memfs: Handle error checks with error.Is

Signed-off-by: Paulo Gomes <[email protected]>

memfs/memory.go

@@ -19,7 +19,9 @@ import (
 
 const separator = filepath.Separator
 
-// Memory a very convenient filesystem based on memory files
+var errNotLink = errors.New("not a link")
+
+// Memory a very convenient filesystem based on memory files.
 type Memory struct {
 	s *storage
 
@@ -72,8 +74,6 @@ func (fs *Memory) OpenFile(filename string, flag int, perm os.FileMode) (billy.F
 	return f.Duplicate(filename, perm, flag), nil
 }
 
-var errNotLink = errors.New("not a link")
-
 func (fs *Memory) resolveLink(fullpath string, f *file) (target string, isLink bool) {
 	if !isSymlink(f.mode) {
 		return fullpath, false
@@ -91,7 +91,7 @@ func (fs *Memory) resolveLink(fullpath string, f *file) (target string, isLink b
 // unit (eg.: `C:\`)  to assert that is absolute, but in this mem implementation
 // any path starting by `separator` is also considered absolute.
 func isAbs(path string) bool {
-	return filepath.IsAbs(path) || strings.HasPrefix(path, string(separator))
+	return filepath.IsAbs(path) || strings.HasPrefix(path, string(filepath.Separator))
 }
 
 func (fs *Memory) Stat(filename string) (os.FileInfo, error) {
@@ -177,6 +177,8 @@ func (fs *Memory) Remove(filename string) error {
 	return fs.s.Remove(filename)
 }
 
+// Falls back to Go's filepath.Join, which works differently depending on the
+// OS where the code is being executed.
 func (fs *Memory) Join(elem ...string) string {
 	return filepath.Join(elem...)
 }
@@ -187,7 +189,7 @@ func (fs *Memory) Symlink(target, link string) error {
 		return os.ErrExist
 	}
 
-	if !os.IsNotExist(err) {
+	if !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
@@ -238,7 +240,7 @@ func (f *file) Read(b []byte) (int, error) {
 	n, err := f.ReadAt(b, f.position)
 	f.position += int64(n)
 
-	if err == io.EOF && n != 0 {
+	if errors.Is(err, io.EOF) && n != 0 {
 		err = nil
 	}
 

memfs/storage.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 )
 
@@ -112,7 +113,7 @@ func (s *storage) Rename(from, to string) error {
 	move := [][2]string{{from, to}}
 
 	for pathFrom := range s.files {
-		if pathFrom == from || !filepath.HasPrefix(pathFrom, from) {
+		if pathFrom == from || !strings.HasPrefix(pathFrom, from) {
 			continue
 		}
 

util/util.go

@@ -1,6 +1,7 @@
 package util
 
 import (
+	"errors"
 	"io"
 	"os"
 	"path/filepath"
@@ -33,14 +34,14 @@ func removeAll(fs billy.Basic, path string) error {
 
 	// Simple case: if Remove works, we're done.
 	err := fs.Remove(path)
-	if err == nil || os.IsNotExist(err) {
+	if err == nil || errors.Is(err, os.ErrNotExist) {
 		return nil
 	}
 
 	// Otherwise, is this a directory we need to recurse into?
 	dir, serr := fs.Stat(path)
 	if serr != nil {
-		if os.IsNotExist(serr) {
+		if errors.Is(serr, os.ErrNotExist) {
 			return nil
 		}
 
@@ -60,7 +61,7 @@ func removeAll(fs billy.Basic, path string) error {
 	// Directory.
 	fis, err := dirfs.ReadDir(path)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, os.ErrNotExist) {
 			// Race. It was deleted between the Lstat and Open.
 			// Return nil per RemoveAll's docs.
 			return nil
@@ -81,7 +82,7 @@ func removeAll(fs billy.Basic, path string) error {
 
 	// Remove directory.
 	err1 := fs.Remove(path)
-	if err1 == nil || os.IsNotExist(err1) {
+	if err1 == nil || errors.Is(err1, os.ErrNotExist) {
 		return nil
 	}
 
@@ -154,7 +155,7 @@ func TempFile(fs billy.Basic, dir, prefix string) (f billy.File, err error) {
 	for i := 0; i < 10000; i++ {
 		name := filepath.Join(dir, prefix+nextSuffix())
 		f, err = fs.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
-		if os.IsExist(err) {
+		if errors.Is(err, os.ErrExist) {
 			if nconflict++; nconflict > 10 {
 				randmu.Lock()
 				rand = reseed()
@@ -185,16 +186,16 @@ func TempDir(fs billy.Dir, dir, prefix string) (name string, err error) {
 	for i := 0; i < 10000; i++ {
 		try := filepath.Join(dir, prefix+nextSuffix())
 		err = fs.MkdirAll(try, 0700)
-		if os.IsExist(err) {
+		if errors.Is(err, os.ErrExist) {
 			if nconflict++; nconflict > 10 {
 				randmu.Lock()
 				rand = reseed()
 				randmu.Unlock()
 			}
 			continue
 		}
-		if os.IsNotExist(err) {
-			if _, err := os.Stat(dir); os.IsNotExist(err) {
+		if errors.Is(err, os.ErrNotExist) {
+			if _, err := os.Stat(dir); errors.Is(err, os.ErrNotExist) {
 				return "", err
 			}
 		}
@@ -272,7 +273,7 @@ func ReadFile(fs billy.Basic, name string) ([]byte, error) {
 		data = data[:len(data)+n]
 
 		if err != nil {
-			if err == io.EOF {
+			if errors.Is(err, io.EOF) {
 				err = nil
 			}