blob: 649fa87405d16df8d0ead218500132f7e43b02f6 [file] [log] [blame]
Don Newton98fd8812019-09-23 15:15:02 -04001// 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
David K. Bainbridgee05cf0c2021-08-19 03:16:50 +00005//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
6// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
Don Newton98fd8812019-09-23 15:15:02 -04007
8// Package unix contains an interface to the low-level operating system
9// primitives. OS details vary depending on the underlying system, and
10// by default, godoc will display OS-specific documentation for the current
11// system. If you want godoc to display OS documentation for another
12// system, set $GOOS and $GOARCH to the desired system. For example, if
13// you want to view documentation for freebsd/arm on linux/amd64, set $GOOS
14// to freebsd and $GOARCH to arm.
15//
16// The primary use of this package is inside other packages that provide a more
17// portable interface to the system, such as "os", "time" and "net". Use
18// those packages rather than this one if you can.
19//
20// For details of the functions and data types in this package consult
21// the manuals for the appropriate operating system.
22//
23// These calls return err == nil to indicate success; otherwise
24// err represents an operating system error describing the failure and
25// holds a value of type syscall.Errno.
26package unix // import "golang.org/x/sys/unix"
27
David K. Bainbridgee05cf0c2021-08-19 03:16:50 +000028import (
29 "bytes"
30 "strings"
31 "unsafe"
32
33 "golang.org/x/sys/internal/unsafeheader"
34)
Don Newton98fd8812019-09-23 15:15:02 -040035
36// ByteSliceFromString returns a NUL-terminated slice of bytes
37// containing the text of s. If s contains a NUL byte at any
38// location, it returns (nil, EINVAL).
39func ByteSliceFromString(s string) ([]byte, error) {
40 if strings.IndexByte(s, 0) != -1 {
41 return nil, EINVAL
42 }
43 a := make([]byte, len(s)+1)
44 copy(a, s)
45 return a, nil
46}
47
48// BytePtrFromString returns a pointer to a NUL-terminated array of
49// bytes containing the text of s. If s contains a NUL byte at any
50// location, it returns (nil, EINVAL).
51func BytePtrFromString(s string) (*byte, error) {
52 a, err := ByteSliceFromString(s)
53 if err != nil {
54 return nil, err
55 }
56 return &a[0], nil
57}
58
David K. Bainbridgee05cf0c2021-08-19 03:16:50 +000059// ByteSliceToString returns a string form of the text represented by the slice s, with a terminating NUL and any
60// bytes after the NUL removed.
61func ByteSliceToString(s []byte) string {
62 if i := bytes.IndexByte(s, 0); i != -1 {
63 s = s[:i]
64 }
65 return string(s)
66}
67
68// BytePtrToString takes a pointer to a sequence of text and returns the corresponding string.
69// If the pointer is nil, it returns the empty string. It assumes that the text sequence is terminated
70// at a zero byte; if the zero byte is not present, the program may crash.
71func BytePtrToString(p *byte) string {
72 if p == nil {
73 return ""
74 }
75 if *p == 0 {
76 return ""
77 }
78
79 // Find NUL terminator.
80 n := 0
81 for ptr := unsafe.Pointer(p); *(*byte)(ptr) != 0; n++ {
82 ptr = unsafe.Pointer(uintptr(ptr) + 1)
83 }
84
85 var s []byte
86 h := (*unsafeheader.Slice)(unsafe.Pointer(&s))
87 h.Data = unsafe.Pointer(p)
88 h.Len = n
89 h.Cap = n
90
91 return string(s)
92}
93
Don Newton98fd8812019-09-23 15:15:02 -040094// Single-word zero for use when we need a valid pointer to 0 bytes.
Don Newton98fd8812019-09-23 15:15:02 -040095var _zero uintptr