// Copyright 2018 The Go Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

package unix

import (

	"syscall"

	"unsafe"

)

// Unveil implements the unveil syscall.

// For more information see unveil(2).

// Note that the special case of blocking further

// unveil calls is handled by UnveilBlock.

func Unveil(path string, flags string) error {

	pathPtr, err := syscall.BytePtrFromString(path)

	if err != nil {

		return err

	}

	flagsPtr, err := syscall.BytePtrFromString(flags)

	if err != nil {

		return err

	}

	_, _, e := syscall.Syscall(SYS_UNVEIL, uintptr(unsafe.Pointer(pathPtr)), uintptr(unsafe.Pointer(flagsPtr)), 0)

	if e != 0 {

		return e

	}

	return nil

}

// UnveilBlock blocks future unveil calls.

// For more information see unveil(2).

func UnveilBlock() error {

	// Both pointers must be nil.

	var pathUnsafe, flagsUnsafe unsafe.Pointer

	_, _, e := syscall.Syscall(SYS_UNVEIL, uintptr(pathUnsafe), uintptr(flagsUnsafe), 0)

	if e != 0 {

		return e

	}

	return nil

}