1#!/bin/sh 2 3# 4# Copyright (c) 2014 EMC Corp. 5# All rights reserved. 6# 7# Redistribution and use in source and binary forms, with or without 8# modification, are permitted provided that the following conditions 9# are met: 10# 1. Redistributions of source code must retain the above copyright 11# notice, this list of conditions and the following disclaimer. 12# 2. Redistributions in binary form must reproduce the above copyright 13# notice, this list of conditions and the following disclaimer in the 14# documentation and/or other materials provided with the distribution. 15# 16# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26# SUCH DAMAGE. 27# 28 29# fcntl(2) locking scenario. 30 31. ../default.cfg 32 33here=`pwd` 34cd /tmp 35sed '1,/^EOF/d' < $here/$0 > fcntl.c 36mycc -o fcntl -Wall -Wextra -O0 -g fcntl.c || exit 1 37rm -f fcntl.c 38 39mkdir -p $RUNDIR 40cd $RUNDIR 41/tmp/fcntl 42status=$? 43 44rm -f /tmp/fcntl 45exit $status 46EOF 47#include <sys/types.h> 48#include <sys/wait.h> 49 50#include <err.h> 51#include <errno.h> 52#include <fcntl.h> 53#include <signal.h> 54#include <stdio.h> 55#include <stdlib.h> 56#include <string.h> 57#include <unistd.h> 58 59#define PARALLEL 16 60#define N 4096 61 62static volatile sig_atomic_t completed; 63const char name[] = "work"; 64int fd; 65 66static void 67ahandler(int s __unused) 68{ 69 unlink(name); 70 _exit(1); 71} 72 73static void 74handler(int s __unused) 75{ 76 completed++; 77} 78 79void 80add(int n, int increment) 81{ 82 struct flock fl; 83 off_t pos; 84 long val, oval; 85 int debug, r; 86 87 debug = 0; /* set to "1" for debug output. */ 88 pos = n * sizeof(val); 89 memset(&fl, 0, sizeof(fl)); 90 fl.l_start = pos; 91 fl.l_len = sizeof(val); 92 fl.l_type = F_WRLCK; 93 fl.l_whence = SEEK_SET; 94 95 while (fcntl(fd, F_SETLK, &fl) < 0) { 96 if (errno != EAGAIN) 97 err(1, "F_SETLK (child)"); 98 usleep(100); 99 } 100 101 if (lseek(fd, pos, SEEK_SET) == -1) 102 err(1, "lseek"); 103 oval = 999999; 104 while ((r = read(fd, &val, sizeof(val)) != sizeof(val))) { 105 if (r == -1 && errno != EAGAIN) 106 err(1, "read"); 107 if (lseek(fd, pos, SEEK_SET) == -1) 108 err(1, "lseek"); 109 } 110 oval = val; 111 val = val + increment; 112 if (debug != 0) 113 fprintf(stderr, "add(%d, %d) @ pos %ld: %ld = %ld + %d\n", 114 n, increment, (long)pos, val, oval, increment); 115 if (lseek(fd, pos, SEEK_SET) == -1) 116 err(1, "lseek"); 117 while ((r = write(fd, &val, sizeof(val)) != sizeof(val))) { 118 if (r == -1 && errno != EAGAIN) 119 err(1, "write"); 120 if (lseek(fd, pos, SEEK_SET) == -1) 121 err(1, "lseek"); 122 } 123 124 fl.l_type = F_UNLCK; 125 if (fcntl(fd, F_SETLK, &fl) < 0) 126 err(1, "F_UNLCK"); 127 128} 129 130void 131up(void) 132{ 133 int flags, i; 134 135 /* Need to re-open after a fork() */ 136 close(fd); 137 if ((fd = open(name, O_RDWR)) == -1) 138 err(1, "open(%s)", name); 139 if ((flags = fcntl(fd, F_GETFL)) == -1) 140 err(1, "fcntl(%d, T_GETFL)", fd); 141 flags |= O_NONBLOCK; 142 if ((flags = fcntl(fd, F_SETFL, flags)) == -1) 143 err(1, "fcntl(%d, T_SETFL, %d)", fd, flags); 144 145 for (i = 0; i < N; i++) 146 add(i, 1); 147 148 kill(getppid(), SIGHUP); 149 while (access("work", R_OK) == 0) 150 usleep(100); 151 152 _exit(0); 153} 154 155void 156down(void) 157{ 158 int flags, i; 159 160 close(fd); 161 if ((fd = open(name, O_RDWR)) == -1) 162 err(1, "open(%s)", name); 163 if ((flags = fcntl(fd, F_GETFL)) == -1) 164 err(1, "fcntl(%d, T_GETFL)", fd); 165 flags |= O_NONBLOCK; 166 if ((flags = fcntl(fd, F_SETFL, flags)) == -1) 167 err(1, "fcntl(%d, T_SETFL, %d)", fd, flags); 168 169 for (i = 0; i < N; i++) 170 add(i, -1); 171 172 kill(getppid(), SIGHUP); 173 while (access("work", R_OK) == 0) 174 usleep(100); 175 176 _exit(0); 177} 178 179int 180main(void) 181{ 182 off_t len; 183 long val, sum; 184 int flags, i; 185 186 signal(SIGHUP, handler); 187 signal(SIGALRM, ahandler); 188 alarm(300); 189 if ((fd = open(name, O_RDWR | O_CREAT | O_TRUNC, 0640)) == -1) 190 err(1, "open(%s)", name); 191 len = N * sizeof(val); 192 if (ftruncate(fd, len) == -1) 193 err(1, "ftruncate"); 194 195 if ((flags = fcntl(fd, F_GETFL)) == -1) 196 err(1, "fcntl(%d, T_GETFL)", fd); 197 flags |= O_NONBLOCK; 198 if ((flags = fcntl(fd, F_SETFL, flags)) == -1) 199 err(1, "fcntl(%d, T_SETFL, %d)", fd, flags); 200 201 for (i = 0; i < PARALLEL; i++) { 202 if (fork() == 0) 203 up(); 204 } 205 for (i = 0; i < PARALLEL; i++) { 206 if (fork() == 0) 207 down(); 208 } 209 210 while (completed != PARALLEL * 2) 211 usleep(200); 212 213 if (lseek(fd, 0, SEEK_SET) == -1) 214 err(1, "lseek"); 215 sum = 0; 216 for (i = 0; i < N; i++) { 217 if (read(fd, &val, sizeof(val)) != sizeof(val)) 218 err(1, "Final read"); 219 if (val != 0) 220 fprintf(stderr, "index %d: %ld\n", i, val); 221 sum += val; 222 } 223 if (sum != 0) 224 fprintf(stderr, "FAIL\n"); 225 unlink(name); 226 227 for (i = 0; i < PARALLEL; i++) { 228 wait(NULL); 229 wait(NULL); 230 } 231 232 close(fd); 233 234 return (sum != 0); 235} 236