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10 package unix
11
12 import (
13 "unsafe"
14 )
15
16
17
18 func CmsgLen(datalen int) int {
19 return cmsgAlignOf(SizeofCmsghdr) + datalen
20 }
21
22
23
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
33 type SocketControlMessage struct {
34 Header Cmsghdr
35 Data []byte
36 }
37
38
39
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
56
57
58 func ParseOneSocketControlMessage(b []byte) (hdr Cmsghdr, data []byte, remainder []byte, err error) {
59 h, dbuf, err := socketControlMessageHeaderAndData(b)
60 if err != nil {
61 return Cmsghdr{}, nil, nil, err
62 }
63 if i := cmsgAlignOf(int(h.Len)); i < len(b) {
64 remainder = b[i:]
65 }
66 return *h, dbuf, remainder, nil
67 }
68
69 func socketControlMessageHeaderAndData(b []byte) (*Cmsghdr, []byte, error) {
70 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
71 if h.Len < SizeofCmsghdr || uint64(h.Len) > uint64(len(b)) {
72 return nil, nil, EINVAL
73 }
74 return h, b[cmsgAlignOf(SizeofCmsghdr):h.Len], nil
75 }
76
77
78
79 func UnixRights(fds ...int) []byte {
80 datalen := len(fds) * 4
81 b := make([]byte, CmsgSpace(datalen))
82 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
83 h.Level = SOL_SOCKET
84 h.Type = SCM_RIGHTS
85 h.SetLen(CmsgLen(datalen))
86 for i, fd := range fds {
87 *(*int32)(h.data(4 * uintptr(i))) = int32(fd)
88 }
89 return b
90 }
91
92
93
94 func ParseUnixRights(m *SocketControlMessage) ([]int, error) {
95 if m.Header.Level != SOL_SOCKET {
96 return nil, EINVAL
97 }
98 if m.Header.Type != SCM_RIGHTS {
99 return nil, EINVAL
100 }
101 fds := make([]int, len(m.Data)>>2)
102 for i, j := 0, 0; i < len(m.Data); i += 4 {
103 fds[j] = int(*(*int32)(unsafe.Pointer(&m.Data[i])))
104 j++
105 }
106 return fds, nil
107 }
108
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