Add option in readDir to enable symlink following of dirs (#12668)

cmd/fs-v1.go

@@ -534,7 +534,7 @@ func (fs *FSObjects) ListBuckets(ctx context.Context) ([]BucketInfo, error) {
 		atomic.AddInt64(&fs.activeIOCount, -1)
 	}()
 
-	entries, err := readDir(fs.fsPath)
+	entries, err := readDirWithOpts(fs.fsPath, readDirOpts{count: -1, followDirSymlink: true})
 	if err != nil {
 		logger.LogIf(ctx, errDiskNotFound)
 		return nil, toObjectErr(errDiskNotFound)

cmd/os-readdir-common.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package cmd
+
+// Options for readDir function call
+type readDirOpts struct {
+	// The maximum number of entries to return
+	count int
+	// Follow directory symlink
+	followDirSymlink bool
+}
+
+// Return all the entries at the directory dirPath.
+func readDir(dirPath string) (entries []string, err error) {
+	return readDirWithOpts(dirPath, readDirOpts{count: -1})
+}
+
+// Return up to count entries at the directory dirPath.
+func readDirN(dirPath string, count int) (entries []string, err error) {
+	return readDirWithOpts(dirPath, readDirOpts{count: count})
+}

cmd/os-readdir_other.go

@@ -30,11 +30,6 @@ func access(name string) error {
 	return err
 }
 
-// Return all the entries at the directory dirPath.
-func readDir(dirPath string) (entries []string, err error) {
-	return readDirN(dirPath, -1)
-}
-
 // readDirFn applies the fn() function on each entries at dirPath, doesn't recurse into
 // the directory itself, if the dirPath doesn't exist this function doesn't return
 // an error.
@@ -90,8 +85,8 @@ func readDirFn(dirPath string, filter func(name string, typ os.FileMode) error)
 	return nil
 }
 
-// Return N entries at the directory dirPath. If count is -1, return all entries
+// Return entries at the directory dirPath.
-func readDirN(dirPath string, count int) (entries []string, err error) {
+func readDirWithOpts(dirPath string, opts readDirOpts) (entries []string, err error) {
 	d, err := Open(dirPath)
 	if err != nil {
 		return nil, osErrToFileErr(err)
@@ -99,12 +94,12 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 	defer d.Close()
 
 	maxEntries := 1000
-	if count > 0 && count < maxEntries {
+	if opts.count > 0 && opts.count < maxEntries {
 		maxEntries = count
 	}
 
 	done := false
-	remaining := count
+	remaining := opts.count
 
 	for !done {
 		// Read up to max number of entries.
@@ -115,7 +110,7 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 			}
 			return nil, osErrToFileErr(err)
 		}
-		if count > -1 {
+		if opts.count > -1 {
 			if remaining <= len(fis) {
 				fis = fis[:remaining]
 				done = true
@@ -136,7 +131,7 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 				}
 
 				// Ignore symlinked directories.
-				if fi.IsDir() {
+				if !opts.followDirSymlink && fi.IsDir() {
 					continue
 				}
 			}
@@ -147,7 +142,7 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 			} else if fi.Mode().IsRegular() {
 				entries = append(entries, fi.Name())
 			}
-			if count > 0 {
+			if opts.count > 0 {
 				remaining--
 			}
 		}

cmd/os-readdir_unix.go

@@ -98,11 +98,6 @@ func parseDirEnt(buf []byte) (consumed int, name []byte, typ os.FileMode, err er
 	return consumed, nameBuf[:nameLen], typ, nil
 }
 
-// Return all the entries at the directory dirPath.
-func readDir(dirPath string) (entries []string, err error) {
-	return readDirN(dirPath, -1)
-}
-
 // readDirFn applies the fn() function on each entries at dirPath, doesn't recurse into
 // the directory itself, if the dirPath doesn't exist this function doesn't return
 // an error.
@@ -184,7 +179,7 @@ func readDirFn(dirPath string, fn func(name string, typ os.FileMode) error) erro
 
 // Return count entries at the directory dirPath and all entries
 // if count is set to -1
-func readDirN(dirPath string, count int) (entries []string, err error) {
+func readDirWithOpts(dirPath string, opts readDirOpts) (entries []string, err error) {
 	f, err := Open(dirPath)
 	if err != nil {
 		return nil, osErrToFileErr(err)
@@ -202,6 +197,8 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 	boff := 0 // starting read position in buf
 	nbuf := 0 // end valid data in buf
 
+	count := opts.count
+
 	for count != 0 {
 		if boff >= nbuf {
 			boff = 0
@@ -242,7 +239,7 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 			}
 
 			// Ignore symlinked directories.
-			if typ&os.ModeSymlink == os.ModeSymlink && fi.IsDir() {
+			if !opts.followDirSymlink && typ&os.ModeSymlink == os.ModeSymlink && fi.IsDir() {
 				continue
 			}
 

cmd/os-readdir_windows.go

@@ -30,11 +30,6 @@ func access(name string) error {
 	return err
 }
 
-// Return all the entries at the directory dirPath.
-func readDir(dirPath string) (entries []string, err error) {
-	return readDirN(dirPath, -1)
-}
-
 // readDirFn applies the fn() function on each entries at dirPath, doesn't recurse into
 // the directory itself, if the dirPath doesn't exist this function doesn't return
 // an error.
@@ -118,8 +113,8 @@ func readDirFn(dirPath string, filter func(name string, typ os.FileMode) error)
 	return nil
 }
 
-// Return N entries at the directory dirPath. If count is -1, return all entries
+// Return N entries at the directory dirPath.
-func readDirN(dirPath string, count int) (entries []string, err error) {
+func readDirWithOpts(dirPath string, opts readDirOpts) (entries []string, err error) {
 	f, err := os.Open(dirPath)
 	if err != nil {
 		return nil, osErrToFileErr(err)
@@ -138,6 +133,7 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 	data := &syscall.Win32finddata{}
 	handle := syscall.Handle(f.Fd())
 
+	count := opts.count
 	for count != 0 {
 		e := syscall.FindNextFile(handle, data)
 		if e != nil {
@@ -172,7 +168,7 @@ func readDirN(dirPath string, count int) (entries []string, err error) {
 				return nil, err
 			}
 
-			if fi.IsDir() {
+			if !opts.followDirSymlink && fi.IsDir() {
 				// directory symlinks are ignored.
 				continue
 			}