lint: enable errcheck and fix problems

.golangci.yml

@@ -2,7 +2,7 @@
 
 linters:
   enable:
-    #- errcheck
+    - errcheck
     - goimports
     #- revive
     - ineffassign

gofakes3.go

@@ -388,7 +388,10 @@ func (g *GoFakeS3) createBucket(bucket string, w http.ResponseWriter, r *http.Re
 	}
 
 	w.Header().Set("Location", "/"+bucket)
-	w.Write([]byte{})
+	_, err := w.Write([]byte{})
+	if err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -417,17 +420,29 @@ func (g *GoFakeS3) headBucket(bucket string, w http.ResponseWriter, r *http.Requ
 		return err
 	}
 
-	w.Write([]byte{})
+	_, err := w.Write([]byte{})
+	if err != nil {
+		return err
+	}
 	return nil
 }
 
+// CheckClose is a utility function used to check the return from
+// Close in a defer statement.
+func CheckClose(c io.Closer, err *error) {
+	cerr := c.Close()
+	if *err == nil {
+		*err = cerr
+	}
+}
+
 // GetObject retrievs a bucket object.
 func (g *GoFakeS3) getObject(
 	bucket, object string,
 	versionID VersionID,
 	w http.ResponseWriter,
 	r *http.Request,
-) error {
+) (err error) {
 
 	g.log.Print(LogInfo, "GET OBJECT", "Bucket:", bucket, "Object:", object)
 
@@ -463,7 +478,7 @@ func (g *GoFakeS3) getObject(
 		g.log.Print(LogErr, "unexpected nil object for key", bucket, object)
 		return ErrInternal
 	}
-	defer obj.Contents.Close()
+	defer CheckClose(obj.Contents, &err)
 
 	if err := g.writeGetOrHeadObjectResponse(obj, w, r); err != nil {
 		return err
@@ -517,7 +532,7 @@ func (g *GoFakeS3) headObject(
 	versionID VersionID,
 	w http.ResponseWriter,
 	r *http.Request,
-) error {
+) (err error) {
 
 	g.log.Print(LogInfo, "HEAD OBJECT", bucket, object)
 
@@ -533,7 +548,7 @@ func (g *GoFakeS3) headObject(
 		g.log.Print(LogErr, "unexpected nil object for key", bucket, object)
 		return ErrInternal
 	}
-	defer obj.Contents.Close()
+	defer CheckClose(obj.Contents, &err)
 
 	if err := g.writeGetOrHeadObjectResponse(obj, w, r); err != nil {
 		return err
@@ -546,7 +561,7 @@ func (g *GoFakeS3) headObject(
 
 // createObjectBrowserUpload allows objects to be created from a multipart upload initiated
 // by a browser form.
-func (g *GoFakeS3) createObjectBrowserUpload(bucket string, w http.ResponseWriter, r *http.Request) error {
+func (g *GoFakeS3) createObjectBrowserUpload(bucket string, w http.ResponseWriter, r *http.Request) (err error) {
 	g.log.Print(LogInfo, "CREATE OBJECT THROUGH BROWSER UPLOAD")
 
 	if err := g.ensureBucketExists(r, bucket); err != nil {
@@ -577,7 +592,7 @@ func (g *GoFakeS3) createObjectBrowserUpload(bucket string, w http.ResponseWrite
 	if err != nil {
 		return err
 	}
-	defer infile.Close()
+	defer CheckClose(infile, &err)
 
 	meta, err := metadataHeaders(r.MultipartForm.Value, g.timeSource.Now(), g.metadataSizeLimit)
 	if err != nil {
@@ -663,7 +678,7 @@ func (g *GoFakeS3) createObject(bucket, object string, w http.ResponseWriter, r
 	// hashingReader is still needed to get the ETag even if integrityCheck
 	// is set to false:
 	rdr, err := newHashingReader(reader, md5Base64)
-	defer r.Body.Close()
+	defer CheckClose(r.Body, &err)
 	if err != nil {
 		return err
 	}
@@ -802,7 +817,7 @@ func (g *GoFakeS3) deleteObjectVersion(bucket, object string, version VersionID,
 
 // deleteMulti deletes multiple S3 objects from the bucket.
 // https://docs.aws.amazon.com/AmazonS3/latest/API/multiobjectdeleteapi.html
-func (g *GoFakeS3) deleteMulti(bucket string, w http.ResponseWriter, r *http.Request) error {
+func (g *GoFakeS3) deleteMulti(bucket string, w http.ResponseWriter, r *http.Request) (err error) {
 	g.log.Print(LogInfo, "delete multi", bucket)
 
 	if err := g.ensureBucketExists(r, bucket); err != nil {
@@ -811,7 +826,7 @@ func (g *GoFakeS3) deleteMulti(bucket string, w http.ResponseWriter, r *http.Req
 
 	var in DeleteRequest
 
-	defer r.Body.Close()
+	defer CheckClose(r.Body, &err)
 	dc := xml.NewDecoder(r.Body)
 	if err := dc.Decode(&in); err != nil {
 		return ErrorMessage(ErrMalformedXML, err.Error())
@@ -861,7 +876,7 @@ func (g *GoFakeS3) initiateMultipartUpload(bucket, object string, w http.Respons
 //	part number that was used with a previous part, the previously uploaded part
 //	is overwritten. Each part must be at least 5 MB in size, except the last
 //	part. There is no size limit on the last part of your multipart upload.
-func (g *GoFakeS3) putMultipartUploadPart(bucket, object string, uploadID UploadID, w http.ResponseWriter, r *http.Request) error {
+func (g *GoFakeS3) putMultipartUploadPart(bucket, object string, uploadID UploadID, w http.ResponseWriter, r *http.Request) (err error) {
 	g.log.Print(LogInfo, "put multipart upload", bucket, object, uploadID)
 
 	partNumber, err := strconv.ParseInt(r.URL.Query().Get("partNumber"), 10, 0)
@@ -883,7 +898,7 @@ func (g *GoFakeS3) putMultipartUploadPart(bucket, object string, uploadID Upload
 		return err
 	}
 
-	defer r.Body.Close()
+	defer CheckClose(r.Body, &err)
 
 	meta, err := metadataHeaders(r.Header, g.timeSource.Now(), g.metadataSizeLimit)
 	if err != nil {
@@ -1089,17 +1104,17 @@ func (g *GoFakeS3) ensureBucketExists(r *http.Request, bucket string) error {
 }
 
 func (g *GoFakeS3) xmlEncoder(w http.ResponseWriter) *xml.Encoder {
-	w.Write([]byte(xml.Header))
+	_, _ = w.Write([]byte(xml.Header))
 	w.Header().Set("Content-Type", "application/xml")
 
 	xe := xml.NewEncoder(w)
 	xe.Indent("", "  ")
 	return xe
 }
 
-func (g *GoFakeS3) xmlDecodeBody(rdr io.ReadCloser, into interface{}) error {
+func (g *GoFakeS3) xmlDecodeBody(rdr io.ReadCloser, into interface{}) (err error) {
 	body, err := ioutil.ReadAll(rdr)
-	defer rdr.Close()
+	defer CheckClose(rdr, &err)
 	if err != nil {
 		return err
 	}

gofakes3_test.go

@@ -248,7 +248,12 @@ func TestCreateObjectWithInvalidContentLength(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer rs.Body.Close()
+	defer func() {
+		err := rs.Body.Close()
+		if err != nil {
+			t.Error(err)
+		}
+	}()
 
 	if rs.StatusCode != http.StatusBadRequest {
 		t.Fatal(rs.StatusCode, "!=", http.StatusBadRequest)
@@ -380,7 +385,12 @@ func TestCopyObject(t *testing.T) {
 	obj, err := ts.backend.GetObject(mockR.Context(), defaultBucket, "dst-key", nil)
 	ts.OK(err)
 
-	defer obj.Contents.Close()
+	defer func() {
+		err := obj.Contents.Close()
+		if err != nil {
+			t.Error(err)
+		}
+	}()
 	data, err := ioutil.ReadAll(obj.Contents)
 	ts.OK(err)
 
@@ -581,7 +591,12 @@ func TestGetObjectRange(t *testing.T) {
 		}
 		if !fail {
 			ts.OK(err)
-			defer obj.Body.Close()
+			defer func() {
+				err := obj.Body.Close()
+				if err != nil {
+					t.Error(err)
+				}
+			}()
 
 			out, err := ioutil.ReadAll(obj.Body)
 			ts.OK(err)
@@ -718,7 +733,10 @@ func TestCreateObjectBrowserUpload(t *testing.T) {
 	}
 
 	upload := func(ts *testServer, bucket string, w *multipart.Writer, body io.Reader) (*http.Response, error) {
-		w.Close()
+		err := w.Close()
+		if err != nil {
+			ts.Error(err)
+		}
 		req, err := http.NewRequest("POST", ts.url("/"+bucket), body)
 		ts.OK(err)
 		req.Header.Set("Content-Type", w.FormDataContentType())
@@ -742,7 +760,12 @@ func TestCreateObjectBrowserUpload(t *testing.T) {
 		if res.StatusCode != expectedCode.Status() {
 			ts.Fatal("bad status", res.StatusCode, "!=", expectedCode.Status())
 		}
-		defer res.Body.Close()
+		defer func() {
+			err := res.Body.Close()
+			if err != nil {
+				ts.Error(err)
+			}
+		}()
 		var errResp gofakes3.ErrorResponse
 		dec := xml.NewDecoder(res.Body)
 		ts.OK(dec.Decode(&errResp))
@@ -891,7 +914,12 @@ func TestObjectVersions(t *testing.T) {
 		}
 		out, err := svc.GetObject(input)
 		ts.OK(err)
-		defer out.Body.Close()
+		defer func() {
+			err := out.Body.Close()
+			if err != nil {
+				ts.Error(err)
+			}
+		}()
 		bts, err := ioutil.ReadAll(out.Body)
 		ts.OK(err)
 		if !bytes.Equal(bts, contents) {

init_test.go

@@ -67,12 +67,11 @@ func TestMain(m *testing.M) {
 	os.Exit(0)
 }
 
-func runTestMain(m *testing.M) error {
+func runTestMain(m *testing.M) (err error) {
 	flag.StringVar(&logFile, "fakes3.log", "", "Log file (temp file by default)")
 	flag.Parse()
 
 	var logOutput *os.File
-	var err error
 
 	if logFile == "" {
 		logOutput, err = ioutil.TempFile("", "gofakes3-*.log")
@@ -82,7 +81,7 @@ func runTestMain(m *testing.M) error {
 	if err != nil {
 		return err
 	}
-	defer logOutput.Close()
+	defer gofakes3.CheckClose(logOutput, &err)
 
 	fmt.Fprintf(os.Stderr, "log output redirected to %q\n", logOutput.Name())
 	log.SetOutput(logOutput)
@@ -261,7 +260,12 @@ func (ts *testServer) backendGetString(bucket, key string, rnge *gofakes3.Object
 	obj, err := ts.backend.GetObject(mockR.Context(), bucket, key, rnge)
 	ts.OK(err)
 
-	defer obj.Contents.Close()
+	defer func() {
+		err := obj.Contents.Close()
+		if err != nil {
+			ts.Error(err)
+		}
+	}()
 	data, err := ioutil.ReadAll(obj.Contents)
 	ts.OK(err)
 
@@ -608,7 +612,12 @@ func (ts *testServer) assertObject(bucket string, object string, meta map[string
 
 	obj, err := ts.backend.GetObject(mockR.Context(), bucket, object, nil)
 	ts.OK(err)
-	defer obj.Contents.Close()
+	defer func() {
+		err := obj.Contents.Close()
+		if err != nil {
+			ts.Error(err)
+		}
+	}()
 
 	data, err := gofakes3.ReadAll(obj.Contents, obj.Size)
 	ts.OK(err)
@@ -874,7 +883,7 @@ func (c *rawClient) SetHeaders(rq *http.Request, body []byte) {
 // SendRaw can be used to bypass Go's http client, which helps us out a lot by taking
 // care of some things for us, but which we actually want to test messing up from
 // time to time.
-func (c *rawClient) SendRaw(rq *http.Request) ([]byte, error) {
+func (c *rawClient) SendRaw(rq *http.Request) (out []byte, err error) {
 	b, err := httputil.DumpRequest(rq, true)
 	if err != nil {
 		return nil, err
@@ -883,10 +892,12 @@ func (c *rawClient) SendRaw(rq *http.Request) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer conn.Close()
+	defer gofakes3.CheckClose(conn, &err)
 
 	deadline := time.Now().Add(2 * time.Second)
-	conn.SetDeadline(deadline)
+	if err := conn.SetDeadline(deadline); err != nil {
+		return nil, err
+	}
 	if _, err := conn.Write(b); err != nil {
 		return nil, err
 	}

internal/s3assumer/s300001_get_version_after_versioning_suspended.go

@@ -74,8 +74,13 @@ func (t *S300001GetVersionAfterVersioningSuspended) Run(ctx *Context) error {
 		}
 	}
 
-	readCloseBody := func(rdr io.ReadCloser) ([]byte, error) {
-		defer rdr.Close()
+	readCloseBody := func(rdr io.ReadCloser) (out []byte, err error) {
+		defer func() {
+			closeErr := rdr.Close()
+			if closeErr != nil && err == nil {
+				err = closeErr
+			}
+		}()
 		return ioutil.ReadAll(rdr)
 	}
 

s3mem/backend.go

@@ -267,7 +267,12 @@ func (db *Backend) CopyObject(ctx context.Context, srcBucket, srcKey, dstBucket,
 	if err != nil {
 		return
 	}
-	defer c.Contents.Close()
+	defer func() {
+		closeErr := c.Contents.Close()
+		if closeErr != nil && err == nil {
+			err = closeErr
+		}
+	}()
 
 	for k, v := range c.Metadata {
 		if _, found := meta[k]; !found && k != "X-Amz-Acl" {

xml/example_test.go

@@ -35,7 +35,7 @@ func ExampleMarshalIndent() {
 		fmt.Printf("error: %v\n", err)
 	}
 
-	os.Stdout.Write(output)
+	_, _ = os.Stdout.Write(output)
 	// Output:
 	//   <person id="13">
 	//       <name>