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Diffstat (limited to 'pkg/fdchannel/fdchannel_unsafe.go')
-rw-r--r-- | pkg/fdchannel/fdchannel_unsafe.go | 146 |
1 files changed, 0 insertions, 146 deletions
diff --git a/pkg/fdchannel/fdchannel_unsafe.go b/pkg/fdchannel/fdchannel_unsafe.go deleted file mode 100644 index 367235be5..000000000 --- a/pkg/fdchannel/fdchannel_unsafe.go +++ /dev/null @@ -1,146 +0,0 @@ -// Copyright 2019 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris - -// Package fdchannel implements passing file descriptors between processes over -// Unix domain sockets. -package fdchannel - -import ( - "fmt" - "reflect" - "sync/atomic" - "syscall" - "unsafe" -) - -// int32 is the real type of a file descriptor. -const sizeofInt32 = int(unsafe.Sizeof(int32(0))) - -// NewConnectedSockets returns a pair of file descriptors, owned by the caller, -// representing connected sockets that may be passed to separate calls to -// NewEndpoint to create connected Endpoints. -func NewConnectedSockets() ([2]int, error) { - return syscall.Socketpair(syscall.AF_UNIX, syscall.SOCK_SEQPACKET|syscall.SOCK_CLOEXEC, 0) -} - -// Endpoint sends file descriptors to, and receives them from, another -// connected Endpoint. -// -// Endpoint is not copyable or movable by value. -type Endpoint struct { - sockfd int32 // accessed using atomic memory operations - msghdr syscall.Msghdr - cmsg *syscall.Cmsghdr // followed by sizeofInt32 bytes of data -} - -// Init must be called on zero-value Endpoints before first use. sockfd must be -// a blocking AF_UNIX SOCK_SEQPACKET socket. -func (ep *Endpoint) Init(sockfd int) { - // "Datagram sockets in various domains (e.g., the UNIX and Internet - // domains) permit zero-length datagrams." - recv(2). Experimentally, - // sendmsg+recvmsg for a zero-length datagram is slightly faster than - // sendmsg+recvmsg for a single byte over a stream socket. - cmsgSlice := make([]byte, syscall.CmsgSpace(sizeofInt32)) - cmsgReflect := (*reflect.SliceHeader)((unsafe.Pointer)(&cmsgSlice)) - ep.sockfd = int32(sockfd) - ep.msghdr.Control = (*byte)((unsafe.Pointer)(cmsgReflect.Data)) - ep.cmsg = (*syscall.Cmsghdr)((unsafe.Pointer)(cmsgReflect.Data)) - // ep.msghdr.Controllen and ep.cmsg.* are mutated by recvmsg(2), so they're - // set before calling sendmsg/recvmsg. -} - -// NewEndpoint is a convenience function that returns an initialized Endpoint -// allocated on the heap. -func NewEndpoint(sockfd int) *Endpoint { - ep := &Endpoint{} - ep.Init(sockfd) - return ep -} - -// Destroy releases resources owned by ep. No other Endpoint methods may be -// called after Destroy. -func (ep *Endpoint) Destroy() { - // These need not use sync/atomic since there must not be any concurrent - // calls to Endpoint methods. - if ep.sockfd >= 0 { - syscall.Close(int(ep.sockfd)) - ep.sockfd = -1 - } -} - -// Shutdown causes concurrent and future calls to ep.SendFD(), ep.RecvFD(), and -// ep.RecvFDNonblock(), as well as the same calls in the connected Endpoint, to -// unblock and return errors. It does not wait for concurrent calls to return. -// -// Shutdown is the only Endpoint method that may be called concurrently with -// other methods. -func (ep *Endpoint) Shutdown() { - if sockfd := int(atomic.SwapInt32(&ep.sockfd, -1)); sockfd >= 0 { - syscall.Shutdown(sockfd, syscall.SHUT_RDWR) - syscall.Close(sockfd) - } -} - -// SendFD sends the open file description represented by the given file -// descriptor to the connected Endpoint. -func (ep *Endpoint) SendFD(fd int) error { - cmsgLen := syscall.CmsgLen(sizeofInt32) - ep.cmsg.Level = syscall.SOL_SOCKET - ep.cmsg.Type = syscall.SCM_RIGHTS - ep.cmsg.SetLen(cmsgLen) - *ep.cmsgData() = int32(fd) - ep.msghdr.SetControllen(cmsgLen) - _, _, e := syscall.Syscall(syscall.SYS_SENDMSG, uintptr(atomic.LoadInt32(&ep.sockfd)), uintptr((unsafe.Pointer)(&ep.msghdr)), 0) - if e != 0 { - return e - } - return nil -} - -// RecvFD receives an open file description from the connected Endpoint and -// returns a file descriptor representing it, owned by the caller. -func (ep *Endpoint) RecvFD() (int, error) { - return ep.recvFD(0) -} - -// RecvFDNonblock receives an open file description from the connected Endpoint -// and returns a file descriptor representing it, owned by the caller. If there -// are no pending receivable open file descriptions, RecvFDNonblock returns -// (<unspecified>, EAGAIN or EWOULDBLOCK). -func (ep *Endpoint) RecvFDNonblock() (int, error) { - return ep.recvFD(syscall.MSG_DONTWAIT) -} - -func (ep *Endpoint) recvFD(flags uintptr) (int, error) { - cmsgLen := syscall.CmsgLen(sizeofInt32) - ep.msghdr.SetControllen(cmsgLen) - _, _, e := syscall.Syscall(syscall.SYS_RECVMSG, uintptr(atomic.LoadInt32(&ep.sockfd)), uintptr((unsafe.Pointer)(&ep.msghdr)), flags|syscall.MSG_TRUNC) - if e != 0 { - return -1, e - } - if int(ep.msghdr.Controllen) != cmsgLen { - return -1, fmt.Errorf("received control message has incorrect length: got %d, wanted %d", ep.msghdr.Controllen, cmsgLen) - } - if ep.cmsg.Level != syscall.SOL_SOCKET || ep.cmsg.Type != syscall.SCM_RIGHTS { - return -1, fmt.Errorf("received control message has incorrect (level, type): got (%v, %v), wanted (%v, %v)", ep.cmsg.Level, ep.cmsg.Type, syscall.SOL_SOCKET, syscall.SCM_RIGHTS) - } - return int(*ep.cmsgData()), nil -} - -func (ep *Endpoint) cmsgData() *int32 { - // syscall.CmsgLen(0) == syscall.cmsgAlignOf(syscall.SizeofCmsghdr) - return (*int32)((unsafe.Pointer)(uintptr((unsafe.Pointer)(ep.cmsg)) + uintptr(syscall.CmsgLen(0)))) -} |