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 //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
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.
25 package unix // import "golang.org/x/sys/unix"
26 27 import (
28 "bytes"
29 "strings"
30 "unsafe"
31 )
32 33 // ByteSliceFromString returns a NUL-terminated slice of bytes
34 // containing the text of s. If s contains a NUL byte at any
35 // location, it returns (nil, EINVAL).
36 func ByteSliceFromString(s string) ([]byte, error) {
37 if strings.IndexByte(s, 0) != -1 {
38 return nil, EINVAL
39 }
40 a := make([]byte, len(s)+1)
41 copy(a, s)
42 return a, nil
43 }
44 45 // BytePtrFromString returns a pointer to a NUL-terminated array of
46 // bytes containing the text of s. If s contains a NUL byte at any
47 // location, it returns (nil, EINVAL).
48 func BytePtrFromString(s string) (*byte, error) {
49 a, err := ByteSliceFromString(s)
50 if err != nil {
51 return nil, err
52 }
53 return &a[0], nil
54 }
55 56 // ByteSliceToString returns a string form of the text represented by the slice s, with a terminating NUL and any
57 // bytes after the NUL removed.
58 func ByteSliceToString(s []byte) string {
59 if i := bytes.IndexByte(s, 0); i != -1 {
60 s = s[:i]
61 }
62 return string(s)
63 }
64 65 // BytePtrToString takes a pointer to a sequence of text and returns the corresponding string.
66 // If the pointer is nil, it returns the empty string. It assumes that the text sequence is terminated
67 // at a zero byte; if the zero byte is not present, the program may crash.
68 func BytePtrToString(p *byte) string {
69 if p == nil {
70 return ""
71 }
72 if *p == 0 {
73 return ""
74 }
75 76 // Find NUL terminator.
77 n := 0
78 for ptr := unsafe.Pointer(p); *(*byte)(ptr) != 0; n++ {
79 ptr = unsafe.Pointer(uintptr(ptr) + 1)
80 }
81 82 return string(unsafe.Slice(p, n))
83 }
84 85 // Single-word zero for use when we need a valid pointer to 0 bytes.
86 var _zero uintptr
87