os/signal: SIGINT cannot be catched with cgo system("ls") call

[jeffwubj]

Please answer these questions before submitting your issue. Thanks!

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

go version go1.9.3 darwin/amd64

Does this issue reproduce with the latest release?

Yes with
go version go1.10.3 darwin/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/wujeff/go"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.9.3/libexec"
GOTOOLDIR="/usr/local/Cellar/go/1.9.3/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/s8/rvfmqfnd28qb86358xcy1zbr00_t7y/T/go-build817291637=/tmp/go-build -gno-record-gcc-switches -fno-common"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"

What did you do?

package main

import (
"fmt"
"os"
"os/signal"
)

/*
#include <stdlib.h>
static inline void RunCmd() {
system("pwd");
}
*/
import "C"

func main() {
fmt.Println("let's test...")
wait := make(chan bool)
C.RunCmd()
fmt.Println("run command finished")
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
go func() {
for sig := range c {
fmt.Println(sig.String())
os.Exit(0)
}
}()
select {
case <-wait:
os.Exit(0)
}
}
build the go file then press command+c in Mac to interrupt

What did you expect to see?

process exit successfully

What did you see instead?

lots of error messages:
fatal: morestack on g0
fatal: morestack on g0
fatal: morestack on g0

[ianlancetaylor]

I can't recreate the morestack on g0 message. I agree that on Darwin calling the C library system function does seem to disable ^C and ^\. If somebody can get an strace of the program, that might show the problem.

The system function is documented to ignore SIGHUP and SIGINT, which is probably somehow causing this. If you can avoid using the system function, you should. Go provides similar functionality in the os/exec package.

[jeffwubj]

Hi Ian,
Thanks for looking at this, I have attached trace file:
sigmiss.txt

Unfortunately, I need to use system as we are loading an existed c lib for some functionalities.

[ianlancetaylor]

I can't recreate this problem on Darwin 10.12 with Go 1.12beta1. The programs works as expected.

What version of Darwin are you using? Can you try Go 1.12 beta1?

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