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Diffstat (limited to 'vendor/github.com/klauspost/compress/huff0/bitreader.go')
-rw-r--r--vendor/github.com/klauspost/compress/huff0/bitreader.go121
1 files changed, 15 insertions, 106 deletions
diff --git a/vendor/github.com/klauspost/compress/huff0/bitreader.go b/vendor/github.com/klauspost/compress/huff0/bitreader.go
index a4979e886..03562db16 100644
--- a/vendor/github.com/klauspost/compress/huff0/bitreader.go
+++ b/vendor/github.com/klauspost/compress/huff0/bitreader.go
@@ -8,118 +8,13 @@ package huff0
import (
"encoding/binary"
"errors"
+ "fmt"
"io"
)
// bitReader reads a bitstream in reverse.
// The last set bit indicates the start of the stream and is used
// for aligning the input.
-type bitReader struct {
- in []byte
- off uint // next byte to read is at in[off - 1]
- value uint64
- bitsRead uint8
-}
-
-// init initializes and resets the bit reader.
-func (b *bitReader) init(in []byte) error {
- if len(in) < 1 {
- return errors.New("corrupt stream: too short")
- }
- b.in = in
- b.off = uint(len(in))
- // The highest bit of the last byte indicates where to start
- v := in[len(in)-1]
- if v == 0 {
- return errors.New("corrupt stream, did not find end of stream")
- }
- b.bitsRead = 64
- b.value = 0
- if len(in) >= 8 {
- b.fillFastStart()
- } else {
- b.fill()
- b.fill()
- }
- b.bitsRead += 8 - uint8(highBit32(uint32(v)))
- return nil
-}
-
-// peekBitsFast requires that at least one bit is requested every time.
-// There are no checks if the buffer is filled.
-func (b *bitReader) peekBitsFast(n uint8) uint16 {
- const regMask = 64 - 1
- v := uint16((b.value << (b.bitsRead & regMask)) >> ((regMask + 1 - n) & regMask))
- return v
-}
-
-// fillFast() will make sure at least 32 bits are available.
-// There must be at least 4 bytes available.
-func (b *bitReader) fillFast() {
- if b.bitsRead < 32 {
- return
- }
-
- // 2 bounds checks.
- v := b.in[b.off-4 : b.off]
- v = v[:4]
- low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
- b.value = (b.value << 32) | uint64(low)
- b.bitsRead -= 32
- b.off -= 4
-}
-
-func (b *bitReader) advance(n uint8) {
- b.bitsRead += n
-}
-
-// fillFastStart() assumes the bitreader is empty and there is at least 8 bytes to read.
-func (b *bitReader) fillFastStart() {
- // Do single re-slice to avoid bounds checks.
- b.value = binary.LittleEndian.Uint64(b.in[b.off-8:])
- b.bitsRead = 0
- b.off -= 8
-}
-
-// fill() will make sure at least 32 bits are available.
-func (b *bitReader) fill() {
- if b.bitsRead < 32 {
- return
- }
- if b.off > 4 {
- v := b.in[b.off-4:]
- v = v[:4]
- low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
- b.value = (b.value << 32) | uint64(low)
- b.bitsRead -= 32
- b.off -= 4
- return
- }
- for b.off > 0 {
- b.value = (b.value << 8) | uint64(b.in[b.off-1])
- b.bitsRead -= 8
- b.off--
- }
-}
-
-// finished returns true if all bits have been read from the bit stream.
-func (b *bitReader) finished() bool {
- return b.off == 0 && b.bitsRead >= 64
-}
-
-// close the bitstream and returns an error if out-of-buffer reads occurred.
-func (b *bitReader) close() error {
- // Release reference.
- b.in = nil
- if b.bitsRead > 64 {
- return io.ErrUnexpectedEOF
- }
- return nil
-}
-
-// bitReader reads a bitstream in reverse.
-// The last set bit indicates the start of the stream and is used
-// for aligning the input.
type bitReaderBytes struct {
in []byte
off uint // next byte to read is at in[off - 1]
@@ -213,10 +108,17 @@ func (b *bitReaderBytes) finished() bool {
return b.off == 0 && b.bitsRead >= 64
}
+func (b *bitReaderBytes) remaining() uint {
+ return b.off*8 + uint(64-b.bitsRead)
+}
+
// close the bitstream and returns an error if out-of-buffer reads occurred.
func (b *bitReaderBytes) close() error {
// Release reference.
b.in = nil
+ if b.remaining() > 0 {
+ return fmt.Errorf("corrupt input: %d bits remain on stream", b.remaining())
+ }
if b.bitsRead > 64 {
return io.ErrUnexpectedEOF
}
@@ -318,10 +220,17 @@ func (b *bitReaderShifted) finished() bool {
return b.off == 0 && b.bitsRead >= 64
}
+func (b *bitReaderShifted) remaining() uint {
+ return b.off*8 + uint(64-b.bitsRead)
+}
+
// close the bitstream and returns an error if out-of-buffer reads occurred.
func (b *bitReaderShifted) close() error {
// Release reference.
b.in = nil
+ if b.remaining() > 0 {
+ return fmt.Errorf("corrupt input: %d bits remain on stream", b.remaining())
+ }
if b.bitsRead > 64 {
return io.ErrUnexpectedEOF
}