cgo crashes with simple argument passing #728
Description
> Before filing a bug, please check whether it has been fixed since
> the latest release: run "hg pull -u" and retry what you did to
> reproduce the problem. Thanks.
>
> What steps will reproduce the problem?
With the attached code, "make testffi" and "./testffi". For quick
reference, here's the critical file:
package badffi
/*
#include <stdio.h>
int somevalue = 100;
void do_something(int x)
{
printf("Hello, %d!\n", x);
}
*/
import "C"
func DoSomething() {
C.do_something(C.somevalue)
}
> What is the expected output? What do you see instead?
The program should output "Hello, 100!". Instead it crashes with a bad
pointer deference:
panic: runtime error: invalid memory address or nil pointer dereference
panic PC=0x7f35d9945ff8
runtime.panic+0x7c /home/pakin/goroot/src/pkg/runtime/proc.c:1011
runtime.panic(0x7f3500000000, 0x404d59)
panicstring+0x60 /home/pakin/goroot/src/pkg/runtime/runtime.c:83
panicstring(0x40d7d8, 0x7f35d993d1f0)
sigpanic+0x84 /home/pakin/goroot/src/pkg/runtime/linux/thread.c:285
sigpanic()
badffi.DoSomething+0x16 /home/pakin/badffi/badffi.cgo1.go:17
badffi.DoSomething()
main.main+0xf /home/pakin/badffi/testffi.go:6
main.main()
mainstart+0xf /home/pakin/goroot/src/pkg/runtime/amd64/asm.s:60
mainstart()
goexit /home/pakin/goroot/src/pkg/runtime/proc.c:145
goexit()
> What is your $GOOS? $GOARCH?
GOOS=linux
GOARCH=amd64
> Which revision are you using? (hg identify)
I tried both
f98f784927ab+ release.2010-04-13/release
and
9b6baa9163d6+ tip
> Please provide any additional information below.
Sticking a
fmt.Printf(">>> %v <<<\n", _C_somevalue)
into badffi.cgo1.go outputs ">>> <nil> <<<". It seems
that _C_somevalue
is not properly getting initialized to &somevalue.
Attachments:
- badffi.tar.gz (449 bytes)