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// 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.
//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
// 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 "golang.org/x/sys/unix"
import (
"bytes"
"strings"
"unsafe"
"golang.org/x/sys/internal/unsafeheader"
)
// 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
}
// ByteSliceToString returns a string form of the text represented by the slice s, with a terminating NUL and any
// bytes after the NUL removed.
func ByteSliceToString(s []byte) string {
if i := bytes.IndexByte(s, 0); i != -1 {
s = s[:i]
}
return string(s)
}
// BytePtrToString takes a pointer to a sequence of text and returns the corresponding string.
// If the pointer is nil, it returns the empty string. It assumes that the text sequence is terminated
// at a zero byte; if the zero byte is not present, the program may crash.
func BytePtrToString(p *byte) string {
if p == nil {
return ""
}
if *p == 0 {
return ""
}
// Find NUL terminator.
n := 0
for ptr := unsafe.Pointer(p); *(*byte)(ptr) != 0; n++ {
ptr = unsafe.Pointer(uintptr(ptr) + 1)
}
var s []byte
h := (*unsafeheader.Slice)(unsafe.Pointer(&s))
h.Data = unsafe.Pointer(p)
h.Len = n
h.Cap = n
return string(s)
}
// Single-word zero for use when we need a valid pointer to 0 bytes.
var _zero uintptr
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