General improvements to memfs

.github/dependabot.yaml

@@ -0,0 +1,15 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    commit-message:
+      prefix: "build"
+
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    commit-message:
+      prefix: "build"

.github/workflows/test.yml

@@ -5,15 +5,15 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.20.x,1.21.x]
+        go-version: [1.20.x,1.21.x,1.22.x]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
     - name: Install Go
       uses: actions/setup-go@v3
       with:
         go-version: ${{ matrix.go-version }}
-    - name: Checkout code
-      uses: actions/checkout@v3
     - name: Test
       run: make test

.github/workflows/test_js.yml

@@ -5,9 +5,12 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.20.x,1.21.x]
+        go-version: [1.21.x,1.22.x]
     runs-on: ubuntu-latest
     steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
+
     - name: Install Go
       uses: actions/setup-go@v3
       with:
@@ -18,9 +21,6 @@ jobs:
         go install github.com/agnivade/wasmbrowsertest@latest
         mv $HOME/go/bin/wasmbrowsertest $HOME/go/bin/go_js_wasm_exec
 
-    - name: Checkout code
-      uses: actions/checkout@v3
-
     - name: Test
       run: go test -exec="$HOME/go/bin/go_js_wasm_exec" ./...
       env:

.github/workflows/test_wasip1.yml

@@ -5,9 +5,12 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.21.x]
+        go-version: [1.21.x,1.22.x]
     runs-on: ubuntu-latest
     steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
+
     - name: Install Go
       uses: actions/setup-go@v3
       with:
@@ -17,8 +20,5 @@ jobs:
       run: |
         go install github.com/stealthrocket/wasi-go/cmd/wasirun@latest
 
-    - name: Checkout code
-      uses: actions/checkout@v3
-
     - name: Test
-      run: make wasitest
+      run: make wasitest

go.mod

@@ -1,19 +1,22 @@
 module github.com/go-git/go-billy/v5
 
 // go-git supports the last 3 stable Go versions.
-go 1.19
+go 1.20
 
 require (
 	github.com/cyphar/filepath-securejoin v0.2.4
 	github.com/onsi/gomega v1.27.10
+	github.com/stretchr/testify v1.9.0
 	golang.org/x/sys v0.18.0
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c
 )
 
 require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/google/go-cmp v0.5.9 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/kr/text v0.2.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rogpeppe/go-internal v1.11.0 // indirect
 	golang.org/x/net v0.23.0 // indirect
 	golang.org/x/text v0.14.0 // indirect

go.sum

@@ -1,6 +1,8 @@
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/cyphar/filepath-securejoin v0.2.4 h1:Ugdm7cg7i6ZK6x3xDF1oEu1nfkyfH53EtKeQYTC3kyg=
 github.com/cyphar/filepath-securejoin v0.2.4/go.mod h1:aPGpWjXOXUn2NCNjFvBE6aRxGGx79pTxQpKOJNYHHl4=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-logr/logr v1.2.4 h1:g01GSCwiDw2xSZfjJ2/T9M+S6pFdcNtFYsp+Y43HYDQ=
 github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572 h1:tfuBGBXKqDEevZMzYi5KSi8KkcZtzBcTgAUUtapy0OI=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
@@ -17,9 +19,13 @@ github.com/onsi/ginkgo/v2 v2.11.0 h1:WgqUCUt/lT6yXoQ8Wef0fsNn5cAuMK7+KT9UFRz2tcU
 github.com/onsi/gomega v1.27.10 h1:naR28SdDFlqrG6kScpT8VWpu1xWY5nJRCF3XaYyBjhI=
 github.com/onsi/gomega v1.27.10/go.mod h1:RsS8tutOdbdgzbPtzzATp12yT7kM5I5aElG3evPbQ0M=
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M=
 github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 golang.org/x/net v0.23.0 h1:7EYJ93RZ9vYSZAIb2x3lnuvqO5zneoD6IvWjuhfxjTs=
 golang.org/x/net v0.23.0/go.mod h1:JKghWKKOSdJwpW2GEx0Ja7fmaKnMsbu+MWVZTokSYmg=
 golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=

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
 
@@ -59,10 +61,9 @@ func (fs *Memory) OpenFile(filename string, flag int, perm os.FileMode) (billy.F
 		}
 
 		if target, isLink := fs.resolveLink(filename, f); isLink {
-			if target == filename {
-				return nil, os.ErrNotExist
+			if target != filename {
+				return fs.OpenFile(target, flag, perm)
 			}
-			return fs.OpenFile(target, flag, perm)
 		}
 	}
 
@@ -73,8 +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
@@ -92,7 +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) {
@@ -136,7 +135,9 @@ func (a ByName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 func (fs *Memory) ReadDir(path string) ([]os.FileInfo, error) {
 	if f, has := fs.s.Get(path); has {
 		if target, isLink := fs.resolveLink(path, f); isLink {
-			return fs.ReadDir(target)
+			if target != path {
+				return fs.ReadDir(target)
+			}
 		}
 	} else {
 		return nil, &os.PathError{Op: "open", Path: path, Err: syscall.ENOENT}
@@ -176,17 +177,19 @@ 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...)
 }
 
 func (fs *Memory) Symlink(target, link string) error {
-	_, err := fs.Stat(link)
+	_, err := fs.Lstat(link)
 	if err == nil {
 		return os.ErrExist
 	}
 
-	if !os.IsNotExist(err) {
+	if !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
 
@@ -237,7 +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
 	}