x/mobile/exp/audio/al: Crash when running al.CloseDevice() on OSX

[emil10001]

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

go version go1.7 darwin/amd64

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

Mac OS X 10.11.5

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/ejf3/workspace/gowork"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/zn/6y_5b8214sdg_1zzx907x3kh0000gn/T/go-build694490723=/tmp/go-build -gno-record-gcc-switches -fno-common"
CXX="clang++"
CGO_ENABLED="1"

What did you do?

import (
    "fmt"

    "golang.org/x/mobile/exp/audio/al"
)

func main() {
    fmt.Println("Hello, playground")

    err := al.OpenDevice()
    if err != nil {
        fmt.Println("failed to open device " + err.Error())
        return
    }
    defer al.CloseDevice()
}

The line defer al.CloseDevice() causes the crash. Removing that line allows the program to run without printing an error.

What did you expect to see?

I expected not to see a crash.

What did you see instead?

fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x41f1927]

runtime stack:
runtime.throw(0x40ae810, 0x2a)
        /usr/local/go/src/runtime/panic.go:566 +0x95
runtime.sigpanic()
        /usr/local/go/src/runtime/sigpanic_unix.go:12 +0x2cc

goroutine 1 [syscall, locked to thread]:
runtime.cgocall(0x4080c00, 0xc420053e10, 0x0)
        /usr/local/go/src/runtime/cgocall.go:131 +0x110 fp=0xc420053de0 sp=0xc420053da0
golang.org/x/mobile/exp/audio/al._Cfunc_alcDestroyContext(0x19)
        golang.org/x/mobile/exp/audio/al/_obj/_cgo_gotypes.go:666 +0x41 fp=0xc420053e10 sp=0xc420053de0
golang.org/x/mobile/exp/audio/al.alcDestroyContext(0x19)
        /Users/ejf3/workspace/gowork/src/golang.org/x/mobile/exp/audio/al/alc_notandroid.go:61 +0x75 fp=0xc420053e58 sp=0xc420053e10
golang.org/x/mobile/exp/audio/al.CloseDevice()
        /Users/ejf3/workspace/gowork/src/golang.org/x/mobile/exp/audio/al/alc.go:70 +0xa9 fp=0xc420053e80 sp=0xc420053e58
main.main()
        /Users/ejf3/workspace/gowork/src/ejf.io/gosoundwave/noise/noise.go:29 +0x3c7 fp=0xc420053f48 sp=0xc420053e80
runtime.main()
        /usr/local/go/src/runtime/proc.go:183 +0x1f4 fp=0xc420053fa0 sp=0xc420053f48
runtime.goexit()
        /usr/local/go/src/runtime/asm_amd64.s:2086 +0x1 fp=0xc420053fa8 sp=0xc420053fa0

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
        /usr/local/go/src/runtime/asm_amd64.s:2086 +0x1

This appears similar to the following two issues:

• x/mobile/exp/audio/al: Flaky crash on Mac OS X
• runtime: OpenReader: Invalid heap pointer in both 1.4rc2 and 1.4rc1