summaryrefslogtreecommitdiffstats
path: root/vendor/github.com/klauspost/compress/s2/decode.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/github.com/klauspost/compress/s2/decode.go')
-rw-r--r--vendor/github.com/klauspost/compress/s2/decode.go565
1 files changed, 565 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/s2/decode.go b/vendor/github.com/klauspost/compress/s2/decode.go
new file mode 100644
index 00000000..d0ae5304
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/s2/decode.go
@@ -0,0 +1,565 @@
+// Copyright 2011 The Snappy-Go Authors. All rights reserved.
+// Copyright (c) 2019 Klaus Post. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package s2
+
+import (
+ "encoding/binary"
+ "errors"
+ "io"
+)
+
+var (
+ // ErrCorrupt reports that the input is invalid.
+ ErrCorrupt = errors.New("s2: corrupt input")
+ // ErrCRC reports that the input failed CRC validation (streams only)
+ ErrCRC = errors.New("s2: corrupt input, crc mismatch")
+ // ErrTooLarge reports that the uncompressed length is too large.
+ ErrTooLarge = errors.New("s2: decoded block is too large")
+ // ErrUnsupported reports that the input isn't supported.
+ ErrUnsupported = errors.New("s2: unsupported input")
+)
+
+// DecodedLen returns the length of the decoded block.
+func DecodedLen(src []byte) (int, error) {
+ v, _, err := decodedLen(src)
+ return v, err
+}
+
+// decodedLen returns the length of the decoded block and the number of bytes
+// that the length header occupied.
+func decodedLen(src []byte) (blockLen, headerLen int, err error) {
+ v, n := binary.Uvarint(src)
+ if n <= 0 || v > 0xffffffff {
+ return 0, 0, ErrCorrupt
+ }
+
+ const wordSize = 32 << (^uint(0) >> 32 & 1)
+ if wordSize == 32 && v > 0x7fffffff {
+ return 0, 0, ErrTooLarge
+ }
+ return int(v), n, nil
+}
+
+const (
+ decodeErrCodeCorrupt = 1
+)
+
+// Decode returns the decoded form of src. The returned slice may be a sub-
+// slice of dst if dst was large enough to hold the entire decoded block.
+// Otherwise, a newly allocated slice will be returned.
+//
+// The dst and src must not overlap. It is valid to pass a nil dst.
+func Decode(dst, src []byte) ([]byte, error) {
+ dLen, s, err := decodedLen(src)
+ if err != nil {
+ return nil, err
+ }
+ if dLen <= cap(dst) {
+ dst = dst[:dLen]
+ } else {
+ dst = make([]byte, dLen)
+ }
+ if s2Decode(dst, src[s:]) != 0 {
+ return nil, ErrCorrupt
+ }
+ return dst, nil
+}
+
+// NewReader returns a new Reader that decompresses from r, using the framing
+// format described at
+// https://github.com/google/snappy/blob/master/framing_format.txt with S2 changes.
+func NewReader(r io.Reader, opts ...ReaderOption) *Reader {
+ nr := Reader{
+ r: r,
+ maxBlock: maxBlockSize,
+ }
+ for _, opt := range opts {
+ if err := opt(&nr); err != nil {
+ nr.err = err
+ return &nr
+ }
+ }
+ nr.maxBufSize = MaxEncodedLen(nr.maxBlock) + checksumSize
+ if nr.lazyBuf > 0 {
+ nr.buf = make([]byte, MaxEncodedLen(nr.lazyBuf)+checksumSize)
+ } else {
+ nr.buf = make([]byte, MaxEncodedLen(defaultBlockSize)+checksumSize)
+ }
+ nr.paramsOK = true
+ return &nr
+}
+
+// ReaderOption is an option for creating a decoder.
+type ReaderOption func(*Reader) error
+
+// ReaderMaxBlockSize allows to control allocations if the stream
+// has been compressed with a smaller WriterBlockSize, or with the default 1MB.
+// Blocks must be this size or smaller to decompress,
+// otherwise the decoder will return ErrUnsupported.
+//
+// For streams compressed with Snappy this can safely be set to 64KB (64 << 10).
+//
+// Default is the maximum limit of 4MB.
+func ReaderMaxBlockSize(blockSize int) ReaderOption {
+ return func(r *Reader) error {
+ if blockSize > maxBlockSize || blockSize <= 0 {
+ return errors.New("s2: block size too large. Must be <= 4MB and > 0")
+ }
+ if r.lazyBuf == 0 && blockSize < defaultBlockSize {
+ r.lazyBuf = blockSize
+ }
+ r.maxBlock = blockSize
+ return nil
+ }
+}
+
+// ReaderAllocBlock allows to control upfront stream allocations
+// and not allocate for frames bigger than this initially.
+// If frames bigger than this is seen a bigger buffer will be allocated.
+//
+// Default is 1MB, which is default output size.
+func ReaderAllocBlock(blockSize int) ReaderOption {
+ return func(r *Reader) error {
+ if blockSize > maxBlockSize || blockSize < 1024 {
+ return errors.New("s2: invalid ReaderAllocBlock. Must be <= 4MB and >= 1024")
+ }
+ r.lazyBuf = blockSize
+ return nil
+ }
+}
+
+// Reader is an io.Reader that can read Snappy-compressed bytes.
+type Reader struct {
+ r io.Reader
+ err error
+ decoded []byte
+ buf []byte
+ // decoded[i:j] contains decoded bytes that have not yet been passed on.
+ i, j int
+ // maximum block size allowed.
+ maxBlock int
+ // maximum expected buffer size.
+ maxBufSize int
+ // alloc a buffer this size if > 0.
+ lazyBuf int
+ readHeader bool
+ paramsOK bool
+ snappyFrame bool
+}
+
+// ensureBufferSize will ensure that the buffer can take at least n bytes.
+// If false is returned the buffer exceeds maximum allowed size.
+func (r *Reader) ensureBufferSize(n int) bool {
+ if len(r.buf) >= n {
+ return true
+ }
+ if n > r.maxBufSize {
+ r.err = ErrCorrupt
+ return false
+ }
+ // Realloc buffer.
+ r.buf = make([]byte, n)
+ return true
+}
+
+// Reset discards any buffered data, resets all state, and switches the Snappy
+// reader to read from r. This permits reusing a Reader rather than allocating
+// a new one.
+func (r *Reader) Reset(reader io.Reader) {
+ if !r.paramsOK {
+ return
+ }
+ r.r = reader
+ r.err = nil
+ r.i = 0
+ r.j = 0
+ r.readHeader = false
+}
+
+func (r *Reader) readFull(p []byte, allowEOF bool) (ok bool) {
+ if _, r.err = io.ReadFull(r.r, p); r.err != nil {
+ if r.err == io.ErrUnexpectedEOF || (r.err == io.EOF && !allowEOF) {
+ r.err = ErrCorrupt
+ }
+ return false
+ }
+ return true
+}
+
+// skipN will skip n bytes.
+// If the supplied reader supports seeking that is used.
+// tmp is used as a temporary buffer for reading.
+// The supplied slice does not need to be the size of the read.
+func (r *Reader) skipN(tmp []byte, n int, allowEOF bool) (ok bool) {
+ if rs, ok := r.r.(io.ReadSeeker); ok {
+ _, err := rs.Seek(int64(n), io.SeekCurrent)
+ if err == nil {
+ return true
+ }
+ if err == io.ErrUnexpectedEOF || (r.err == io.EOF && !allowEOF) {
+ r.err = ErrCorrupt
+ return false
+ }
+ }
+ for n > 0 {
+ if n < len(tmp) {
+ tmp = tmp[:n]
+ }
+ if _, r.err = io.ReadFull(r.r, tmp); r.err != nil {
+ if r.err == io.ErrUnexpectedEOF || (r.err == io.EOF && !allowEOF) {
+ r.err = ErrCorrupt
+ }
+ return false
+ }
+ n -= len(tmp)
+ }
+ return true
+}
+
+// Read satisfies the io.Reader interface.
+func (r *Reader) Read(p []byte) (int, error) {
+ if r.err != nil {
+ return 0, r.err
+ }
+ for {
+ if r.i < r.j {
+ n := copy(p, r.decoded[r.i:r.j])
+ r.i += n
+ return n, nil
+ }
+ if !r.readFull(r.buf[:4], true) {
+ return 0, r.err
+ }
+ chunkType := r.buf[0]
+ if !r.readHeader {
+ if chunkType != chunkTypeStreamIdentifier {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ r.readHeader = true
+ }
+ chunkLen := int(r.buf[1]) | int(r.buf[2])<<8 | int(r.buf[3])<<16
+
+ // The chunk types are specified at
+ // https://github.com/google/snappy/blob/master/framing_format.txt
+ switch chunkType {
+ case chunkTypeCompressedData:
+ // Section 4.2. Compressed data (chunk type 0x00).
+ if chunkLen < checksumSize {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ if !r.ensureBufferSize(chunkLen) {
+ if r.err == nil {
+ r.err = ErrUnsupported
+ }
+ return 0, r.err
+ }
+ buf := r.buf[:chunkLen]
+ if !r.readFull(buf, false) {
+ return 0, r.err
+ }
+ checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
+ buf = buf[checksumSize:]
+
+ n, err := DecodedLen(buf)
+ if err != nil {
+ r.err = err
+ return 0, r.err
+ }
+ if r.snappyFrame && n > maxSnappyBlockSize {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+
+ if n > len(r.decoded) {
+ if n > r.maxBlock {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ r.decoded = make([]byte, n)
+ }
+ if _, err := Decode(r.decoded, buf); err != nil {
+ r.err = err
+ return 0, r.err
+ }
+ if crc(r.decoded[:n]) != checksum {
+ r.err = ErrCRC
+ return 0, r.err
+ }
+ r.i, r.j = 0, n
+ continue
+
+ case chunkTypeUncompressedData:
+ // Section 4.3. Uncompressed data (chunk type 0x01).
+ if chunkLen < checksumSize {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ if !r.ensureBufferSize(chunkLen) {
+ if r.err == nil {
+ r.err = ErrUnsupported
+ }
+ return 0, r.err
+ }
+ buf := r.buf[:checksumSize]
+ if !r.readFull(buf, false) {
+ return 0, r.err
+ }
+ checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
+ // Read directly into r.decoded instead of via r.buf.
+ n := chunkLen - checksumSize
+ if r.snappyFrame && n > maxSnappyBlockSize {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ if n > len(r.decoded) {
+ if n > r.maxBlock {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ r.decoded = make([]byte, n)
+ }
+ if !r.readFull(r.decoded[:n], false) {
+ return 0, r.err
+ }
+ if crc(r.decoded[:n]) != checksum {
+ r.err = ErrCRC
+ return 0, r.err
+ }
+ r.i, r.j = 0, n
+ continue
+
+ case chunkTypeStreamIdentifier:
+ // Section 4.1. Stream identifier (chunk type 0xff).
+ if chunkLen != len(magicBody) {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ if !r.readFull(r.buf[:len(magicBody)], false) {
+ return 0, r.err
+ }
+ if string(r.buf[:len(magicBody)]) != magicBody {
+ if string(r.buf[:len(magicBody)]) != magicBodySnappy {
+ r.err = ErrCorrupt
+ return 0, r.err
+ } else {
+ r.snappyFrame = true
+ }
+ } else {
+ r.snappyFrame = false
+ }
+ continue
+ }
+
+ if chunkType <= 0x7f {
+ // Section 4.5. Reserved unskippable chunks (chunk types 0x02-0x7f).
+ r.err = ErrUnsupported
+ return 0, r.err
+ }
+ // Section 4.4 Padding (chunk type 0xfe).
+ // Section 4.6. Reserved skippable chunks (chunk types 0x80-0xfd).
+ if chunkLen > maxBlockSize {
+ r.err = ErrUnsupported
+ return 0, r.err
+ }
+
+ if !r.skipN(r.buf, chunkLen, false) {
+ return 0, r.err
+ }
+ }
+}
+
+// Skip will skip n bytes forward in the decompressed output.
+// For larger skips this consumes less CPU and is faster than reading output and discarding it.
+// CRC is not checked on skipped blocks.
+// io.ErrUnexpectedEOF is returned if the stream ends before all bytes have been skipped.
+// If a decoding error is encountered subsequent calls to Read will also fail.
+func (r *Reader) Skip(n int64) error {
+ if n < 0 {
+ return errors.New("attempted negative skip")
+ }
+ if r.err != nil {
+ return r.err
+ }
+
+ for n > 0 {
+ if r.i < r.j {
+ // Skip in buffer.
+ // decoded[i:j] contains decoded bytes that have not yet been passed on.
+ left := int64(r.j - r.i)
+ if left >= n {
+ r.i += int(n)
+ return nil
+ }
+ n -= int64(r.j - r.i)
+ r.i, r.j = 0, 0
+ }
+
+ // Buffer empty; read blocks until we have content.
+ if !r.readFull(r.buf[:4], true) {
+ if r.err == io.EOF {
+ r.err = io.ErrUnexpectedEOF
+ }
+ return r.err
+ }
+ chunkType := r.buf[0]
+ if !r.readHeader {
+ if chunkType != chunkTypeStreamIdentifier {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ r.readHeader = true
+ }
+ chunkLen := int(r.buf[1]) | int(r.buf[2])<<8 | int(r.buf[3])<<16
+
+ // The chunk types are specified at
+ // https://github.com/google/snappy/blob/master/framing_format.txt
+ switch chunkType {
+ case chunkTypeCompressedData:
+ // Section 4.2. Compressed data (chunk type 0x00).
+ if chunkLen < checksumSize {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ if !r.ensureBufferSize(chunkLen) {
+ if r.err == nil {
+ r.err = ErrUnsupported
+ }
+ return r.err
+ }
+ buf := r.buf[:chunkLen]
+ if !r.readFull(buf, false) {
+ return r.err
+ }
+ checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
+ buf = buf[checksumSize:]
+
+ dLen, err := DecodedLen(buf)
+ if err != nil {
+ r.err = err
+ return r.err
+ }
+ if dLen > r.maxBlock {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ // Check if destination is within this block
+ if int64(dLen) > n {
+ if len(r.decoded) < dLen {
+ r.decoded = make([]byte, dLen)
+ }
+ if _, err := Decode(r.decoded, buf); err != nil {
+ r.err = err
+ return r.err
+ }
+ if crc(r.decoded[:dLen]) != checksum {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ } else {
+ // Skip block completely
+ n -= int64(dLen)
+ dLen = 0
+ }
+ r.i, r.j = 0, dLen
+ continue
+ case chunkTypeUncompressedData:
+ // Section 4.3. Uncompressed data (chunk type 0x01).
+ if chunkLen < checksumSize {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ if !r.ensureBufferSize(chunkLen) {
+ if r.err != nil {
+ r.err = ErrUnsupported
+ }
+ return r.err
+ }
+ buf := r.buf[:checksumSize]
+ if !r.readFull(buf, false) {
+ return r.err
+ }
+ checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
+ // Read directly into r.decoded instead of via r.buf.
+ n2 := chunkLen - checksumSize
+ if n2 > len(r.decoded) {
+ if n2 > r.maxBlock {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ r.decoded = make([]byte, n2)
+ }
+ if !r.readFull(r.decoded[:n2], false) {
+ return r.err
+ }
+ if int64(n2) < n {
+ if crc(r.decoded[:n2]) != checksum {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ }
+ r.i, r.j = 0, n2
+ continue
+ case chunkTypeStreamIdentifier:
+ // Section 4.1. Stream identifier (chunk type 0xff).
+ if chunkLen != len(magicBody) {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ if !r.readFull(r.buf[:len(magicBody)], false) {
+ return r.err
+ }
+ if string(r.buf[:len(magicBody)]) != magicBody {
+ if string(r.buf[:len(magicBody)]) != magicBodySnappy {
+ r.err = ErrCorrupt
+ return r.err
+ }
+ }
+
+ continue
+ }
+
+ if chunkType <= 0x7f {
+ // Section 4.5. Reserved unskippable chunks (chunk types 0x02-0x7f).
+ r.err = ErrUnsupported
+ return r.err
+ }
+ if chunkLen > maxBlockSize {
+ r.err = ErrUnsupported
+ return r.err
+ }
+ // Section 4.4 Padding (chunk type 0xfe).
+ // Section 4.6. Reserved skippable chunks (chunk types 0x80-0xfd).
+ if !r.skipN(r.buf, chunkLen, false) {
+ return r.err
+ }
+ }
+ return nil
+}
+
+// ReadByte satisfies the io.ByteReader interface.
+func (r *Reader) ReadByte() (byte, error) {
+ if r.err != nil {
+ return 0, r.err
+ }
+ if r.i < r.j {
+ c := r.decoded[r.i]
+ r.i++
+ return c, nil
+ }
+ var tmp [1]byte
+ for i := 0; i < 10; i++ {
+ n, err := r.Read(tmp[:])
+ if err != nil {
+ return 0, err
+ }
+ if n == 1 {
+ return tmp[0], nil
+ }
+ }
+ return 0, io.ErrNoProgress
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 17:08:20 +0000