Roland McGrath <[EMAIL PROTECTED]> writes: > Saying "bidirectional pipe" is descriptive too. :-) They're the same thing. > As we discussed in great detail here at the time, `pipe' now creates a > bidirectional pipe, i.e. it creates a socketpair and does not call > shutdown.
You ought to set some flag somewhere so that you get the PIPE_BUF behaviour for pipes, but *not* for socketpairs, right? Problem is as follows: Say I want to write 200 bytes, and 200 < PIPE_BUF. I use non-blocking i/o, and call select to wait until the fd is writable. Lets assume that at this point, there's 100 bytes left in the pipe buffers. Then write will fail: It won't do a partial write of 100 bytes, because it wants to guarantee that writes smaller than PIPE_BUF are atomic. This makes it painful to use pipes with non-blocking i/o (the easiest work-around is to fall back to writing a single byte whenever select says the fd is writable, but write fails). Or simply use socketpair instead, as that doesn't have the PIPE_BUF behaviour; in the above example write ought to return 100, and the next select call will wait until there's more buffer space. Regards, /Niels _______________________________________________ Bug-hurd mailing list [EMAIL PROTECTED] http://mail.gnu.org/mailman/listinfo/bug-hurd
