deviceIoControl

fn deviceIoControl(o: *const Io.Operation.DeviceIoControl) Io.Cancelable!Io.Operation.DeviceIoControl.Result

File

Code

fn deviceIoControl(o: *const Io.Operation.DeviceIoControl) Io.Cancelable!Io.Operation.DeviceIoControl.Result {
    if (is_windows) {
        const NtControlFile = switch (o.code.DeviceType) {
            .FILE_SYSTEM, .NAMED_PIPE => &windows.ntdll.NtFsControlFile,
            else => &windows.ntdll.NtDeviceIoControlFile,
        };
        var iosb: windows.IO_STATUS_BLOCK = undefined;
        if (o.file.flags.nonblocking) {
            var done: bool = false;
            switch (NtControlFile(
                o.file.handle,
                null, // event
                flagApc,
                &done, // APC context
                &iosb,
                o.code,
                if (o.in.len > 0) o.in.ptr else null,
                @intCast(o.in.len),
                if (o.out.len > 0) o.out.ptr else null,
                @intCast(o.out.len),
            )) {
                // We must wait for the APC routine.
                .PENDING, .SUCCESS => while (!done) {
                    // Once we get here we must not return from the function until the
                    // operation completes, thereby releasing reference to io_status_block.
                    const alertable_syscall = AlertableSyscall.start() catch |err| switch (err) {
                        error.Canceled => |e| {
                            var cancel_iosb: windows.IO_STATUS_BLOCK = undefined;
                            _ = windows.ntdll.NtCancelIoFileEx(o.file.handle, &iosb, &cancel_iosb);
                            while (!done) waitForApcOrAlert();
                            return e;
                        },
                    };
                    waitForApcOrAlert();
                    alertable_syscall.finish();
                },
                else => |status| iosb.u.Status = status,
            }
        } else {
            const syscall: Syscall = try .start();
            while (true) switch (NtControlFile(
                o.file.handle,
                null, // event
                null, // APC routine
                null, // APC context
                &iosb,
                o.code,
                if (o.in.len > 0) o.in.ptr else null,
                @intCast(o.in.len),
                if (o.out.len > 0) o.out.ptr else null,
                @intCast(o.out.len),
            )) {
                .PENDING => unreachable, // unrecoverable: wrong asynchronous flag
                .CANCELLED => {
                    try syscall.checkCancel();
                    continue;
                },
                else => |status| {
                    syscall.finish();
                    iosb.u.Status = status;
                    break;
                },
            };
        }
        return iosb;
    } else {
        const syscall: Syscall = try .start();
        while (true) {
            const rc = posix.system.ioctl(o.file.handle, @bitCast(o.code), @intFromPtr(o.arg));
            switch (posix.errno(rc)) {
                .SUCCESS => {
                    syscall.finish();
                    if (@TypeOf(rc) == usize) return @bitCast(@as(u32, @truncate(rc)));
                    return rc;
                },
                .INTR => {
                    try syscall.checkCancel();
                    continue;
                },
                else => |err| {
                    syscall.finish();
                    return -@as(i32, @backingInt(err));
                },
            }
        }
    }
}