From b1c0c32ba6b43bbdeaecbb66ca463b1a1e24c6fb Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Mon, 27 Apr 2020 06:30:12 -0700
Subject: [PATCH] fix: ignore symlinks in backend filesystems (#9457)

fixes #9419
---
 cmd/posix-list-dir_other.go   | 22 +---------------------
 cmd/posix-list-dir_test.go    |  2 +-
 cmd/posix-list-dir_unix.go    |  7 +++++--
 cmd/posix-list-dir_windows.go | 29 ++++++-----------------------
 4 files changed, 13 insertions(+), 47 deletions(-)

diff --git a/cmd/posix-list-dir_other.go b/cmd/posix-list-dir_other.go
index 5bdfaa1e6..febd16f48 100644
--- a/cmd/posix-list-dir_other.go
+++ b/cmd/posix-list-dir_other.go
@@ -21,10 +21,7 @@ package cmd
 import (
 	"io"
 	"os"
-	"path"
 	"strings"
-
-	"github.com/minio/minio/cmd/logger"
 )
 
 // Return all the entries at the directory dirPath.
@@ -111,25 +108,8 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 			}
 		}
 		for _, fi := range fis {
-			// Stat symbolic link and follow to get the final value.
+			// Not need to follow symlink.
 			if fi.Mode()&os.ModeSymlink == os.ModeSymlink {
-				var st os.FileInfo
-				st, err = os.Stat(path.Join(dirPath, fi.Name()))
-				if err != nil {
-					reqInfo := (&logger.ReqInfo{}).AppendTags("path", path.Join(dirPath, fi.Name()))
-					ctx := logger.SetReqInfo(GlobalContext, reqInfo)
-					logger.LogIf(ctx, err)
-					continue
-				}
-				// Append to entries if symbolic link exists and is valid.
-				if st.IsDir() {
-					entries = append(entries, fi.Name()+SlashSeparator)
-				} else if st.Mode().IsRegular() {
-					entries = append(entries, fi.Name())
-				}
-				if count > 0 {
-					remaining--
-				}
 				continue
 			}
 			if fi.Mode().IsDir() {
diff --git a/cmd/posix-list-dir_test.go b/cmd/posix-list-dir_test.go
index 1ad0225cd..2c6afb2b5 100644
--- a/cmd/posix-list-dir_test.go
+++ b/cmd/posix-list-dir_test.go
@@ -149,7 +149,7 @@ func setupTestReadDirSymlink(t *testing.T) (testResults []result) {
 		}
 		// Add to entries.
 		entries = append(entries, name1)
-		entries = append(entries, name2)
+		// Symlinks are ignored.
 	}
 	if err := os.MkdirAll(filepath.Join(dir, "mydir"), 0777); err != nil {
 		t.Fatalf("Unable to create \"mydir\", %s", err)
diff --git a/cmd/posix-list-dir_unix.go b/cmd/posix-list-dir_unix.go
index c4d101f98..be903b6cd 100644
--- a/cmd/posix-list-dir_unix.go
+++ b/cmd/posix-list-dir_unix.go
@@ -172,8 +172,8 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 		// Fallback for filesystems (like old XFS) that don't
 		// support Dirent.Type and have DT_UNKNOWN (0) there
 		// instead.
-		if typ == unexpectedFileMode || typ&os.ModeSymlink == os.ModeSymlink {
-			fi, err := os.Stat(pathJoin(dirPath, name))
+		if typ == unexpectedFileMode {
+			fi, err := os.Lstat(pathJoin(dirPath, name))
 			if err != nil {
 				// It got deleted in the meantime, not found
 				// or returns too many symlinks ignore this
@@ -186,6 +186,9 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 			}
 			typ = fi.Mode() & os.ModeType
 		}
+		if typ&os.ModeSymlink == os.ModeSymlink {
+			continue
+		}
 		if typ.IsRegular() {
 			entries = append(entries, name)
 		} else if typ.IsDir() {
diff --git a/cmd/posix-list-dir_windows.go b/cmd/posix-list-dir_windows.go
index 158221ff9..cf211c842 100644
--- a/cmd/posix-list-dir_windows.go
+++ b/cmd/posix-list-dir_windows.go
@@ -121,17 +121,16 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 	data := &syscall.Win32finddata{}
 
 	for count != 0 {
-		e := syscall.FindNextFile(syscall.Handle(d.Fd()), data)
-		if e != nil {
-			if e == syscall.ERROR_NO_MORE_FILES {
+		err = syscall.FindNextFile(syscall.Handle(d.Fd()), data)
+		if err != nil {
+			if err == syscall.ERROR_NO_MORE_FILES {
 				break
 			} else {
-				err = &os.PathError{
+				return nil, &os.PathError{
 					Op:   "FindNextFile",
 					Path: dirPath,
-					Err:  e,
+					Err:  err,
 				}
-				return
 			}
 		}
 		name := syscall.UTF16ToString(data.FileName[0:])
@@ -140,23 +139,7 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 		}
 		switch {
 		case data.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT != 0:
-			// If its symbolic link, follow the link using os.Stat()
-			var fi os.FileInfo
-			fi, err = os.Stat(pathJoin(dirPath, name))
-			if err != nil {
-				// If file does not exist, we continue and skip it.
-				// Could happen if it was deleted in the middle while
-				// this list was being performed.
-				if os.IsNotExist(err) {
-					continue
-				}
-				return nil, err
-			}
-			if fi.IsDir() {
-				entries = append(entries, name+SlashSeparator)
-			} else if fi.Mode().IsRegular() {
-				entries = append(entries, name)
-			}
+			continue
 		case data.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY != 0:
 			entries = append(entries, name+SlashSeparator)
 		default: