* Daniel P. Berrange (berra...@redhat.com) wrote: > On Wed, Oct 12, 2016 at 08:15:02PM +0100, Dr. David Alan Gilbert wrote: > > Hi, > > I had a look at a couple of readline like libraries; > > editline and linenoise. A difficulty with using them is that > > they both want fd's or FILE*'s; editline takes either but > > from a brief look I think it's expecting to extract the fd. > > That makes them tricky to integrate into qemu, where > > the chardev's hide a whole bunch of non-fd things; in particular > > tls, mux, ringbuffers etc. > > > > If we could get away with just a FILE* then we could use fopencookie, > > but that's GNU only. > > > > Is there any sane way of shepherding all chardev's into having an > > fd? > > The entire chardev abstraction model exists precisely because we cannot > make all chardevs look like a single fd. Even those which are fd based > may have separate FDs for input and output.
Note that editline takes separate in/out streams, but it does want those streams to be FILE*'s. > IMHO the only viable approach would be to enhance linenoise/editline to > not assume use of fd* or FILE * abstractions. I think if it came to that then we'd probably end up sticking with what we had for a very long time; I'd assume it would take a long time before any mods we made to the libraries would come around to be generally useful. > BTW, what is the actual thread issue you are facing ? Chardevs at least > ought to be usable from a separate thread, as long as each distinct > chardev object instance was only used from one thread at a time ? Marc-André pointed that out; I hadn't realised they were thread safe. But what are the rules? You say 'only used from one thread at a time' - what happens if we have a mux and the different streams to the mux come from different threads? My actual thoughts for threads came from a few sides: a) Maybe I could have a shim thread that fed the editline fd from a chardev b) I'd eventually like multiple monitor threads. Dave > Regards, > Daniel > -- > |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| > |: http://libvirt.org -o- http://virt-manager.org :| > |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :| -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
