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From: piet@cs.ruu.nl (Piet van Oostrum)
Newsgroups: comp.lang.perl,comp.sys.hp
Subject: Re: make test fails on hp 9000s300, why?
Message-ID: <4670@ruuinf.cs.ruu.nl>
Date: 16 Jan 91 10:05:25 GMT
References: <1991Jan11.133837@cs.utwente.nl>
Sender: news@ruuinf.cs.ruu.nl
Reply-To: piet@cs.ruu.nl (Piet van Oostrum)
Followup-To: comp.lang.perl
Organization: Dept of Computer Science, Utrecht University, The Netherlands
Lines: 54
In-reply-to: belinfan@cs.utwente.nl (Axel Belinfante)

>>>>> In message <1991Jan11.133837@cs.utwente.nl>, belinfan@cs.utwente.nl (Axel Belinfante) (AB) writes:

AB> I tried to compile perl 3.41 on a hp9000s300 machine, running hp-ux 7.0.
AB> It compiles ok, as long as i don't try to compile it with -O
AB> (if i do, cc hangs in eval.c).
AB> The problems start when i run `make test'.
AB> test op.read fails, the other tests run ok:
>>  % op.read
>>  1..4
>>  ok 1
>>  ok 2
>>  not ok 3
>>  not ok 4

I experienced the same problem. Even more strangely, the test also failed
on pl 41 and on an old perl pl 18.

I traced it with adb, and found that the read after the seek(20000)
returned a full buffer of zero bytes.

I finally traced it down to the perl directory being on a NFS mounted
filesystem. So I bet you have your perl directory also on NFS. When I run
the test from the machine where perl was located the problem disappeared.

It seems that the HP-UX implementation of NFS returns a full buffer of zero
bytes if you do a lseek after the end of file, followed by a read. I would
say this is a bug.

The problem does not appear to be in the server as it works correctly from
other machines (e.g. a Sun), even if the actual file system is on a HP.

Here is a short C program that duplicates the problem:

#include <stdio.h>
main()
{
    /* Note : use an NFS mounted file */
    FILE * f = fopen ("/usr/staff/src/perl3.0/README", "r");
    int i, n;
    char buf[80];

    fseek (f, 20000L, 0);
    n = fread (buf, 1,5,f);
    printf ("%d: ", n);
    for (i=0; i<n; i++) {
	printf ("%x ", buf[i]);
    }
    printf ("\n");
}
-- 
Piet* van Oostrum, Dept of Computer Science, Utrecht University,
Padualaan 14, P.O. Box 80.089, 3508 TB Utrecht, The Netherlands.
Telephone: +31 30 531806   Uucp:   uunet!mcsun!ruuinf!piet
Telefax:   +31 30 513791   Internet:  piet@cs.ruu.nl   (*`Pete')