On almost every build of Go I have made so far, "Building packages and commands" have failed with either:

go build ...: ...: fork/exec .../pkg/tool/plan9_amd64/compile: fd out of range or not open

or:

go build ...: ...: fork/exec .../pkg/tool/plan9_amd64/asm: fd out of range or not open

Completing a build tends to take quite a few tries.

I have traced the error to forkAndExecInChild (

    // Close fds we don't need.
    for i = 0; i < len(fdsToClose); i++ {
        r1, _, _ = RawSyscall(SYS_CLOSE, uintptr(fdsToClose[i]), 0, 0)
        if int32(r1) == -1 {
            goto childerror
        }
    }

This is in the child right after the fork succeeded.

I haven't figured out why this occurs yet. fd closed, fd never valid in the first place, ... The fd and index in "fdsToClose" changes, so it's not just the first fd (and maybe all of them), nor it is always the same fd. I do not yet know if the fds are open and valid prior to forking.

OS and Go versions

OS: plan9 (up-to-date 9front amd64)
Go: head of master
Go bootstrap: 1.4.3

Steps to reproduce

• Install a version of Go for bootstrapping (pre master)
• Fetch master
• GOROOT_BOOTSTRAP=/the/other/go ./make.rc

Expected result

Go build completes and gives me a freshly baked toolchain.

Actual result

Build crashes the vast majority of the time. Completing a build takes many attempts with --no-clean.