Properly handle closing of files after writing (#113)

internal/api/cache.go

@@ -170,33 +170,39 @@ func (fs *fileStorage) read(key string) (*http.Response, error) {
 	return res, err
 }
 
-func (fs *fileStorage) store(key string, res *http.Response) error {
+func (fs *fileStorage) store(key string, res *http.Response) (storeErr error) {
 	cacheFile := fs.filePath(key)
 
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
 
-	err := os.MkdirAll(filepath.Dir(cacheFile), 0755)
-	if err != nil {
-		return err
+	if storeErr = os.MkdirAll(filepath.Dir(cacheFile), 0755); storeErr != nil {
+		return
 	}
 
-	f, err := os.OpenFile(cacheFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
-	if err != nil {
-		return err
+	var f *os.File
+	if f, storeErr = os.OpenFile(cacheFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600); storeErr != nil {
+		return
 	}
-	defer f.Close()
+
+	defer func() {
+		if err := f.Close(); storeErr == nil && err != nil {
+			storeErr = err
+		}
+	}()
 
 	var origBody io.ReadCloser
 	if res.Body != nil {
 		origBody, res.Body = copyStream(res.Body)
 		defer res.Body.Close()
 	}
-	err = res.Write(f)
+
+	storeErr = res.Write(f)
 	if origBody != nil {
 		res.Body = origBody
 	}
-	return err
+
+	return
 }
 
 func copyStream(r io.ReadCloser) (io.ReadCloser, io.ReadCloser) {

pkg/config/config.go

@@ -281,18 +281,21 @@ func readFile(filename string) ([]byte, error) {
 	return data, nil
 }
 
-func writeFile(filename string, data []byte) error {
-	err := os.MkdirAll(filepath.Dir(filename), 0771)
-	if err != nil {
-		return err
+func writeFile(filename string, data []byte) (writeErr error) {
+	if writeErr = os.MkdirAll(filepath.Dir(filename), 0771); writeErr != nil {
+		return
 	}
-	file, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
-	if err != nil {
-		return err
+	var file *os.File
+	if file, writeErr = os.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600); writeErr != nil {
+		return
 	}
-	defer file.Close()
-	_, err = file.Write(data)
-	return err
+	defer func() {
+		if err := file.Close(); writeErr == nil && err != nil {
+			writeErr = err
+		}
+	}()
+	_, writeErr = file.Write(data)
+	return
 }
 
 var defaultGeneralEntries = `