Libguestfs - Apr 2020 - golang: panic: runtime error: cgo argument has Go pointer to Go pointer

Hello,
when i use libguestfs to ceph rbd by golang, but there has panic:




panic: runtime error: cgo argument has Go pointer to Go pointer


goroutine 1 [running]:
guestfs.(*Guestfs).Add_drive.func11(0xc000010028, 0xcda6a0, 0xc0000d6000,
0xc000090280)
/opt/gopath/src/guestfs/guestfs.go:1440 +0xc2
guestfs.(*Guestfs).Add_drive(0xc000010028, 0x7ffd4b5d67ff, 0xd, 0xc00008d9d8,
0x0)
/opt/gopath/src/guestfs/guestfs.go:1440 +0x1b2
main.OpenImage(0x7ffd4b5d67ff, 0xd, 0x0, 0x0, 0x42110b, 0x7c87e0, 0x4f41e0)
/opt/gopath/src/disk/disk.go:34 +0x371
main.resizeext4(0x7ffd4b5d67ff, 0xd, 0x0, 0x0)
/opt/gopath/src/disk/disk.go:677 +0x60
main.main()
/opt/gopath/src/disk/disk.go:970 +0x5e5


i found struct in guestfs.h
struct guestfs_add_drive_opts_argv {
...
char *const *server; 
...
}


so i make a daemon to test. has the same error.  how could i to use libguestfs
to connect ceph rbd use golang interface.


package main


/*
#include <stdio.h>
#include <string.h>
struct t_server {
  const char *protocol;
  char *const *addr;
};


void show(struct t_server *optargs) {
        if (optargs->protocol == NULL){
                printf("protocol is  null \n");
        }
        printf("proto is %s\n", optargs->protocol);
        int num = strlen(*optargs->addr)-1;
        int i = 0;
        for(i=0;i<num;i++){
                printf("%s\n",optargs->addr[i]);
        }
}


*/
import "C"


import (
        "unsafe"
)


func main(){
c_optargs := C.struct_t_server{}
        c_optargs.protocol = C.CString("test")
        serverlist := []string{"aaa", "bbb",
"ccc"}
        var buf []*C.char
        for i, _ := range serverlist {
            buf = append(buf,
(*C.char)(unsafe.Pointer(C.CString(serverlist[i]))))
        }
        buf = append(buf, (*C.char)(unsafe.Pointer(nil)))
        c_optargs.addr = &buf[0]
        C.show(&c_optargs)
}