package jpegstructure import ( "bufio" "bytes" "io" "os" "github.com/dsoprea/go-logging" "github.com/dsoprea/go-utility/image" ) // JpegMediaParser is a `riimage.MediaParser` that knows how to parse JPEG // images. type JpegMediaParser struct { } // NewJpegMediaParser returns a new JpegMediaParser. func NewJpegMediaParser() *JpegMediaParser { // TODO(dustin): Add test return new(JpegMediaParser) } // Parse parses a JPEG uses an `io.ReadSeeker`. Even if it fails, it will return // the list of segments encountered prior to the failure. func (jmp *JpegMediaParser) Parse(rs io.ReadSeeker, size int) (ec riimage.MediaContext, err error) { defer func() { if state := recover(); state != nil { err = log.Wrap(state.(error)) } }() s := bufio.NewScanner(rs) // Since each segment can be any size, our buffer must allowed to grow as // large as the file. buffer := []byte{} s.Buffer(buffer, size) js := NewJpegSplitter(nil) s.Split(js.Split) for s.Scan() != false { } // Always return the segments that were parsed, at least until there was an // error. ec = js.Segments() log.PanicIf(s.Err()) return ec, nil } // ParseFile parses a JPEG file. Even if it fails, it will return the list of // segments encountered prior to the failure. func (jmp *JpegMediaParser) ParseFile(filepath string) (ec riimage.MediaContext, err error) { defer func() { if state := recover(); state != nil { err = log.Wrap(state.(error)) } }() // TODO(dustin): Add test f, err := os.Open(filepath) log.PanicIf(err) defer f.Close() stat, err := f.Stat() log.PanicIf(err) size := stat.Size() sl, err := jmp.Parse(f, int(size)) // Always return the segments that were parsed, at least until there was an // error. ec = sl log.PanicIf(err) return ec, nil } // ParseBytes parses a JPEG byte-slice. Even if it fails, it will return the // list of segments encountered prior to the failure. func (jmp *JpegMediaParser) ParseBytes(data []byte) (ec riimage.MediaContext, err error) { defer func() { if state := recover(); state != nil { err = log.Wrap(state.(error)) } }() br := bytes.NewReader(data) sl, err := jmp.Parse(br, len(data)) // Always return the segments that were parsed, at least until there was an // error. ec = sl log.PanicIf(err) return ec, nil } // LooksLikeFormat indicates whether the data looks like a JPEG image. func (jmp *JpegMediaParser) LooksLikeFormat(data []byte) bool { if len(data) < 4 { return false } l := len(data) if data[0] != 0xff || data[1] != MARKER_SOI || data[l-2] != 0xff || data[l-1] != MARKER_EOI { return false } return true } var ( // Enforce interface conformance. _ riimage.MediaParser = new(JpegMediaParser) )