diff options
author | kevin.xu <cming.xu@gmail.com> | 2020-04-27 21:51:31 +0800 |
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committer | GitHub <noreply@github.com> | 2020-04-27 21:51:31 +0800 |
commit | e896ca54db67524afc20b644d43c72185e72dc0e (patch) | |
tree | 2a16f3a62a5cafd098f1f028c621f1b655589d69 /pkg/usermem/bytes_io.go | |
parent | 1f19624fa127d7d59cabe29593cc80b7fe6c81f8 (diff) | |
parent | 3c67754663f424f2ebbc0ff2a4c80e30618d5355 (diff) |
Merge pull request #1 from google/master
catch up
Diffstat (limited to 'pkg/usermem/bytes_io.go')
-rw-r--r-- | pkg/usermem/bytes_io.go | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/pkg/usermem/bytes_io.go b/pkg/usermem/bytes_io.go new file mode 100644 index 000000000..e177d30eb --- /dev/null +++ b/pkg/usermem/bytes_io.go @@ -0,0 +1,141 @@ +// Copyright 2018 The gVisor Authors. +// +// 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 usermem + +import ( + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/safemem" + "gvisor.dev/gvisor/pkg/syserror" +) + +const maxInt = int(^uint(0) >> 1) + +// BytesIO implements IO using a byte slice. Addresses are interpreted as +// offsets into the slice. Reads and writes beyond the end of the slice return +// EFAULT. +type BytesIO struct { + Bytes []byte +} + +// CopyOut implements IO.CopyOut. +func (b *BytesIO) CopyOut(ctx context.Context, addr Addr, src []byte, opts IOOpts) (int, error) { + rngN, rngErr := b.rangeCheck(addr, len(src)) + if rngN == 0 { + return 0, rngErr + } + return copy(b.Bytes[int(addr):], src[:rngN]), rngErr +} + +// CopyIn implements IO.CopyIn. +func (b *BytesIO) CopyIn(ctx context.Context, addr Addr, dst []byte, opts IOOpts) (int, error) { + rngN, rngErr := b.rangeCheck(addr, len(dst)) + if rngN == 0 { + return 0, rngErr + } + return copy(dst[:rngN], b.Bytes[int(addr):]), rngErr +} + +// ZeroOut implements IO.ZeroOut. +func (b *BytesIO) ZeroOut(ctx context.Context, addr Addr, toZero int64, opts IOOpts) (int64, error) { + if toZero > int64(maxInt) { + return 0, syserror.EINVAL + } + rngN, rngErr := b.rangeCheck(addr, int(toZero)) + if rngN == 0 { + return 0, rngErr + } + zeroSlice := b.Bytes[int(addr) : int(addr)+rngN] + for i := range zeroSlice { + zeroSlice[i] = 0 + } + return int64(rngN), rngErr +} + +// CopyOutFrom implements IO.CopyOutFrom. +func (b *BytesIO) CopyOutFrom(ctx context.Context, ars AddrRangeSeq, src safemem.Reader, opts IOOpts) (int64, error) { + dsts, rngErr := b.blocksFromAddrRanges(ars) + n, err := src.ReadToBlocks(dsts) + if err != nil { + return int64(n), err + } + return int64(n), rngErr +} + +// CopyInTo implements IO.CopyInTo. +func (b *BytesIO) CopyInTo(ctx context.Context, ars AddrRangeSeq, dst safemem.Writer, opts IOOpts) (int64, error) { + srcs, rngErr := b.blocksFromAddrRanges(ars) + n, err := dst.WriteFromBlocks(srcs) + if err != nil { + return int64(n), err + } + return int64(n), rngErr +} + +func (b *BytesIO) rangeCheck(addr Addr, length int) (int, error) { + if length == 0 { + return 0, nil + } + if length < 0 { + return 0, syserror.EINVAL + } + max := Addr(len(b.Bytes)) + if addr >= max { + return 0, syserror.EFAULT + } + end, ok := addr.AddLength(uint64(length)) + if !ok || end > max { + return int(max - addr), syserror.EFAULT + } + return length, nil +} + +func (b *BytesIO) blocksFromAddrRanges(ars AddrRangeSeq) (safemem.BlockSeq, error) { + switch ars.NumRanges() { + case 0: + return safemem.BlockSeq{}, nil + case 1: + block, err := b.blockFromAddrRange(ars.Head()) + return safemem.BlockSeqOf(block), err + default: + blocks := make([]safemem.Block, 0, ars.NumRanges()) + for !ars.IsEmpty() { + block, err := b.blockFromAddrRange(ars.Head()) + if block.Len() != 0 { + blocks = append(blocks, block) + } + if err != nil { + return safemem.BlockSeqFromSlice(blocks), err + } + ars = ars.Tail() + } + return safemem.BlockSeqFromSlice(blocks), nil + } +} + +func (b *BytesIO) blockFromAddrRange(ar AddrRange) (safemem.Block, error) { + n, err := b.rangeCheck(ar.Start, int(ar.Length())) + if n == 0 { + return safemem.Block{}, err + } + return safemem.BlockFromSafeSlice(b.Bytes[int(ar.Start) : int(ar.Start)+n]), err +} + +// BytesIOSequence returns an IOSequence representing the given byte slice. +func BytesIOSequence(buf []byte) IOSequence { + return IOSequence{ + IO: &BytesIO{buf}, + Addrs: AddrRangeSeqOf(AddrRange{0, Addr(len(buf))}), + } +} |