99 lines
2.8 KiB
Go
99 lines
2.8 KiB
Go
// Copyright 2018 Google LLC
|
|
//
|
|
// 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.
|
|
|
|
package host
|
|
|
|
import (
|
|
"syscall"
|
|
"unsafe"
|
|
)
|
|
|
|
// fdReadVec receives from fd to bufs.
|
|
//
|
|
// If the total length of bufs is > maxlen, fdReadVec will do a partial read
|
|
// and err will indicate why the message was truncated.
|
|
func fdReadVec(fd int, bufs [][]byte, control []byte, peek bool, maxlen int) (readLen uintptr, msgLen uintptr, controlLen uint64, err error) {
|
|
flags := uintptr(syscall.MSG_DONTWAIT | syscall.MSG_TRUNC)
|
|
if peek {
|
|
flags |= syscall.MSG_PEEK
|
|
}
|
|
|
|
// Always truncate the receive buffer. All socket types will truncate
|
|
// received messages.
|
|
length, iovecs, intermediate, err := buildIovec(bufs, maxlen, true)
|
|
if err != nil && len(iovecs) == 0 {
|
|
// No partial write to do, return error immediately.
|
|
return 0, 0, 0, err
|
|
}
|
|
|
|
var msg syscall.Msghdr
|
|
if len(control) != 0 {
|
|
msg.Control = &control[0]
|
|
msg.Controllen = uint64(len(control))
|
|
}
|
|
|
|
if len(iovecs) != 0 {
|
|
msg.Iov = &iovecs[0]
|
|
msg.Iovlen = uint64(len(iovecs))
|
|
}
|
|
|
|
n, _, e := syscall.RawSyscall(syscall.SYS_RECVMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), flags)
|
|
if e != 0 {
|
|
// N.B. prioritize the syscall error over the buildIovec error.
|
|
return 0, 0, 0, e
|
|
}
|
|
|
|
// Copy data back to bufs.
|
|
if intermediate != nil {
|
|
copyToMulti(bufs, intermediate)
|
|
}
|
|
|
|
if n > length {
|
|
return length, n, msg.Controllen, err
|
|
}
|
|
|
|
return n, n, msg.Controllen, err
|
|
}
|
|
|
|
// fdWriteVec sends from bufs to fd.
|
|
//
|
|
// If the total length of bufs is > maxlen && truncate, fdWriteVec will do a
|
|
// partial write and err will indicate why the message was truncated.
|
|
func fdWriteVec(fd int, bufs [][]byte, maxlen int, truncate bool) (uintptr, uintptr, error) {
|
|
length, iovecs, intermediate, err := buildIovec(bufs, maxlen, truncate)
|
|
if err != nil && len(iovecs) == 0 {
|
|
// No partial write to do, return error immediately.
|
|
return 0, length, err
|
|
}
|
|
|
|
// Copy data to intermediate buf.
|
|
if intermediate != nil {
|
|
copyFromMulti(intermediate, bufs)
|
|
}
|
|
|
|
var msg syscall.Msghdr
|
|
if len(iovecs) > 0 {
|
|
msg.Iov = &iovecs[0]
|
|
msg.Iovlen = uint64(len(iovecs))
|
|
}
|
|
|
|
n, _, e := syscall.RawSyscall(syscall.SYS_SENDMSG, uintptr(fd), uintptr(unsafe.Pointer(&msg)), syscall.MSG_DONTWAIT|syscall.MSG_NOSIGNAL)
|
|
if e != 0 {
|
|
// N.B. prioritize the syscall error over the buildIovec error.
|
|
return 0, length, e
|
|
}
|
|
|
|
return n, length, err
|
|
}
|