From 62c3df0ca3c6089d42368bfb3768c167278b078e Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Wed, 5 Apr 2023 14:36:49 -0700
Subject: [PATCH] fix: directory listing on Go 1.20 windows (#16976)

---
 .github/workflows/go-lint.yml |  7 +---
 cmd/os_windows.go             | 69 +++++++++++++++--------------------
 2 files changed, 30 insertions(+), 46 deletions(-)

diff --git a/.github/workflows/go-lint.yml b/.github/workflows/go-lint.yml
index 514ea6eb2..c47b5665f 100644
--- a/.github/workflows/go-lint.yml
+++ b/.github/workflows/go-lint.yml
@@ -20,13 +20,8 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        go-version: [1.20.x, 1.19.x]
+        go-version: [1.20.x]
         os: [ubuntu-latest, windows-latest]
-        exclude:
-          - os: ubuntu-latest
-            go-version: 1.19.x
-          - os: windows-latest
-            go-version: 1.20.x
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-go@v3
diff --git a/cmd/os_windows.go b/cmd/os_windows.go
index 0c2e236f9..ce9d1c2ee 100644
--- a/cmd/os_windows.go
+++ b/cmd/os_windows.go
@@ -21,8 +21,8 @@
 package cmd
 
 import (
-	"io"
 	"os"
+	"path/filepath"
 	"syscall"
 )
 
@@ -39,38 +39,32 @@ func osMkdirAll(dirPath string, perm os.FileMode) error {
 // the directory itself, if the dirPath doesn't exist this function doesn't return
 // an error.
 func readDirFn(dirPath string, filter func(name string, typ os.FileMode) error) error {
-	f, err := Open(dirPath)
+	// Ensure we don't pick up files as directories.
+	globAll := filepath.Clean(dirPath) + `\*`
+	globAllP, err := syscall.UTF16PtrFromString(globAll)
 	if err != nil {
-		if osErrToFileErr(err) == errFileNotFound {
-			return nil
-		}
-		return osErrToFileErr(err)
+		return errInvalidArgument
 	}
-	defer f.Close()
-
-	// Check if file or dir. This is the quickest way.
-	// Do not remove this check, on windows syscall.FindNextFile
-	// would throw an exception if Fd() points to a file
-	// instead of a directory, we need to quickly fail
-	// in such situations - this workadound is expected.
-	if _, err = f.Seek(0, io.SeekStart); err == nil {
+	data := &syscall.Win32finddata{}
+	handle, err := syscall.FindFirstFile(globAllP, data)
+	if err != nil {
+		// Fails on file not found and when not a directory.
 		return errFileNotFound
 	}
+	defer syscall.CloseHandle(handle)
 
-	data := &syscall.Win32finddata{}
-	for {
-		e := syscall.FindNextFile(syscall.Handle(f.Fd()), data)
-		if e != nil {
-			if e == syscall.ERROR_NO_MORE_FILES {
+	for ; ; err = syscall.FindNextFile(handle, data) {
+		if err != nil {
+			if err == syscall.ERROR_NO_MORE_FILES {
 				break
 			} else {
-				if isSysErrPathNotFound(e) {
+				if isSysErrPathNotFound(err) {
 					return nil
 				}
 				err = osErrToFileErr(&os.PathError{
 					Op:   "FindNextFile",
 					Path: dirPath,
-					Err:  e,
+					Err:  err,
 				})
 				if err == errFileNotFound {
 					return nil
@@ -109,7 +103,7 @@ func readDirFn(dirPath string, filter func(name string, typ os.FileMode) error)
 			typ = os.ModeDir
 		}
 
-		if e = filter(name, typ); e == errDoneForNow {
+		if err = filter(name, typ); err == errDoneForNow {
 			// filtering requested to return by caller.
 			return nil
 		}
@@ -120,35 +114,30 @@ func readDirFn(dirPath string, filter func(name string, typ os.FileMode) error)
 
 // Return N entries at the directory dirPath.
 func readDirWithOpts(dirPath string, opts readDirOpts) (entries []string, err error) {
-	f, err := Open(dirPath)
+	// Ensure we don't pick up files as directories.
+	globAll := filepath.Clean(dirPath) + `\*`
+	globAllP, err := syscall.UTF16PtrFromString(globAll)
 	if err != nil {
-		return nil, osErrToFileErr(err)
+		return nil, errInvalidArgument
 	}
-	defer f.Close()
-
-	// Check if file or dir. This is the quickest way.
-	// Do not remove this check, on windows syscall.FindNextFile
-	// would throw an exception if Fd() points to a file
-	// instead of a directory, we need to quickly fail
-	// in such situations - this workadound is expected.
-	if _, err = f.Seek(0, io.SeekStart); err == nil {
+	data := &syscall.Win32finddata{}
+	handle, err := syscall.FindFirstFile(globAllP, data)
+	if err != nil {
+		// Fails on file not found and when not a directory.
 		return nil, errFileNotFound
 	}
-
-	data := &syscall.Win32finddata{}
-	handle := syscall.Handle(f.Fd())
+	defer syscall.CloseHandle(handle)
 
 	count := opts.count
-	for count != 0 {
-		e := syscall.FindNextFile(handle, data)
-		if e != nil {
-			if e == syscall.ERROR_NO_MORE_FILES {
+	for ; count != 0; err = syscall.FindNextFile(handle, data) {
+		if err != nil {
+			if err == syscall.ERROR_NO_MORE_FILES {
 				break
 			} else {
 				return nil, osErrToFileErr(&os.PathError{
 					Op:   "FindNextFile",
 					Path: dirPath,
-					Err:  e,
+					Err:  err,
 				})
 			}
 		}