diff options
Diffstat (limited to 'Godeps/_workspace/src/golang.org/x/sys/unix/sockcmsg_unix.go')
-rw-r--r-- | Godeps/_workspace/src/golang.org/x/sys/unix/sockcmsg_unix.go | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/golang.org/x/sys/unix/sockcmsg_unix.go b/Godeps/_workspace/src/golang.org/x/sys/unix/sockcmsg_unix.go new file mode 100644 index 000000000..70af5a728 --- /dev/null +++ b/Godeps/_workspace/src/golang.org/x/sys/unix/sockcmsg_unix.go @@ -0,0 +1,103 @@ +// Copyright 2011 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 darwin dragonfly freebsd linux netbsd openbsd solaris + +// Socket control messages + +package unix + +import "unsafe" + +// Round the length of a raw sockaddr up to align it properly. +func cmsgAlignOf(salen int) int { + salign := sizeofPtr + // NOTE: It seems like 64-bit Darwin and DragonFly BSD kernels + // still require 32-bit aligned access to network subsystem. + if darwin64Bit || dragonfly64Bit { + salign = 4 + } + return (salen + salign - 1) & ^(salign - 1) +} + +// CmsgLen returns the value to store in the Len field of the Cmsghdr +// structure, taking into account any necessary alignment. +func CmsgLen(datalen int) int { + return cmsgAlignOf(SizeofCmsghdr) + datalen +} + +// CmsgSpace returns the number of bytes an ancillary element with +// payload of the passed data length occupies. +func CmsgSpace(datalen int) int { + return cmsgAlignOf(SizeofCmsghdr) + cmsgAlignOf(datalen) +} + +func cmsgData(h *Cmsghdr) unsafe.Pointer { + return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(SizeofCmsghdr))) +} + +// SocketControlMessage represents a socket control message. +type SocketControlMessage struct { + Header Cmsghdr + Data []byte +} + +// ParseSocketControlMessage parses b as an array of socket control +// messages. +func ParseSocketControlMessage(b []byte) ([]SocketControlMessage, error) { + var msgs []SocketControlMessage + i := 0 + for i+CmsgLen(0) <= len(b) { + h, dbuf, err := socketControlMessageHeaderAndData(b[i:]) + if err != nil { + return nil, err + } + m := SocketControlMessage{Header: *h, Data: dbuf} + msgs = append(msgs, m) + i += cmsgAlignOf(int(h.Len)) + } + return msgs, nil +} + +func socketControlMessageHeaderAndData(b []byte) (*Cmsghdr, []byte, error) { + h := (*Cmsghdr)(unsafe.Pointer(&b[0])) + if h.Len < SizeofCmsghdr || int(h.Len) > len(b) { + return nil, nil, EINVAL + } + return h, b[cmsgAlignOf(SizeofCmsghdr):h.Len], nil +} + +// UnixRights encodes a set of open file descriptors into a socket +// control message for sending to another process. +func UnixRights(fds ...int) []byte { + datalen := len(fds) * 4 + b := make([]byte, CmsgSpace(datalen)) + h := (*Cmsghdr)(unsafe.Pointer(&b[0])) + h.Level = SOL_SOCKET + h.Type = SCM_RIGHTS + h.SetLen(CmsgLen(datalen)) + data := cmsgData(h) + for _, fd := range fds { + *(*int32)(data) = int32(fd) + data = unsafe.Pointer(uintptr(data) + 4) + } + return b +} + +// ParseUnixRights decodes a socket control message that contains an +// integer array of open file descriptors from another process. +func ParseUnixRights(m *SocketControlMessage) ([]int, error) { + if m.Header.Level != SOL_SOCKET { + return nil, EINVAL + } + if m.Header.Type != SCM_RIGHTS { + return nil, EINVAL + } + fds := make([]int, len(m.Data)>>2) + for i, j := 0, 0; i < len(m.Data); i += 4 { + fds[j] = int(*(*int32)(unsafe.Pointer(&m.Data[i]))) + j++ + } + return fds, nil +} |