diff options
| -rw-r--r-- | pkg/buffer/BUILD | 39 | ||||
| -rw-r--r-- | pkg/buffer/buffer.go | 67 | ||||
| -rw-r--r-- | pkg/buffer/safemem.go | 131 | ||||
| -rw-r--r-- | pkg/buffer/view.go | 382 | ||||
| -rw-r--r-- | pkg/buffer/view_test.go | 233 | ||||
| -rw-r--r-- | pkg/buffer/view_unsafe.go (renamed from pkg/sentry/kernel/pipe/buffer_test.go) | 21 | ||||
| -rw-r--r-- | pkg/sentry/kernel/pipe/BUILD | 18 | ||||
| -rw-r--r-- | pkg/sentry/kernel/pipe/buffer.go | 115 | ||||
| -rw-r--r-- | pkg/sentry/kernel/pipe/pipe.go | 118 | ||||
| -rw-r--r-- | pkg/sentry/kernel/pipe/pipe_util.go | 25 |
10 files changed, 894 insertions, 255 deletions
diff --git a/pkg/buffer/BUILD b/pkg/buffer/BUILD new file mode 100644 index 000000000..a77a3beea --- /dev/null +++ b/pkg/buffer/BUILD @@ -0,0 +1,39 @@ +load("//tools:defs.bzl", "go_library", "go_test") +load("//tools/go_generics:defs.bzl", "go_template_instance") + +package(licenses = ["notice"]) + +go_template_instance( + name = "buffer_list", + out = "buffer_list.go", + package = "buffer", + prefix = "buffer", + template = "//pkg/ilist:generic_list", + types = { + "Element": "*Buffer", + "Linker": "*Buffer", + }, +) + +go_library( + name = "buffer", + srcs = [ + "buffer.go", + "buffer_list.go", + "safemem.go", + "view.go", + "view_unsafe.go", + ], + visibility = ["//visibility:public"], + deps = [ + "//pkg/log", + "//pkg/safemem", + ], +) + +go_test( + name = "buffer_test", + size = "small", + srcs = ["view_test.go"], + library = ":buffer", +) diff --git a/pkg/buffer/buffer.go b/pkg/buffer/buffer.go new file mode 100644 index 000000000..d5f64609b --- /dev/null +++ b/pkg/buffer/buffer.go @@ -0,0 +1,67 @@ +// Copyright 2020 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 buffer provides the implementation of a buffer view. +package buffer + +import ( + "sync" +) + +const bufferSize = 8144 // See below. + +// Buffer encapsulates a queueable byte buffer. +// +// Note that the total size is slightly less than two pages. This is done +// intentionally to ensure that the buffer object aligns with runtime +// internals. We have no hard size or alignment requirements. This two page +// size will effectively minimize internal fragmentation, but still have a +// large enough chunk to limit excessive segmentation. +// +// +stateify savable +type Buffer struct { + data [bufferSize]byte + read int + write int + bufferEntry +} + +// Reset resets internal data. +// +// This must be called before use. +func (b *Buffer) Reset() { + b.read = 0 + b.write = 0 +} + +// Empty indicates the buffer is empty. +// +// This indicates there is no data left to read. +func (b *Buffer) Empty() bool { + return b.read == b.write +} + +// Full indicates the buffer is full. +// +// This indicates there is no capacity left to write. +func (b *Buffer) Full() bool { + return b.write == len(b.data) +} + +// bufferPool is a pool for buffers. +var bufferPool = sync.Pool{ + New: func() interface{} { + return new(Buffer) + }, +} diff --git a/pkg/buffer/safemem.go b/pkg/buffer/safemem.go new file mode 100644 index 000000000..071aaa488 --- /dev/null +++ b/pkg/buffer/safemem.go @@ -0,0 +1,131 @@ +// Copyright 2020 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 buffer + +import ( + "io" + + "gvisor.dev/gvisor/pkg/safemem" +) + +// WriteBlock returns this buffer as a write Block. +func (b *Buffer) WriteBlock() safemem.Block { + return safemem.BlockFromSafeSlice(b.data[b.write:]) +} + +// ReadBlock returns this buffer as a read Block. +func (b *Buffer) ReadBlock() safemem.Block { + return safemem.BlockFromSafeSlice(b.data[b.read:b.write]) +} + +// WriteFromBlocks implements safemem.Writer.WriteFromBlocks. +// +// This will advance the write index. +func (v *View) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, error) { + need := int(srcs.NumBytes()) + if need == 0 { + return 0, nil + } + + var ( + dst safemem.BlockSeq + blocks []safemem.Block + ) + + // Need at least one buffer. + firstBuf := v.data.Back() + if firstBuf == nil { + firstBuf = bufferPool.Get().(*Buffer) + v.data.PushBack(firstBuf) + } + + // Does the last block have sufficient capacity alone? + if l := len(firstBuf.data) - firstBuf.write; l >= need { + dst = safemem.BlockSeqOf(firstBuf.WriteBlock()) + } else { + // Append blocks until sufficient. + need -= l + blocks = append(blocks, firstBuf.WriteBlock()) + for need > 0 { + emptyBuf := bufferPool.Get().(*Buffer) + v.data.PushBack(emptyBuf) + need -= len(emptyBuf.data) // Full block. + blocks = append(blocks, emptyBuf.WriteBlock()) + } + dst = safemem.BlockSeqFromSlice(blocks) + } + + // Perform the copy. + n, err := safemem.CopySeq(dst, srcs) + v.size += int64(n) + + // Update all indices. + for left := int(n); left > 0; firstBuf = firstBuf.Next() { + if l := len(firstBuf.data) - firstBuf.write; left >= l { + firstBuf.write += l // Whole block. + left -= l + } else { + firstBuf.write += left // Partial block. + left = 0 + } + } + + return n, err +} + +// ReadToBlocks implements safemem.Reader.ReadToBlocks. +// +// This will not advance the read index; the caller should follow +// this call with a call to TrimFront in order to remove the read +// data from the buffer. This is done to support pipe sematics. +func (v *View) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) { + need := int(dsts.NumBytes()) + if need == 0 { + return 0, nil + } + + var ( + src safemem.BlockSeq + blocks []safemem.Block + ) + + firstBuf := v.data.Front() + if firstBuf == nil { + return 0, io.EOF + } + + // Is all the data in a single block? + if l := firstBuf.write - firstBuf.read; l >= need { + src = safemem.BlockSeqOf(firstBuf.ReadBlock()) + } else { + // Build a list of all the buffers. + need -= l + blocks = append(blocks, firstBuf.ReadBlock()) + for buf := firstBuf.Next(); buf != nil && need > 0; buf = buf.Next() { + need -= buf.write - buf.read + blocks = append(blocks, buf.ReadBlock()) + } + src = safemem.BlockSeqFromSlice(blocks) + } + + // Perform the copy. + n, err := safemem.CopySeq(dsts, src) + + // See above: we would normally advance the read index here, but we + // don't do that in order to support pipe semantics. We rely on a + // separate call to TrimFront() in this case. + + return n, err +} diff --git a/pkg/buffer/view.go b/pkg/buffer/view.go new file mode 100644 index 000000000..00fc11e9c --- /dev/null +++ b/pkg/buffer/view.go @@ -0,0 +1,382 @@ +// Copyright 2020 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 buffer + +import ( + "fmt" + "io" +) + +// View is a non-linear buffer. +// +// All methods are thread compatible. +// +// +stateify savable +type View struct { + data bufferList + size int64 +} + +// TrimFront removes the first count bytes from the buffer. +func (v *View) TrimFront(count int64) { + if count >= v.size { + v.advanceRead(v.size) + } else { + v.advanceRead(count) + } +} + +// Read implements io.Reader.Read. +// +// Note that reading does not advance the read index. This must be done +// manually using TrimFront or other methods. +func (v *View) Read(p []byte) (int, error) { + return v.ReadAt(p, 0) +} + +// ReadAt implements io.ReaderAt.ReadAt. +func (v *View) ReadAt(p []byte, offset int64) (int, error) { + var ( + skipped int64 + done int64 + ) + for buf := v.data.Front(); buf != nil && done < int64(len(p)); buf = buf.Next() { + needToSkip := int(offset - skipped) + if l := buf.write - buf.read; l <= needToSkip { + skipped += int64(l) + continue + } + + // Actually read data. + n := copy(p[done:], buf.data[buf.read+needToSkip:buf.write]) + skipped += int64(needToSkip) + done += int64(n) + } + if int(done) < len(p) { + return int(done), io.EOF + } + return int(done), nil +} + +// Write implements io.Writer.Write. +func (v *View) Write(p []byte) (int, error) { + v.Append(p) // Does not fail. + return len(p), nil +} + +// advanceRead advances the view's read index. +// +// Precondition: there must be sufficient bytes in the buffer. +func (v *View) advanceRead(count int64) { + for buf := v.data.Front(); buf != nil && count > 0; { + l := int64(buf.write - buf.read) + if l > count { + // There is still data for reading. + buf.read += int(count) + v.size -= count + count = 0 + break + } + + // Read from this buffer. + buf.read += int(l) + count -= l + v.size -= l + + // When all data has been read from a buffer, we push + // it into the empty buffer pool for reuse. + oldBuf := buf + buf = buf.Next() // Iterate. + v.data.Remove(oldBuf) + oldBuf.Reset() + bufferPool.Put(oldBuf) + } + if count > 0 { + panic(fmt.Sprintf("advanceRead still has %d bytes remaining", count)) + } +} + +// Truncate truncates the view to the given bytes. +func (v *View) Truncate(length int64) { + if length < 0 || length >= v.size { + return // Nothing to do. + } + for buf := v.data.Back(); buf != nil && v.size > length; buf = v.data.Back() { + l := int64(buf.write - buf.read) // Local bytes. + switch { + case v.size-l >= length: + // Drop the buffer completely; see above. + v.data.Remove(buf) + v.size -= l + buf.Reset() + bufferPool.Put(buf) + + case v.size > length && v.size-l < length: + // Just truncate the buffer locally. + delta := (length - (v.size - l)) + buf.write = buf.read + int(delta) + v.size = length + + default: + // Should never happen. + panic("invalid buffer during truncation") + } + } + v.size = length // Save the new size. +} + +// Grow grows the given view to the number of bytes. If zero +// is true, all these bytes will be zero. If zero is false, +// then this is the caller's responsibility. +// +// Precondition: length must be >= 0. +func (v *View) Grow(length int64, zero bool) { + if length < 0 { + panic("negative length provided") + } + for v.size < length { + buf := v.data.Back() + + // Is there at least one buffer? + if buf == nil || buf.Full() { + buf = bufferPool.Get().(*Buffer) + v.data.PushBack(buf) + } + + // Write up to length bytes. + l := len(buf.data) - buf.write + if int64(l) > length-v.size { + l = int(length - v.size) + } + + // Zero the written section; note that this pattern is + // specifically recognized and optimized by the compiler. + if zero { + for i := buf.write; i < buf.write+l; i++ { + buf.data[i] = 0 + } + } + + // Advance the index. + buf.write += l + v.size += int64(l) + } +} + +// Prepend prepends the given data. +func (v *View) Prepend(data []byte) { + // Is there any space in the first buffer? + if buf := v.data.Front(); buf != nil && buf.read > 0 { + // Fill up before the first write. + avail := buf.read + copy(buf.data[0:], data[len(data)-avail:]) + data = data[:len(data)-avail] + v.size += int64(avail) + } + + for len(data) > 0 { + // Do we need an empty buffer? + buf := bufferPool.Get().(*Buffer) + v.data.PushFront(buf) + + // The buffer is empty; copy last chunk. + start := len(data) - len(buf.data) + if start < 0 { + start = 0 // Everything. + } + + // We have to put the data at the end of the current + // buffer in order to ensure that the next prepend will + // correctly fill up the beginning of this buffer. + bStart := len(buf.data) - len(data[start:]) + n := copy(buf.data[bStart:], data[start:]) + buf.read = bStart + buf.write = len(buf.data) + data = data[:start] + v.size += int64(n) + } +} + +// Append appends the given data. +func (v *View) Append(data []byte) { + for done := 0; done < len(data); { + buf := v.data.Back() + + // Find the first empty buffer. + if buf == nil || buf.Full() { + buf = bufferPool.Get().(*Buffer) + v.data.PushBack(buf) + } + + // Copy in to the given buffer. + n := copy(buf.data[buf.write:], data[done:]) + done += n + buf.write += n + v.size += int64(n) + } +} + +// Flatten returns a flattened copy of this data. +// +// This method should not be used in any performance-sensitive paths. It may +// allocate a fresh byte slice sufficiently large to contain all the data in +// the buffer. +// +// N.B. Tee data still belongs to this view, as if there is a single buffer +// present, then it will be returned directly. This should be used for +// temporary use only, and a reference to the given slice should not be held. +func (v *View) Flatten() []byte { + if buf := v.data.Front(); buf.Next() == nil { + return buf.data[buf.read:buf.write] // Only one buffer. + } + data := make([]byte, 0, v.size) // Need to flatten. + for buf := v.data.Front(); buf != nil; buf = buf.Next() { + // Copy to the allocated slice. + data = append(data, buf.data[buf.read:buf.write]...) + } + return data +} + +// Size indicates the total amount of data available in this view. +func (v *View) Size() (sz int64) { + sz = v.size // Pre-calculated. + return sz +} + +// Copy makes a strict copy of this view. +func (v *View) Copy() (other View) { + for buf := v.data.Front(); buf != nil; buf = buf.Next() { + other.Append(buf.data[buf.read:buf.write]) + } + return other +} + +// Apply applies the given function across all valid data. +func (v *View) Apply(fn func([]byte)) { + for buf := v.data.Front(); buf != nil; buf = buf.Next() { + if l := int64(buf.write - buf.read); l > 0 { + fn(buf.data[buf.read:buf.write]) + } + } +} + +// Merge merges the provided View with this one. +// +// The other view will be empty after this operation. +func (v *View) Merge(other *View) { + // Copy over all buffers. + for buf := other.data.Front(); buf != nil && !buf.Empty(); buf = other.data.Front() { + other.data.Remove(buf) + v.data.PushBack(buf) + } + + // Adjust sizes. + v.size += other.size + other.size = 0 +} + +// WriteFromReader writes to the buffer from an io.Reader. +func (v *View) WriteFromReader(r io.Reader, count int64) (int64, error) { + var ( + done int64 + n int + err error + ) + for done < count { + buf := v.data.Back() + + // Find the first empty buffer. + if buf == nil || buf.Full() { + buf = bufferPool.Get().(*Buffer) + v.data.PushBack(buf) + } + + // Is this less than the minimum batch? + if len(buf.data[buf.write:]) < minBatch && (count-done) >= int64(minBatch) { + tmp := make([]byte, minBatch) + n, err = r.Read(tmp) + v.Write(tmp[:n]) + done += int64(n) + if err != nil { + break + } + continue + } + + // Limit the read, if necessary. + end := len(buf.data) + if int64(end-buf.write) > (count - done) { + end = buf.write + int(count-done) + } + + // Pass the relevant portion of the buffer. + n, err = r.Read(buf.data[buf.write:end]) + buf.write += n + done += int64(n) + v.size += int64(n) + if err == io.EOF { + err = nil // Short write allowed. + break + } else if err != nil { + break + } + } + return done, err +} + +// ReadToWriter reads from the buffer into an io.Writer. +// +// N.B. This does not consume the bytes read. TrimFront should +// be called appropriately after this call in order to do so. +func (v *View) ReadToWriter(w io.Writer, count int64) (int64, error) { + var ( + done int64 + n int + err error + ) + offset := 0 // Spill-over for batching. + for buf := v.data.Front(); buf != nil && done < count; buf = buf.Next() { + l := buf.write - buf.read - offset + + // Is this less than the minimum batch? + if l < minBatch && (count-done) >= int64(minBatch) && (v.size-done) >= int64(minBatch) { + tmp := make([]byte, minBatch) + n, err = v.ReadAt(tmp, done) + w.Write(tmp[:n]) + done += int64(n) + offset = n - l // Reset below. + if err != nil { + break + } + continue + } + + // Limit the write if necessary. + if int64(l) >= (count - done) { + l = int(count - done) + } + + // Perform the actual write. + n, err = w.Write(buf.data[buf.read+offset : buf.read+offset+l]) + done += int64(n) + if err != nil { + break + } + + // Reset spill-over. + offset = 0 + } + return done, err +} diff --git a/pkg/buffer/view_test.go b/pkg/buffer/view_test.go new file mode 100644 index 000000000..37e652f16 --- /dev/null +++ b/pkg/buffer/view_test.go @@ -0,0 +1,233 @@ +// Copyright 2020 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 buffer + +import ( + "bytes" + "strings" + "testing" +) + +func TestView(t *testing.T) { + testCases := []struct { + name string + input string + output string + ops []func(*View) + }{ + // Prepend. + { + name: "prepend", + input: "world", + ops: []func(*View){ + func(v *View) { + v.Prepend([]byte("hello ")) + }, + }, + output: "hello world", + }, + { + name: "prepend fill", + input: strings.Repeat("1", bufferSize-1), + ops: []func(*View){ + func(v *View) { + v.Prepend([]byte("0")) + }, + }, + output: "0" + strings.Repeat("1", bufferSize-1), + }, + { + name: "prepend overflow", + input: strings.Repeat("1", bufferSize), + ops: []func(*View){ + func(v *View) { + v.Prepend([]byte("0")) + }, + }, + output: "0" + strings.Repeat("1", bufferSize), + }, + { + name: "prepend multiple buffers", + input: strings.Repeat("1", bufferSize-1), + ops: []func(*View){ + func(v *View) { + v.Prepend([]byte(strings.Repeat("0", bufferSize*3))) + }, + }, + output: strings.Repeat("0", bufferSize*3) + strings.Repeat("1", bufferSize-1), + }, + + // Append. + { + name: "append", + input: "hello", + ops: []func(*View){ + func(v *View) { + v.Append([]byte(" world")) + }, + }, + output: "hello world", + }, + { + name: "append fill", + input: strings.Repeat("1", bufferSize-1), + ops: []func(*View){ + func(v *View) { + v.Append([]byte("0")) + }, + }, + output: strings.Repeat("1", bufferSize-1) + "0", + }, + { + name: "append overflow", + input: strings.Repeat("1", bufferSize), + ops: []func(*View){ + func(v *View) { + v.Append([]byte("0")) + }, + }, + output: strings.Repeat("1", bufferSize) + "0", + }, + { + name: "append multiple buffers", + input: strings.Repeat("1", bufferSize-1), + ops: []func(*View){ + func(v *View) { + v.Append([]byte(strings.Repeat("0", bufferSize*3))) + }, + }, + output: strings.Repeat("1", bufferSize-1) + strings.Repeat("0", bufferSize*3), + }, + + // Truncate. + { + name: "truncate", + input: "hello world", + ops: []func(*View){ + func(v *View) { + v.Truncate(5) + }, + }, + output: "hello", + }, + { + name: "truncate multiple buffers", + input: strings.Repeat("1", bufferSize*2), + ops: []func(*View){ + func(v *View) { + v.Truncate(bufferSize*2 - 1) + }, + }, + output: strings.Repeat("1", bufferSize*2-1), + }, + { + name: "truncate multiple buffers to one buffer", + input: strings.Repeat("1", bufferSize*2), + ops: []func(*View){ + func(v *View) { + v.Truncate(5) + }, + }, + output: "11111", + }, + + // TrimFront. + { + name: "trim", + input: "hello world", + ops: []func(*View){ + func(v *View) { + v.TrimFront(6) + }, + }, + output: "world", + }, + { + name: "trim multiple buffers", + input: strings.Repeat("1", bufferSize*2), + ops: []func(*View){ + func(v *View) { + v.TrimFront(1) + }, + }, + output: strings.Repeat("1", bufferSize*2-1), + }, + { + name: "trim multiple buffers to one buffer", + input: strings.Repeat("1", bufferSize*2), + ops: []func(*View){ + func(v *View) { + v.TrimFront(bufferSize*2 - 1) + }, + }, + output: "1", + }, + + // Grow. + { + name: "grow", + input: "hello world", + ops: []func(*View){ + func(v *View) { + v.Grow(1, true) + }, + }, + output: "hello world", + }, + { + name: "grow from zero", + ops: []func(*View){ + func(v *View) { + v.Grow(1024, true) + }, + }, + output: strings.Repeat("\x00", 1024), + }, + { + name: "grow from non-zero", + input: strings.Repeat("1", bufferSize), + ops: []func(*View){ + func(v *View) { + v.Grow(bufferSize*2, true) + }, + }, + output: strings.Repeat("1", bufferSize) + strings.Repeat("\x00", bufferSize), + }, + } + + for _, tc := range testCases { + t.Run(tc.name, func(t *testing.T) { + // Construct the new view. + var view View + view.Append([]byte(tc.input)) + + // Run all operations. + for _, op := range tc.ops { + op(&view) + } + + // Flatten and validate. + out := view.Flatten() + if !bytes.Equal([]byte(tc.output), out) { + t.Errorf("expected %q, got %q", tc.output, string(out)) + } + + // Ensure the size is correct. + if len(out) != int(view.Size()) { + t.Errorf("size is wrong: expected %d, got %d", len(out), view.Size()) + } + }) + } +} diff --git a/pkg/sentry/kernel/pipe/buffer_test.go b/pkg/buffer/view_unsafe.go index 4d54b8b8f..d1ef39b26 100644 --- a/pkg/sentry/kernel/pipe/buffer_test.go +++ b/pkg/buffer/view_unsafe.go @@ -1,4 +1,4 @@ -// Copyright 2019 The gVisor Authors. +// Copyright 2020 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. @@ -12,21 +12,14 @@ // See the License for the specific language governing permissions and // limitations under the License. -package pipe +package buffer import ( - "testing" "unsafe" - - "gvisor.dev/gvisor/pkg/usermem" ) -func TestBufferSize(t *testing.T) { - bufferSize := unsafe.Sizeof(buffer{}) - if bufferSize < usermem.PageSize { - t.Errorf("buffer is less than a page") - } - if bufferSize > (2 * usermem.PageSize) { - t.Errorf("buffer is greater than two pages") - } -} +// minBatch is the smallest Read or Write operation that the +// WriteFromReader and ReadToWriter functions will use. +// +// This is defined as the size of a native pointer. +const minBatch = int(unsafe.Sizeof(uintptr(0))) diff --git a/pkg/sentry/kernel/pipe/BUILD b/pkg/sentry/kernel/pipe/BUILD index 4c049d5b4..f29dc0472 100644 --- a/pkg/sentry/kernel/pipe/BUILD +++ b/pkg/sentry/kernel/pipe/BUILD @@ -1,25 +1,10 @@ load("//tools:defs.bzl", "go_library", "go_test") -load("//tools/go_generics:defs.bzl", "go_template_instance") package(licenses = ["notice"]) -go_template_instance( - name = "buffer_list", - out = "buffer_list.go", - package = "pipe", - prefix = "buffer", - template = "//pkg/ilist:generic_list", - types = { - "Element": "*buffer", - "Linker": "*buffer", - }, -) - go_library( name = "pipe", srcs = [ - "buffer.go", - "buffer_list.go", "device.go", "node.go", "pipe.go", @@ -33,8 +18,8 @@ go_library( deps = [ "//pkg/abi/linux", "//pkg/amutex", + "//pkg/buffer", "//pkg/context", - "//pkg/safemem", "//pkg/sentry/arch", "//pkg/sentry/device", "//pkg/sentry/fs", @@ -51,7 +36,6 @@ go_test( name = "pipe_test", size = "small", srcs = [ - "buffer_test.go", "node_test.go", "pipe_test.go", ], diff --git a/pkg/sentry/kernel/pipe/buffer.go b/pkg/sentry/kernel/pipe/buffer.go deleted file mode 100644 index fe3be5dbd..000000000 --- a/pkg/sentry/kernel/pipe/buffer.go +++ /dev/null @@ -1,115 +0,0 @@ -// 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 pipe - -import ( - "io" - - "gvisor.dev/gvisor/pkg/safemem" - "gvisor.dev/gvisor/pkg/sync" -) - -// buffer encapsulates a queueable byte buffer. -// -// Note that the total size is slightly less than two pages. This -// is done intentionally to ensure that the buffer object aligns -// with runtime internals. We have no hard size or alignment -// requirements. This two page size will effectively minimize -// internal fragmentation, but still have a large enough chunk -// to limit excessive segmentation. -// -// +stateify savable -type buffer struct { - data [8144]byte - read int - write int - bufferEntry -} - -// Reset resets internal data. -// -// This must be called before use. -func (b *buffer) Reset() { - b.read = 0 - b.write = 0 -} - -// Empty indicates the buffer is empty. -// -// This indicates there is no data left to read. -func (b *buffer) Empty() bool { - return b.read == b.write -} - -// Full indicates the buffer is full. -// -// This indicates there is no capacity left to write. -func (b *buffer) Full() bool { - return b.write == len(b.data) -} - -// WriteFromBlocks implements safemem.Writer.WriteFromBlocks. -func (b *buffer) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, error) { - dst := safemem.BlockSeqOf(safemem.BlockFromSafeSlice(b.data[b.write:])) - n, err := safemem.CopySeq(dst, srcs) - b.write += int(n) - return n, err -} - -// WriteFromReader writes to the buffer from an io.Reader. -func (b *buffer) WriteFromReader(r io.Reader, count int64) (int64, error) { - dst := b.data[b.write:] - if count < int64(len(dst)) { - dst = b.data[b.write:][:count] - } - n, err := r.Read(dst) - b.write += n - return int64(n), err -} - -// ReadToBlocks implements safemem.Reader.ReadToBlocks. -func (b *buffer) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) { - src := safemem.BlockSeqOf(safemem.BlockFromSafeSlice(b.data[b.read:b.write])) - n, err := safemem.CopySeq(dsts, src) - b.read += int(n) - return n, err -} - -// ReadToWriter reads from the buffer into an io.Writer. -func (b *buffer) ReadToWriter(w io.Writer, count int64, dup bool) (int64, error) { - src := b.data[b.read:b.write] - if count < int64(len(src)) { - src = b.data[b.read:][:count] - } - n, err := w.Write(src) - if !dup { - b.read += n - } - return int64(n), err -} - -// bufferPool is a pool for buffers. -var bufferPool = sync.Pool{ - New: func() interface{} { - return new(buffer) - }, -} - -// newBuffer grabs a new buffer from the pool. -func newBuffer() *buffer { - b := bufferPool.Get().(*buffer) - b.Reset() - return b -} diff --git a/pkg/sentry/kernel/pipe/pipe.go b/pkg/sentry/kernel/pipe/pipe.go index 08410283f..725e9db7d 100644 --- a/pkg/sentry/kernel/pipe/pipe.go +++ b/pkg/sentry/kernel/pipe/pipe.go @@ -20,6 +20,7 @@ import ( "sync/atomic" "syscall" + "gvisor.dev/gvisor/pkg/buffer" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sync" @@ -70,10 +71,10 @@ type Pipe struct { // mu protects all pipe internal state below. mu sync.Mutex `state:"nosave"` - // data is the buffer queue of pipe contents. + // view is the underlying set of buffers. // // This is protected by mu. - data bufferList + view buffer.View // max is the maximum size of the pipe in bytes. When this max has been // reached, writers will get EWOULDBLOCK. @@ -81,11 +82,6 @@ type Pipe struct { // This is protected by mu. max int64 - // size is the current size of the pipe in bytes. - // - // This is protected by mu. - size int64 - // hadWriter indicates if this pipe ever had a writer. Note that this // does not necessarily indicate there is *currently* a writer, just // that there has been a writer at some point since the pipe was @@ -196,7 +192,7 @@ type readOps struct { limit func(int64) // read performs the actual read operation. - read func(*buffer) (int64, error) + read func(*buffer.View) (int64, error) } // read reads data from the pipe into dst and returns the number of bytes @@ -213,7 +209,7 @@ func (p *Pipe) read(ctx context.Context, ops readOps) (int64, error) { defer p.mu.Unlock() // Is the pipe empty? - if p.size == 0 { + if p.view.Size() == 0 { if !p.HasWriters() { // There are no writers, return EOF. return 0, nil @@ -222,71 +218,13 @@ func (p *Pipe) read(ctx context.Context, ops readOps) (int64, error) { } // Limit how much we consume. - if ops.left() > p.size { - ops.limit(p.size) + if ops.left() > p.view.Size() { + ops.limit(p.view.Size()) } - done := int64(0) - for ops.left() > 0 { - // Pop the first buffer. - first := p.data.Front() - if first == nil { - break - } - - // Copy user data. - n, err := ops.read(first) - done += int64(n) - p.size -= n - - // Empty buffer? - if first.Empty() { - // Push to the free list. - p.data.Remove(first) - bufferPool.Put(first) - } - - // Handle errors. - if err != nil { - return done, err - } - } - - return done, nil -} - -// dup duplicates all data from this pipe into the given writer. -// -// There is no blocking behavior implemented here. The writer may propagate -// some blocking error. All the writes must be complete writes. -func (p *Pipe) dup(ctx context.Context, ops readOps) (int64, error) { - p.mu.Lock() - defer p.mu.Unlock() - - // Is the pipe empty? - if p.size == 0 { - if !p.HasWriters() { - // See above. - return 0, nil - } - return 0, syserror.ErrWouldBlock - } - - // Limit how much we consume. - if ops.left() > p.size { - ops.limit(p.size) - } - - done := int64(0) - for buf := p.data.Front(); buf != nil; buf = buf.Next() { - n, err := ops.read(buf) - done += n - if err != nil { - return done, err - } - } - - return done, nil + // Copy user data; the read op is responsible for trimming. + done, err := ops.read(&p.view) + return done, err } type writeOps struct { @@ -297,7 +235,7 @@ type writeOps struct { limit func(int64) // write should write to the provided buffer. - write func(*buffer) (int64, error) + write func(*buffer.View) (int64, error) } // write writes data from sv into the pipe and returns the number of bytes @@ -317,33 +255,19 @@ func (p *Pipe) write(ctx context.Context, ops writeOps) (int64, error) { // POSIX requires that a write smaller than atomicIOBytes (PIPE_BUF) be // atomic, but requires no atomicity for writes larger than this. wanted := ops.left() - if avail := p.max - p.size; wanted > avail { + if avail := p.max - p.view.Size(); wanted > avail { if wanted <= p.atomicIOBytes { return 0, syserror.ErrWouldBlock } ops.limit(avail) } - done := int64(0) - for ops.left() > 0 { - // Need a new buffer? - last := p.data.Back() - if last == nil || last.Full() { - // Add a new buffer to the data list. - last = newBuffer() - p.data.PushBack(last) - } - - // Copy user data. - n, err := ops.write(last) - done += int64(n) - p.size += n - - // Handle errors. - if err != nil { - return done, err - } + // Copy user data. + done, err := ops.write(&p.view) + if err != nil { + return done, err } + if wanted > done { // Partial write due to full pipe. return done, syserror.ErrWouldBlock @@ -396,7 +320,7 @@ func (p *Pipe) HasWriters() bool { // Precondition: mu must be held. func (p *Pipe) rReadinessLocked() waiter.EventMask { ready := waiter.EventMask(0) - if p.HasReaders() && p.data.Front() != nil { + if p.HasReaders() && p.view.Size() != 0 { ready |= waiter.EventIn } if !p.HasWriters() && p.hadWriter { @@ -422,7 +346,7 @@ func (p *Pipe) rReadiness() waiter.EventMask { // Precondition: mu must be held. func (p *Pipe) wReadinessLocked() waiter.EventMask { ready := waiter.EventMask(0) - if p.HasWriters() && p.size < p.max { + if p.HasWriters() && p.view.Size() < p.max { ready |= waiter.EventOut } if !p.HasReaders() { @@ -451,7 +375,7 @@ func (p *Pipe) rwReadiness() waiter.EventMask { func (p *Pipe) queued() int64 { p.mu.Lock() defer p.mu.Unlock() - return p.size + return p.view.Size() } // FifoSize implements fs.FifoSizer.FifoSize. @@ -474,7 +398,7 @@ func (p *Pipe) SetFifoSize(size int64) (int64, error) { } p.mu.Lock() defer p.mu.Unlock() - if size < p.size { + if size < p.view.Size() { return 0, syserror.EBUSY } p.max = size diff --git a/pkg/sentry/kernel/pipe/pipe_util.go b/pkg/sentry/kernel/pipe/pipe_util.go index 80158239e..5a1d4fd57 100644 --- a/pkg/sentry/kernel/pipe/pipe_util.go +++ b/pkg/sentry/kernel/pipe/pipe_util.go @@ -21,6 +21,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/amutex" + "gvisor.dev/gvisor/pkg/buffer" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" "gvisor.dev/gvisor/pkg/sync" @@ -49,9 +50,10 @@ func (p *Pipe) Read(ctx context.Context, dst usermem.IOSequence) (int64, error) limit: func(l int64) { dst = dst.TakeFirst64(l) }, - read: func(buf *buffer) (int64, error) { - n, err := dst.CopyOutFrom(ctx, buf) + read: func(view *buffer.View) (int64, error) { + n, err := dst.CopyOutFrom(ctx, view) dst = dst.DropFirst64(n) + view.TrimFront(n) return n, err }, }) @@ -70,16 +72,15 @@ func (p *Pipe) WriteTo(ctx context.Context, w io.Writer, count int64, dup bool) limit: func(l int64) { count = l }, - read: func(buf *buffer) (int64, error) { - n, err := buf.ReadToWriter(w, count, dup) + read: func(view *buffer.View) (int64, error) { + n, err := view.ReadToWriter(w, count) + if !dup { + view.TrimFront(n) + } count -= n return n, err }, } - if dup { - // There is no notification for dup operations. - return p.dup(ctx, ops) - } n, err := p.read(ctx, ops) if n > 0 { p.Notify(waiter.EventOut) @@ -96,8 +97,8 @@ func (p *Pipe) Write(ctx context.Context, src usermem.IOSequence) (int64, error) limit: func(l int64) { src = src.TakeFirst64(l) }, - write: func(buf *buffer) (int64, error) { - n, err := src.CopyInTo(ctx, buf) + write: func(view *buffer.View) (int64, error) { + n, err := src.CopyInTo(ctx, view) src = src.DropFirst64(n) return n, err }, @@ -117,8 +118,8 @@ func (p *Pipe) ReadFrom(ctx context.Context, r io.Reader, count int64) (int64, e limit: func(l int64) { count = l }, - write: func(buf *buffer) (int64, error) { - n, err := buf.WriteFromReader(r, count) + write: func(view *buffer.View) (int64, error) { + n, err := view.WriteFromReader(r, count) count -= n return n, err }, |