build: resolve 8.3 filename format to long one on Windows

build/git.go

@@ -46,9 +46,9 @@ func getGitAttributes(ctx context.Context, contextPath string, dockerfilePath st
 	if filepath.IsAbs(contextPath) {
 		wd = contextPath
 	} else {
-		cwd, _ := os.Getwd()
-		wd, _ = filepath.Abs(filepath.Join(cwd, contextPath))
+		wd, _ = filepath.Abs(filepath.Join(getWd(), contextPath))
 	}
+	wd = gitutil.SanitizePath(wd)
 
 	gitc, err := gitutil.New(gitutil.WithContext(ctx), gitutil.WithWorkingDir(wd))
 	if err != nil {
@@ -104,8 +104,7 @@ func getGitAttributes(ctx context.Context, contextPath string, dockerfilePath st
 			dockerfilePath = filepath.Join(wd, "Dockerfile")
 		}
 		if !filepath.IsAbs(dockerfilePath) {
-			cwd, _ := os.Getwd()
-			dockerfilePath = filepath.Join(cwd, dockerfilePath)
+			dockerfilePath = filepath.Join(getWd(), dockerfilePath)
 		}
 		if r, err := filepath.Rel(root, dockerfilePath); err == nil && !strings.HasPrefix(r, "..") {
 			res["label:"+DockerfileLabel] = r
@@ -125,9 +124,21 @@ func getGitAttributes(ctx context.Context, contextPath string, dockerfilePath st
 			if err != nil {
 				continue
 			}
+			if lp, err := getLongPathName(dir); err == nil {
+				dir = lp
+			}
+			dir = gitutil.SanitizePath(dir)
 			if r, err := filepath.Rel(root, dir); err == nil && !strings.HasPrefix(r, "..") {
 				so.FrontendAttrs["vcs:localdir:"+k] = r
 			}
 		}
 	}, nil
 }
+
+func getWd() string {
+	wd, _ := os.Getwd()
+	if lp, err := getLongPathName(wd); err == nil {
+		return lp
+	}
+	return wd
+}

build/git_unix.go

@@ -0,0 +1,9 @@
+//go:build !windows
+// +build !windows
+
+package build
+
+// getLongPathName is a no-op on non-Windows platforms.
+func getLongPathName(path string) (string, error) {
+	return path, nil
+}

build/git_windows.go

@@ -0,0 +1,26 @@
+package build
+
+import "golang.org/x/sys/windows"
+
+// getLongPathName converts Windows short pathnames to full pathnames.
+// For example C:\Users\ADMIN~1 --> C:\Users\Administrator.
+func getLongPathName(path string) (string, error) {
+	// See https://groups.google.com/forum/#!topic/golang-dev/1tufzkruoTg
+	p, err := windows.UTF16FromString(path)
+	if err != nil {
+		return "", err
+	}
+	b := p // GetLongPathName says we can reuse buffer
+	n, err := windows.GetLongPathName(&p[0], &b[0], uint32(len(b)))
+	if err != nil {
+		return "", err
+	}
+	if n > uint32(len(b)) {
+		b = make([]uint16, n)
+		_, err = windows.GetLongPathName(&p[0], &b[0], uint32(len(b)))
+		if err != nil {
+			return "", err
+		}
+	}
+	return windows.UTF16ToString(b), nil
+}

go.mod

@@ -46,6 +46,7 @@ require (
 	go.opentelemetry.io/otel/trace v1.19.0
 	golang.org/x/mod v0.11.0
 	golang.org/x/sync v0.3.0
+	golang.org/x/sys v0.15.0
 	golang.org/x/term v0.15.0
 	google.golang.org/grpc v1.58.3
 	gopkg.in/yaml.v3 v3.0.1
@@ -152,7 +153,6 @@ require (
 	golang.org/x/exp v0.0.0-20230713183714-613f0c0eb8a1 // indirect
 	golang.org/x/net v0.17.0 // indirect
 	golang.org/x/oauth2 v0.10.0 // indirect
-	golang.org/x/sys v0.15.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	golang.org/x/time v0.3.0 // indirect
 	golang.org/x/tools v0.10.0 // indirect

util/gitutil/gitutil.go

@@ -70,7 +70,7 @@ func (c *Git) RootDir() (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return sanitizePath(root), nil
+	return SanitizePath(root), nil
 }
 
 func (c *Git) GitDir() (string, error) {

util/gitutil/path_unix.go → util/gitutil/path.go

@@ -45,7 +45,7 @@ func gitPath(wd string) (string, error) {
 
 var windowsPathRegex = regexp.MustCompile(`^[A-Za-z]:[\\/].*$`)
 
-func sanitizePath(path string) string {
+func SanitizePath(path string) string {
 	// If we're running in WSL, we need to convert Windows paths to Unix paths.
 	// This is because the git binary can be invoked through `git.exe` and
 	// therefore returns Windows paths.

util/gitutil/path_unix_test.go

@@ -10,10 +10,10 @@ import (
 )
 
 func TestSanitizePathUnix(t *testing.T) {
-	assert.Equal(t, "/home/foobar", sanitizePath("/home/foobar"))
+	assert.Equal(t, "/home/foobar", SanitizePath("/home/foobar"))
 }
 
 func TestSanitizePathWSL(t *testing.T) {
 	t.Setenv("WSL_DISTRO_NAME", "Ubuntu")
-	assert.Equal(t, "/mnt/c/Users/foobar", sanitizePath("C:\\Users\\foobar"))
+	assert.Equal(t, "/mnt/c/Users/foobar", SanitizePath("C:\\Users\\foobar"))
 }

util/gitutil/path_windows.go

@@ -9,6 +9,6 @@ func gitPath(wd string) (string, error) {
 	return exec.LookPath("git.exe")
 }
 
-func sanitizePath(path string) string {
+func SanitizePath(path string) string {
 	return filepath.ToSlash(filepath.Clean(path))
 }

util/gitutil/path_windows_test.go

@@ -7,5 +7,5 @@ import (
 )
 
 func TestSanitizePathWindows(t *testing.T) {
-	assert.Equal(t, "C:\\Users\\foobar", sanitizePath("C:/Users/foobar"))
+	assert.Equal(t, "C:\\Users\\foobar", SanitizePath("C:/Users/foobar"))
 }