Tuesday December 07 1993 01:35, david nugent wrote to Jason Lingohr:


 >> My question is basically this: is it
 >> silly/dangerous/stupid/insane to mix file handles and
 >> buffered, high-level I/O??

 dn> It can be done safely (although not portably), but there are some gotchas.
 dn> It depends on what you're "mixing".

Ahhhh, the usual answer of any good, knowledgable programmer!!

 dn> Why not use fsopen() or fdopen() or similar - it obviously depends what
 dn> your library has, neither are ISO functions, but most MSDOS compilers have
 dn> them.

Well, basically, to quote from my trusty Waite Group's Turbo C Bible,
fdopen() shouldn't be used when a low-level file has been opened in a
sharing mode. Their reason is that buffered I/O with a shared file
basically defeats the whole purpose of file-sharing - at any one time the
physical file is not 100% up to date with high-level, which, I guess makes
sense.... sigh.

Although the funniest bit about all this is that the files I'm opening for
sharing are only read mode anyhow - RemoteAccess and D'Bridge paramater
files, for things such as log filenames etc.... man, I've spent too many
hours on this project!!

Other than that, it doesn't mention any "trap bugs" that might
occur, just the non-Vulcan illogic in the whole idea of buffered I/O and
shared files.

 dn> Does it work on a network _without_ using shared opens?

I don't believe so.

 >> Got any resolutions?

 dn> Without knowing the cause of the problem, it's a little difficult to
 dn> solve. :-)

Well, I'd tell you the cause too, but that's what I'm trying to discover -
I'll go away now, back to my hole in the corner and try using fdopen...


Jason Lingohr, 201:300/320 - jason.lingohr{at}dbridge.com
LingSoft Developments BBS - +61-3-770-1093 300-14.4k V.32b/V.42b
jason{at}csource.oz.au
lingman{at}yoyo.cc.monash.edu.au


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