mbox-lock.c revision ff7056842f14fd3b30a2d327dfab165b9d15dd30
8fcff4c5b52f24d9c681805fdf06b486f1d0fcbeTimo Sirainen/* Copyright (C) 2002 Timo Sirainen */
8fcff4c5b52f24d9c681805fdf06b486f1d0fcbeTimo Sirainen/* 0.1 .. 0.2msec */
8fcff4c5b52f24d9c681805fdf06b486f1d0fcbeTimo Sirainen#define LOCK_RANDOM_USLEEP_TIME (100000 + (unsigned int)rand() % 100000)
8fcff4c5b52f24d9c681805fdf06b486f1d0fcbeTimo Sirainen/* lock methods to use in wanted order */
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen#define DEFAULT_WRITE_LOCK_METHODS "dotlock fcntl"
8fcff4c5b52f24d9c681805fdf06b486f1d0fcbeTimo Sirainen/* lock timeout */
8fcff4c5b52f24d9c681805fdf06b486f1d0fcbeTimo Sirainen/* assume stale dotlock if mbox file hasn't changed for n seconds */
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen int (*func)(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_dotlock(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_fcntl(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_flock(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_lockf(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen { MBOX_LOCK_DOTLOCK, "dotlock", mbox_lock_dotlock },
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen { MBOX_LOCK_FCNTL, "fcntl", mbox_lock_fcntl },
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen { MBOX_LOCK_FLOCK, "flock", mbox_lock_flock },
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen { MBOX_LOCK_LOCKF, "lockf", mbox_lock_lockf },
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainenstatic enum mbox_lock_type read_locks[MBOX_LOCK_COUNT+1];
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainenstatic enum mbox_lock_type write_locks[MBOX_LOCK_COUNT+1];
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainenstatic int lock_timeout, dotlock_change_timeout;
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_list(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_unlock_files(struct mbox_lock_context *ctx);
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainenstatic void mbox_read_lock_methods(const char *str, const char *env,
8fcff4c5b52f24d9c681805fdf06b486f1d0fcbeTimo Sirainen const char *const *lock;
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen for (lock = t_strsplit(str, " "), dest = 0; *lock != NULL; lock++) {
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen for (type = 0; lock_data[type].name != NULL; type++) {
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen if (strcasecmp(*lock, lock_data[type].name) == 0) {
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen for (i = 0; i < dest; i++) {
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen i_fatal("%s: Duplicated value %s", env, *lock);
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen /* @UNSAFE */
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen const char *str;
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen if (str == NULL) str = DEFAULT_READ_LOCK_METHODS;
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen mbox_read_lock_methods(str, "MBOX_READ_LOCKS", read_locks);
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen if (str == NULL) str = DEFAULT_WRITE_LOCK_METHODS;
fc1696e32dd732a5bbabc3c8f64810448e327043Timo Sirainen mbox_read_lock_methods(str, "MBOX_WRITE_LOCKS", write_locks);
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* check that read/write list orders match. write_locks must contain
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen at least read_locks and possibly more. */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen for (r = w = 0; write_locks[w] != (enum mbox_lock_type)-1; w++) {
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen if (read_locks[r] != (enum mbox_lock_type)-1) {
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen i_fatal("mbox read/write lock list settings are invalid. "
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen "Lock ordering must be the same with both, "
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen "and write locks must contain all read locks "
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen "(and possibly more)");
d9fdacd5fb3e07997e5c389739d2054f0c8441d8Timo Sirainen lock_timeout = str == NULL ? MBOX_DEFAULT_LOCK_TIMEOUT : atoi(str);
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_file_open_latest(struct mbox_lock_context *ctx, int lock_type)
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen if (ctx->checked_file || lock_type == F_UNLCK)
6ef7e31619edfaa17ed044b45861d106a86191efTimo Sirainenstatic bool dotlock_callback(unsigned int secs_left, bool stale, void *context)
a505d1beb29cbffab724b92ad16d0c44ebbaffb9Timo Sirainen /* get next index we wish to try locking. it's the one after
a505d1beb29cbffab724b92ad16d0c44ebbaffb9Timo Sirainen dotlocking. */
a505d1beb29cbffab724b92ad16d0c44ebbaffb9Timo Sirainen for (i = 0; lock_types[i] != (enum mbox_lock_type)-1; i++) {
a505d1beb29cbffab724b92ad16d0c44ebbaffb9Timo Sirainen if (lock_types[i] != (enum mbox_lock_type)-1 &&
a505d1beb29cbffab724b92ad16d0c44ebbaffb9Timo Sirainen if (mbox_lock_list(ctx, ctx->lock_type, 0, i) <= 0) {
a505d1beb29cbffab724b92ad16d0c44ebbaffb9Timo Sirainen /* we couldn't get fd lock -
a505d1beb29cbffab724b92ad16d0c44ebbaffb9Timo Sirainen it's really locked */
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen index_storage_lock_notify(&ctx->mbox->ibox, stale ?
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_dotlock(struct mbox_lock_context *ctx, int lock_type,
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen if (file_dotlock_delete(&mbox->mbox_dotlock) <= 0) {
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen mbox_set_syscall_error(mbox, "file_dotlock_delete()");
ccc895c0358108d2304239063e940b7d75f364abTimo Sirainen set.use_excl_lock = (mbox->storage->storage.flags &
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen ret = file_dotlock_create(&set, mbox->path, 0, &mbox->mbox_dotlock);
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen mbox_set_syscall_error(mbox, "file_lock_dotlock()");
ccc895c0358108d2304239063e940b7d75f364abTimo Sirainen mail_storage_set_error(&mbox->storage->storage,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen if (mbox_file_open_latest(ctx, lock_type) < 0)
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_flock(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen if (mbox_file_open_latest(ctx, lock_type) < 0)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen if (lock_type == F_UNLCK && ctx->mbox->mbox_fd == -1)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen while (flock(ctx->mbox->mbox_fd, lock_type | LOCK_NB) < 0) {
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_lockf(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen if (mbox_file_open_latest(ctx, lock_type) < 0)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen if (lock_type == F_UNLCK && ctx->mbox->mbox_fd == -1)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen while (lockf(ctx->mbox->mbox_fd, lock_type, 0) < 0) {
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_fcntl(struct mbox_lock_context *ctx, int lock_type,
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen if (mbox_file_open_latest(ctx, lock_type) < 0)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen if (lock_type == F_UNLCK && ctx->mbox->mbox_fd == -1)
7c27b0ab7213121ea43994499c04059413f6d0f2Timo Sirainen /* usually we're waiting here, but if we came from
7c27b0ab7213121ea43994499c04059413f6d0f2Timo Sirainen mbox_lock_dotlock(), we just want to try locking */
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen while (fcntl(ctx->mbox->mbox_fd, wait_type, &fl) < 0) {
88de8e8fb4ad86f59ac0c4d85f5a9103dfd3fcc0Timo Sirainen /* non-blocking lock trying failed */
2767104d81e97a109f0aa9758792bfa1da325a97Timo Sirainen /* notify locks once every 5 seconds.
2767104d81e97a109f0aa9758792bfa1da325a97Timo Sirainen try to use rounded values. */
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_lock_list(struct mbox_lock_context *ctx, int lock_type,
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen (lock_type == F_UNLCK && ctx->mbox->mbox_lock_type == F_WRLCK) ?
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen for (i = idx; lock_types[i] != (enum mbox_lock_type)-1; i++) {
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen ret = lock_data[type].func(ctx, lock_type, max_wait_time);
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainenstatic int mbox_update_locking(struct mbox_mailbox *mbox, int lock_type)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen if (mbox->mbox_fd == -1 && mbox->mbox_file_stream != NULL) {
04ab375449dd97eed50ada88dd0df2abab01cfeeTimo Sirainen /* read-only mbox stream. no need to lock. */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* dropping to shared lock. first drop those that we
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen don't remove completely. */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen for (i = 0; i < MBOX_LOCK_COUNT; i++)
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen for (i = 0; read_locks[i] != (enum mbox_lock_type)-1; i++)
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen ret = mbox_lock_list(&ctx, lock_type, max_wait_time, 0);
ccc895c0358108d2304239063e940b7d75f364abTimo Sirainen mail_storage_set_error(&mbox->storage->storage,
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* dropping to shared lock: drop the locks that are only
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen in write list */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen memset(ctx.lock_status, 0, sizeof(ctx.lock_status));
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen for (i = 0; write_locks[i] != (enum mbox_lock_type)-1; i++)
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen for (i = 0; read_locks[i] != (enum mbox_lock_type)-1; i++)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainenint mbox_lock(struct mbox_mailbox *mbox, int lock_type,
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen unsigned int *lock_id_r)
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* allow only unlock -> shared/exclusive or exclusive -> shared */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen i_assert(lock_type == F_RDLCK || lock_type == F_WRLCK);
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen i_assert(lock_type == F_RDLCK || mbox->mbox_lock_type != F_RDLCK);
6dc4af35c045e10609b13fe80f9cf33f3a06c3ceTimo Sirainen /* mbox must be locked before index */
6dc4af35c045e10609b13fe80f9cf33f3a06c3ceTimo Sirainen i_assert(mbox->ibox.index->lock_type != F_WRLCK);
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainenstatic int mbox_unlock_files(struct mbox_lock_context *ctx)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainenint mbox_unlock(struct mbox_mailbox *mbox, unsigned int lock_id)
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen i_assert(mbox->mbox_lock_id == (lock_id & ~1));
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* dropping exclusive lock */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* drop to shared lock */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* dropping shared lock */
2c7ab05ef98c46eb70c8ba6ea85e49749aafb2a3Timo Sirainen /* all locks gone */
704efd0b34e3611e3decf1d559fe6a93214b0bd0Timo Sirainen for (i = 0; i < MBOX_LOCK_COUNT; i++)