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comparison vendor/golang.org/x/sys/unix/sockcmsg_unix.go @ 66:787b5ee0289d draft

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Use vendored modules Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja>
author yakumo.izuru
date Sun, 23 Jul 2023 13:18:53 +0000
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65:6d985efa0f7a 66:787b5ee0289d
1 // Copyright 2011 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 // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
7
8 // Socket control messages
9
10 package unix
11
12 import (
13 "unsafe"
14 )
15
16 // CmsgLen returns the value to store in the Len field of the Cmsghdr
17 // structure, taking into account any necessary alignment.
18 func CmsgLen(datalen int) int {
19 return cmsgAlignOf(SizeofCmsghdr) + datalen
20 }
21
22 // CmsgSpace returns the number of bytes an ancillary element with
23 // payload of the passed data length occupies.
24 func CmsgSpace(datalen int) int {
25 return cmsgAlignOf(SizeofCmsghdr) + cmsgAlignOf(datalen)
26 }
27
28 func (h *Cmsghdr) data(offset uintptr) unsafe.Pointer {
29 return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(SizeofCmsghdr)) + offset)
30 }
31
32 // SocketControlMessage represents a socket control message.
33 type SocketControlMessage struct {
34 Header Cmsghdr
35 Data []byte
36 }
37
38 // ParseSocketControlMessage parses b as an array of socket control
39 // messages.
40 func ParseSocketControlMessage(b []byte) ([]SocketControlMessage, error) {
41 var msgs []SocketControlMessage
42 i := 0
43 for i+CmsgLen(0) <= len(b) {
44 h, dbuf, err := socketControlMessageHeaderAndData(b[i:])
45 if err != nil {
46 return nil, err
47 }
48 m := SocketControlMessage{Header: *h, Data: dbuf}
49 msgs = append(msgs, m)
50 i += cmsgAlignOf(int(h.Len))
51 }
52 return msgs, nil
53 }
54
55 func socketControlMessageHeaderAndData(b []byte) (*Cmsghdr, []byte, error) {
56 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
57 if h.Len < SizeofCmsghdr || uint64(h.Len) > uint64(len(b)) {
58 return nil, nil, EINVAL
59 }
60 return h, b[cmsgAlignOf(SizeofCmsghdr):h.Len], nil
61 }
62
63 // UnixRights encodes a set of open file descriptors into a socket
64 // control message for sending to another process.
65 func UnixRights(fds ...int) []byte {
66 datalen := len(fds) * 4
67 b := make([]byte, CmsgSpace(datalen))
68 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
69 h.Level = SOL_SOCKET
70 h.Type = SCM_RIGHTS
71 h.SetLen(CmsgLen(datalen))
72 for i, fd := range fds {
73 *(*int32)(h.data(4 * uintptr(i))) = int32(fd)
74 }
75 return b
76 }
77
78 // ParseUnixRights decodes a socket control message that contains an
79 // integer array of open file descriptors from another process.
80 func ParseUnixRights(m *SocketControlMessage) ([]int, error) {
81 if m.Header.Level != SOL_SOCKET {
82 return nil, EINVAL
83 }
84 if m.Header.Type != SCM_RIGHTS {
85 return nil, EINVAL
86 }
87 fds := make([]int, len(m.Data)>>2)
88 for i, j := 0, 0; i < len(m.Data); i += 4 {
89 fds[j] = int(*(*int32)(unsafe.Pointer(&m.Data[i])))
90 j++
91 }
92 return fds, nil
93 }