os: StartProcess doesn't allow paths starting with "./"

[xiaq]

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

$ go version
go version go1.20.1 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=C:\Users\xiaq\go\bin
set GOCACHE=C:\Users\xiaq\AppData\Local\go-build
set GOENV=C:\Users\xiaq\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\xiaq\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\xiaq\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:\Program Files\Go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=C:\Program Files\Go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.20.1
set GCCGO=gccgo
set GOAMD64=v1
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=NUL
set GOWORK=
set CGO_CFLAGS=-O2 -g
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-O2 -g
set CGO_FFLAGS=-O2 -g
set CGO_LDFLAGS=-O2 -g
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=C:\Users\xiaq\AppData\Local\Temp\go-build1714456318=/tmp/go-build -gno-record-gcc-switches

What did you do?

Save the following program as a.go:

package main

import (
  "log"
  "os"
)

func main() {
  args := os.Args[1:]

  p, err := os.StartProcess(args[0], args[1:], &os.ProcAttr{Files: []*os.File{os.Stdin, os.Stdout, os.Stderr}})
  if err != nil {
    log.Fatalln("StartProcess:", err)
  }
  _, err = p.Wait()
  if err != nil {
    log.Fatalln("Wait:", err)
  }
}

Save the following as foo.bat:

echo foo

Run the following:

go run a.go ./foo.bat

What did you expect to see?

The foo.bat script gets executed successfully.

What did you see instead?

The following output:

'.' is not recognized as an internal or external command,
operable program or batch file.

However, all of the following work:

• go run a.go .\foo.bat
• go run a.go c:\users\xiaq\tmp\foo.bat (c:\users\xiaq\tmp is the working directory)
• go run a.go c:/users/xiaq/tmp/foo.bat

Both / and \ are valid path separators on Windows, and os.StartProcess supports both in an absolute path. Not supporting ./ seems to be a bug.

[seankhliao]

That's an error from windows, not a limitation Go imposes.
https://stackoverflow.com/questions/20765337/how-to-fix-is-not-an-internal-or-external-command-error