107 lines
3.0 KiB
Go
107 lines
3.0 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package host
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import (
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"unsafe"
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"golang.org/x/sys/unix"
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)
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// LINT.IfChange
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// fdReadVec receives from fd to bufs.
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//
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// If the total length of bufs is > maxlen, fdReadVec will do a partial read
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// and err will indicate why the message was truncated.
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func fdReadVec(fd int, bufs [][]byte, control []byte, peek bool, maxlen int64) (readLen int64, msgLen int64, controlLen uint64, controlTrunc bool, err error) {
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flags := uintptr(unix.MSG_DONTWAIT | unix.MSG_TRUNC)
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if peek {
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flags |= unix.MSG_PEEK
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}
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// Always truncate the receive buffer. All socket types will truncate
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// received messages.
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length, iovecs, intermediate, err := buildIovec(bufs, maxlen, true)
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if err != nil && len(iovecs) == 0 {
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// No partial write to do, return error immediately.
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return 0, 0, 0, false, err
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}
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var msg unix.Msghdr
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if len(control) != 0 {
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msg.Control = &control[0]
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msg.Controllen = uint64(len(control))
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}
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if len(iovecs) != 0 {
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msg.Iov = &iovecs[0]
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msg.Iovlen = uint64(len(iovecs))
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}
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rawN, _, e := unix.RawSyscall(unix.SYS_RECVMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), flags)
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if e != 0 {
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// N.B. prioritize the syscall error over the buildIovec error.
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return 0, 0, 0, false, e
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}
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n := int64(rawN)
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// Copy data back to bufs.
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if intermediate != nil {
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copyToMulti(bufs, intermediate)
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}
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controlTrunc = msg.Flags&unix.MSG_CTRUNC == unix.MSG_CTRUNC
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if n > length {
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return length, n, msg.Controllen, controlTrunc, nil
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}
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return n, n, msg.Controllen, controlTrunc, nil
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}
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// fdWriteVec sends from bufs to fd.
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//
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// If the total length of bufs is > maxlen && truncate, fdWriteVec will do a
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// partial write and err will indicate why the message was truncated.
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func fdWriteVec(fd int, bufs [][]byte, maxlen int64, truncate bool) (int64, int64, error) {
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length, iovecs, intermediate, err := buildIovec(bufs, maxlen, truncate)
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if err != nil && len(iovecs) == 0 {
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// No partial write to do, return error immediately.
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return 0, length, err
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}
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// Copy data to intermediate buf.
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if intermediate != nil {
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copyFromMulti(intermediate, bufs)
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}
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var msg unix.Msghdr
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if len(iovecs) > 0 {
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msg.Iov = &iovecs[0]
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msg.Iovlen = uint64(len(iovecs))
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}
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n, _, e := unix.RawSyscall(unix.SYS_SENDMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), unix.MSG_DONTWAIT|unix.MSG_NOSIGNAL)
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if e != 0 {
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// N.B. prioritize the syscall error over the buildIovec error.
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return 0, length, e
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}
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return int64(n), length, err
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}
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// LINT.ThenChange(../../fsimpl/host/socket_unsafe.go)
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