fileUnlock

fn fileUnlock(userdata: ?*anyopaque, file: File) void {
    if (native_os == .wasi) return;
    const t: *Threaded = @ptrCast(@alignCast(userdata));
    _ = t;

    if (is_windows) {
        var io_status_block: windows.IO_STATUS_BLOCK = undefined;
        while (true) switch (windows.ntdll.NtUnlockFile(
            file.handle,
            &io_status_block,
            &windows_lock_range_off,
            &windows_lock_range_len,
            0,
        )) {
            .SUCCESS => return,
            .CANCELLED => continue,
            .RANGE_NOT_LOCKED => if (is_debug) unreachable else return, // Function asserts unlocked.
            .ACCESS_VIOLATION => if (is_debug) unreachable else return, // bad io_status_block pointer
            else => if (is_debug) unreachable else return, // Resource deallocation must succeed.
        };
    }

    while (true) {
        switch (posix.errno(posix.system.flock(file.handle, posix.LOCK.UN))) {
            .SUCCESS => return,
            .CANCELED, .INTR => continue,
            .AGAIN => return assert(!is_debug), // unlocking can't block
            .BADF => return assert(!is_debug), // File descriptor used after closed.
            .INVAL => return assert(!is_debug), // invalid parameters
            .NOLCK => return assert(!is_debug), // Resource deallocation.
            .OPNOTSUPP => return assert(!is_debug), // We already got the lock.
            else => return assert(!is_debug), // Resource deallocation must succeed.
        }
    }
}