Gibheer
fa05045d31
This is the import from the separate monfront repository. The history could not be imported, but this should suffice.
94 lines
2.7 KiB
Go
94 lines
2.7 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
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// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
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// Socket control messages
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package unix
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import (
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"unsafe"
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)
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// CmsgLen returns the value to store in the Len field of the Cmsghdr
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// structure, taking into account any necessary alignment.
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func CmsgLen(datalen int) int {
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return cmsgAlignOf(SizeofCmsghdr) + datalen
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}
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// CmsgSpace returns the number of bytes an ancillary element with
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// payload of the passed data length occupies.
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func CmsgSpace(datalen int) int {
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return cmsgAlignOf(SizeofCmsghdr) + cmsgAlignOf(datalen)
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}
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func (h *Cmsghdr) data(offset uintptr) unsafe.Pointer {
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return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(SizeofCmsghdr)) + offset)
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}
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// SocketControlMessage represents a socket control message.
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type SocketControlMessage struct {
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Header Cmsghdr
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Data []byte
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}
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// ParseSocketControlMessage parses b as an array of socket control
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// messages.
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func ParseSocketControlMessage(b []byte) ([]SocketControlMessage, error) {
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var msgs []SocketControlMessage
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i := 0
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for i+CmsgLen(0) <= len(b) {
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h, dbuf, err := socketControlMessageHeaderAndData(b[i:])
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if err != nil {
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return nil, err
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}
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m := SocketControlMessage{Header: *h, Data: dbuf}
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msgs = append(msgs, m)
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i += cmsgAlignOf(int(h.Len))
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}
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return msgs, nil
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}
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func socketControlMessageHeaderAndData(b []byte) (*Cmsghdr, []byte, error) {
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h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
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if h.Len < SizeofCmsghdr || uint64(h.Len) > uint64(len(b)) {
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return nil, nil, EINVAL
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}
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return h, b[cmsgAlignOf(SizeofCmsghdr):h.Len], nil
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}
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// UnixRights encodes a set of open file descriptors into a socket
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// control message for sending to another process.
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func UnixRights(fds ...int) []byte {
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datalen := len(fds) * 4
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b := make([]byte, CmsgSpace(datalen))
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h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
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h.Level = SOL_SOCKET
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h.Type = SCM_RIGHTS
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h.SetLen(CmsgLen(datalen))
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for i, fd := range fds {
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*(*int32)(h.data(4 * uintptr(i))) = int32(fd)
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}
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return b
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}
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// ParseUnixRights decodes a socket control message that contains an
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// integer array of open file descriptors from another process.
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func ParseUnixRights(m *SocketControlMessage) ([]int, error) {
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if m.Header.Level != SOL_SOCKET {
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return nil, EINVAL
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}
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if m.Header.Type != SCM_RIGHTS {
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return nil, EINVAL
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}
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fds := make([]int, len(m.Data)>>2)
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for i, j := 0, 0; i < len(m.Data); i += 4 {
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fds[j] = int(*(*int32)(unsafe.Pointer(&m.Data[i])))
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j++
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}
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return fds, nil
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}
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