зеркало из https://github.com/golang/snappy.git
Merge pull request #51 from topos-ai/bytereader
Add ReadByte method, satisfies the io.ByteReader interface
This commit is contained in:
Nigel Tao
GitHub
Коммит
3ff355f7bb
83
decode.go
83
decode.go
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@ -118,32 +118,23 @@ func (r *Reader) readFull(p []byte, allowEOF bool) (ok bool) {
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return true
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}
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// Read satisfies the io.Reader interface.
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func (r *Reader) Read(p []byte) (int, error) {
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if r.err != nil {
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return 0, r.err
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}
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for {
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if r.i < r.j {
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n := copy(p, r.decoded[r.i:r.j])
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r.i += n
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return n, nil
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}
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func (r *Reader) fill() error {
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for r.i >= r.j {
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if !r.readFull(r.buf[:4], true) {
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return 0, r.err
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return r.err
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}
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chunkType := r.buf[0]
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if !r.readHeader {
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if chunkType != chunkTypeStreamIdentifier {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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r.readHeader = true
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}
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chunkLen := int(r.buf[1]) | int(r.buf[2])<<8 | int(r.buf[3])<<16
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if chunkLen > len(r.buf) {
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r.err = ErrUnsupported
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return 0, r.err
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return r.err
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}
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// The chunk types are specified at
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@ -153,11 +144,11 @@ func (r *Reader) Read(p []byte) (int, error) {
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// Section 4.2. Compressed data (chunk type 0x00).
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if chunkLen < checksumSize {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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buf := r.buf[:chunkLen]
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if !r.readFull(buf, false) {
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return 0, r.err
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return r.err
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}
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checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
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buf = buf[checksumSize:]
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@ -165,19 +156,19 @@ func (r *Reader) Read(p []byte) (int, error) {
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n, err := DecodedLen(buf)
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if err != nil {
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r.err = err
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return 0, r.err
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return r.err
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}
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if n > len(r.decoded) {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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if _, err := Decode(r.decoded, buf); err != nil {
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r.err = err
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return 0, r.err
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return r.err
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}
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if crc(r.decoded[:n]) != checksum {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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r.i, r.j = 0, n
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continue
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@ -186,25 +177,25 @@ func (r *Reader) Read(p []byte) (int, error) {
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// Section 4.3. Uncompressed data (chunk type 0x01).
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if chunkLen < checksumSize {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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buf := r.buf[:checksumSize]
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if !r.readFull(buf, false) {
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return 0, r.err
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return r.err
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}
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checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
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// Read directly into r.decoded instead of via r.buf.
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n := chunkLen - checksumSize
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if n > len(r.decoded) {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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if !r.readFull(r.decoded[:n], false) {
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return 0, r.err
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return r.err
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}
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if crc(r.decoded[:n]) != checksum {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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r.i, r.j = 0, n
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continue
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@ -213,15 +204,15 @@ func (r *Reader) Read(p []byte) (int, error) {
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// Section 4.1. Stream identifier (chunk type 0xff).
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if chunkLen != len(magicBody) {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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if !r.readFull(r.buf[:len(magicBody)], false) {
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return 0, r.err
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return r.err
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}
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for i := 0; i < len(magicBody); i++ {
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if r.buf[i] != magicBody[i] {
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r.err = ErrCorrupt
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return 0, r.err
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return r.err
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}
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}
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continue
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@ -230,12 +221,44 @@ func (r *Reader) Read(p []byte) (int, error) {
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if chunkType <= 0x7f {
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// Section 4.5. Reserved unskippable chunks (chunk types 0x02-0x7f).
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r.err = ErrUnsupported
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return 0, r.err
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return r.err
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}
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// Section 4.4 Padding (chunk type 0xfe).
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// Section 4.6. Reserved skippable chunks (chunk types 0x80-0xfd).
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if !r.readFull(r.buf[:chunkLen], false) {
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return 0, r.err
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return r.err
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}
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}
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return nil
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}
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// Read satisfies the io.Reader interface.
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func (r *Reader) Read(p []byte) (int, error) {
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if r.err != nil {
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return 0, r.err
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}
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if err := r.fill(); err != nil {
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return 0, err
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}
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n := copy(p, r.decoded[r.i:r.j])
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r.i += n
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return n, nil
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}
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// ReadByte satisfies the io.ByteReader interface.
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func (r *Reader) ReadByte() (byte, error) {
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if r.err != nil {
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return 0, r.err
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}
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if err := r.fill(); err != nil {
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return 0, err
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}
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c := r.decoded[r.i]
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r.i++
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return c, nil
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}
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@ -1037,6 +1037,71 @@ func TestReaderReset(t *testing.T) {
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}
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}
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func TestReaderReadByte(t *testing.T) {
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// Test all 32 possible sub-sequences of these 5 input slices prefixed by
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// their size encoded as a uvarint.
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//
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// Their lengths sum to 400,000, which is over 6 times the Writer ibuf
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// capacity: 6 * maxBlockSize is 393,216.
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inputs := [][]byte{
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bytes.Repeat([]byte{'a'}, 40000),
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bytes.Repeat([]byte{'b'}, 150000),
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bytes.Repeat([]byte{'c'}, 60000),
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bytes.Repeat([]byte{'d'}, 120000),
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bytes.Repeat([]byte{'e'}, 30000),
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}
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loop:
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for i := 0; i < 1<<uint(len(inputs)); i++ {
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var want []int
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buf := new(bytes.Buffer)
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w := NewBufferedWriter(buf)
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p := make([]byte, binary.MaxVarintLen64)
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for j, input := range inputs {
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if i&(1<<uint(j)) == 0 {
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continue
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}
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n := binary.PutUvarint(p, uint64(len(input)))
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if _, err := w.Write(p[:n]); err != nil {
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t.Errorf("i=%#02x: j=%d: Write Uvarint: %v", i, j, err)
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continue loop
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}
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if _, err := w.Write(input); err != nil {
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t.Errorf("i=%#02x: j=%d: Write: %v", i, j, err)
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continue loop
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}
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want = append(want, j)
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}
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if err := w.Close(); err != nil {
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t.Errorf("i=%#02x: Close: %v", i, err)
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continue
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}
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r := NewReader(buf)
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for _, j := range want {
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size, err := binary.ReadUvarint(r)
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if err != nil {
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t.Errorf("i=%#02x: ReadUvarint: %v", i, err)
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continue loop
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}
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if wantedSize := uint64(len(inputs[j])); size != wantedSize {
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t.Errorf("i=%#02x: expected size %d, got %d", i, wantedSize, size)
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continue loop
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}
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got := make([]byte, size)
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if _, err := io.ReadFull(r, got); err != nil {
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t.Errorf("i=%#02x: ReadFull: %v", i, err)
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continue loop
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}
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if err := cmp(got, inputs[j]); err != nil {
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t.Errorf("i=%#02x: %v", i, err)
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continue
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}
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}
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if _, err := r.ReadByte(); err != io.EOF {
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t.Errorf("i=%#02x: expected size EOF, got %v", i, err)
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}
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}
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}
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func TestWriterReset(t *testing.T) {
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gold := bytes.Repeat([]byte("Not all those who wander are lost;\n"), 10000)
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const n = 20
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