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/* This is just a driver to test the filerwlock objects defined in fcntl.c */
/* MAXCHILD processes are forked. They take turns in using LOCKSSIZE locks.*/
/* I compiled the program as follows */
/* cc fcntlmain.c fcntl.c -o fcntlmain */
/* and then run the image fcntlmain. */
/* Notice that after the program has run I find the file "mylock" in my */
/* directory. Not very desirable. Perhaps there is a way to avoid that? */
#include <stdio.h>
#include <sys/types.h>
#include "fcntl.h"
#define LOCKFILE "mylock"
#define LOCKSSIZE 5
#define MAXCHILD 4
void child (int self);
pid_t cldrn[4];
filerwlock *fl;
int
main(void){
int i;
fl = filerwlockCreate(LOCKFILE, LOCKSSIZE);
for (i=0;i < MAXCHILD; i++) {
if ((cldrn[i]=fork()) < 0) {
perror("fork");
exit(1);}
if (cldrn[i]==0)
child(i);
}
for (i=0; i < MAXCHILD; i++)
wait();
filerwlockDelete(fl);
exit(0);
}
void child (int self) {
int i, j;
char s[256];
for (j=0; j<8; j++) {
if (self == 0) {
filerwwritelock(fl,1);
} else if (self == (MAXCHILD-1)) {
filerwlongreadlock(fl);
} else {
filerwreadlock(fl,1);
}
printf("Child %d starts to sleep on lock %d\n", self, 1);
sleep(3);
printf("Child %d ends sleep on lock %d\n", self, 1);
if (self == (MAXCHILD-1)) {
filerwlongunlock(fl);
} else {
filerwunlock(fl,1);
}
sleep(1);
}
exit(0);
}
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