perf(error): better deal with deferred errors

cbz/cbz_creator.go

@@ -4,6 +4,7 @@ import (
 	"archive/zip"
 	"fmt"
 	"github.com/belphemur/CBZOptimizer/manga"
+	"github.com/belphemur/CBZOptimizer/utils/errs"
 	"os"
 	"time"
 )
@@ -14,14 +15,14 @@ func WriteChapterToCBZ(chapter *manga.Chapter, outputFilePath string) error {
 	if err != nil {
 		return fmt.Errorf("failed to create .cbz file: %w", err)
 	}
-	defer zipFile.Close()
+	defer errs.Capture(&err, zipFile.Close, "failed to close .cbz file")
 
 	// Create a new ZIP writer
 	zipWriter := zip.NewWriter(zipFile)
 	if err != nil {
 		return err
 	}
-	defer zipWriter.Close()
+	defer errs.Capture(&err, zipWriter.Close, "failed to close .cbz writer")
 
 	// Write each page to the ZIP archive
 	for _, page := range chapter.Pages {

cbz/cbz_loader.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"github.com/araddon/dateparse"
 	"github.com/belphemur/CBZOptimizer/manga"
+	"github.com/belphemur/CBZOptimizer/utils/errs"
 	"io"
 	"path/filepath"
 	"strings"
@@ -18,7 +19,7 @@ func LoadChapter(filePath string) (*manga.Chapter, error) {
 	if err != nil {
 		return nil, fmt.Errorf("failed to open .cbz file: %w", err)
 	}
-	defer r.Close()
+	defer errs.Capture(&err, r.Close, "failed to close opened .cbz file")
 
 	chapter := &manga.Chapter{
 		FilePath: filePath,
@@ -39,12 +40,15 @@ func LoadChapter(filePath string) (*manga.Chapter, error) {
 		if f.FileInfo().IsDir() {
 			continue
 		}
+		err := func() error {
 			// Open the file inside the zip
 			rc, err := f.Open()
 			if err != nil {
-			return nil, fmt.Errorf("failed to open file inside .cbz: %w", err)
+				return fmt.Errorf("failed to open file inside .cbz: %w", err)
 			}
 
+			defer errs.Capture(&err, rc.Close, "failed to close file inside .cbz")
+
 			// Determine the file extension
 			ext := strings.ToLower(filepath.Ext(f.Name))
 
@@ -52,23 +56,20 @@ func LoadChapter(filePath string) (*manga.Chapter, error) {
 				// Read the ComicInfo.xml file content
 				xmlContent, err := io.ReadAll(rc)
 				if err != nil {
-				rc.Close()
+					return fmt.Errorf("failed to read ComicInfo.xml content: %w", err)
-				return nil, fmt.Errorf("failed to read ComicInfo.xml content: %w", err)
 				}
 				chapter.ComicInfoXml = string(xmlContent)
 			} else if !chapter.IsConverted && ext == ".txt" && strings.ToLower(filepath.Base(f.Name)) == "converted.txt" {
 				textContent, err := io.ReadAll(rc)
 				if err != nil {
-				rc.Close()
+					return fmt.Errorf("failed to read Converted.xml content: %w", err)
-				return nil, fmt.Errorf("failed to read Converted.xml content: %w", err)
 				}
 				scanner := bufio.NewScanner(bytes.NewReader(textContent))
 				if scanner.Scan() {
 					convertedTime := scanner.Text()
 					chapter.ConvertedTime, err = dateparse.ParseAny(convertedTime)
 					if err != nil {
-					rc.Close()
+						return fmt.Errorf("failed to parse converted time: %w", err)
-					return nil, fmt.Errorf("failed to parse converted time: %w", err)
 					}
 					chapter.IsConverted = true
 				}
@@ -77,8 +78,7 @@ func LoadChapter(filePath string) (*manga.Chapter, error) {
 				buf := new(bytes.Buffer)
 				_, err = io.Copy(buf, rc)
 				if err != nil {
-				rc.Close()
+					return fmt.Errorf("failed to read file contents: %w", err)
-				return nil, fmt.Errorf("failed to read file contents: %w", err)
 				}
 
 				// Create a new Page object
@@ -93,8 +93,11 @@ func LoadChapter(filePath string) (*manga.Chapter, error) {
 				// Add the page to the chapter
 				chapter.Pages = append(chapter.Pages, page)
 			}
-		rc.Close()
+			return nil
-
+		}()
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	return chapter, nil

utils/errs/errors_defer.go

@@ -0,0 +1,16 @@
+package errs
+
+import (
+	"errors"
+	"fmt"
+)
+
+// Capture runs errFunc and assigns the error, if any, to *errPtr. Preserves the
+// original error by wrapping with errors.Join if the errFunc err is non-nil.
+func Capture(errPtr *error, errFunc func() error, msg string) {
+	err := errFunc()
+	if err == nil {
+		return
+	}
+	*errPtr = errors.Join(*errPtr, fmt.Errorf("%s: %w", msg, err))
+}

utils/errs/errors_defer_test.go

@@ -0,0 +1,58 @@
+package errs
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+func TestCapture(t *testing.T) {
+	tests := []struct {
+		name     string
+		initial  error
+		errFunc  func() error
+		msg      string
+		expected string
+	}{
+		{
+			name:     "No error from errFunc",
+			initial:  nil,
+			errFunc:  func() error { return nil },
+			msg:      "test message",
+			expected: "",
+		},
+		{
+			name:     "Error from errFunc with no initial error",
+			initial:  nil,
+			errFunc:  func() error { return errors.New("error from func") },
+			msg:      "test message",
+			expected: "test message: error from func",
+		},
+		{
+			name:     "Error from errFunc with initial error",
+			initial:  errors.New("initial error"),
+			errFunc:  func() error { return errors.New("error from func") },
+			msg:      "test message",
+			expected: "initial error\ntest message: error from func",
+		},
+		{
+			name:     "Error from errFunc with initial wrapped error",
+			initial:  fmt.Errorf("wrapped error: %w", errors.New("initial error")),
+			errFunc:  func() error { return errors.New("error from func") },
+			msg:      "test message",
+			expected: "wrapped error: initial error\ntest message: error from func",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var err error = tt.initial
+			Capture(&err, tt.errFunc, tt.msg)
+			if err != nil && err.Error() != tt.expected {
+				t.Errorf("expected %q, got %q", tt.expected, err.Error())
+			} else if err == nil && tt.expected != "" {
+				t.Errorf("expected %q, got nil", tt.expected)
+			}
+		})
+	}
+}