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Date:      Tue, 3 Jul 2012 18:54:22 +0000 (UTC)
From:      Peter Holm <pho@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-user@freebsd.org
Subject:   svn commit: r238082 - user/pho/stress2/misc
Message-ID:  <201207031854.q63IsM1F064734@svn.freebsd.org>

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Author: pho
Date: Tue Jul  3 18:54:21 2012
New Revision: 238082
URL: http://svn.freebsd.org/changeset/base/238082

Log:
  Added a regression test.

Added:
  user/pho/stress2/misc/f_offset.sh   (contents, props changed)

Added: user/pho/stress2/misc/f_offset.sh
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ user/pho/stress2/misc/f_offset.sh	Tue Jul  3 18:54:21 2012	(r238082)
@@ -0,0 +1,160 @@
+#!/bin/sh
+
+#
+# Copyright (c) 2012 Peter Holm <pho@FreeBSD.org>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+#
+
+# Problem seen with atomic assingment of f_offset. Fixed in r238029.
+
+# Test scenario by kib@
+
+here=`pwd`
+cd /tmp
+sed '1,/^EOF/d' < $here/$0 > f_offset.c
+cc -o f_offset -Wall -Wextra -O2 f_offset.c -lpthread
+rm -f f_offset.c
+
+/tmp/f_offset
+
+rm -f /tmp/f_offset
+exit 0
+EOF
+/*
+   Description by kib:
+To really exercise the race conditions, all the following items must
+be fulfilled simultaneously:
+1. you use 32bit host, i.e. i386
+2. you operate on the file offsets larger than 4GB (but see below)
+3. there are several threads or processes that operate on the same
+   file descriptor simultaneously.
+
+Please note that the normal fork(2) causes file descriptor table
+copy, so only rfork(2) call with RFFDG flag unset causes sharing. Or,
+multi-threading can be used.
+ */
+
+#include <err.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int errors, fd;
+char file[128];
+
+#define START 0x100000000ULL
+#define N 1000000
+
+void *
+t1(void *arg __unused)
+{
+	int i;
+	off_t offset;
+
+	offset = START + 2;
+
+	for (i = 0; i < N; i++) {
+		if (lseek(fd, offset, SEEK_SET) == -1)
+			err(1, "lseek error");
+	}
+
+	return (0);
+}
+
+void *
+t2(void *arg __unused)
+{
+	int i;
+	off_t offset;
+
+	offset = 1;
+
+	for (i = 0; i < N; i++) {
+		if (lseek(fd, offset, SEEK_SET) == -1)
+			err(1, "lseek error");
+	}
+	return (0);
+}
+void *
+t3(void *arg __unused)
+{
+	int i;
+	off_t offset;
+
+	offset = 1;
+
+	for (i = 0; i < N; i++) {
+		if ((offset = lseek(fd, 0, SEEK_CUR)) == -1)
+			err(1, "lseek error");
+		if (offset != 1 && offset != START + 2)
+			fprintf(stderr, "FAIL #%d offset = %10jd (0x%09jx)\n", 
+					errors++, offset, offset);
+	}
+
+	return (0);
+}
+
+int
+main(void)
+{
+	pthread_t threads[3];
+	int r;
+	int i;
+	off_t offset;
+
+	snprintf(file, sizeof(file), "file.%06d", getpid());
+	if ((fd = open(file, O_RDWR | O_CREAT | O_TRUNC, 0600)) < 0)
+		err(1, "%s", file);
+
+	offset = 1;
+	if (lseek(fd, offset, SEEK_SET) == -1)
+		err(1, "lseek error");
+
+	for (i = 0; i < 20 && errors < 10; i++) {
+		if ((r = pthread_create(&threads[0], NULL, t1, 0)) != 0)
+			err(1, "pthread_create(): %s\n", strerror(r));
+		if ((r = pthread_create(&threads[1], NULL, t2, 0)) != 0)
+			err(1, "pthread_create(): %s\n", strerror(r));
+		if ((r = pthread_create(&threads[2], NULL, t3, 0)) != 0)
+			err(1, "pthread_create(): %s\n", strerror(r));
+
+		if (pthread_join(threads[0], NULL) != 0)
+			err(1, "pthread_join(%d)", 0);
+		if (pthread_join(threads[1], NULL) != 0)
+			err(1, "pthread_join(%d)", 1);
+		if (pthread_join(threads[2], NULL) != 0)
+			err(1, "pthread_join(%d)", 2);
+	}
+	close(fd);
+	if (unlink(file) == -1)
+		err(3, "unlink(%s)", file);
+		
+	return (0);
+}



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