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From: bank@lea.ncsu.edu (Dave The DM)
Newsgroups: comp.lang.pascal,comp.os.msdos.programmer
Subject: Re: Statusof a msdos file after dos error
Message-ID: <1990Dec7.053930.14807@ncsuvx.ncsu.edu>
Date: 7 Dec 90 05:39:30 GMT
References: <2350@bnlux0.bnl.gov>
Organization: /etc/organization
Lines: 61

In article <2350@bnlux0.bnl.gov> kushmer@bnlux0.bnl.gov (christopher kushmerick) writes:
>After a file has been opened (Via assign, reset/rewrite) what is its
>status following a disk operation that results in dos reporting an io error?
>
>
>Here is the exact situation:
>
>turbo pascal 5.0
>
>I open a file. the reset/rewite occurs with success.
>
>Now I do an operation, and it fails, perhas, for example, because the
>user took the diskette out of the drive. What is the status of the file?
>Do I have to close it? Can I close it? should I close it?
>
>It should be obvious that I am compiling this with {$I-} set so that I may 
>process my own io errors.
>
>
>
>-- 
>Chris Kushmerick
>kushmer@bnlux0.bnl.gov    <===Try this one first
>kushmerick@pofvax.sunysb.edu 

    1) What do you mean by "status"?? The location of the file pointer
       is (in most situations) undefined. The file is probably still
       there. I'm not sure what you're looking for here.

    2) Implicit in your question is "Is the file still open?"  Yes, it
       is (well, in all the PC language implementations I have worked
       in - TP 2.0 thru 5.0, MS C 5.1 thru 6.00a, etc). Do you "have"
       to close it?? I dunno. What do you want to do with it. You may
       want to retry your operation. Or you may want to close it, then
       reopen, then retry. You don't HAVE to close it, altho in some
       cases this can be a good idea (depends on the nature of the
       I/O error).

    3) Can you close it?? Again, depends on the exact I/O error. If
       the problem came about because some lobotomized pea-brain
       opened a diskette drive door, then I daresay that a close
       operation won't have much success. If it was just a system burp,
       then you may not have any problem.
 
    4) Should you close it?? See 2) above. It all depends on exactly
       what the problem was and what you are doing with the file.
       Depending on what you're using for, closing the file can range
       from a great idea (perhaps its your master database file) to
       a so-so idea (its your temporary data file). Its rarely a bad
       idea.

    File ops are always a pain. The DOS 3.x critical error handler lists
gobs and gobs of different error codes for file operations (which is
a good thing - I HATE not knowing >>exactly<< what the system thinks
went wrong.
           )
    
    Anyway, hope this helps.

Dave the DM
bank@lea.csc.ncsu.edu