affected/package: io.copy() ; did not achieve the expected result.

[imkos]

code1:

func UploadFileV3(url string, fileName string, fsr io.Reader) ([]byte, error) {
	pR, pW := io.Pipe()
	// Set up multipart body for reading
	multipartW := multipart.NewWriter(pW)
	go func() {
		partW, err0 := multipartW.CreateFormFile("file", fileName)
		if err0 != nil {
			log.Info("multipartW CreateFormFile err,", err0)
			pW.CloseWithError(err0)
			return
		}
		tr := io.TeeReader(fsr, partW)
		// 256kb
		buf := make([]byte, 256<<10)
		for {
			// fsr -> partW -> multipartW -> pW -> pR
			_, err := tr.Read(buf)
			if err == io.EOF {
				multipartW.Close()
				pW.Close()
				break
			}
			if err != nil {
				log.Errorf("The error reading from connector: %v", err)
				break
			}
		}
	}()
	// Send http request chunk encoding the multipart message
	req, err := http.NewRequest("POST", url, pR)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", multipartW.FormDataContentType())
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		log.Error("POST err1,", err)
		return nil, err
	}
	defer resp.Body.Close()

	content, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	log.Info("content:", string(content))
	return content, nil
}

code2:

func UploadFileV3(url string, fileName string, fsr io.Reader) ([]byte, error) {
	pR, pW := io.Pipe()
	// Set up multipart body for reading
	multipartW := multipart.NewWriter(pW)
	go func() {
		partW, err0 := multipartW.CreateFormFile("file", fileName)
		if err0 != nil {
			log.Info("multipartW CreateFormFile err,", err0)
			pW.CloseWithError(err0)
			return
		}
		io.Copy(partW, fsr)
	}()
	// Send http request chunk encoding the multipart message
	req, err := http.NewRequest("POST", url, pR)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", multipartW.FormDataContentType())
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		log.Error("POST err1,", err)
		return nil, err
	}
	defer resp.Body.Close()

	content, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	log.Info("content:", string(content))
	return content, nil
}

What did you expect to see?

code1: ok
code2: ok

What did you see instead?

code1: ok
code2: hang

[seankhliao]

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