On 23.01.2013 17:41, John Eckersberg wrote: > I'm running the following test program, and it works as written with a > blocking stream. Inside the guest I'm running: > > [root@f17-minimal ~]# socat /usr/share/dict/words /dev/virtio-ports/org.libguestfs.channel.0 > > As expected on the client side, I get all the words dumped. However if > I swap the virStreamNew lines and instead use the non-blocking stream, > the virStreamRecv call always returns -2. > >>From http://libvirt.org/internals/rpc.html#apiclientdispatch, I see: > > When no thread is performing any RPC method call, or sending stream > data there is still a need to monitor the socket for incoming I/O > related to asynchronous events, or stream data receipt. For this task, > a watch is registered with the event loop which triggers whenever the > socket is readable. This watch is automatically disabled whenever any > other thread grabs the buck, and re-enabled when the buck is released. > > If I understand that correctly, shouldn't the watch be responsible for > reading the stream data in this case? Or am I just completely missing > something? > > ----- > #include <libvirt.h> > > int main() > { > virConnectPtr conn; > virDomainPtr dom; > virStreamPtr st; > char buf[1024+1]; > int got = 0; > > conn = virConnectOpen("qemu+ssh://root@localhost/system"); > dom = virDomainLookupByName(conn, "f17-minimal"); > /* st = virStreamNew(conn, VIR_STREAM_NONBLOCK); */ > st = virStreamNew(conn, 0); > virDomainOpenChannel(dom, "org.libguestfs.channel.0", st, 0); > > while (1) { > got = virStreamRecv(st, buf, 1024); > > switch (got) { > case 0: > goto finish; > case -1: > goto free; > case -2: > puts("Retrying"); > sleep(1); > continue; > } > > buf[got] = '\0'; > puts(buf); > } > > finish: > virStreamFinish(st); > free: > virStreamFree(st); > > return 0; > } > > -- > libvir-list mailing list > libvir-list(a)redhat.com > https://www.redhat.com/mailman/listinfo/libvir-list > In order to use VIR_STREAM_NONBLOCK, you need to call virStreamEventAddCallback() which registers your stream in libvirtd event loop so data is sent to you as read from chardev's socket. However, you need a client event loop then. So the simple program should look like this [1].

1: http://pastebin.com/JffxfSmg