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From: LEICHTER-JERRY@YALE.ARPA.UUCP
Newsgroups: mod.computers.vax
Subject: Re: problem with C fopen(), file revision date
Message-ID: <8606051013.AA09107@ucbvax.Berkeley.EDU>
Date: Thu, 5-Jun-86 06:13:54 EDT
Article-I.D.: ucbvax.8606051013.AA09107
Posted: Thu Jun  5 06:13:54 1986
Date-Received: Thu, 5-Jun-86 20:42:44 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: <LEICHTER-JERRY@YALE.ARPA>
Organization: The ARPA Internet
Lines: 36
Approved: info-vax@sri-kl.arpa


    The following program behaves curiously.  When you run it, the revision,
    date of the file it opens is updated, if that file is a stream_lf file.,
    If the file is variable length or fixed length, the revision date is not,
    updated.

    This even occurs when the file protection is (s,o,g,w:r), and the file is
    on a directory which is not mine.
    
    Any explanations?
    
    #include        <stdio.h>
    main(argc, argv)
            int     argc;
            char    **argv;
            {
            FILE    *inf;
            char    line[BUFSIZ];
    
            argc--; argv++;
            if ( (inf = fopen(*argv, "r")) != NULL)
                    puts("Opened");
            else
                    puts("Can't open");
            }
The VAX C RTL has to do some strange hacking to make stream files work right.
(Long story.  Basically, as far as RMS is concerned, stream files are just
as record oriented as other files, so you can't position to arbitrary bytes.
But C requires that you be able to do this.  So the C RTL ignores RMS and does
block I/O, which sometimes requires fixing up the file header - which is why
stream files don't work quite right over DECnet, and probably ultimately is
why this program acts as it does.)  Apparently there are some changes in VMS
V4.4, which has a new version of the C RTL - try it and see what happens.

							-- Jerry
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