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-rw-r--r--vendor/golang.org/x/image/riff/riff.go193
1 files changed, 193 insertions, 0 deletions
diff --git a/vendor/golang.org/x/image/riff/riff.go b/vendor/golang.org/x/image/riff/riff.go
new file mode 100644
index 0000000..38dc0e5
--- /dev/null
+++ b/vendor/golang.org/x/image/riff/riff.go
@@ -0,0 +1,193 @@
+// Copyright 2014 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 riff implements the Resource Interchange File Format, used by media
+// formats such as AVI, WAVE and WEBP.
+//
+// A RIFF stream contains a sequence of chunks. Each chunk consists of an 8-byte
+// header (containing a 4-byte chunk type and a 4-byte chunk length), the chunk
+// data (presented as an io.Reader), and some padding bytes.
+//
+// A detailed description of the format is at
+// http://www.tactilemedia.com/info/MCI_Control_Info.html
+package riff // import "golang.org/x/image/riff"
+
+import (
+ "errors"
+ "io"
+ "io/ioutil"
+ "math"
+)
+
+var (
+ errMissingPaddingByte = errors.New("riff: missing padding byte")
+ errMissingRIFFChunkHeader = errors.New("riff: missing RIFF chunk header")
+ errListSubchunkTooLong = errors.New("riff: list subchunk too long")
+ errShortChunkData = errors.New("riff: short chunk data")
+ errShortChunkHeader = errors.New("riff: short chunk header")
+ errStaleReader = errors.New("riff: stale reader")
+)
+
+// u32 decodes the first four bytes of b as a little-endian integer.
+func u32(b []byte) uint32 {
+ return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+const chunkHeaderSize = 8
+
+// FourCC is a four character code.
+type FourCC [4]byte
+
+// LIST is the "LIST" FourCC.
+var LIST = FourCC{'L', 'I', 'S', 'T'}
+
+// NewReader returns the RIFF stream's form type, such as "AVI " or "WAVE", and
+// its chunks as a *Reader.
+func NewReader(r io.Reader) (formType FourCC, data *Reader, err error) {
+ var buf [chunkHeaderSize]byte
+ if _, err := io.ReadFull(r, buf[:]); err != nil {
+ if err == io.EOF || err == io.ErrUnexpectedEOF {
+ err = errMissingRIFFChunkHeader
+ }
+ return FourCC{}, nil, err
+ }
+ if buf[0] != 'R' || buf[1] != 'I' || buf[2] != 'F' || buf[3] != 'F' {
+ return FourCC{}, nil, errMissingRIFFChunkHeader
+ }
+ return NewListReader(u32(buf[4:]), r)
+}
+
+// NewListReader returns a LIST chunk's list type, such as "movi" or "wavl",
+// and its chunks as a *Reader.
+func NewListReader(chunkLen uint32, chunkData io.Reader) (listType FourCC, data *Reader, err error) {
+ if chunkLen < 4 {
+ return FourCC{}, nil, errShortChunkData
+ }
+ z := &Reader{r: chunkData}
+ if _, err := io.ReadFull(chunkData, z.buf[:4]); err != nil {
+ if err == io.EOF || err == io.ErrUnexpectedEOF {
+ err = errShortChunkData
+ }
+ return FourCC{}, nil, err
+ }
+ z.totalLen = chunkLen - 4
+ return FourCC{z.buf[0], z.buf[1], z.buf[2], z.buf[3]}, z, nil
+}
+
+// Reader reads chunks from an underlying io.Reader.
+type Reader struct {
+ r io.Reader
+ err error
+
+ totalLen uint32
+ chunkLen uint32
+
+ chunkReader *chunkReader
+ buf [chunkHeaderSize]byte
+ padded bool
+}
+
+// Next returns the next chunk's ID, length and data. It returns io.EOF if there
+// are no more chunks. The io.Reader returned becomes stale after the next Next
+// call, and should no longer be used.
+//
+// It is valid to call Next even if all of the previous chunk's data has not
+// been read.
+func (z *Reader) Next() (chunkID FourCC, chunkLen uint32, chunkData io.Reader, err error) {
+ if z.err != nil {
+ return FourCC{}, 0, nil, z.err
+ }
+
+ // Drain the rest of the previous chunk.
+ if z.chunkLen != 0 {
+ want := z.chunkLen
+ var got int64
+ got, z.err = io.Copy(ioutil.Discard, z.chunkReader)
+ if z.err == nil && uint32(got) != want {
+ z.err = errShortChunkData
+ }
+ if z.err != nil {
+ return FourCC{}, 0, nil, z.err
+ }
+ }
+ z.chunkReader = nil
+ if z.padded {
+ if z.totalLen == 0 {
+ z.err = errListSubchunkTooLong
+ return FourCC{}, 0, nil, z.err
+ }
+ z.totalLen--
+ _, z.err = io.ReadFull(z.r, z.buf[:1])
+ if z.err != nil {
+ if z.err == io.EOF {
+ z.err = errMissingPaddingByte
+ }
+ return FourCC{}, 0, nil, z.err
+ }
+ }
+
+ // We are done if we have no more data.
+ if z.totalLen == 0 {
+ z.err = io.EOF
+ return FourCC{}, 0, nil, z.err
+ }
+
+ // Read the next chunk header.
+ if z.totalLen < chunkHeaderSize {
+ z.err = errShortChunkHeader
+ return FourCC{}, 0, nil, z.err
+ }
+ z.totalLen -= chunkHeaderSize
+ if _, z.err = io.ReadFull(z.r, z.buf[:chunkHeaderSize]); z.err != nil {
+ if z.err == io.EOF || z.err == io.ErrUnexpectedEOF {
+ z.err = errShortChunkHeader
+ }
+ return FourCC{}, 0, nil, z.err
+ }
+ chunkID = FourCC{z.buf[0], z.buf[1], z.buf[2], z.buf[3]}
+ z.chunkLen = u32(z.buf[4:])
+ if z.chunkLen > z.totalLen {
+ z.err = errListSubchunkTooLong
+ return FourCC{}, 0, nil, z.err
+ }
+ z.padded = z.chunkLen&1 == 1
+ z.chunkReader = &chunkReader{z}
+ return chunkID, z.chunkLen, z.chunkReader, nil
+}
+
+type chunkReader struct {
+ z *Reader
+}
+
+func (c *chunkReader) Read(p []byte) (int, error) {
+ if c != c.z.chunkReader {
+ return 0, errStaleReader
+ }
+ z := c.z
+ if z.err != nil {
+ if z.err == io.EOF {
+ return 0, errStaleReader
+ }
+ return 0, z.err
+ }
+
+ n := int(z.chunkLen)
+ if n == 0 {
+ return 0, io.EOF
+ }
+ if n < 0 {
+ // Converting uint32 to int overflowed.
+ n = math.MaxInt32
+ }
+ if n > len(p) {
+ n = len(p)
+ }
+ n, err := z.r.Read(p[:n])
+ z.totalLen -= uint32(n)
+ z.chunkLen -= uint32(n)
+ if err != io.EOF {
+ z.err = err
+ }
+ return n, err
+}