Function svn_io_lock_open_file 

pub unsafe extern "C" fn svn_io_lock_open_file(
    lockfile_handle: *mut apr_file_t,
    exclusive: svn_boolean_t,
    nonblocking: svn_boolean_t,
    pool: *mut apr_pool_t,
) -> *mut svn_error_t

Lock the file @a lockfile_handle. If @a exclusive is TRUE, obtain exclusive lock, otherwise obtain shared lock.

If @a nonblocking is TRUE, do not wait for the lock if it is not available: throw an error instead.

Lock will be automatically released when @a pool is cleared or destroyed. You may also explicitly call svn_io_unlock_open_file(). Use @a pool for memory allocations. @a pool must be the pool that @a lockfile_handle has been created in or one of its sub-pools.

@since New in 1.8.