Golang FileReader.Close方法代碼示例

// readPrefixOrFile executes a given func with a reader on the passed prefix and
// falls back to passing a reader on the whole file if the func returns an error.
func readPrefixOrFile(prefix []byte, fetcher blob.Fetcher, b *schema.Blob, fn func(filePrefixReader) error) (err error) {
	pr := bytes.NewReader(prefix)
	err = fn(pr)
	if err == io.EOF || err == io.ErrUnexpectedEOF {
		var fr *schema.FileReader
		fr, err = b.NewFileReader(fetcher)
		if err == nil {
			err = fn(fr)
			fr.Close()
		}
	}
	return err
}

// b: the parsed file schema blob
// mm: keys to populate
func (ix *Index) populateFile(fetcher blob.Fetcher, b *schema.Blob, mm *mutationMap) (err error) {
	var times []time.Time // all creation or mod times seen; may be zero
	times = append(times, b.ModTime())

	blobRef := b.BlobRef()
	fr, err := b.NewFileReader(fetcher)
	if err != nil {
		return err
	}
	defer fr.Close()
	mime, reader := magic.MIMETypeFromReader(fr)

	sha1 := sha1.New()
	var copyDest io.Writer = sha1
	var imageBuf *keepFirstN // or nil
	if strings.HasPrefix(mime, "image/") {
		imageBuf = &keepFirstN{N: 512 << 10}
		copyDest = io.MultiWriter(copyDest, imageBuf)
	}
	size, err := io.Copy(copyDest, reader)
	if err != nil {
		return err
	}
	wholeRef := blob.RefFromHash(sha1)

	if imageBuf != nil {
		conf, err := images.DecodeConfig(bytes.NewReader(imageBuf.Bytes))
		// If our optimistic 512KB in-memory prefix from above was too short to get the dimensions, pass the whole thing instead and try again.
		if err == io.ErrUnexpectedEOF {
			var fr *schema.FileReader
			fr, err = b.NewFileReader(fetcher)
			if err == nil {
				conf, err = images.DecodeConfig(fr)
				fr.Close()
			}
		}
		if err == nil {
			mm.Set(keyImageSize.Key(blobRef), keyImageSize.Val(fmt.Sprint(conf.Width), fmt.Sprint(conf.Height)))
		}
		if ft, err := schema.FileTime(bytes.NewReader(imageBuf.Bytes)); err == nil {
			log.Printf("filename %q exif = %v, %v", b.FileName(), ft, err)
			times = append(times, ft)
		} else {
			log.Printf("filename %q exif = %v, %v", b.FileName(), ft, err)
		}

		// TODO(mpl): find (generate?) more broken EXIF images to experiment with.
		err = indexEXIF(wholeRef, bytes.NewReader(imageBuf.Bytes), mm)
		if err == io.EOF {
			var fr *schema.FileReader
			fr, err = b.NewFileReader(fetcher)
			if err == nil {
				err = indexEXIF(wholeRef, fr, mm)
				fr.Close()
			}
		}
		if err != nil {
			log.Printf("error parsing EXIF: %v", err)
		}
	}

	var sortTimes []time.Time
	for _, t := range times {
		if !t.IsZero() {
			sortTimes = append(sortTimes, t)
		}
	}
	sort.Sort(types.ByTime(sortTimes))
	var time3339s string
	switch {
	case len(sortTimes) == 1:
		time3339s = types.Time3339(sortTimes[0]).String()
	case len(sortTimes) >= 2:
		oldest, newest := sortTimes[0], sortTimes[len(sortTimes)-1]
		time3339s = types.Time3339(oldest).String() + "," + types.Time3339(newest).String()
	}

	mm.Set(keyWholeToFileRef.Key(wholeRef, blobRef), "1")
	mm.Set(keyFileInfo.Key(blobRef), keyFileInfo.Val(size, b.FileName(), mime, wholeRef))
	mm.Set(keyFileTimes.Key(blobRef), keyFileTimes.Val(time3339s))

	if strings.HasPrefix(mime, "audio/") {
		indexMusic(io.NewSectionReader(fr, 0, fr.Size()), wholeRef, mm)
	}

	return nil
}