refactor: add more go linters (#970)

files/file.go

@@ -1,8 +1,8 @@
 package files
 
 import (
-	"crypto/md5"
-	"crypto/sha1"
+	"crypto/md5"  //nolint:gosec
+	"crypto/sha1" //nolint:gosec
 	"crypto/sha256"
 	"crypto/sha512"
 	"encoding/hex"
@@ -17,9 +17,10 @@ import (
 	"strings"
 	"time"
 
+	"github.com/spf13/afero"
+
 	"github.com/filebrowser/filebrowser/v2/errors"
 	"github.com/filebrowser/filebrowser/v2/rules"
-	"github.com/spf13/afero"
 )
 
 // FileInfo describes a file.
@@ -74,7 +75,10 @@ func NewFileInfo(opts FileOptions) (*FileInfo, error) {
 
 	if opts.Expand {
 		if file.IsDir {
-			return file, file.readListing(opts.Checker)
+			if err := file.readListing(opts.Checker); err != nil { //nolint:shadow
+				return nil, err
+			}
+			return file, nil
 		}
 
 		err = file.detectType(opts.Modify, true)
@@ -105,6 +109,7 @@ func (i *FileInfo) Checksum(algo string) error {
 
 	var h hash.Hash
 
+	//nolint:gosec
 	switch algo {
 	case "md5":
 		h = md5.New()
@@ -127,6 +132,8 @@ func (i *FileInfo) Checksum(algo string) error {
 	return nil
 }
 
+//nolint:goconst
+//TODO: use constants
 func (i *FileInfo) detectType(modify, saveContent bool) error {
 	// failing to detect the type should not return error.
 	// imagine the situation where a file in a dir with thousands
@@ -198,9 +205,9 @@ func (i *FileInfo) detectSubtitles() {
 
 	// TODO: detect multiple languages. Base.Lang.vtt
 
-	path := strings.TrimSuffix(i.Path, ext) + ".vtt"
-	if _, err := i.Fs.Stat(path); err == nil {
-		i.Subtitles = append(i.Subtitles, path)
+	fPath := strings.TrimSuffix(i.Path, ext) + ".vtt"
+	if _, err := i.Fs.Stat(fPath); err == nil {
+		i.Subtitles = append(i.Subtitles, fPath)
 	}
 }
 
@@ -219,16 +226,16 @@ func (i *FileInfo) readListing(checker rules.Checker) error {
 
 	for _, f := range dir {
 		name := f.Name()
-		path := path.Join(i.Path, name)
+		fPath := path.Join(i.Path, name)
 
-		if !checker.Check(path) {
+		if !checker.Check(fPath) {
 			continue
 		}
 
 		if strings.HasPrefix(f.Mode().String(), "L") {
 			// It's a symbolic link. We try to follow it. If it doesn't work,
 			// we stay with the link information instead if the target's.
-			info, err := i.Fs.Stat(path)
+			info, err := i.Fs.Stat(fPath)
 			if err == nil {
 				f = info
 			}
@@ -242,7 +249,7 @@ func (i *FileInfo) readListing(checker rules.Checker) error {
 			Mode:      f.Mode(),
 			IsDir:     f.IsDir(),
 			Extension: filepath.Ext(name),
-			Path:      path,
+			Path:      fPath,
 		}
 
 		if file.IsDir {

files/listing.go

@@ -16,8 +16,10 @@ type Listing struct {
 }
 
 // ApplySort applies the sort order using .Order and .Sort
+//nolint:goconst
 func (l Listing) ApplySort() {
 	// Check '.Order' to know how to sort
+	// TODO: use enum
 	if !l.Sorting.Asc {
 		switch l.Sorting.By {
 		case "name":

files/utils.go

@@ -4,41 +4,45 @@ import (
 	"unicode/utf8"
 )
 
-func isBinary(content []byte, n int) bool {
+func isBinary(content []byte, _ int) bool {
 	maybeStr := string(content)
 	runeCnt := utf8.RuneCount(content)
 	runeIndex := 0
 	gotRuneErrCnt := 0
 	firstRuneErrIndex := -1
 
-	for _, b := range maybeStr {
+	const (
 		// 8 and below are control chars (e.g. backspace, null, eof, etc)
-		if b <= 8 {
+		maxControlCharsCode = 8
+		// 0xFFFD(65533) is  the "error" Rune or "Unicode replacement character"
+		// see https://golang.org/pkg/unicode/utf8/#pkg-constants
+		unicodeReplacementChar = 0xFFFD
+	)
+
+	for _, b := range maybeStr {
+		if b <= maxControlCharsCode {
 			return true
 		}
 
-		// 0xFFFD(65533) is  the "error" Rune or "Unicode replacement character"
-		// see https://golang.org/pkg/unicode/utf8/#pkg-constants
-		if b == 0xFFFD {
-			//if it is not the last (utf8.UTFMax - x) rune
+		if b == unicodeReplacementChar {
+			// if it is not the last (utf8.UTFMax - x) rune
 			if runeCnt > utf8.UTFMax && runeIndex < runeCnt-utf8.UTFMax {
 				return true
-			} else {
-				//else it is the last (utf8.UTFMax - x) rune
-				//there maybe Vxxx, VVxx, VVVx, thus, we may got max 3 0xFFFD rune (asume V is the byte we got)
-				//for Chinese, it can only be Vxx, VVx, we may got max 2 0xFFFD rune
-				gotRuneErrCnt++
+			}
+			// else it is the last (utf8.UTFMax - x) rune
+			// there maybe Vxxx, VVxx, VVVx, thus, we may got max 3 0xFFFD rune (assume V is the byte we got)
+			// for Chinese, it can only be Vxx, VVx, we may got max 2 0xFFFD rune
+			gotRuneErrCnt++
 
-				//mark the first time
-				if firstRuneErrIndex == -1 {
-					firstRuneErrIndex = runeIndex
-				}
+			// mark the first time
+			if firstRuneErrIndex == -1 {
+				firstRuneErrIndex = runeIndex
 			}
 		}
 		runeIndex++
 	}
 
-	//if last (utf8.UTFMax - x ) rune has the "error" Rune, but not all
+	// if last (utf8.UTFMax - x ) rune has the "error" Rune, but not all
 	if firstRuneErrIndex != -1 && gotRuneErrCnt != runeCnt-firstRuneErrIndex {
 		return true
 	}