Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!mcvax!hp4nl!botter!star.cs.vu.nl!maart
From: maart@cs.vu.nl (Maarten Litmaath)
Newsgroups: comp.unix.xenix
Subject: Re: NEED HELP: fread, fwrite, fseek, ftell
Keywords: AAAAAAAAARRRRRGGGHHH
Message-ID: <2445@solo3.cs.vu.nl>
Date: 3 May 89 03:34:59 GMT
References: <7327@mrspoc.UUCP>
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 26

itkin@mrspoc.UUCP (Steven M. List) writes:
\...
\	byteswritten = fwrite (outbuf, sizeof (char), bytesread, swabfile);
\...
\	bytesread = fread (inbuf, sizeof (char), sizeof inbuf, swabfile);

RTFM (fopen(3s)):

     When a file is opened for update, both input and output  may
     be done on the resulting stream.  However, output may not be
				       ^^^^^^^^^^^^^^^^^^^^^^^^^^
     directly followed by input without an intervening  fseek [...] :-(
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Solution: insert

	fseek(swabfile, ftell(swabfile), 0);

At first sight this looks like a no-op, but there are some `interesting'
side-effects...
What to do if you f*ck things up? Just put it in the FM: it's a feature!
(Which will live on forever.)
BTW, whom can we sue for this? :-)
-- 
 "If it isn't aesthetically pleasing, |Maarten Litmaath @ VU Amsterdam:
  it's probably wrong." (jim@bilpin)  |maart@cs.vu.nl, mcvax!botter!maart