all: improve code quality

internal/aghio/limitedreadcloser.go

@@ -47,9 +47,9 @@ func (lrc *limitedReadCloser) Close() error {
 
 // LimitReadCloser wraps ReadCloser to make it's Reader stop with
 // ErrLimitReached after n bytes read.
-func LimitReadCloser(rc io.ReadCloser, n int64) (new io.ReadCloser, err error) {
+func LimitReadCloser(rc io.ReadCloser, n int64) (newRC io.ReadCloser, err error) {
 	if n < 0 {
-		return nil, fmt.Errorf("invalid n: %d", n)
+		return nil, fmt.Errorf("aghio: invalid n in LimitReadCloser: %d", n)
 	}
 	return &limitedReadCloser{
 		limit: n,

internal/aghio/limitedreadcloser_test.go

@@ -26,7 +26,7 @@ func TestLimitReadCloser(t *testing.T) {
 	}, {
 		name: "negative",
 		n:    -1,
-		want: fmt.Errorf("invalid n: -1"),
+		want: fmt.Errorf("aghio: invalid n in LimitReadCloser: -1"),
 	}}
 
 	for _, tc := range testCases {

internal/home/auth_glinet.go

@@ -83,10 +83,11 @@ func glGetTokenDate(file string) uint32 {
 		log.Error("os.Open: %s", err)
 		return 0
 	}
+	defer f.Close()
+
 	fileReadCloser, err := aghio.LimitReadCloser(f, MaxFileSize)
 	if err != nil {
 		log.Error("LimitReadCloser: %s", err)
-		f.Close()
 		return 0
 	}
 	defer fileReadCloser.Close()

internal/home/middlewares.go

@@ -5,6 +5,8 @@ import (
 	"strings"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghio"
+
+	"github.com/AdguardTeam/golibs/log"
 )
 
 // middlerware is a wrapper function signature.
@@ -31,6 +33,8 @@ func limitRequestBody(h http.Handler) (limited http.Handler) {
 		var err error
 		r.Body, err = aghio.LimitReadCloser(r.Body, RequestBodySizeLimit)
 		if err != nil {
+			log.Error("limitRequestBody: %s", err)
+
 			return
 		}
 

internal/home/whois.go

@@ -129,9 +129,10 @@ func (w *Whois) query(target, serverAddr string) (string, error) {
 	if err != nil {
 		return "", err
 	}
+	defer conn.Close()
+
 	connReadCloser, err := aghio.LimitReadCloser(conn, MaxConnReadSize)
 	if err != nil {
-		conn.Close()
 		return "", err
 	}
 	defer connReadCloser.Close()

internal/update/check.go

@@ -35,9 +35,10 @@ func (u *Updater) GetVersionResponse(forceRecheck bool) (VersionInfo, error) {
 	if err != nil {
 		return VersionInfo{}, fmt.Errorf("updater: HTTP GET %s: %w", u.VersionURL, err)
 	}
+	defer resp.Body.Close()
+
 	resp.Body, err = aghio.LimitReadCloser(resp.Body, MaxResponseSize)
 	if err != nil {
-		resp.Body.Close()
 		return VersionInfo{}, fmt.Errorf("updater: LimitReadCloser: %w", err)
 	}
 	defer resp.Body.Close()

internal/update/updater.go

@@ -219,7 +219,8 @@ func (u *Updater) clean() {
 }
 
 // MaxPackageFileSize is a maximum package file length in bytes. The largest
-// package whose size is limited by this constant has size of 9MiB for now.
+// package whose size is limited by this constant currently has the size of
+// approximately 9 MiB.
 const MaxPackageFileSize = 32 * 1024 * 1024
 
 // Download package file and save it to disk
@@ -228,10 +229,10 @@ func (u *Updater) downloadPackageFile(url string, filename string) error {
 	if err != nil {
 		return fmt.Errorf("http request failed: %w", err)
 	}
+	defer resp.Body.Close()
 
 	resp.Body, err = aghio.LimitReadCloser(resp.Body, MaxPackageFileSize)
 	if err != nil {
-		resp.Body.Close()
 		return fmt.Errorf("http request failed: %w", err)
 	}
 	defer resp.Body.Close()