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[github/fretlink/terraform-provider-statuscake.git] / vendor / github.com / fsouza / go-dockerclient / external / golang.org / x / sys / unix / sockcmsg_unix.go
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 // +build darwin dragonfly freebsd linux netbsd openbsd solaris
6
7 // Socket control messages
8
9 package unix
10
11 import "unsafe"
12
13 // Round the length of a raw sockaddr up to align it properly.
14 func cmsgAlignOf(salen int) int {
15 salign := sizeofPtr
16 // NOTE: It seems like 64-bit Darwin and DragonFly BSD kernels
17 // still require 32-bit aligned access to network subsystem.
18 if darwin64Bit || dragonfly64Bit {
19 salign = 4
20 }
21 return (salen + salign - 1) & ^(salign - 1)
22 }
23
24 // CmsgLen returns the value to store in the Len field of the Cmsghdr
25 // structure, taking into account any necessary alignment.
26 func CmsgLen(datalen int) int {
27 return cmsgAlignOf(SizeofCmsghdr) + datalen
28 }
29
30 // CmsgSpace returns the number of bytes an ancillary element with
31 // payload of the passed data length occupies.
32 func CmsgSpace(datalen int) int {
33 return cmsgAlignOf(SizeofCmsghdr) + cmsgAlignOf(datalen)
34 }
35
36 func cmsgData(h *Cmsghdr) unsafe.Pointer {
37 return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(SizeofCmsghdr)))
38 }
39
40 // SocketControlMessage represents a socket control message.
41 type SocketControlMessage struct {
42 Header Cmsghdr
43 Data []byte
44 }
45
46 // ParseSocketControlMessage parses b as an array of socket control
47 // messages.
48 func ParseSocketControlMessage(b []byte) ([]SocketControlMessage, error) {
49 var msgs []SocketControlMessage
50 i := 0
51 for i+CmsgLen(0) <= len(b) {
52 h, dbuf, err := socketControlMessageHeaderAndData(b[i:])
53 if err != nil {
54 return nil, err
55 }
56 m := SocketControlMessage{Header: *h, Data: dbuf}
57 msgs = append(msgs, m)
58 i += cmsgAlignOf(int(h.Len))
59 }
60 return msgs, nil
61 }
62
63 func socketControlMessageHeaderAndData(b []byte) (*Cmsghdr, []byte, error) {
64 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
65 if h.Len < SizeofCmsghdr || int(h.Len) > len(b) {
66 return nil, nil, EINVAL
67 }
68 return h, b[cmsgAlignOf(SizeofCmsghdr):h.Len], nil
69 }
70
71 // UnixRights encodes a set of open file descriptors into a socket
72 // control message for sending to another process.
73 func UnixRights(fds ...int) []byte {
74 datalen := len(fds) * 4
75 b := make([]byte, CmsgSpace(datalen))
76 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
77 h.Level = SOL_SOCKET
78 h.Type = SCM_RIGHTS
79 h.SetLen(CmsgLen(datalen))
80 data := cmsgData(h)
81 for _, fd := range fds {
82 *(*int32)(data) = int32(fd)
83 data = unsafe.Pointer(uintptr(data) + 4)
84 }
85 return b
86 }
87
88 // ParseUnixRights decodes a socket control message that contains an
89 // integer array of open file descriptors from another process.
90 func ParseUnixRights(m *SocketControlMessage) ([]int, error) {
91 if m.Header.Level != SOL_SOCKET {
92 return nil, EINVAL
93 }
94 if m.Header.Type != SCM_RIGHTS {
95 return nil, EINVAL
96 }
97 fds := make([]int, len(m.Data)>>2)
98 for i, j := 0, 0; i < len(m.Data); i += 4 {
99 fds[j] = int(*(*int32)(unsafe.Pointer(&m.Data[i])))
100 j++
101 }
102 return fds, nil
103 }