On Thu, Nov 14, 2024 at 02:25:09AM -0800, Purna Pavan Chandra Aekkaladevi wrote:
> Thanks for the review, Michal.
>
> I will add your suggestion to not abort() and fix the possible memory
> leak issue in V4.
>
> On Mon, Nov 11, 2024 at 02:37:00PM +0100, Michal Prívozník wrote:
> > On 10/23/24 10:02, Purna Pavan Chandra Aekkaladevi wrote:
> > > Implement `chReadProcessEvents` and `chProcessEvents` to read events from
> > > event monitor FIFO file and parse them accordingly.
> > >
> > > diff --git a/src/ch/ch_events.c b/src/ch/ch_events.c
> > > index bb27f340e2..d0ad5af0af 100644
> > > --- a/src/ch/ch_events.c
> > > +++ b/src/ch/ch_events.c
> > > @@ -28,6 +28,136 @@
> > >
> > > +static void virCHReadProcessEvents(virCHMonitor *mon,
> > > + int event_monitor_fd)
> > > +{
> > > + /* Event json string must always terminate with null char.
> > > + * So, reserve one byte for '\0' at the end.
> > > + */
> > > + size_t max_sz = CH_EVENT_BUFFER_SZ - 1;
> > > + char *buf = mon->event_buffer.buffer;
> > > + virDomainObj *vm = mon->vm;
> > > + bool incomplete = false;
> > > + size_t sz = 0;
> > > +
> > > + memset(buf, 0, max_sz);
> > > + do {
> > > + ssize_t ret;
> > > +
> > > + ret = read(event_monitor_fd, buf + sz, max_sz - sz);
> >
> > You mean saferead()?
>
> Sure, will use saferead().
>
Actually, saferead() is not apt here since it read()-s until count
bytes. But we are unsure of the byte count we want to read beforehand.
Simple read() fits in here.
> >
> > Also, I know you're opened this event_monitor_fd in blocking mode, so
> > this won't loop every second, so I'm not going to require use of event loop.
> >
>
> Yes, event_monitor_fd is in blocking mode and it might seem like this
> loop is not required. But we could end up read()-ing a partial event
> json; a loop here makes it possible to read the rest of the json ...
>
> > > + if (ret == 0 || (ret < 0 && errno == EINTR)) {
> > > + g_usleep(G_USEC_PER_SEC);
> > > + continue;
> > > + } else if (ret < 0) {
> > > + /* We should never reach here. read(2) says possible errors
> > > + * are EINTR, EAGAIN, EBADF, EFAULT, EINVAL, EIO, EISDIR
> > > + * We handle EINTR gracefully. There is some serious issue
> > > + * if we encounter any of the other errors(either in our code
> > > + * or in the system). Better to bail out.
> > > + */
> > > + VIR_ERROR(_("%1$s: Failed to read ch events!: %2$s"),
> > > + vm->def->name, g_strerror(errno));
> > > + VIR_FORCE_CLOSE(event_monitor_fd);
> > > + abort();
> >
> > Again, aborting is unacceptable.
> >
> > > + }
> > > +
> > > + sz += ret;
> > > + mon->event_buffer.buf_fill_sz = sz;
> > > +
> > > + if (virCHProcessEvents(mon) < 0)
> > > + VIR_WARN("%s: Failed to parse and process events", vm->def->name);
> > > +
> > > + if (mon->event_buffer.buf_fill_sz != 0)
> > > + incomplete = true;
> > > + else
> > > + incomplete = false;
> > > + sz = mon->event_buffer.buf_fill_sz;
> > > +
> > > + } while (virDomainObjIsActive(vm) && (sz < max_sz) && incomplete);
> > > +
>
> ... and the loop is run only when the read() event json is incomplete.
>
> > > + return;
> > > +}
> > > +
> >
> > Michal
>
> Regards,
> Pavan
Regards,
Pavan
