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From: Hiroaki Komatsu <pine@math.okayama-u.ac.jp>
Subject: [Q] NFS + mmap
Sender: newsmaster@cc.okayama-u.ac.jp (News System Admin)
Message-ID: <Pine.BSF.3.95LJ1.1b3.970620162341.1331C-100000@decpc5.math.okayama-u.ac.jp>
Date: Fri, 20 Jun 1997 07:25:09 GMT
Content-Type: TEXT/PLAIN; charset=US-ASCII
Mime-Version: 1.0
Organization: Okayama University, Japan
Lines: 42
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:43201
I have a problem about NFS. I am using machines running
FreeBSD 2.1.0-RELEASE or 2.2.2-RELEASE, and NFS server is
SPARC station 20 running SunOS 4.1.3.
The problem occurs whenever an argument, say `foo', of the
following program is a remote file via NFS. While the
program is sleeping 10 seconds, if another machine executes
`echo >foo' then write() call can not return.
------------------------------------------------------------
#include <stdio.h>
#include <sys/mman.h>
main(int argc, char *argv[])
{
FILE *fin;
char *buf;
if (argc != 2 || (fin = fopen(argv[1], "r")) == NULL) {
fprintf(stderr, "Usage: %s file\n", argv[0]);
exit(-1);
}
fprintf(stderr, "sleep 10 seconds ...\n");
sleep(10);
buf = mmap(0, 1, PROT_READ, MAP_SHARED, fileno(fin), 0);
if ((int)buf < 0) {
fprintf(stderr, "? mmap\n");
exit(-1);
}
write(1, buf, 1);
}
------------------------------------------------------------
I do not know wheather this is a problem peculiar to my
environment or not. Is this an unavoidable facts? Please
tell me the truth.
--
Hiroaki Komatsu (pine@math.okayama-u.ac.jp)
Okayama University
Graduate School of Natural Science and Technology