diff options
| -rw-r--r-- | source3/lib/util_tdb.c | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/source3/lib/util_tdb.c b/source3/lib/util_tdb.c index 4756fd84ef..ade46bf18e 100644 --- a/source3/lib/util_tdb.c +++ b/source3/lib/util_tdb.c @@ -28,6 +28,101 @@ #undef calloc #undef strdup +#ifdef BUILD_TDB2 +static struct flock flock_struct; + +/* Return a value which is none of v1, v2 or v3. */ +static inline short int invalid_value(short int v1, short int v2, short int v3) +{ + short int try = (v1+v2+v3)^((v1+v2+v3) << 16); + while (try == v1 || try == v2 || try == v3) + try++; + return try; +} + +/* We invalidate in as many ways as we can, so the OS rejects it */ +static void invalidate_flock_struct(int signum) +{ + flock_struct.l_type = invalid_value(F_RDLCK, F_WRLCK, F_UNLCK); + flock_struct.l_whence = invalid_value(SEEK_SET, SEEK_CUR, SEEK_END); + flock_struct.l_start = -1; + /* A large negative. */ + flock_struct.l_len = (((off_t)1 << (sizeof(off_t)*CHAR_BIT - 1)) + 1); +} + +static int timeout_lock(int fd, int rw, off_t off, off_t len, bool waitflag, + void *_timeout) +{ + int ret, saved_errno; + unsigned int timeout = *(unsigned int *)_timeout; + + flock_struct.l_type = rw; + flock_struct.l_whence = SEEK_SET; + flock_struct.l_start = off; + flock_struct.l_len = len; + + CatchSignal(SIGALRM, invalidate_flock_struct); + alarm(timeout); + + for (;;) { + if (waitflag) + ret = fcntl(fd, F_SETLKW, &flock_struct); + else + ret = fcntl(fd, F_SETLK, &flock_struct); + + if (ret == 0) + break; + + /* Not signalled? Something else went wrong. */ + if (flock_struct.l_len == len) { + if (errno == EAGAIN || errno == EINTR) + continue; + saved_errno = errno; + break; + } else { + saved_errno = EINTR; + break; + } + } + + alarm(0); + errno = saved_errno; + return ret; +} + +static int tdb_chainlock_with_timeout_internal(struct tdb_context *tdb, + TDB_DATA key, + unsigned int timeout, + int rw_type) +{ + union tdb_attribute locking; + enum TDB_ERROR ecode; + + if (timeout) { + locking.base.attr = TDB_ATTRIBUTE_FLOCK; + ecode = tdb_get_attribute(tdb, &locking); + if (ecode != TDB_SUCCESS) + return ecode; + + /* Replace locking function with our own. */ + locking.flock.data = &timeout; + locking.flock.lock = timeout_lock; + + ecode = tdb_set_attribute(tdb, &locking); + if (ecode != TDB_SUCCESS) + return ecode; + } + if (rw_type == F_RDLCK) + ecode = tdb_chainlock_read(tdb, key); + else + ecode = tdb_chainlock(tdb, key); + + if (timeout) { + tdb_unset_attribute(tdb, TDB_ATTRIBUTE_FLOCK); + } + return ecode == TDB_SUCCESS ? 0 : -1; +} +#else /* these are little tdb utility functions that are meant to make dealing with a tdb database a little less cumbersome in Samba */ @@ -80,6 +175,7 @@ static int tdb_chainlock_with_timeout_internal( TDB_CONTEXT *tdb, TDB_DATA key, return ret == 0 ? 0 : -1; } +#endif /* TDB1 */ /**************************************************************************** Write lock a chain. Return non-zero if timeout or lock failed. |