106 lines
2.1 KiB
Go
106 lines
2.1 KiB
Go
package upload
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import (
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"bytes"
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"io"
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"errors"
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)
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const (
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// QingStor has a max upload parts limit to 10000.
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maxUploadParts = 10000
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// We read from stream for read 1024B.
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segmentSize = 1024
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)
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// chunk provides a struct to read file
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type chunk struct {
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fd io.Reader
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cur int64
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size int64
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partSize int
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}
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// newChunk creates a FileChunk struct
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func newChunk(fd io.Reader, partSize int) *chunk {
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f := &chunk{
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fd: fd,
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partSize: partSize,
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}
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f.initSize()
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return f
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}
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// nextPart reads the next part of the file
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func (f *chunk) nextPart() (io.ReadSeeker, error) {
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type readerAtSeeker interface {
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io.ReaderAt
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io.ReadSeeker
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}
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switch r := f.fd.(type) {
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case readerAtSeeker:
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var sectionSize int64
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var err error
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leftSize := f.size - f.cur
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if leftSize >= int64(f.partSize) {
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sectionSize = int64(f.partSize)
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} else if leftSize > 0 {
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sectionSize = f.size - f.cur
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} else {
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err = io.EOF
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}
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seekReader := io.NewSectionReader(r, f.cur, sectionSize)
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f.cur += sectionSize
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return seekReader, err
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case io.Reader:
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buf := make([]byte, segmentSize)
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var n, lenBuf int
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var err error
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var chunk []byte
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for {
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n, _ = r.Read(buf)
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if n == 0 {
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if lenBuf == 0 {
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err = io.EOF
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}
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break
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}
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lenBuf = lenBuf + n
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chunk = append(chunk, buf...)
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if lenBuf == f.partSize {
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break
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}
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}
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partBody := bytes.NewReader(chunk[:lenBuf])
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return partBody, err
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default:
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return nil, errors.New("file does not support read")
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}
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}
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// initSize tries to detect the total stream size, setting u.size. If
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// the size is not known, size is set to -1.
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func (f *chunk) initSize() {
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f.size = -1
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switch r := f.fd.(type) {
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case io.Seeker:
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pos, _ := r.Seek(0, 1)
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defer r.Seek(pos, 0)
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n, err := r.Seek(0, 2)
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if err != nil {
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return
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}
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f.size = n
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// Try to adjust partSize if it is too small and account for
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// integer division truncation.
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if f.size/int64(f.partSize) >= int64(maxUploadParts) {
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// Add one to the part size to account for remainders
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// during the size calculation. e.g odd number of bytes.
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f.partSize = int(f.size/int64(maxUploadParts)) + 1
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}
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}
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}
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