| // 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. |
| |
| // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris |
| |
| // 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 |