Shorten error messages to D&K style

internal/objectstore/multipart.go

@@ -76,7 +76,7 @@ func NewMultipart(ctx context.Context, partURLs []string, completeURL, abortURL,
 
 		n, err := io.Copy(ioutil.Discard, pr)
 		if err != nil {
-			m.uploadError = fmt.Errorf("cannot drain pipe: %v", err)
+			m.uploadError = fmt.Errorf("drain pipe: %v", err)
 			return
 		}
 		if n > 0 {
@@ -120,12 +120,12 @@ func (m *Multipart) cleanup(ctx context.Context) {
 func (m *Multipart) complete(cmu *CompleteMultipartUpload) error {
 	body, err := xml.Marshal(cmu)
 	if err != nil {
-		return fmt.Errorf("cannot marshal CompleteMultipartUpload request: %v", err)
+		return fmt.Errorf("marshal CompleteMultipartUpload request: %v", err)
 	}
 
 	req, err := http.NewRequest("POST", m.CompleteURL, bytes.NewReader(body))
 	if err != nil {
-		return fmt.Errorf("cannot create CompleteMultipartUpload request: %v", err)
+		return fmt.Errorf("create CompleteMultipartUpload request: %v", err)
 	}
 	req.ContentLength = int64(len(body))
 	req.Header.Set("Content-Type", "application/xml")
@@ -144,7 +144,7 @@ func (m *Multipart) complete(cmu *CompleteMultipartUpload) error {
 	result := &compoundCompleteMultipartUploadResult{}
 	decoder := xml.NewDecoder(resp.Body)
 	if err := decoder.Decode(&result); err != nil {
-		return fmt.Errorf("cannot decode CompleteMultipartUpload answer: %v", err)
+		return fmt.Errorf("decode CompleteMultipartUpload answer: %v", err)
 	}
 
 	if result.isError() {
@@ -152,7 +152,7 @@ func (m *Multipart) complete(cmu *CompleteMultipartUpload) error {
 	}
 
 	if result.CompleteMultipartUploadResult == nil {
-		return fmt.Errorf("cannot read CompleteMultipartUpload answer")
+		return fmt.Errorf("empty CompleteMultipartUploadResult")
 	}
 
 	m.extractETag(result.ETag)
@@ -178,7 +178,7 @@ func (m *Multipart) verifyETag(cmu *CompleteMultipartUpload) error {
 func (m *Multipart) readAndUploadOnePart(partURL string, putHeaders map[string]string, src io.Reader, partNumber int) (*completeMultipartUploadPart, error) {
 	file, err := ioutil.TempFile("", "part-buffer")
 	if err != nil {
-		return nil, fmt.Errorf("unable to create a temporary file for buffering: %v", err)
+		return nil, fmt.Errorf("create temporary buffer file: %v", err)
 	}
 	defer func(path string) {
 		if err := os.Remove(path); err != nil {
@@ -188,19 +188,19 @@ func (m *Multipart) readAndUploadOnePart(partURL string, putHeaders map[string]s
 
 	n, err := io.Copy(file, src)
 	if err != nil {
-		return nil, fmt.Errorf("cannot write part %d to disk: %v", partNumber, err)
+		return nil, fmt.Errorf("write part %d to disk: %v", partNumber, err)
 	}
 	if n == 0 {
 		return nil, nil
 	}
 
 	if _, err = file.Seek(0, io.SeekStart); err != nil {
-		return nil, fmt.Errorf("cannot rewind part %d temporary dump : %v", partNumber, err)
+		return nil, fmt.Errorf("rewind part %d temporary dump : %v", partNumber, err)
 	}
 
 	etag, err := m.uploadPart(partURL, putHeaders, file, n)
 	if err != nil {
-		return nil, fmt.Errorf("cannot upload part %d: %v", partNumber, err)
+		return nil, fmt.Errorf("upload part %d: %v", partNumber, err)
 	}
 	return &completeMultipartUploadPart{PartNumber: partNumber, ETag: etag}, nil
 }

internal/sendfile/sendfile.go

@@ -132,7 +132,7 @@ func sendFileFromDisk(w http.ResponseWriter, r *http.Request, file string) {
 	if contentTypeHeaderPresent {
 		data, err := ioutil.ReadAll(io.LimitReader(content, headers.MaxDetectSize))
 		if err != nil {
-			helper.Fail500(w, r, fmt.Errorf("error reading the file"))
+			helper.Fail500(w, r, fmt.Errorf("content type detection: %v", err))
 			return
 		}