114 lines
2.6 KiB
Go
114 lines
2.6 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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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/errors/linuxerr"
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"gvisor.dev/gvisor/pkg/sentry/hostfd"
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)
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// LINT.IfChange
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// copyToMulti copies as many bytes from src to dst as possible.
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func copyToMulti(dst [][]byte, src []byte) {
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for _, d := range dst {
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done := copy(d, src)
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src = src[done:]
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if len(src) == 0 {
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break
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}
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}
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}
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// copyFromMulti copies as many bytes from src to dst as possible.
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func copyFromMulti(dst []byte, src [][]byte) {
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for _, s := range src {
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done := copy(dst, s)
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dst = dst[done:]
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if len(dst) == 0 {
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break
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}
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}
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}
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// buildIovec builds an iovec slice from the given []byte slice.
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//
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// If truncate, truncate bufs > maxlen. Otherwise, immediately return an error.
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//
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// If length < the total length of bufs, err indicates why, even when returning
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// a truncated iovec.
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//
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// If intermediate != nil, iovecs references intermediate rather than bufs and
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// the caller must copy to/from bufs as necessary.
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func buildIovec(bufs [][]byte, maxlen int64, truncate bool) (length int64, iovecs []unix.Iovec, intermediate []byte, err error) {
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var iovsRequired int
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for _, b := range bufs {
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length += int64(len(b))
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if len(b) > 0 {
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iovsRequired++
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}
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}
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stopLen := length
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if length > maxlen {
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if truncate {
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stopLen = maxlen
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err = linuxerr.EAGAIN
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} else {
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return 0, nil, nil, linuxerr.EMSGSIZE
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}
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}
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if iovsRequired > hostfd.MaxSendRecvMsgIov {
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// The kernel will reject our call if we pass this many iovs.
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// Use a single intermediate buffer instead.
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b := make([]byte, stopLen)
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return stopLen, []unix.Iovec{{
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Base: &b[0],
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Len: uint64(stopLen),
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}}, b, err
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}
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var total int64
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iovecs = make([]unix.Iovec, 0, iovsRequired)
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for i := range bufs {
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l := len(bufs[i])
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if l == 0 {
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continue
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}
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stop := int64(l)
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if total+stop > stopLen {
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stop = stopLen - total
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}
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iovecs = append(iovecs, unix.Iovec{
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Base: &bufs[i][0],
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Len: uint64(stop),
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})
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total += stop
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if total >= stopLen {
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break
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}
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}
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return total, iovecs, nil, err
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}
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// LINT.ThenChange(../../fsimpl/host/socket_iovec.go)
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