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 plan9
6
7// Package plan9 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 the OS-specific documentation for the current
10// system. If you want godoc to display 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.ErrorString.
25package plan9 // import "golang.org/x/sys/plan9"
26
27import (
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).
36func 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).
48func 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.
58func 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.
68func 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// See mksyscall.pl.
87var _zero uintptr
88
89func (ts *Timespec) Unix() (sec int64, nsec int64) {
90 return int64(ts.Sec), int64(ts.Nsec)
91}
92
93func (tv *Timeval) Unix() (sec int64, nsec int64) {
94 return int64(tv.Sec), int64(tv.Usec) * 1000
95}
96
97func (ts *Timespec) Nano() int64 {
98 return int64(ts.Sec)*1e9 + int64(ts.Nsec)
99}
100
101func (tv *Timeval) Nano() int64 {
102 return int64(tv.Sec)*1e9 + int64(tv.Usec)*1000
103}
104
105// use is a no-op, but the compiler cannot see that it is.
106// Calling use(p) ensures that p is kept live until that point.
107//
108//go:noescape
109func use(p unsafe.Pointer)