os: make Stdin.Stat() return ModeCharDevice if Stdin is console

CL 20845 changed Stdin.Stat() so it returns ModeNamedPipe.
But introduced TestStatStdin does not test what Stdin.Stat()
returns when Stdin is console.

This CL adjusts both TestStatStdin and Stdin.Stat
implementations to handle console. Return ModeCharDevice
from Stdin.Stat() when Stdin is console on windows,
just like it does on unix.

Fixes #14853.

Change-Id: I54d73caee2aea45a99618d11600d8e82fe20d0c0
Reviewed-on: https://go-review.googlesource.com/34090
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

3 files changed, 25 insertions, 10 deletions

diff --git a/src/os/os_test.go b/src/os/os_test.go
index 7ad9aac70e..9d74070e7f 100644
--- a/src/os/os_test.go
+++ b/src/os/os_test.go
@@ -1669,6 +1669,17 @@ func TestStatStdin(t *testing.T) {
 		Exit(0)
 	}
 
+	fi, err := Stdin.Stat()
+	if err != nil {
+		t.Fatal(err)
+	}
+	switch mode := fi.Mode(); {
+	case mode&ModeCharDevice != 0:
+	case mode&ModeNamedPipe != 0:
+	default:
+		t.Fatalf("unexpected Stdin mode (%v), want ModeCharDevice or ModeNamedPipe", mode)
+	}
+
 	var cmd *osexec.Cmd
 	if runtime.GOOS == "windows" {
 		cmd = osexec.Command("cmd", "/c", "echo output | "+Args[0]+" -test.run=TestStatStdin")
diff --git a/src/os/stat_windows.go b/src/os/stat_windows.go
index fdabf73cba..c8379381b1 100644
--- a/src/os/stat_windows.go
+++ b/src/os/stat_windows.go
@@ -31,8 +31,9 @@ func (file *File) Stat() (FileInfo, error) {
 	if err != nil {
 		return nil, &PathError{"GetFileType", file.name, err}
 	}
-	if ft == syscall.FILE_TYPE_PIPE {
-		return &fileStat{name: basename(file.name), pipe: true}, nil
+	switch ft {
+	case syscall.FILE_TYPE_PIPE, syscall.FILE_TYPE_CHAR:
+		return &fileStat{name: basename(file.name), filetype: ft}, nil
 	}
 
 	var d syscall.ByHandleFileInformation
@@ -50,10 +51,10 @@ func (file *File) Stat() (FileInfo, error) {
 			FileSizeHigh:   d.FileSizeHigh,
 			FileSizeLow:    d.FileSizeLow,
 		},
-		vol:   d.VolumeSerialNumber,
-		idxhi: d.FileIndexHigh,
-		idxlo: d.FileIndexLow,
-		pipe:  false,
+		filetype: ft,
+		vol:      d.VolumeSerialNumber,
+		idxhi:    d.FileIndexHigh,
+		idxlo:    d.FileIndexLow,
 	}, nil
 }
 
diff --git a/src/os/types_windows.go b/src/os/types_windows.go
index ad4e863fcb..772b9e5d24 100644
--- a/src/os/types_windows.go
+++ b/src/os/types_windows.go
@@ -12,9 +12,9 @@ import (
 
 // A fileStat is the implementation of FileInfo returned by Stat and Lstat.
 type fileStat struct {
-	name string
-	sys  syscall.Win32FileAttributeData
-	pipe bool
+	name     string
+	sys      syscall.Win32FileAttributeData
+	filetype uint32 // what syscall.GetFileType returns
 
 	// used to implement SameFile
 	sync.Mutex
@@ -43,8 +43,11 @@ func (fs *fileStat) Mode() (m FileMode) {
 	if fs.sys.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT != 0 {
 		m |= ModeSymlink
 	}
-	if fs.pipe {
+	switch fs.filetype {
+	case syscall.FILE_TYPE_PIPE:
 		m |= ModeNamedPipe
+	case syscall.FILE_TYPE_CHAR:
+		m |= ModeCharDevice
 	}
 	return m
 }