Am 03.08.2012 00:21, schrieb Corey Bryant:
>>> @@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
>>> int ret;
>>> int mode = 0;
>>>
>>> +#ifndef _WIN32
>>> + const char *fdset_id_str;
>>> +
>>> + /* Attempt dup of fd from fd set */
>>> + if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
>>> + int64_t fdset_id;
>>> + int fd, dupfd;
>>> +
>>> + fdset_id = qemu_parse_fdset(fdset_id_str);
>>> + if (fdset_id == -1) {
>>> + errno = EINVAL;
>>> + return -1;
>>> + }
>>> +
>>> + fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
>>
>> I know that use of default_mon in this patch is not correct, but I
>> wanted to get these patches out for review. I used default_mon for
>> testing because cur_mon wasn't pointing to the monitor I'd added fd sets
>> to. I need to figure out why.
>>
>
> Does it make sense to use default_mon here? After digging into this
> some more, I'm thinking it makes sense, and I'll explain why.
>
> It looks like cur_mon can't be used. cur_mon will point to the monitor
> object for the duration of a command, and be reset to old_mon (NULL in
> my case) after the command completes.
>
> qemu_open() and qemu_close() are frequently called long after a monitor
> command has come and gone, so cur_mon won't work. For example,
> drive_add will cause qemu_open() to be called, but after the command has
> completed, the file will keep getting opened/closed during normal QEMU
> operation. I'm not sure why, I've just noticed this behavior.
>
> Does anyone have any thoughts on this? It would require fd sets to be
> added to the default monitor only.
I think we have two design options that would make sense:
1. Make the file descriptors global instead of per-monitor. Is there a
reason why each monitor has its own set of fds? (Also I'm wondering
if they survive a monitor disconnect this way?)
2. Save a monitor reference with the fdset information.
Allowing to send file descriptors on every monitor, but making only
those of the default monitor actually usable, sounds like a bad choice
to me.
Kevin
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