[Xen-devel] Question regarding suspend in libxc

[soyer yoo <soyer.yoo@xxxxxxxxx>]

Hi all,

I was reading source code around saving and restoring domains, and I found the following function in _libxl_save_msgs_helper.c, which looks like causing seg fault.

int helper_stub_suspend(void *user)
{
    unsigned char *buf = 0;
    int len = 0, allocd = 0;
   
    for (;;) {
        uint16_t_put(buf, &len, 3 /* suspend */);
        if (buf) break;
        buf = helper_allocbuf(len, user);
        assert(buf);
        allocd = len;
        len = 0;
    }
    assert(len == allocd);
    helper_transmitmsg(buf, len, user);
    int r = helper_getreply(user);
    return r;
}  

Here, buf is null, and inside the for loop it tries to write '3' into buf, which will cause seg fault.

Is it intended for suspending domain or am I misunderstanding?

Also, could you tell me what does '3' do for suspending domain.

On more question:

helper_transmitmsg in the above writes the 'buf' to file descriptor 1 (i.e., /dev/tty1).

I have idea what is going on here, and could anybody please enlighten me?

Best,

Soyer

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel