faulted, check if
           the file had changed while doing that. Only after the last
           page has faulted, the size returned by fstat() can be
           trusted. Otherwise it might point to a page boundary while
           the next page is still being written.

           Without this check we might see partial transactions,
           sometimes causing "Extension record updated without intro
           prefix" errors. */
        if (fstat(file->fd, &st) < 0) {
            log_file_set_syscall_error(file, "fstat()");
            return -1;
        }
        if ((uoff_t)st.st_size != file->last_size) {
            file->last_size = st.st_size;
            *retry_r = TRUE;
            return 0;
        }
    }

    avail = file->sync_offset - file->buffer_offset;
    if (avail != size) {
        /* There's more data than we could sync at the moment. If the
           last record's size wasn't valid, we can't know if it will
           be updated unless we've locked the log. */
        if (file->locked) {
            mail_transaction_log_file_set_corrupted(file,
                "Unexpected garbage at EOF");
            return 0;
        }
        /* The size field will be updated soon */
        mail_index_flush_read_cache(file->log->index, file->filepath,
                        file->fd, file->locked);
    }

    if (file->next != NULL &&
        file->hdr.file_seq == file->next->hdr.prev_file_seq &&
        file->next->hdr.prev_file_offset != file->sync_offset) {
        mail_transaction_log_file_set_corrupted(file,
            "Invalid transaction log size "
            "(%"PRIuUOFF_T" vs %u): %s", file->sync_offset,
            file->log->head->hdr.prev_file_offset, file->filepath);
        return 0;
    }

    return 1;
}

static int
mail_transaction_log_file_insert_read(struct mail_transaction_log_file *file,
                      uoff_t offset)
{
    void *data;
    size_t size;
    ssize_t ret;

    size = file->buffer_offset - offset;
    buffer_copy(file->buffer, size, file->buffer, 0, (size_t)-1);

    data = buffer_get_space_unsafe(file->buffer, 0, size);
    ret = pread_full(file->fd, data, size, offset);
    if (ret > 0) {
        /* success */
        file->buffer_offset -= size;
        return 1;
    }

    /* failure. don't leave ourself to inconsistent state */
    buffer_copy(file->buffer, 0, file->buffer, size, (size_t)-1);
    buffer_set_used_size(file->buffer, file->buffer->used - size);

    if (ret == 0) {
        mail_transaction_log_file_set_corrupted(file, "file shrank");
        return 0;
    } else if (errno == ESTALE) {
        /* log file was deleted in NFS server, fail silently */
        return 0;
    } else {
        log_file_set_syscall_error(file, "pread()");
        return -1;
    }
}

static int
mail_transaction_log_file_read_more(struct mail_transaction_log_file *file)
{
    void *data;
    size_t size;
    uint32_t read_offset;
    ssize_t ret;

    read_offset = file->buffer_offset + file->buffer->used;

    do {
        data = buffer_append_space_unsafe(file->buffer, LOG_PREFETCH);
        ret = pread(file->fd, data, LOG_PREFETCH, read_offset);
        if (ret > 0)
            read_offset += ret;

        size = read_offset - file->buffer_offset;
        buffer_set_used_size(file->buffer, size);
    } while (ret > 0 || (ret < 0 && errno == EINTR));

    file->last_size = read_offset;

    if (ret < 0) {
        if (errno == ESTALE) {
            /* log file was deleted in NFS server, fail silently */
            return 0;
        }
        log_file_set_syscall_error(file, "pread()");
        return -1;
    }
    return 1;
}

static bool
mail_transaction_log_file_need_nfs_flush(struct mail_transaction_log_file *file)
{
    const struct mail_index_header *hdr = &file->log->index->map->hdr;
    uoff_t max_offset = file->last_size;

    if (file->next != NULL &&
        file->hdr.file_seq == file->next->hdr.prev_file_seq &&
        file->next->hdr.prev_file_offset != max_offset) {
        /* we already have a newer log file which says that we haven't
           synced the entire file. */
        return TRUE;
    }

    if (file->hdr.file_seq == hdr->log_file_seq &&
        max_offset < hdr->log_file_head_offset)
        return TRUE;

    return FALSE;
}

static int
mail_transaction_log_file_read(struct mail_transaction_log_file *file,
                   uoff_t start_offset, bool nfs_flush)
{
    bool retry;
    int ret;

    i_assert(file->mmap_base == NULL);

    /* NFS: if file isn't locked, we're optimistic that we can read enough
       data without flushing attribute cache. if after reading we notice
       that we really should have read more, flush the cache and try again.
       if file is locked, the attribute cache was already flushed when
       refreshing the log. */
    if (file->log->nfs_flush && nfs_flush) {
        if (!file->locked)
            nfs_flush_attr_cache_unlocked(file->filepath);
        else
            nfs_flush_attr_cache_fd_locked(file->filepath, file->fd);
    }

    if (file->buffer != NULL && file->buffer_offset > start_offset) {
        /* we have to insert missing data to beginning of buffer */
        ret = mail_transaction_log_file_insert_read(file, start_offset);
        if (ret <= 0)
            return ret;
    }

    if (file->buffer == NULL) {
        file->buffer =
            buffer_create_dynamic(default_pool, LOG_PREFETCH);
        file->buffer_offset = start_offset;
    }

    if ((ret = mail_transaction_log_file_read_more(file)) <= 0)
        ;
    else if (file->log->nfs_flush && !nfs_flush &&
         mail_transaction_log_file_need_nfs_flush(file)) {
        /* we didn't read enough data. flush and try again. */
        return mail_transaction_log_file_read(file, start_offset, TRUE);
    } else if ((ret = mail_transaction_log_file_sync(file, &retry)) == 0) {
        i_assert(!retry); /* retry happens only with mmap */
    }
    i_assert(file->sync_offset >= file->buffer_offset);
    buffer_set_used_size(file->buffer,
                 file->sync_offset - file->buffer_offset);
    return ret;
}

static int
log_file_map_check_offsets(struct mail_transaction_log_file *file,
               uoff_t start_offset, uoff_t end_offset)
{
    if (start_offset > file->sync_offset) {
        /* broken start offset */
        mail_index_set_error(file->log->index,
            "%s: start_offset (%"PRIuUOFF_T") > "
            "current sync_offset (%"PRIuUOFF_T")",
            file->filepath, start_offset, file->sync_offset);
        return 0;
    }
    if (end_offset != (uoff_t)-1 && end_offset > file->sync_offset) {
        mail_index_set_error(file->log->index,
            "%s: end_offset (%"PRIuUOFF_T") > "
            "current sync_offset (%"PRIuUOFF_T")",
            file->filepath, start_offset, file->sync_offset);
        return 0;
    }

    return 1;
}

static int
mail_transaction_log_file_mmap(struct mail_transaction_log_file *file)
{
    if (file->buffer != NULL) {
        /* in case we just switched to mmaping */
        buffer_free(&file->buffer);
    }
    file->mmap_size = file->last_size;
    file->mmap_base = mmap(NULL, file->mmap_size, PROT_READ, MAP_SHARED,
                   file->fd, 0);
    if (file->mmap_base == MAP_FAILED) {
        file->mmap_base = NULL;
        if (ioloop_time != file->last_mmap_error_time) {
            file->last_mmap_error_time = ioloop_time;
            log_file_set_syscall_error(file, t_strdup_printf(
                "mmap(size=%"PRIuSIZE_T")", file->mmap_size));
        }
        file->mmap_size = 0;
        return -1;
    }

    if (file->mmap_size > mmap_get_page_size()) {
        if (madvise(file->mmap_base, file->mmap_size,
                MADV_SEQUENTIAL) < 0)
            log_file_set_syscall_error(file, "madvise()");
    }

    buffer_create_from_const_data(&file->mmap_buffer,
                      file->mmap_base, file->mmap_size);
    file->buffer = &file->mmap_buffer;
    file->buffer_offset = 0;
    return 0;
}

static void
mail_transaction_log_file_munmap(struct mail_transaction_log_file *file)
{
    if (file->mmap_base == NULL)
        return;

    i_assert(file->buffer != NULL);
    if (munmap(file->mmap_base, file->mmap_size) < 0)
        log_file_set_syscall_error(file, "munmap()");
    file->mmap_base = NULL;
    file->mmap_size = 0;
    buffer_free(&file->buffer);
}

static int
mail_transaction_log_file_map_mmap(struct mail_transaction_log_file *file,
                   uoff_t start_offset)
{
    struct stat st;
    bool retry;
    int ret;

    /* we are going to mmap() this file, but it's not necessarily
       mmaped currently. */
    i_assert(file->buffer_offset == 0 || file->mmap_base == NULL);
    i_assert(file->mmap_size == 0 || file->mmap_base != NULL);

    if (fstat(file->fd, &st) < 0) {
        log_file_set_syscall_error(file, "fstat()");
        return -1;
    }
    file->last_size = st.st_size;

    if ((uoff_t)st.st_size < file->sync_offset) {
        mail_transaction_log_file_set_corrupted(file,
            "file size shrank (%"PRIuUOFF_T" < %"PRIuUOFF_T")",
            (uoff_t)st.st_size, file->sync_offset);
        return 0;
    }

    if (file->buffer != NULL && file->buffer_offset <= start_offset &&
        (uoff_t)st.st_size == file->buffer_offset + file->buffer->used) {
        /* we already have the whole file mapped */
        if ((ret = mail_transaction_log_file_sync(file, &retry)) != 0 ||
            !retry)
            return ret;
        /* size changed, re-mmap */
    }

    do {
        mail_transaction_log_file_munmap(file);

        if (file->last_size - start_offset < mmap_get_page_size()) {
            /* just reading the file is probably faster */
            return mail_transaction_log_file_read(file,
                                  start_offset,
                                  FALSE);
        }

        if (mail_transaction_log_file_mmap(file) < 0)
            return -1;
        ret = mail_transaction_log_file_sync(file, &retry);
    } while (retry);

    return ret;
}

int mail_transaction_log_file_map(struct mail_transaction_log_file *file,
                  uoff_t start_offset, uoff_t end_offset)
{
    struct mail_index *index = file->log->index;
    uoff_t map_start_offset = start_offset;
    size_t size;
    int ret;

    if (file->hdr.indexid == 0) {
        /* corrupted */
        return 0;
    }

    i_assert(start_offset >= file->hdr.hdr_size);
    i_assert(start_offset <= end_offset);
    i_assert(file->buffer == NULL || file->mmap_base != NULL ||
         file->sync_offset >= file->buffer_offset + file->buffer->used);

    if (file->locked_sync_offset_updated && file == file->log->head &&
        end_offset == (uoff_t)-1) {
        /* we're not interested of going further than sync_offset */
        if (log_file_map_check_offsets(file, start_offset,
                           end_offset) == 0)
            return 0;
        i_assert(start_offset <= file->sync_offset);
        end_offset = file->sync_offset;
    }

    if (file->buffer != NULL && file->buffer_offset <= start_offset) {
        /* see if we already have it */
        size = file->buffer->used;
        if (file->buffer_offset + size >= end_offset)
            return 1;
    }

    if (file->locked) {
        /* set this only when we've synced to end of file while locked
           (either end_offset=(uoff_t)-1 or we had to read anyway) */
        file->locked_sync_offset_updated = TRUE;
    }

    if (MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(file)) {
        if (start_offset < file->buffer_offset || file->buffer == NULL) {
            /* we had moved the log to memory but failed to read
               the beginning of the log file */
            mail_index_set_error(index,
                "%s: Beginning of the log isn't available",
                file->filepath);
            return 0;
        }
        return log_file_map_check_offsets(file, start_offset,
                          end_offset);
    }

    if (start_offset > file->sync_offset)
        mail_transaction_log_file_skip_to_head(file);
    if (start_offset > file->sync_offset) {
        /* although we could just skip over the unwanted data, we have
           to sync everything so that modseqs are calculated
           correctly */
        map_start_offset = file->sync_offset;
    }

    if ((file->log->index->flags & MAIL_INDEX_OPEN_FLAG_MMAP_DISABLE) == 0)
        ret = mail_transaction_log_file_map_mmap(file, map_start_offset);
    else {
        mail_transaction_log_file_munmap(file);
        ret = mail_transaction_log_file_read(file, map_start_offset, FALSE);
    }

    i_assert(file->buffer == NULL || file->mmap_base != NULL ||
         file->sync_offset >= file->buffer_offset + file->buffer->used);
    if (ret <= 0)
        return ret;

    i_assert(file->buffer != NULL);
    return log_file_map_check_offsets(file, start_offset, end_offset);
}

void mail_transaction_log_file_move_to_memory(struct mail_transaction_log_file
                          *file)
{
    buffer_t *buf;

    if (MAIL_TRANSACTION_LOG_FILE_IN_MEMORY(file))
        return;

    if (file->mmap_base != NULL) {
        /* just copy to memory */
        i_assert(file->buffer_offset == 0);

        buf = buffer_create_dynamic(default_pool, file->mmap_size);
        buffer_append(buf, file->mmap_base, file->mmap_size);
        buffer_free(&file->buffer);
        file->buffer = buf;

        /* and lose the mmap */
        if (munmap(file->mmap_base, file->mmap_size) < 0)
            log_file_set_syscall_error(file, "munmap()");
        file->mmap_base = NULL;
    } else if (file->buffer_offset != 0) {
        /* we don't have the full log in the memory. read it. */
        (void)mail_transaction_log_file_read(file, 0, FALSE);
    }
    file->last_size = 0;

    if (close(file->fd) < 0)
        log_file_set_syscall_error(file, "close()");
    file->fd = -1;

    i_free(file->filepath);
    file->filepath = i_strdup(file->log->filepath);
}