1// Copyright 2009 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris 6 7// Package unix contains an interface to the low-level operating system 8// primitives. OS details vary depending on the underlying system, and 9// by default, godoc will display OS-specific documentation for the current 10// system. If you want godoc to display OS documentation for another 11// system, set $GOOS and $GOARCH to the desired system. For example, if 12// you want to view documentation for freebsd/arm on linux/amd64, set $GOOS 13// to freebsd and $GOARCH to arm. 14// 15// The primary use of this package is inside other packages that provide a more 16// portable interface to the system, such as "os", "time" and "net". Use 17// those packages rather than this one if you can. 18// 19// For details of the functions and data types in this package consult 20// the manuals for the appropriate operating system. 21// 22// These calls return err == nil to indicate success; otherwise 23// err represents an operating system error describing the failure and 24// holds a value of type syscall.Errno. 25package unix // import "golang.org/x/sys/unix" 26 27import ( 28 "bytes" 29 "strings" 30 "unsafe" 31 32 "golang.org/x/sys/internal/unsafeheader" 33) 34 35// ByteSliceFromString returns a NUL-terminated slice of bytes 36// containing the text of s. If s contains a NUL byte at any 37// location, it returns (nil, EINVAL). 38func ByteSliceFromString(s string) ([]byte, error) { 39 if strings.IndexByte(s, 0) != -1 { 40 return nil, EINVAL 41 } 42 a := make([]byte, len(s)+1) 43 copy(a, s) 44 return a, nil 45} 46 47// BytePtrFromString returns a pointer to a NUL-terminated array of 48// bytes containing the text of s. If s contains a NUL byte at any 49// location, it returns (nil, EINVAL). 50func BytePtrFromString(s string) (*byte, error) { 51 a, err := ByteSliceFromString(s) 52 if err != nil { 53 return nil, err 54 } 55 return &a[0], nil 56} 57 58// ByteSliceToString returns a string form of the text represented by the slice s, with a terminating NUL and any 59// bytes after the NUL removed. 60func ByteSliceToString(s []byte) string { 61 if i := bytes.IndexByte(s, 0); i != -1 { 62 s = s[:i] 63 } 64 return string(s) 65} 66 67// BytePtrToString takes a pointer to a sequence of text and returns the corresponding string. 68// If the pointer is nil, it returns the empty string. It assumes that the text sequence is terminated 69// at a zero byte; if the zero byte is not present, the program may crash. 70func BytePtrToString(p *byte) string { 71 if p == nil { 72 return "" 73 } 74 if *p == 0 { 75 return "" 76 } 77 78 // Find NUL terminator. 79 n := 0 80 for ptr := unsafe.Pointer(p); *(*byte)(ptr) != 0; n++ { 81 ptr = unsafe.Pointer(uintptr(ptr) + 1) 82 } 83 84 var s []byte 85 h := (*unsafeheader.Slice)(unsafe.Pointer(&s)) 86 h.Data = unsafe.Pointer(p) 87 h.Len = n 88 h.Cap = n 89 90 return string(s) 91} 92 93// Single-word zero for use when we need a valid pointer to 0 bytes. 94var _zero uintptr 95