summaryrefslogtreecommitdiff
path: root/vendor/github.com/klauspost/compress/flate/inflate.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/github.com/klauspost/compress/flate/inflate.go')
-rw-r--r--vendor/github.com/klauspost/compress/flate/inflate.go793
1 files changed, 793 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/flate/inflate.go b/vendor/github.com/klauspost/compress/flate/inflate.go
new file mode 100644
index 000000000..414c0bea9
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/inflate.go
@@ -0,0 +1,793 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package flate implements the DEFLATE compressed data format, described in
+// RFC 1951. The gzip and zlib packages implement access to DEFLATE-based file
+// formats.
+package flate
+
+import (
+ "bufio"
+ "compress/flate"
+ "fmt"
+ "io"
+ "math/bits"
+ "sync"
+)
+
+const (
+ maxCodeLen = 16 // max length of Huffman code
+ maxCodeLenMask = 15 // mask for max length of Huffman code
+ // The next three numbers come from the RFC section 3.2.7, with the
+ // additional proviso in section 3.2.5 which implies that distance codes
+ // 30 and 31 should never occur in compressed data.
+ maxNumLit = 286
+ maxNumDist = 30
+ numCodes = 19 // number of codes in Huffman meta-code
+
+ debugDecode = false
+)
+
+// Value of length - 3 and extra bits.
+type lengthExtra struct {
+ length, extra uint8
+}
+
+var decCodeToLen = [32]lengthExtra{{length: 0x0, extra: 0x0}, {length: 0x1, extra: 0x0}, {length: 0x2, extra: 0x0}, {length: 0x3, extra: 0x0}, {length: 0x4, extra: 0x0}, {length: 0x5, extra: 0x0}, {length: 0x6, extra: 0x0}, {length: 0x7, extra: 0x0}, {length: 0x8, extra: 0x1}, {length: 0xa, extra: 0x1}, {length: 0xc, extra: 0x1}, {length: 0xe, extra: 0x1}, {length: 0x10, extra: 0x2}, {length: 0x14, extra: 0x2}, {length: 0x18, extra: 0x2}, {length: 0x1c, extra: 0x2}, {length: 0x20, extra: 0x3}, {length: 0x28, extra: 0x3}, {length: 0x30, extra: 0x3}, {length: 0x38, extra: 0x3}, {length: 0x40, extra: 0x4}, {length: 0x50, extra: 0x4}, {length: 0x60, extra: 0x4}, {length: 0x70, extra: 0x4}, {length: 0x80, extra: 0x5}, {length: 0xa0, extra: 0x5}, {length: 0xc0, extra: 0x5}, {length: 0xe0, extra: 0x5}, {length: 0xff, extra: 0x0}, {length: 0x0, extra: 0x0}, {length: 0x0, extra: 0x0}, {length: 0x0, extra: 0x0}}
+
+var bitMask32 = [32]uint32{
+ 0, 1, 3, 7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF,
+ 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF,
+ 0x1ffff, 0x3ffff, 0x7FFFF, 0xfFFFF, 0x1fFFFF, 0x3fFFFF, 0x7fFFFF, 0xffFFFF,
+ 0x1ffFFFF, 0x3ffFFFF, 0x7ffFFFF, 0xfffFFFF, 0x1fffFFFF, 0x3fffFFFF, 0x7fffFFFF,
+} // up to 32 bits
+
+// Initialize the fixedHuffmanDecoder only once upon first use.
+var fixedOnce sync.Once
+var fixedHuffmanDecoder huffmanDecoder
+
+// A CorruptInputError reports the presence of corrupt input at a given offset.
+type CorruptInputError = flate.CorruptInputError
+
+// An InternalError reports an error in the flate code itself.
+type InternalError string
+
+func (e InternalError) Error() string { return "flate: internal error: " + string(e) }
+
+// A ReadError reports an error encountered while reading input.
+//
+// Deprecated: No longer returned.
+type ReadError = flate.ReadError
+
+// A WriteError reports an error encountered while writing output.
+//
+// Deprecated: No longer returned.
+type WriteError = flate.WriteError
+
+// Resetter resets a ReadCloser returned by NewReader or NewReaderDict to
+// to switch to a new underlying Reader. This permits reusing a ReadCloser
+// instead of allocating a new one.
+type Resetter interface {
+ // Reset discards any buffered data and resets the Resetter as if it was
+ // newly initialized with the given reader.
+ Reset(r io.Reader, dict []byte) error
+}
+
+// The data structure for decoding Huffman tables is based on that of
+// zlib. There is a lookup table of a fixed bit width (huffmanChunkBits),
+// For codes smaller than the table width, there are multiple entries
+// (each combination of trailing bits has the same value). For codes
+// larger than the table width, the table contains a link to an overflow
+// table. The width of each entry in the link table is the maximum code
+// size minus the chunk width.
+//
+// Note that you can do a lookup in the table even without all bits
+// filled. Since the extra bits are zero, and the DEFLATE Huffman codes
+// have the property that shorter codes come before longer ones, the
+// bit length estimate in the result is a lower bound on the actual
+// number of bits.
+//
+// See the following:
+// http://www.gzip.org/algorithm.txt
+
+// chunk & 15 is number of bits
+// chunk >> 4 is value, including table link
+
+const (
+ huffmanChunkBits = 9
+ huffmanNumChunks = 1 << huffmanChunkBits
+ huffmanCountMask = 15
+ huffmanValueShift = 4
+)
+
+type huffmanDecoder struct {
+ maxRead int // the maximum number of bits we can read and not overread
+ chunks *[huffmanNumChunks]uint16 // chunks as described above
+ links [][]uint16 // overflow links
+ linkMask uint32 // mask the width of the link table
+}
+
+// Initialize Huffman decoding tables from array of code lengths.
+// Following this function, h is guaranteed to be initialized into a complete
+// tree (i.e., neither over-subscribed nor under-subscribed). The exception is a
+// degenerate case where the tree has only a single symbol with length 1. Empty
+// trees are permitted.
+func (h *huffmanDecoder) init(lengths []int) bool {
+ // Sanity enables additional runtime tests during Huffman
+ // table construction. It's intended to be used during
+ // development to supplement the currently ad-hoc unit tests.
+ const sanity = false
+
+ if h.chunks == nil {
+ h.chunks = &[huffmanNumChunks]uint16{}
+ }
+ if h.maxRead != 0 {
+ *h = huffmanDecoder{chunks: h.chunks, links: h.links}
+ }
+
+ // Count number of codes of each length,
+ // compute maxRead and max length.
+ var count [maxCodeLen]int
+ var min, max int
+ for _, n := range lengths {
+ if n == 0 {
+ continue
+ }
+ if min == 0 || n < min {
+ min = n
+ }
+ if n > max {
+ max = n
+ }
+ count[n&maxCodeLenMask]++
+ }
+
+ // Empty tree. The decompressor.huffSym function will fail later if the tree
+ // is used. Technically, an empty tree is only valid for the HDIST tree and
+ // not the HCLEN and HLIT tree. However, a stream with an empty HCLEN tree
+ // is guaranteed to fail since it will attempt to use the tree to decode the
+ // codes for the HLIT and HDIST trees. Similarly, an empty HLIT tree is
+ // guaranteed to fail later since the compressed data section must be
+ // composed of at least one symbol (the end-of-block marker).
+ if max == 0 {
+ return true
+ }
+
+ code := 0
+ var nextcode [maxCodeLen]int
+ for i := min; i <= max; i++ {
+ code <<= 1
+ nextcode[i&maxCodeLenMask] = code
+ code += count[i&maxCodeLenMask]
+ }
+
+ // Check that the coding is complete (i.e., that we've
+ // assigned all 2-to-the-max possible bit sequences).
+ // Exception: To be compatible with zlib, we also need to
+ // accept degenerate single-code codings. See also
+ // TestDegenerateHuffmanCoding.
+ if code != 1<<uint(max) && !(code == 1 && max == 1) {
+ if debugDecode {
+ fmt.Println("coding failed, code, max:", code, max, code == 1<<uint(max), code == 1 && max == 1, "(one should be true)")
+ }
+ return false
+ }
+
+ h.maxRead = min
+ chunks := h.chunks[:]
+ for i := range chunks {
+ chunks[i] = 0
+ }
+
+ if max > huffmanChunkBits {
+ numLinks := 1 << (uint(max) - huffmanChunkBits)
+ h.linkMask = uint32(numLinks - 1)
+
+ // create link tables
+ link := nextcode[huffmanChunkBits+1] >> 1
+ if cap(h.links) < huffmanNumChunks-link {
+ h.links = make([][]uint16, huffmanNumChunks-link)
+ } else {
+ h.links = h.links[:huffmanNumChunks-link]
+ }
+ for j := uint(link); j < huffmanNumChunks; j++ {
+ reverse := int(bits.Reverse16(uint16(j)))
+ reverse >>= uint(16 - huffmanChunkBits)
+ off := j - uint(link)
+ if sanity && h.chunks[reverse] != 0 {
+ panic("impossible: overwriting existing chunk")
+ }
+ h.chunks[reverse] = uint16(off<<huffmanValueShift | (huffmanChunkBits + 1))
+ if cap(h.links[off]) < numLinks {
+ h.links[off] = make([]uint16, numLinks)
+ } else {
+ links := h.links[off][:0]
+ h.links[off] = links[:numLinks]
+ }
+ }
+ } else {
+ h.links = h.links[:0]
+ }
+
+ for i, n := range lengths {
+ if n == 0 {
+ continue
+ }
+ code := nextcode[n]
+ nextcode[n]++
+ chunk := uint16(i<<huffmanValueShift | n)
+ reverse := int(bits.Reverse16(uint16(code)))
+ reverse >>= uint(16 - n)
+ if n <= huffmanChunkBits {
+ for off := reverse; off < len(h.chunks); off += 1 << uint(n) {
+ // We should never need to overwrite
+ // an existing chunk. Also, 0 is
+ // never a valid chunk, because the
+ // lower 4 "count" bits should be
+ // between 1 and 15.
+ if sanity && h.chunks[off] != 0 {
+ panic("impossible: overwriting existing chunk")
+ }
+ h.chunks[off] = chunk
+ }
+ } else {
+ j := reverse & (huffmanNumChunks - 1)
+ if sanity && h.chunks[j]&huffmanCountMask != huffmanChunkBits+1 {
+ // Longer codes should have been
+ // associated with a link table above.
+ panic("impossible: not an indirect chunk")
+ }
+ value := h.chunks[j] >> huffmanValueShift
+ linktab := h.links[value]
+ reverse >>= huffmanChunkBits
+ for off := reverse; off < len(linktab); off += 1 << uint(n-huffmanChunkBits) {
+ if sanity && linktab[off] != 0 {
+ panic("impossible: overwriting existing chunk")
+ }
+ linktab[off] = chunk
+ }
+ }
+ }
+
+ if sanity {
+ // Above we've sanity checked that we never overwrote
+ // an existing entry. Here we additionally check that
+ // we filled the tables completely.
+ for i, chunk := range h.chunks {
+ if chunk == 0 {
+ // As an exception, in the degenerate
+ // single-code case, we allow odd
+ // chunks to be missing.
+ if code == 1 && i%2 == 1 {
+ continue
+ }
+ panic("impossible: missing chunk")
+ }
+ }
+ for _, linktab := range h.links {
+ for _, chunk := range linktab {
+ if chunk == 0 {
+ panic("impossible: missing chunk")
+ }
+ }
+ }
+ }
+
+ return true
+}
+
+// The actual read interface needed by NewReader.
+// If the passed in io.Reader does not also have ReadByte,
+// the NewReader will introduce its own buffering.
+type Reader interface {
+ io.Reader
+ io.ByteReader
+}
+
+// Decompress state.
+type decompressor struct {
+ // Input source.
+ r Reader
+ roffset int64
+
+ // Huffman decoders for literal/length, distance.
+ h1, h2 huffmanDecoder
+
+ // Length arrays used to define Huffman codes.
+ bits *[maxNumLit + maxNumDist]int
+ codebits *[numCodes]int
+
+ // Output history, buffer.
+ dict dictDecoder
+
+ // Next step in the decompression,
+ // and decompression state.
+ step func(*decompressor)
+ stepState int
+ err error
+ toRead []byte
+ hl, hd *huffmanDecoder
+ copyLen int
+ copyDist int
+
+ // Temporary buffer (avoids repeated allocation).
+ buf [4]byte
+
+ // Input bits, in top of b.
+ b uint32
+
+ nb uint
+ final bool
+}
+
+func (f *decompressor) nextBlock() {
+ for f.nb < 1+2 {
+ if f.err = f.moreBits(); f.err != nil {
+ return
+ }
+ }
+ f.final = f.b&1 == 1
+ f.b >>= 1
+ typ := f.b & 3
+ f.b >>= 2
+ f.nb -= 1 + 2
+ switch typ {
+ case 0:
+ f.dataBlock()
+ if debugDecode {
+ fmt.Println("stored block")
+ }
+ case 1:
+ // compressed, fixed Huffman tables
+ f.hl = &fixedHuffmanDecoder
+ f.hd = nil
+ f.huffmanBlockDecoder()()
+ if debugDecode {
+ fmt.Println("predefinied huffman block")
+ }
+ case 2:
+ // compressed, dynamic Huffman tables
+ if f.err = f.readHuffman(); f.err != nil {
+ break
+ }
+ f.hl = &f.h1
+ f.hd = &f.h2
+ f.huffmanBlockDecoder()()
+ if debugDecode {
+ fmt.Println("dynamic huffman block")
+ }
+ default:
+ // 3 is reserved.
+ if debugDecode {
+ fmt.Println("reserved data block encountered")
+ }
+ f.err = CorruptInputError(f.roffset)
+ }
+}
+
+func (f *decompressor) Read(b []byte) (int, error) {
+ for {
+ if len(f.toRead) > 0 {
+ n := copy(b, f.toRead)
+ f.toRead = f.toRead[n:]
+ if len(f.toRead) == 0 {
+ return n, f.err
+ }
+ return n, nil
+ }
+ if f.err != nil {
+ return 0, f.err
+ }
+ f.step(f)
+ if f.err != nil && len(f.toRead) == 0 {
+ f.toRead = f.dict.readFlush() // Flush what's left in case of error
+ }
+ }
+}
+
+// Support the io.WriteTo interface for io.Copy and friends.
+func (f *decompressor) WriteTo(w io.Writer) (int64, error) {
+ total := int64(0)
+ flushed := false
+ for {
+ if len(f.toRead) > 0 {
+ n, err := w.Write(f.toRead)
+ total += int64(n)
+ if err != nil {
+ f.err = err
+ return total, err
+ }
+ if n != len(f.toRead) {
+ return total, io.ErrShortWrite
+ }
+ f.toRead = f.toRead[:0]
+ }
+ if f.err != nil && flushed {
+ if f.err == io.EOF {
+ return total, nil
+ }
+ return total, f.err
+ }
+ if f.err == nil {
+ f.step(f)
+ }
+ if len(f.toRead) == 0 && f.err != nil && !flushed {
+ f.toRead = f.dict.readFlush() // Flush what's left in case of error
+ flushed = true
+ }
+ }
+}
+
+func (f *decompressor) Close() error {
+ if f.err == io.EOF {
+ return nil
+ }
+ return f.err
+}
+
+// RFC 1951 section 3.2.7.
+// Compression with dynamic Huffman codes
+
+var codeOrder = [...]int{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
+
+func (f *decompressor) readHuffman() error {
+ // HLIT[5], HDIST[5], HCLEN[4].
+ for f.nb < 5+5+4 {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ nlit := int(f.b&0x1F) + 257
+ if nlit > maxNumLit {
+ if debugDecode {
+ fmt.Println("nlit > maxNumLit", nlit)
+ }
+ return CorruptInputError(f.roffset)
+ }
+ f.b >>= 5
+ ndist := int(f.b&0x1F) + 1
+ if ndist > maxNumDist {
+ if debugDecode {
+ fmt.Println("ndist > maxNumDist", ndist)
+ }
+ return CorruptInputError(f.roffset)
+ }
+ f.b >>= 5
+ nclen := int(f.b&0xF) + 4
+ // numCodes is 19, so nclen is always valid.
+ f.b >>= 4
+ f.nb -= 5 + 5 + 4
+
+ // (HCLEN+4)*3 bits: code lengths in the magic codeOrder order.
+ for i := 0; i < nclen; i++ {
+ for f.nb < 3 {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ f.codebits[codeOrder[i]] = int(f.b & 0x7)
+ f.b >>= 3
+ f.nb -= 3
+ }
+ for i := nclen; i < len(codeOrder); i++ {
+ f.codebits[codeOrder[i]] = 0
+ }
+ if !f.h1.init(f.codebits[0:]) {
+ if debugDecode {
+ fmt.Println("init codebits failed")
+ }
+ return CorruptInputError(f.roffset)
+ }
+
+ // HLIT + 257 code lengths, HDIST + 1 code lengths,
+ // using the code length Huffman code.
+ for i, n := 0, nlit+ndist; i < n; {
+ x, err := f.huffSym(&f.h1)
+ if err != nil {
+ return err
+ }
+ if x < 16 {
+ // Actual length.
+ f.bits[i] = x
+ i++
+ continue
+ }
+ // Repeat previous length or zero.
+ var rep int
+ var nb uint
+ var b int
+ switch x {
+ default:
+ return InternalError("unexpected length code")
+ case 16:
+ rep = 3
+ nb = 2
+ if i == 0 {
+ if debugDecode {
+ fmt.Println("i==0")
+ }
+ return CorruptInputError(f.roffset)
+ }
+ b = f.bits[i-1]
+ case 17:
+ rep = 3
+ nb = 3
+ b = 0
+ case 18:
+ rep = 11
+ nb = 7
+ b = 0
+ }
+ for f.nb < nb {
+ if err := f.moreBits(); err != nil {
+ if debugDecode {
+ fmt.Println("morebits:", err)
+ }
+ return err
+ }
+ }
+ rep += int(f.b & uint32(1<<(nb&regSizeMaskUint32)-1))
+ f.b >>= nb & regSizeMaskUint32
+ f.nb -= nb
+ if i+rep > n {
+ if debugDecode {
+ fmt.Println("i+rep > n", i, rep, n)
+ }
+ return CorruptInputError(f.roffset)
+ }
+ for j := 0; j < rep; j++ {
+ f.bits[i] = b
+ i++
+ }
+ }
+
+ if !f.h1.init(f.bits[0:nlit]) || !f.h2.init(f.bits[nlit:nlit+ndist]) {
+ if debugDecode {
+ fmt.Println("init2 failed")
+ }
+ return CorruptInputError(f.roffset)
+ }
+
+ // As an optimization, we can initialize the maxRead bits to read at a time
+ // for the HLIT tree to the length of the EOB marker since we know that
+ // every block must terminate with one. This preserves the property that
+ // we never read any extra bytes after the end of the DEFLATE stream.
+ if f.h1.maxRead < f.bits[endBlockMarker] {
+ f.h1.maxRead = f.bits[endBlockMarker]
+ }
+ if !f.final {
+ // If not the final block, the smallest block possible is
+ // a predefined table, BTYPE=01, with a single EOB marker.
+ // This will take up 3 + 7 bits.
+ f.h1.maxRead += 10
+ }
+
+ return nil
+}
+
+// Copy a single uncompressed data block from input to output.
+func (f *decompressor) dataBlock() {
+ // Uncompressed.
+ // Discard current half-byte.
+ left := (f.nb) & 7
+ f.nb -= left
+ f.b >>= left
+
+ offBytes := f.nb >> 3
+ // Unfilled values will be overwritten.
+ f.buf[0] = uint8(f.b)
+ f.buf[1] = uint8(f.b >> 8)
+ f.buf[2] = uint8(f.b >> 16)
+ f.buf[3] = uint8(f.b >> 24)
+
+ f.roffset += int64(offBytes)
+ f.nb, f.b = 0, 0
+
+ // Length then ones-complement of length.
+ nr, err := io.ReadFull(f.r, f.buf[offBytes:4])
+ f.roffset += int64(nr)
+ if err != nil {
+ f.err = noEOF(err)
+ return
+ }
+ n := uint16(f.buf[0]) | uint16(f.buf[1])<<8
+ nn := uint16(f.buf[2]) | uint16(f.buf[3])<<8
+ if nn != ^n {
+ if debugDecode {
+ ncomp := ^n
+ fmt.Println("uint16(nn) != uint16(^n)", nn, ncomp)
+ }
+ f.err = CorruptInputError(f.roffset)
+ return
+ }
+
+ if n == 0 {
+ f.toRead = f.dict.readFlush()
+ f.finishBlock()
+ return
+ }
+
+ f.copyLen = int(n)
+ f.copyData()
+}
+
+// copyData copies f.copyLen bytes from the underlying reader into f.hist.
+// It pauses for reads when f.hist is full.
+func (f *decompressor) copyData() {
+ buf := f.dict.writeSlice()
+ if len(buf) > f.copyLen {
+ buf = buf[:f.copyLen]
+ }
+
+ cnt, err := io.ReadFull(f.r, buf)
+ f.roffset += int64(cnt)
+ f.copyLen -= cnt
+ f.dict.writeMark(cnt)
+ if err != nil {
+ f.err = noEOF(err)
+ return
+ }
+
+ if f.dict.availWrite() == 0 || f.copyLen > 0 {
+ f.toRead = f.dict.readFlush()
+ f.step = (*decompressor).copyData
+ return
+ }
+ f.finishBlock()
+}
+
+func (f *decompressor) finishBlock() {
+ if f.final {
+ if f.dict.availRead() > 0 {
+ f.toRead = f.dict.readFlush()
+ }
+ f.err = io.EOF
+ }
+ f.step = (*decompressor).nextBlock
+}
+
+// noEOF returns err, unless err == io.EOF, in which case it returns io.ErrUnexpectedEOF.
+func noEOF(e error) error {
+ if e == io.EOF {
+ return io.ErrUnexpectedEOF
+ }
+ return e
+}
+
+func (f *decompressor) moreBits() error {
+ c, err := f.r.ReadByte()
+ if err != nil {
+ return noEOF(err)
+ }
+ f.roffset++
+ f.b |= uint32(c) << (f.nb & regSizeMaskUint32)
+ f.nb += 8
+ return nil
+}
+
+// Read the next Huffman-encoded symbol from f according to h.
+func (f *decompressor) huffSym(h *huffmanDecoder) (int, error) {
+ // Since a huffmanDecoder can be empty or be composed of a degenerate tree
+ // with single element, huffSym must error on these two edge cases. In both
+ // cases, the chunks slice will be 0 for the invalid sequence, leading it
+ // satisfy the n == 0 check below.
+ n := uint(h.maxRead)
+ // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
+ // but is smart enough to keep local variables in registers, so use nb and b,
+ // inline call to moreBits and reassign b,nb back to f on return.
+ nb, b := f.nb, f.b
+ for {
+ for nb < n {
+ c, err := f.r.ReadByte()
+ if err != nil {
+ f.b = b
+ f.nb = nb
+ return 0, noEOF(err)
+ }
+ f.roffset++
+ b |= uint32(c) << (nb & regSizeMaskUint32)
+ nb += 8
+ }
+ chunk := h.chunks[b&(huffmanNumChunks-1)]
+ n = uint(chunk & huffmanCountMask)
+ if n > huffmanChunkBits {
+ chunk = h.links[chunk>>huffmanValueShift][(b>>huffmanChunkBits)&h.linkMask]
+ n = uint(chunk & huffmanCountMask)
+ }
+ if n <= nb {
+ if n == 0 {
+ f.b = b
+ f.nb = nb
+ if debugDecode {
+ fmt.Println("huffsym: n==0")
+ }
+ f.err = CorruptInputError(f.roffset)
+ return 0, f.err
+ }
+ f.b = b >> (n & regSizeMaskUint32)
+ f.nb = nb - n
+ return int(chunk >> huffmanValueShift), nil
+ }
+ }
+}
+
+func makeReader(r io.Reader) Reader {
+ if rr, ok := r.(Reader); ok {
+ return rr
+ }
+ return bufio.NewReader(r)
+}
+
+func fixedHuffmanDecoderInit() {
+ fixedOnce.Do(func() {
+ // These come from the RFC section 3.2.6.
+ var bits [288]int
+ for i := 0; i < 144; i++ {
+ bits[i] = 8
+ }
+ for i := 144; i < 256; i++ {
+ bits[i] = 9
+ }
+ for i := 256; i < 280; i++ {
+ bits[i] = 7
+ }
+ for i := 280; i < 288; i++ {
+ bits[i] = 8
+ }
+ fixedHuffmanDecoder.init(bits[:])
+ })
+}
+
+func (f *decompressor) Reset(r io.Reader, dict []byte) error {
+ *f = decompressor{
+ r: makeReader(r),
+ bits: f.bits,
+ codebits: f.codebits,
+ h1: f.h1,
+ h2: f.h2,
+ dict: f.dict,
+ step: (*decompressor).nextBlock,
+ }
+ f.dict.init(maxMatchOffset, dict)
+ return nil
+}
+
+// NewReader returns a new ReadCloser that can be used
+// to read the uncompressed version of r.
+// If r does not also implement io.ByteReader,
+// the decompressor may read more data than necessary from r.
+// It is the caller's responsibility to call Close on the ReadCloser
+// when finished reading.
+//
+// The ReadCloser returned by NewReader also implements Resetter.
+func NewReader(r io.Reader) io.ReadCloser {
+ fixedHuffmanDecoderInit()
+
+ var f decompressor
+ f.r = makeReader(r)
+ f.bits = new([maxNumLit + maxNumDist]int)
+ f.codebits = new([numCodes]int)
+ f.step = (*decompressor).nextBlock
+ f.dict.init(maxMatchOffset, nil)
+ return &f
+}
+
+// NewReaderDict is like NewReader but initializes the reader
+// with a preset dictionary. The returned Reader behaves as if
+// the uncompressed data stream started with the given dictionary,
+// which has already been read. NewReaderDict is typically used
+// to read data compressed by NewWriterDict.
+//
+// The ReadCloser returned by NewReader also implements Resetter.
+func NewReaderDict(r io.Reader, dict []byte) io.ReadCloser {
+ fixedHuffmanDecoderInit()
+
+ var f decompressor
+ f.r = makeReader(r)
+ f.bits = new([maxNumLit + maxNumDist]int)
+ f.codebits = new([numCodes]int)
+ f.step = (*decompressor).nextBlock
+ f.dict.init(maxMatchOffset, dict)
+ return &f
+}
generated by cgit v1.2.3 (git 2.46.0) at 2025-08-04 04:28:19 +0000