os: Windows named pipes are listed as regular by Stat

[secDre4mer]

What version of Go are you using (go version)?

$ go version
go version go1.15.2 windows/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\Max\AppData\Local\go-build
set GOENV=C:\Users\Max\AppData\Roaming\go\env
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\Max\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\Max\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=c:\go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=c:\go\pkg\tool\windows_amd64
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\Max\AppData\Local\Temp\go-build300293506=/tmp/go-build -gno-record-gcc-switches

The underlying OS is Windows 10, version 2004.

What did you do?

I ran os.Stat, passing an existing pipe as an example. Source code for this can be found at https://play.golang.org/p/a1O5axVpLOO
In this example, the Pipe is created in the Golang program, but the issue is also reproducible when using a different, existing pipe.

What did you expect to see?

The FileInfo should have ModeNamedPipe set.

What did you see instead?

The FileInfo had no ModeNamedPipe set and was listed as a regular file.
Output from the example code:

$ go run .
0
438
true

[ianlancetaylor]

CC @alexbrainman

[networkimprov]

cc @iwdgo @mattn

[mattn]

When calling os.Stat(\\.\pipe\somepipe), fileStat is returned from result of GetFileAttributesEx

go/src/os/stat_windows.go

Lines 63 to 75 in bb48f99

	// Not a symlink.
	fs := &fileStat{
	FileAttributes: fa.FileAttributes,
	CreationTime: fa.CreationTime,
	LastAccessTime: fa.LastAccessTime,
	LastWriteTime: fa.LastWriteTime,
	FileSizeHigh: fa.FileSizeHigh,
	FileSizeLow: fa.FileSizeLow,
	}
	if err := fs.saveInfoFromPath(name); err != nil {
	return nil, err
	}
	return fs, nil

So the filetype field that is used by FileInfo.Mode() always become 0. To get filetype, it should call GetFileInformationByHandle, but that named pipe can not be called CreateFile since the pipe is not connected yet by ConnectNamedPipe. CreateFile retrurn ERROR_PIPE_BUSY until ConnectNamedPipe is called.

Most easy way to detect that the path is pipe is checking the path start with \.\pipe. but this is ugly.

[alexbrainman]

Same as @mattn . I do not know how to determine if opened file is named pipe or not.

Alex

[gopherbot]

Change https://golang.org/cl/373354 mentions this issue: os: set file mode for pipes on windows

[bcmills]

(CC @golang/windows)