visor/pkg/sentry/fsimpl/host/host_unsafe.go

// Copyright 2021 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package host

import (
	"unsafe"

	"golang.org/x/sys/unix"
	"gvisor.dev/gvisor/pkg/abi/linux"
)

func ioctlFionread(fd int) (uint32, error) {
	var v uint32
	if _, _, errno := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), linux.FIONREAD, uintptr(unsafe.Pointer(&v))); errno != 0 {
		return 0, errno
	}
	return v, nil
}