Messages in this thread | | | From | "jds" <> | Subject | Re: problems in kernel 2.4.20 stat() seems to return always size zero for any fifo (named pipe) | Date | Fri, 7 Mar 2003 12:58:11 -0600 |
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In fact, do you have any idea of what's wrong? I tryed to fix this in diferent ways but it doesn't seem to work.
Do you have any sugestion?
---------- Original Message ---------- From: "Richard B. Johnson" <root@chaos.analogic.com> To: jds <jds@soltis.cc> Sent: Thu, 6 Mar 2003 14:21:49 -0500 (EST) Subject: Re: problems in kernel 2.4.20 stat() seems to return always size zero for any fifo (named pipe)
> On Thu, 6 Mar 2003, jds wrote: > > > > > Hi: > > > > I have a problem using stat() with kernel 2.4.20 > > The size of ANY fifo is always 0. > > There is no backward compatibility. > > Probably it is a kernel bug in this particular version. > > The problem shows up when using the ls, stat commands. > > > > How reproducible: > > Always > [SNIPPED...] > > Have you ever tried this before? I'm not aware that stat > or lstat is supposed to return the byte-count of a pipe > of FIFO. It certainly doesn't on my Sun SunOS 5.5.1 or > Linux 2.4.18. In fact, the Sun prevents ^Z when reading > the FIFO interactively so your script won't test it. > > The second echo "abcd" >xx blocks so the pipe never > accepts anything anyway, there are never any "bytes- > in-the-pipe" that should be visible anyway. You can't > write to a pipe until a reader is reading, and if the > reader is suspended, there is no requirement for writing > to be buffered, i.e., a write to be accepted for such > a pipe. > > Pipes do not work like you propose and, if they ever did, > that was the bug. > > > Expected Results: prw-rw-r-- 1 kostadin kostadin 5 Feb 21 13:54 xx > > > > In Kernel 2.4.18-X the RedHat work perfect, > > e inclusive in 2.4.20-X the Redhat > > beta 8.0.94 > > > > Linux 2.4.18 does not accept writes to a pipe when a reader is > not actively reading. As such, a byte-count cannot exist. > > If you have a program that expects a byte-count from a FIFO, > the program is broken. FIFOs must have readers before any > writes are accepted. > > Cheers, > Dick Johnson > Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips). > Why is the government concerned about the lunatic fringe? Think > about it. ------- End of Original Message -------
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