runtime: SIGCONT and SIGTSTP aren't handle-able

[gopherbot]

by burke@libbey.me:

signal.Notify accepts SIGCONT as a parameter, but SIGCONT is never actually delivered to
the channel. I was able to register SIGCONT handler with cgo, but couldn't find any way
from Go.

Tested on:

* go version go1.3.1 darwin/amd64
* go version go1.3.3 linux/amd64

With the following source, I would expect the program to terminate immediately; however,
it hangs indefinitely. You can change SIGCONT into nearly any other signal to verify.
SIGTSTP has the same issue.

package main

import (
    "os"
    "os/signal"
    "syscall"
)

func main() {
    ch := make(chan os.Signal)
    signal.Notify(ch, syscall.SIGCONT)
    syscall.Kill(0, syscall.SIGCONT)
    <-ch
}

[ianlancetaylor]

Comment 1:

We don't set up a signal handler for SIGCONT or SIGTSTP (or SIGTTIN or SIGTTOU).  I
think it should be OK to always use a signal handler for SIGCONT, and just ignore it if
the signal arrives.  For SIGTSTP, SIGTTIN, and SIGTTOU we can only set up a signal
handler if the program explicitly requests notification for the signal, and we have to
remove the signal handler--return to the default signal action--if the program no longer
wants notification.  I think we now have the framework for this if anybody wants to work
on it.

Labels changed: added repo-main, release-none, suggested.

Status changed to Accepted.

[gopherbot]

CL https://golang.org/cl/18185 mentions this issue.