142 lines
3.9 KiB
Go
142 lines
3.9 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 usermem
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import (
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/safemem"
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"gvisor.dev/gvisor/pkg/syserror"
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)
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const maxInt = int(^uint(0) >> 1)
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// BytesIO implements IO using a byte slice. Addresses are interpreted as
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// offsets into the slice. Reads and writes beyond the end of the slice return
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// EFAULT.
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type BytesIO struct {
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Bytes []byte
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}
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// CopyOut implements IO.CopyOut.
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func (b *BytesIO) CopyOut(ctx context.Context, addr Addr, src []byte, opts IOOpts) (int, error) {
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rngN, rngErr := b.rangeCheck(addr, len(src))
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if rngN == 0 {
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return 0, rngErr
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}
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return copy(b.Bytes[int(addr):], src[:rngN]), rngErr
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}
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// CopyIn implements IO.CopyIn.
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func (b *BytesIO) CopyIn(ctx context.Context, addr Addr, dst []byte, opts IOOpts) (int, error) {
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rngN, rngErr := b.rangeCheck(addr, len(dst))
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if rngN == 0 {
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return 0, rngErr
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}
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return copy(dst[:rngN], b.Bytes[int(addr):]), rngErr
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}
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// ZeroOut implements IO.ZeroOut.
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func (b *BytesIO) ZeroOut(ctx context.Context, addr Addr, toZero int64, opts IOOpts) (int64, error) {
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if toZero > int64(maxInt) {
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return 0, syserror.EINVAL
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}
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rngN, rngErr := b.rangeCheck(addr, int(toZero))
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if rngN == 0 {
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return 0, rngErr
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}
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zeroSlice := b.Bytes[int(addr) : int(addr)+rngN]
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for i := range zeroSlice {
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zeroSlice[i] = 0
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}
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return int64(rngN), rngErr
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}
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// CopyOutFrom implements IO.CopyOutFrom.
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func (b *BytesIO) CopyOutFrom(ctx context.Context, ars AddrRangeSeq, src safemem.Reader, opts IOOpts) (int64, error) {
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dsts, rngErr := b.blocksFromAddrRanges(ars)
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n, err := src.ReadToBlocks(dsts)
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if err != nil {
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return int64(n), err
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}
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return int64(n), rngErr
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}
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// CopyInTo implements IO.CopyInTo.
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func (b *BytesIO) CopyInTo(ctx context.Context, ars AddrRangeSeq, dst safemem.Writer, opts IOOpts) (int64, error) {
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srcs, rngErr := b.blocksFromAddrRanges(ars)
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n, err := dst.WriteFromBlocks(srcs)
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if err != nil {
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return int64(n), err
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}
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return int64(n), rngErr
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}
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func (b *BytesIO) rangeCheck(addr Addr, length int) (int, error) {
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if length == 0 {
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return 0, nil
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}
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if length < 0 {
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return 0, syserror.EINVAL
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}
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max := Addr(len(b.Bytes))
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if addr >= max {
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return 0, syserror.EFAULT
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}
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end, ok := addr.AddLength(uint64(length))
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if !ok || end > max {
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return int(max - addr), syserror.EFAULT
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}
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return length, nil
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}
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func (b *BytesIO) blocksFromAddrRanges(ars AddrRangeSeq) (safemem.BlockSeq, error) {
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switch ars.NumRanges() {
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case 0:
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return safemem.BlockSeq{}, nil
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case 1:
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block, err := b.blockFromAddrRange(ars.Head())
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return safemem.BlockSeqOf(block), err
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default:
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blocks := make([]safemem.Block, 0, ars.NumRanges())
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for !ars.IsEmpty() {
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block, err := b.blockFromAddrRange(ars.Head())
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if block.Len() != 0 {
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blocks = append(blocks, block)
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}
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if err != nil {
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return safemem.BlockSeqFromSlice(blocks), err
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}
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ars = ars.Tail()
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}
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return safemem.BlockSeqFromSlice(blocks), nil
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}
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}
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func (b *BytesIO) blockFromAddrRange(ar AddrRange) (safemem.Block, error) {
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n, err := b.rangeCheck(ar.Start, int(ar.Length()))
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if n == 0 {
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return safemem.Block{}, err
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}
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return safemem.BlockFromSafeSlice(b.Bytes[int(ar.Start) : int(ar.Start)+n]), err
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}
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// BytesIOSequence returns an IOSequence representing the given byte slice.
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func BytesIOSequence(buf []byte) IOSequence {
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return IOSequence{
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IO: &BytesIO{buf},
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Addrs: AddrRangeSeqOf(AddrRange{0, Addr(len(buf))}),
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}
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}
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