os: make Readdir & Readdirnames return os.EOF at end

Fixes #678

R=rsc, r, alex.brainman, bsiegert, jdpoirier
CC=golang-dev
https://golang.org/cl/4536058

src/pkg/os/dir_unix.go

@@ -12,30 +12,40 @@ const (
 	blockSize = 4096
 )
 
-// Readdirnames reads the contents of the directory associated with file and
-// returns an array of up to count names, in directory order.  Subsequent
-// calls on the same file will yield further names.
-// A negative count means to read until EOF.
-// Readdirnames returns the array and an Error, if any.
-func (file *File) Readdirnames(count int) (names []string, err Error) {
+// Readdirnames reads and returns a slice of names from the directory f.
+//
+// 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 os.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 os.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 this file has no dirinfo, create one.
-	if file.dirinfo == nil {
-		file.dirinfo = new(dirInfo)
+	if f.dirinfo == nil {
+		f.dirinfo = new(dirInfo)
 		// The buffer must be at least a block long.
-		file.dirinfo.buf = make([]byte, blockSize)
+		f.dirinfo.buf = make([]byte, blockSize)
 	}
-	d := file.dirinfo
-	size := count
+	d := f.dirinfo
+	wantAll := n < 0
+
+	size := n
 	if size < 0 {
 		size = 100
 	}
+
 	names = make([]string, 0, size) // Empty with room to grow.
-	for count != 0 {
+	for n != 0 {
 		// Refill the buffer if necessary
 		if d.bufp >= d.nbuf {
 			d.bufp = 0
 			var errno int
-			d.nbuf, errno = syscall.ReadDirent(file.fd, d.buf)
+			d.nbuf, errno = syscall.ReadDirent(f.fd, d.buf)
 			if errno != 0 {
 				return names, NewSyscallError("readdirent", errno)
 			}
@@ -46,9 +56,12 @@ func (file *File) Readdirnames(count int) (names []string, err Error) {
 
 		// Drain the buffer
 		var nb, nc int
-		nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], count, names)
+		nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], n, names)
 		d.bufp += nb
-		count -= nc
+		n -= nc
+	}
+	if !wantAll && len(names) == 0 {
+		return names, EOF
 	}
 	return names, nil
 }

src/pkg/os/dir_windows.go

@@ -4,14 +4,16 @@
 
 package os
 
-func (file *File) Readdirnames(count int) (names []string, err Error) {
-	fis, e := file.Readdir(count)
-	if e != nil {
-		return nil, e
+func (file *File) Readdirnames(n int) (names []string, err Error) {
+	fis, err := file.Readdir(n)
+	// If n > 0 and we get an error, we return now.
+	// If n < 0, we return whatever we got + any error.
+	if n > 0 && e != nil {
+		return nil, err
 	}
 	names = make([]string, len(fis))
 	for i, fi := range fis {
 		names[i] = fi.Name
 	}
-	return names, nil
+	return names, err
 }

src/pkg/os/file_unix.go

@@ -70,19 +70,29 @@ func (file *File) Stat() (fi *FileInfo, err Error) {
 
 // Readdir reads the contents of the directory associated with file and
 // returns an array of up to count FileInfo structures, as would be returned
-// by Lstat, in directory order.  Subsequent calls on the same file will yield
+// by Lstat, in directory order. Subsequent calls on the same file will yield
 // further FileInfos.
-// A negative count means to read until EOF.
-// Readdir returns the array and an Error, if any.
-func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
+//
+// If n > 0, Readdir 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 os.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 os.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.
+func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 	dirname := file.name
 	if dirname == "" {
 		dirname = "."
 	}
 	dirname += "/"
-	names, err1 := file.Readdirnames(count)
-	if err1 != nil {
-		return nil, err1
+	wantAll := n < 0
+	names, namesErr := file.Readdirnames(n)
+	if namesErr != nil && !wantAll {
+		return nil, namesErr
 	}
 	fi = make([]FileInfo, len(names))
 	for i, filename := range names {
@@ -93,6 +103,9 @@ func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
 			fi[i] = *fip
 		}
 	}
+	if !wantAll && namesErr != EOF {
+		err = namesErr
+	}
 	return
 }
 

src/pkg/os/file_windows.go

@@ -124,11 +124,20 @@ func (file *File) Stat() (fi *FileInfo, err Error) {
 
 // Readdir reads the contents of the directory associated with file and
 // returns an array of up to count FileInfo structures, as would be returned
-// by Lstat, in directory order.  Subsequent calls on the same file will yield
+// by Lstat, in directory order. Subsequent calls on the same file will yield
 // further FileInfos.
-// A negative count means to read until EOF.
-// Readdir returns the array and an Error, if any.
-func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
+//
+// If n > 0, Readdir 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 os.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 os.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.
+func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 	if file == nil || file.fd < 0 {
 		return nil, EINVAL
 	}
@@ -136,12 +145,13 @@ func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
 		return nil, &PathError{"Readdir", file.name, ENOTDIR}
 	}
 	di := file.dirinfo
-	size := count
+	wantAll := n < 0
+	size := n
 	if size < 0 {
 		size = 100
 	}
 	fi = make([]FileInfo, 0, size) // Empty with room to grow.
-	for count != 0 {
+	for n != 0 {
 		if di.usefirststat {
 			di.usefirststat = false
 		} else {
@@ -150,7 +160,11 @@ func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
 				if e == syscall.ERROR_NO_MORE_FILES {
 					break
 				} else {
-					return nil, &PathError{"FindNextFile", file.name, Errno(e)}
+					err = &PathError{"FindNextFile", file.name, Errno(e)}
+					if !wantAll {
+						fi = nil
+					}
+					return
 				}
 			}
 		}
@@ -159,9 +173,12 @@ func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
 		if f.Name == "." || f.Name == ".." { // Useless names
 			continue
 		}
-		count--
+		n--
 		fi = append(fi, f)
 	}
+	if !wantAll && len(fi) == 0 {
+		return fi, EOF
+	}
 	return fi, nil
 }
 

src/pkg/os/os_test.go

@@ -236,11 +236,14 @@ func smallReaddirnames(file *File, length int, t *testing.T) []string {
 	count := 0
 	for {
 		d, err := file.Readdirnames(1)
+		if err == EOF {
+			break
+		}
 		if err != nil {
-			t.Fatalf("readdir %q failed: %v", file.Name(), err)
+			t.Fatalf("readdirnames %q failed: %v", file.Name(), err)
 		}
 		if len(d) == 0 {
-			break
+			t.Fatalf("readdirnames %q returned empty slice and no error")
 		}
 		names[count] = d[0]
 		count++

src/pkg/os/path.go

@@ -95,6 +95,9 @@ func RemoveAll(path string) Error {
 				err = err1
 			}
 		}
+		if err1 == EOF {
+			break
+		}
 		// If Readdirnames returned an error, use it.
 		if err == nil {
 			err = err1