os: implement readdir for darwin

Author: dkegel-fastly

src/os/dir.go

@@ -0,0 +1,73 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+type readdirMode int
+
+const (
+	readdirName readdirMode = iota
+	readdirDirEntry
+	readdirFileInfo
+)
+
+// Readdir reads the contents of the directory associated with file and
+// returns a slice of up to n FileInfo values, as would be returned
+// by Lstat, in directory order. Subsequent calls on the same file will yield
+// further FileInfos.
+//
+// If n > 0, Readdir returns at most n FileInfo structures. In this case, if
+// Readdir returns an empty slice, it will return a non-nil error
+// explaining why. At the end of a directory, the error is io.EOF.
+//
+// If n <= 0, Readdir returns all the FileInfo from the directory in
+// a single slice. In this case, if Readdir succeeds (reads all
+// the way to the end of the directory), it returns the slice and a
+// nil error. If it encounters an error before the end of the
+// directory, Readdir returns the FileInfo read until that point
+// and a non-nil error.
+//
+// Most clients are better served by the more efficient ReadDir method.
+func (f *File) Readdir(n int) ([]FileInfo, error) {
+	if f == nil {
+		return nil, ErrInvalid
+	}
+	_, _, infos, err := f.readdir(n, readdirFileInfo)
+	if infos == nil {
+		// Readdir has historically always returned a non-nil empty slice, never nil,
+		// even on error (except misuse with nil receiver above).
+		// Keep it that way to avoid breaking overly sensitive callers.
+		infos = []FileInfo{}
+	}
+	return infos, err
+}
+
+// Readdirnames reads the contents of the directory associated with file
+// and returns a slice of up to n names of files in the directory,
+// in directory order. Subsequent calls on the same file will yield
+// further names.
+//
+// If n > 0, Readdirnames returns at most n names. In this case, if
+// Readdirnames returns an empty slice, it will return a non-nil error
+// explaining why. At the end of a directory, the error is io.EOF.
+//
+// If n <= 0, Readdirnames returns all the names from the directory in
+// a single slice. In this case, if Readdirnames succeeds (reads all
+// the way to the end of the directory), it returns the slice and a
+// nil error. If it encounters an error before the end of the
+// directory, Readdirnames returns the names read until that point and
+// a non-nil error.
+func (f *File) Readdirnames(n int) (names []string, err error) {
+	if f == nil {
+		return nil, ErrInvalid
+	}
+	names, _, _, err = f.readdir(n, readdirName)
+	if names == nil {
+		// Readdirnames has historically always returned a non-nil empty slice, never nil,
+		// even on error (except misuse with nil receiver above).
+		// Keep it that way to avoid breaking overly sensitive callers.
+		names = []string{}
+	}
+	return names, err
+}

src/os/dir_darwin.go

@@ -0,0 +1,132 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+import (
+	"io"
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+// Auxiliary information if the File describes a directory
+type dirInfo struct {
+	dir uintptr // Pointer to DIR structure from dirent.h
+}
+
+func (d *dirInfo) close() {
+	if d.dir == 0 {
+		return
+	}
+	closedir(d.dir)
+	d.dir = 0
+}
+
+func (f *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
+	if f.dirinfo == nil {
+		dir, call, errno := darwinOpenDir(syscallFd(f.handle.(unixFileHandle)))
+		if errno != nil {
+			return nil, nil, nil, &PathError{Op: call, Path: f.name, Err: errno}
+		}
+		f.dirinfo = &dirInfo{
+			dir: dir,
+		}
+	}
+	d := f.dirinfo
+
+	size := n
+	if size <= 0 {
+		size = 100
+		n = -1
+	}
+
+	var dirent syscall.Dirent
+	var entptr *syscall.Dirent
+	for len(names)+len(dirents)+len(infos) < size || n == -1 {
+		if errno := readdir_r(d.dir, &dirent, &entptr); errno != 0 {
+			if errno == syscall.EINTR {
+				continue
+			}
+			return names, dirents, infos, &PathError{Op: "readdir", Path: f.name, Err: errno}
+		}
+		if entptr == nil { // EOF
+			break
+		}
+		if dirent.Ino == 0 {
+			continue
+		}
+		name := (*[len(syscall.Dirent{}.Name)]byte)(unsafe.Pointer(&dirent.Name))[:]
+		for i, c := range name {
+			if c == 0 {
+				name = name[:i]
+				break
+			}
+		}
+		// Check for useless names before allocating a string.
+		if string(name) == "." || string(name) == ".." {
+			continue
+		}
+		if mode == readdirName {
+			names = append(names, string(name))
+		} else if mode == readdirDirEntry {
+			typ := dtToType(dirent.Type)
+			de, err := newUnixDirent(f.name, string(name), typ)
+			if IsNotExist(err) {
+				// File disappeared between readdir and stat.
+				// Treat as if it didn't exist.
+				continue
+			}
+			if err != nil {
+				return nil, dirents, nil, err
+			}
+			dirents = append(dirents, de)
+		} else {
+			info, err := lstat(f.name + "/" + string(name))
+			if IsNotExist(err) {
+				// File disappeared between readdir + stat.
+				// Treat as if it didn't exist.
+				continue
+			}
+			if err != nil {
+				return nil, nil, infos, err
+			}
+			infos = append(infos, info)
+		}
+		runtime.KeepAlive(f)
+	}
+
+	if n > 0 && len(names)+len(dirents)+len(infos) == 0 {
+		return nil, nil, nil, io.EOF
+	}
+	return names, dirents, infos, nil
+}
+
+func dtToType(typ uint8) FileMode {
+	switch typ {
+	case syscall.DT_BLK:
+		return ModeDevice
+	case syscall.DT_CHR:
+		return ModeDevice | ModeCharDevice
+	case syscall.DT_DIR:
+		return ModeDir
+	case syscall.DT_FIFO:
+		return ModeNamedPipe
+	case syscall.DT_LNK:
+		return ModeSymlink
+	case syscall.DT_REG:
+		return 0
+	case syscall.DT_SOCK:
+		return ModeSocket
+	}
+	return ^FileMode(0)
+}
+
+// Implemented in syscall/syscall_darwin.go.
+
+//go:linkname closedir syscall.closedir
+func closedir(dir uintptr) (err error)
+
+//go:linkname readdir_r syscall.readdir_r
+func readdir_r(dir uintptr, entry *syscall.Dirent, result **syscall.Dirent) (res syscall.Errno)

src/os/dir_other.go

@@ -0,0 +1,15 @@
+// +build baremetal wasm,!wasi
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+import (
+	"syscall"
+)
+
+func (f *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
+	return nil, nil, nil, &PathError{Op: "readdir unimplemented", Err: syscall.ENOTDIR}
+}

src/os/dir_unix.go

@@ -0,0 +1,20 @@
+// +build linux,!baremetal
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+import (
+	"syscall"
+)
+
+// Auxiliary information if the File describes a directory
+type dirInfo struct {
+	// TODO
+}
+
+func (f *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
+	return nil, nil, nil, &PathError{Op: "readdir unimplemented", Err: syscall.ENOTDIR}
+}

src/os/dir_windows.go

@@ -0,0 +1,13 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+import (
+	"syscall"
+)
+
+func (file *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
+	return nil, nil, nil, &PathError{Op: "readdir unimplemented", Path: file.name, Err: syscall.ENOTDIR}
+}

src/os/file.go

@@ -24,6 +24,9 @@ const (
 	SEEK_END int = io.SeekEnd
 )
 
+// lstat is overridden in tests.
+var lstat = Lstat
+
 // Mkdir creates a directory. If the operation fails, it will return an error of
 // type *PathError.
 func Mkdir(path string, perm FileMode) error {
@@ -62,12 +65,6 @@ func RemoveAll(path string) error {
 	return ErrNotImplemented
 }
 
-// File represents an open file descriptor.
-type File struct {
-	handle FileHandle
-	name   string
-}
-
 // Name returns the name of the file with which it was opened.
 func (f *File) Name() string {
 	return f.name
@@ -84,7 +81,7 @@ func OpenFile(name string, flag int, perm FileMode) (*File, error) {
 	if err != nil {
 		return nil, &PathError{"open", name, err}
 	}
-	return &File{name: name, handle: handle}, nil
+	return NewFile(handle, name), nil
 }
 
 // Open opens the file named for reading.
@@ -166,16 +163,6 @@ func (f *File) Close() (err error) {
 	return
 }
 
-// Readdir is a stub, not yet implemented
-func (f *File) Readdir(n int) ([]FileInfo, error) {
-	return nil, &PathError{"readdir", f.name, ErrNotImplemented}
-}
-
-// Readdirnames is a stub, not yet implemented
-func (f *File) Readdirnames(n int) (names []string, err error) {
-	return nil, &PathError{"readdirnames", f.name, ErrNotImplemented}
-}
-
 // Seek is a stub, not yet implemented
 func (f *File) Seek(offset int64, whence int) (ret int64, err error) {
 	return 0, &PathError{"seek", f.name, ErrNotImplemented}

src/os/file_anyos.go

@@ -20,9 +20,9 @@ func init() {
 // Stdin, Stdout, and Stderr are open Files pointing to the standard input,
 // standard output, and standard error file descriptors.
 var (
-	Stdin  = &File{unixFileHandle(syscall.Stdin), "/dev/stdin"}
-	Stdout = &File{unixFileHandle(syscall.Stdout), "/dev/stdout"}
-	Stderr = &File{unixFileHandle(syscall.Stderr), "/dev/stderr"}
+	Stdin  = NewFile(unixFileHandle(syscall.Stdin), "/dev/stdin")
+	Stdout = NewFile(unixFileHandle(syscall.Stdout), "/dev/stdout")
+	Stderr = NewFile(unixFileHandle(syscall.Stderr), "/dev/stderr")
 )
 
 const DevNull = "/dev/null"

src/os/file_go_116.go

@@ -5,22 +5,14 @@ package os
 import (
 	"io"
 	"io/fs"
+	"sort"
 )
 
 type (
-	DirEntry = fs.DirEntry
 	FileMode = fs.FileMode
 	FileInfo = fs.FileInfo
 )
 
-func (f *File) ReadDir(n int) ([]DirEntry, error) {
-	return nil, &PathError{"ReadDir", f.name, ErrNotImplemented}
-}
-
-func ReadDir(name string) ([]DirEntry, error) {
-	return nil, &PathError{"ReadDir", name, ErrNotImplemented}
-}
-
 // The followings are copied from Go 1.16 official implementation:
 // https://github.com/golang/go/blob/go1.16/src/os/file.go
 
@@ -111,3 +103,52 @@ const (
 
 	ModePerm = fs.ModePerm // Unix permission bits, 0o777
 )
+
+// TODO: move to dir.go once we drop go 1.15
+
+// A DirEntry is an entry read from a directory
+// (using the ReadDir function or a File's ReadDir method).
+type DirEntry = fs.DirEntry
+
+// ReadDir reads the contents of the directory associated with the file f
+// and returns a slice of DirEntry values in directory order.
+// Subsequent calls on the same file will yield later DirEntry records in the directory.
+//
+// If n > 0, ReadDir returns at most n DirEntry records.
+// In this case, if ReadDir returns an empty slice, it will return an error explaining why.
+// At the end of a directory, the error is io.EOF.
+//
+// If n <= 0, ReadDir returns all the DirEntry records remaining in the directory.
+// When it succeeds, it returns a nil error (not io.EOF).
+func (f *File) ReadDir(n int) ([]DirEntry, error) {
+	if f == nil {
+		return nil, ErrInvalid
+	}
+	_, dirents, _, err := f.readdir(n, readdirDirEntry)
+	if dirents == nil {
+		// Match Readdir and Readdirnames: don't return nil slices.
+		dirents = []DirEntry{}
+	}
+	return dirents, err
+}
+
+// testingForceReadDirLstat forces ReadDir to call Lstat, for testing that code path.
+// This can be difficult to provoke on some Unix systems otherwise.
+var testingForceReadDirLstat bool
+
+// ReadDir reads the named directory,
+// returning all its directory entries sorted by filename.
+// If an error occurs reading the directory,
+// ReadDir returns the entries it was able to read before the error,
+// along with the error.
+func ReadDir(name string) ([]DirEntry, error) {
+	f, err := Open(name)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	dirs, err := f.ReadDir(-1)
+	sort.Slice(dirs, func(i, j int) bool { return dirs[i].Name() < dirs[j].Name() })
+	return dirs, err
+}