On Mon, Aug 20, 2012 at 10:15 PM, Roland Mainz <roland.ma...@nrubsig.org> wrote: > Attached (as "astksh_builtin_poll20120819_001.diff.txt") is the 5th > iteration of the poll(1) patch per review feedback... > > * Changes: > - The test suite has been extended to cover fifos, POLLNVAL, POLLHUP, > fd==-1 (to get entries ignored) and other little details. > > - Minor code cleanup and movements to make the |b_poll()| function > smaller and more readable > > > * Known issues: > - Currently poll(1) doesn't work well with user-defined types (e.g. > typeset -T ...). The problem is outlined in > http://marc.info/?l=ast-developers&m=134526131905059&w=3 - it seems a > compound variable within a type can't be extended with new elements in > certain cases (e.g. in such cases the shell will abort the builtin > instead of returning a plain "variable not found" (= return |NULL| > pointer) to the calling C function). > The "workaround" for using poll(1) with types is to declare _all_ > possible members in the "events" and "revents" variables, e.g. ... > -- snip -- > typeset -T poll_t=( typeset -l -i fd ; > compound events=( typeset pollin=false pollpri=false > pollout=false pollrdnorm=false pollwrnorm=false pollrdband=false > pollwrband=false pollmsg=false pollremove=false pollrdhup=false > pollerr=false pollhup=false pollnval=false ; ) > compound revents=( typeset pollin=false pollpri=false > pollout=false pollrdnorm=false pollwrnorm=false pollrdband=false > pollwrband=false pollmsg=false pollremove=false pollrdhup=false > pollerr=false pollhup=false pollnval=false ; ) > function pinit { _.fd=$1 ; _.events.pollin=true ; } ; > ) > -- snip -- > > > * Future directions: > - Implement support for plain string arrays (e.g. typeset -a/-A) for > compatibility with a possible bash4 version of the poll(1) builtin > (bash4 doesn't have compound variables... the idea is basically that > if the array is made out of compound -a/-A or foo_t -a/-A the current > mode is used... while if the array is a plain typeset -a/-A array it > wil use plain strings for input/output (e.g. all information is > squeezed into one single string)). > The main idea is to get common functionality between bash4 and ksh93 > and then move forward and propose this to the Austin Group for the > next POSIX standard. > > - It would be nice to have a way to open files via "redirect" (e.g. " > command exec") with |O_NONBLOCK|. It seems to be part of POSIX (see > http://pubs.opengroup.org/onlinepubs/7908799/xsh/open.html) and would > help a lot if a process wants to open a fifo with seperate fds for > both reading and writing. Right now we use the following trick to > archive this... > -- snip -- > mkfifo "${fifo_name}" > > # little "trick" with fifos - "redirect" would block if > # there is no reader... so we create one in a > # sub-process and kill it below after we opened the fd > { redirect {dummy}<"${fifo_name}" ; for (( ;; )) ; do sleep 15 ; done ; } & > (( pid=$! )) > > redirect {out_fd}>"${fifo_name}" > > kill $pid ; wait $pid 2>'/dev/null' > > redirect {in_fd}<"${fifo_name}" > -- snip -- > ... but I'm not happy with this. > IMO something like $ redirect --noblock {in_fd}<"${fifo_name} ; > redirect {out_fd}>"${fifo_name}"" # would be nice... assuming all > platforms supported by AST have |O_NONBLOCK| and support this for all > of { fifos, pipes, sockets } as required by POSIX. Glenn ?
Erm... I forgot to say that the patch is for ksh93v- only. For ksh93u+ the old patch in http://marc.info/?l=ast-developers&m=134431288721969&w=3 will just work fine... ---- Bye, Roland -- __ . . __ (o.\ \/ /.o) roland.ma...@nrubsig.org \__\/\/__/ MPEG specialist, C&&JAVA&&Sun&&Unix programmer /O /==\ O\ TEL +49 641 3992797 (;O/ \/ \O;) _______________________________________________ ast-developers mailing list ast-developers@research.att.com https://mailman.research.att.com/mailman/listinfo/ast-developers
