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/*-
* Copyright (c) 2006, Stephan Uphoff <ups@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 unmodified, 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 ``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 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.
*
* $FreeBSD$
*/
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/mman.h>
int prepareFile(char* filename,int* fdp);
int mapBuffer(char** bufferp,int fd1,int fd2);
int startIO(int fd,char *buffer);
int pagesize;
#define FILESIZE (32*1024)
char wbuffer[FILESIZE];
/* Create a FILESIZE sized file - then remove file data from the cache*/
int prepareFile(char* filename,int* fdp)
{
int fd;
int len;
int status;
void *addr;
fd = open(filename,O_CREAT | O_TRUNC | O_RDWR,S_IRWXU);
if (fd == -1)
{
perror("Creating file");
return fd;
}
len = write(fd,wbuffer,FILESIZE);
if (len < 0)
{
perror("Write failed");
return 1;
}
status = fsync(fd);
if (status != 0)
{
perror("fsync failed");
return 1;
}
addr = mmap(NULL,FILESIZE, PROT_READ | PROT_WRITE , MAP_SHARED, fd, 0);
if (addr == MAP_FAILED)
{
perror("Mmap failed");
return 1;
}
status = msync(addr,FILESIZE,MS_INVALIDATE | MS_SYNC);
if (status != 0)
{
perror("Msync failed");
return 1;
}
munmap(addr,FILESIZE);
*fdp = fd;
return 0;
}
/* mmap a 2 page buffer - first page is from fd1, second page from fd2 */
int mapBuffer(char** bufferp,int fd1,int fd2)
{
void* addr;
char *buffer;
addr = mmap(NULL,pagesize*2, PROT_READ | PROT_WRITE , MAP_SHARED, fd1, 0);
if (addr == MAP_FAILED)
{
perror("Mmap failed");
return 1;
}
buffer = addr;
addr = mmap(buffer + pagesize,pagesize, PROT_READ | PROT_WRITE , MAP_FIXED |
MAP_SHARED, fd2, 0);
if (addr == MAP_FAILED)
{
perror("Mmap2 failed");
return 1;
}
*bufferp = buffer;
return 0;
}
int startIO(int fd,char *buffer)
{
ssize_t len;
len = write(fd,buffer,2*pagesize);
if (len == -1)
{
perror("write failed");
return 1;
}
return 0;
}
int main(int argc,char *argv[],char *envp[])
{
int fdA,fdB,fdDelayA,fdDelayB;
int status;
char *bufferA,*bufferB;
pid_t pid;
pagesize = getpagesize();
if ((prepareFile("A",&fdA))
|| (prepareFile("B",&fdB))
|| (prepareFile("DelayA",&fdDelayA))
|| (prepareFile("DelayB",&fdDelayB))
|| (mapBuffer(&bufferA,fdDelayA,fdB))
|| (mapBuffer(&bufferB,fdDelayB,fdA)))
exit(1);
pid = fork();
if (pid == 0)
{
status = startIO(fdA,bufferA);
exit(status);
}
if (pid == -1)
{
exit(1);
}
status = startIO(fdB,bufferB);
exit(status);
}
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