// Copyright 2009 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.

// +build darwin dragonfly freebsd linux netbsd openbsd solaris

// Package unix contains an interface to the low-level operating system
// primitives. OS details vary depending on the underlying system, and
// by default, godoc will display OS-specific documentation for the current
// system. If you want godoc to display OS documentation for another
// system, set $GOOS and $GOARCH to the desired system. For example, if
// you want to view documentation for freebsd/arm on linux/amd64, set $GOOS
// to freebsd and $GOARCH to arm.
//
// The primary use of this package is inside other packages that provide a more
// portable interface to the system, such as "os", "time" and "net".  Use
// those packages rather than this one if you can.
//
// For details of the functions and data types in this package consult
// the manuals for the appropriate operating system.
//
// These calls return err == nil to indicate success; otherwise
// err represents an operating system error describing the failure and
// holds a value of type syscall.Errno.
package unix

import "strings"

// ByteSliceFromString returns a NUL-terminated slice of bytes
// containing the text of s. If s contains a NUL byte at any
// location, it returns (nil, EINVAL).
func ByteSliceFromString(s string) ([]byte, error) {
	if strings.IndexByte(s, 0) != -1 {
		return nil, EINVAL
	}
	a := make([]byte, len(s)+1)
	copy(a, s)
	return a, nil
}

// BytePtrFromString returns a pointer to a NUL-terminated array of
// bytes containing the text of s. If s contains a NUL byte at any
// location, it returns (nil, EINVAL).
func BytePtrFromString(s string) (*byte, error) {
	a, err := ByteSliceFromString(s)
	if err != nil {
		return nil, err
	}
	return &a[0], nil
}

// Single-word zero for use when we need a valid pointer to 0 bytes.
// See mkunix.pl.
var _zero uintptr