83 lines
2.1 KiB
Go
83 lines
2.1 KiB
Go
// Copyright 2018 Google Inc.
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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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"syscall"
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"unsafe"
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)
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// buildIovec builds an iovec slice from the given []byte slice.
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func buildIovec(bufs [][]byte) (uintptr, []syscall.Iovec) {
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var length uintptr
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iovecs := make([]syscall.Iovec, 0, 10)
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for i := range bufs {
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if l := len(bufs[i]); l > 0 {
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length += uintptr(l)
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iovecs = append(iovecs, syscall.Iovec{
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Base: &bufs[i][0],
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Len: uint64(l),
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})
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}
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}
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return length, iovecs
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}
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func fdReadVec(fd int, bufs [][]byte, control []byte, peek bool) (readLen uintptr, msgLen uintptr, controlLen uint64, err error) {
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flags := uintptr(syscall.MSG_DONTWAIT | syscall.MSG_TRUNC)
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if peek {
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flags |= syscall.MSG_PEEK
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}
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length, iovecs := buildIovec(bufs)
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var msg syscall.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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n, _, e := syscall.RawSyscall(syscall.SYS_RECVMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), flags)
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if e != 0 {
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return 0, 0, 0, e
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}
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if n > length {
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return length, n, msg.Controllen, nil
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}
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return n, n, msg.Controllen, nil
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}
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func fdWriteVec(fd int, bufs [][]byte) (uintptr, error) {
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_, iovecs := buildIovec(bufs)
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var msg syscall.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 := syscall.RawSyscall(syscall.SYS_SENDMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), syscall.MSG_DONTWAIT|syscall.MSG_NOSIGNAL)
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if e != 0 {
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return 0, e
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}
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return n, nil
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}
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