os: waitid: function not implemented on Windows 10(Bash on Ubuntu)

[xiaoxiaoyijian]

Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?
   go version go1.7rc5 linux/amd64
2. What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN="/usr/local/go/bin"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/steven/gopath"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"

1. What did you do?
   If possible, provide a recipe for reproducing the error.
   A complete runnable program is good.
   A link on play.golang.org is best.

cat hello.go

//hellogolang.go


package main


import (
        "fmt"
)


func main() {
        fmt.Println("Hello Golang!")
}

go build hello.go
go build command-line-arguments: /usr/local/go/pkg/tool/linux_amd64/compile: waitid: function not implemented

1. What did you expect to see?
   works OK in go1.7rc5
2. What did you see instead?
   go build hello.go
   go build command-line-arguments: /usr/local/go/pkg/tool/linux_amd64/compile: waitid: function not implemented

But when I switched it to go1.6.3, it works OK.

[ianlancetaylor]

Why do you refers to Windows 10 in the topic?

What Linux version are you running?

[xiaoxiaoyijian]

Bash on Ubuntu for Win10

lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.4 LTS
Release:        14.04
Codename:       trusty

[bradfitz]

Ian, this is Microsoft's implementation of the Linux system calls atop the Window 10 kernel. It's Linux-like. They didn't implement this system call apparently.

[xiaoxiaoyijian]

go1.6.3 works OK, but go1.7rc5 NOT OK.

[ianlancetaylor]

https://golang.org/cl/25507

[gopherbot]

CL https://golang.org/cl/25507 mentions this issue.

[xiaoxiaoyijian]

OK, thanks.

[bradfitz]

Maybe we should ask Microsoft if they'd rather fix this than us work around it. I believe it's still in development and they're targeting Linux parity. Their goal is Docker stuff iiuc.

[xiaoxiaoyijian]

Yes, maybe they will fix it in future.

[bradfitz]

@jstarks, are you involved with Windows' Linux subsystem? Windows 10 doesn't seem to implement the waitid system call, which Go 1.7 started using. Is that known and going to be fixed? Or should we work around it?

[jstarks]

waitid support is tracked here: microsoft/WSL#638. It's not in the stable build of Windows 10 released August 2, so it's unlikely to be widely available to customers in the next several months. Depending on if/when it's implemented, it might be available in a preview release sooner.

cc @benhillis

[ianlancetaylor]

@bradfitz Given the above I'm inclined to submit CL 25507 for the 1.7 release. It's simple and safe.

[bradfitz]

Fine by me.

[benhillis]

WSL has implemented the waitid system call and it will be available in a post Anniversary Update Windows Insider flight. One caveat: the P_PGID IdType is not yet implemented, are you using that?

[bradfitz]

@benhillis, nope. Just P_PID:

const _P_PID = 1
....
    // The waitid system call expects a pointer to a siginfo_t,
    // which is 128 bytes on all GNU/Linux systems.
    // On Darwin, it requires greater than or equal to 64 bytes
    // for darwin/{386,arm} and 104 bytes for darwin/amd64.
    // We don't care about the values it returns.
    var siginfo [128]byte
    psig := &siginfo[0]
    _, _, e := syscall.Syscall6(syscall.SYS_WAITID, _P_PID, uintptr(p.Pid), uintptr(unsafe.Pointer(psig)), syscall.WEXITED|syscall.WNOWAIT, 0, 0)

[tirpen]

Insiders Build 14901 implemented waitid. Here's the output for 'go build', though:

command-line-arguments: /usr/local/go/pkg/tool/linux_amd64/compile: waitid: invalid argument

This is Go 1.7rc6 linux/amd64. Microsoft/BashOnWindows#638.

[bradfitz]

I guess it's not fully implemented yet.

[benhillis]

@aschneiderg Do you happen to have an strace of the failing waited system call? We should handle everything except P_PGID IdType but it's possible we missed something.

[bradfitz]

@benhillis, use of waitid occurs exactly once in the Go codebase as of Go 1.7:

        _, _, e := syscall.Syscall6(syscall.SYS_WAITID, _P_PID, uintptr(p.Pid), uintptr(unsafe.Pointer(psig)), syscall.WEXITED|syscall.WNOWAIT, 0, 0)

Where those constants are:

const _P_PID = 1

zsysnum_linux_amd64.go: SYS_WAITID                 = 247

zerrors_linux_amd64.go: WEXITED                          = 0x4
zerrors_linux_amd64.go: WNOWAIT                          = 0x1000000

[benhillis]

@bradfitz thanks for the pointer. I suspect we aren't handling the nowait flag correctly. I'll take a look this morning.

[stuart-warren]

Still getting /usr/local/go/pkg/tool/linux_amd64/compile: waitid: invalid argument for go 1.7 final on build 14905 :(

https://wpdev.uservoice.com/forums/266908-command-prompt-console-bash-on-ubuntu-on-windo/suggestions/15807382-support-compiling-golang

[bradfitz]

@stuart-warren, the bug you're looking for is microsoft/WSL#638

This is Go's issue tracker and this issue is closed. We're probably not going to go out of our way to support a variant of Linux when that Linux variant is still under development and has a goal to not feel like a variant.

[benhillis]

FYI I've checked this fix in to WSL and it should be available in an upcoming Windows Insider build. Thanks again for bringing this to my attention.

[bradfitz]

@benhillis, excellent. Thanks for the fix and the update.

[benhillis]

The fix should be available in Windows version 14936 and later.

microsoft/WSL#638 (comment)