From 5bd7b99f355f9e8a3b3cbfd654daab6dd9fa432f Mon Sep 17 00:00:00 2001
From: Michael Sverdlov <sverdlov93@gmail.com>
Date: Tue, 26 Sep 2023 12:28:07 +0300
Subject: [PATCH] Improve fileutils error handling (#196)

---
 utils/fileutils.go | 102 +++++++++++++++++----------------------------
 1 file changed, 39 insertions(+), 63 deletions(-)

diff --git a/utils/fileutils.go b/utils/fileutils.go
index 921cb54a..7bc59b04 100644
--- a/utils/fileutils.go
+++ b/utils/fileutils.go
@@ -107,50 +107,44 @@ func MoveFile(sourcePath, destPath string) (err error) {
 	var inputFile *os.File
 	inputFile, err = os.Open(sourcePath)
 	if err != nil {
-		return err
+		return
 	}
 	defer func() {
 		if inputFileOpen {
-			e := inputFile.Close()
-			if err == nil {
-				err = e
-			}
+			err = errors.Join(err, inputFile.Close())
 		}
 	}()
 	inputFileInfo, err := inputFile.Stat()
 	if err != nil {
-		return err
+		return
 	}
 
 	var outputFile *os.File
 	outputFile, err = os.Create(destPath)
 	if err != nil {
-		return err
+		return
 	}
 	defer func() {
-		e := outputFile.Close()
-		if err == nil {
-			err = e
-		}
+		err = errors.Join(err, outputFile.Close())
 	}()
 
 	_, err = io.Copy(outputFile, inputFile)
 	if err != nil {
-		return err
+		return
 	}
 	err = os.Chmod(destPath, inputFileInfo.Mode())
 	if err != nil {
-		return err
+		return
 	}
 
 	// The copy was successful, so now delete the original file
 	err = inputFile.Close()
 	if err != nil {
-		return err
+		return
 	}
 	inputFileOpen = false
 	err = os.Remove(sourcePath)
-	return err
+	return
 }
 
 // Return the list of files and directories in the specified path
@@ -232,12 +226,10 @@ func DownloadFile(downloadTo string, fromUrl string) (err error) {
 	// Get the data
 	resp, err := http.Get(fromUrl)
 	if err != nil {
-		return err
+		return
 	}
 	defer func() {
-		if deferErr := resp.Body.Close(); err == nil {
-			err = deferErr
-		}
+		err = errors.Join(err, resp.Body.Close())
 	}()
 	if resp.StatusCode != http.StatusOK {
 		err = fmt.Errorf("download failed. status code: %s", resp.Status)
@@ -250,9 +242,7 @@ func DownloadFile(downloadTo string, fromUrl string) (err error) {
 		return
 	}
 	defer func() {
-		if deferErr := out.Close(); err == nil {
-			err = deferErr
-		}
+		err = errors.Join(err, out.Close())
 	}()
 	// Write the body to file
 	_, err = io.Copy(out, resp.Body)
@@ -311,22 +301,19 @@ func removeDirContents(dirPath string) (err error) {
 		return
 	}
 	defer func() {
-		e := d.Close()
-		if err == nil {
-			err = e
-		}
+		err = errors.Join(err, d.Close())
 	}()
 	names, err := d.Readdirnames(-1)
 	if err != nil {
-		return err
+		return
 	}
 	for _, name := range names {
 		err = os.RemoveAll(filepath.Join(dirPath, name))
 		if err != nil {
-			return err
+			return
 		}
 	}
-	return nil
+	return
 }
 
 // Old runs/tests may leave junk at temp dir.
@@ -535,17 +522,15 @@ func Unmarshal(filePath string, loadTarget interface{}) (err error) {
 		return
 	}
 	defer func() {
-		closeErr := jsonFile.Close()
-		if err == nil {
-			err = closeErr
-		}
+		err = errors.Join(err, jsonFile.Close())
 	}()
 	var byteValue []byte
 	byteValue, err = io.ReadAll(jsonFile)
 	if err != nil {
 		return
 	}
-	return json.Unmarshal(byteValue, &loadTarget)
+	err = json.Unmarshal(byteValue, &loadTarget)
+	return
 }
 
 // strip '\n' or read until EOF, return error if read error
@@ -553,26 +538,25 @@ func Unmarshal(filePath string, loadTarget interface{}) (err error) {
 func ReadNLines(path string, total int) (lines []string, err error) {
 	reader, err := os.Open(path)
 	if err != nil {
-		return nil, err
+		return
 	}
 	defer func() {
-		deferErr := reader.Close()
-		if err == nil {
-			err = deferErr
-		}
+		err = errors.Join(err, reader.Close())
 	}()
-	r := bufio.NewReader(reader)
+	bufferedReader := bufio.NewReader(reader)
 	for i := 0; i < total; i++ {
-		line, _, err := r.ReadLine()
+		var line []byte
+		line, _, err = bufferedReader.ReadLine()
 		lines = append(lines, string(line))
 		if err == io.EOF {
+			err = nil
 			break
 		}
 		if err != nil {
-			return nil, err
+			return
 		}
 	}
-	return lines, nil
+	return
 }
 
 type FileDetails struct {
@@ -585,7 +569,7 @@ func GetFileDetails(filePath string, includeChecksums bool) (details *FileDetail
 	if includeChecksums {
 		details.Checksum, err = calcChecksumDetails(filePath)
 		if err != nil {
-			return details, err
+			return
 		}
 	} else {
 		details.Checksum = entities.Checksum{}
@@ -593,40 +577,32 @@ func GetFileDetails(filePath string, includeChecksums bool) (details *FileDetail
 
 	file, err := os.Open(filePath)
 	defer func() {
-		e := file.Close()
-		if err == nil {
-			err = e
-		}
+		err = errors.Join(err, file.Close())
 	}()
 	if err != nil {
-		return nil, err
+		return
 	}
 	fileInfo, err := file.Stat()
 	if err != nil {
-		return nil, err
+		return
 	}
 	details.Size = fileInfo.Size()
-	return details, nil
+	return
 }
 
 func calcChecksumDetails(filePath string) (checksum entities.Checksum, err error) {
 	file, err := os.Open(filePath)
-	defer func() {
-		e := file.Close()
-		if err == nil {
-			err = e
-		}
-	}()
 	if err != nil {
-		return entities.Checksum{}, err
+		return
 	}
-	return calcChecksumDetailsFromReader(file)
-}
+	defer func() {
+		err = errors.Join(err, file.Close())
+	}()
 
-func calcChecksumDetailsFromReader(reader io.Reader) (entities.Checksum, error) {
-	checksumInfo, err := CalcChecksums(reader)
+	checksumInfo, err := CalcChecksums(file)
 	if err != nil {
 		return entities.Checksum{}, err
 	}
-	return entities.Checksum{Md5: checksumInfo[MD5], Sha1: checksumInfo[SHA1], Sha256: checksumInfo[SHA256]}, nil
+	checksum = entities.Checksum{Md5: checksumInfo[MD5], Sha1: checksumInfo[SHA1], Sha256: checksumInfo[SHA256]}
+	return
 }