1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
|
#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#define NSEM 3
union semun {
int val;
struct semid_ds *buf;
ushort *array;
};
int shmid, semid;
void quit(signum)
int signum;
{
shmctl(shmid, IPC_RMID, NULL);
semctl(semid, IPC_RMID, 0);
}
int main(argc, argv)
int argc;
char **argv;
{
int i, pid, n_read, n_write, w;
char *mem, **arg_r, **arg_w;
union semun semarg;
if (argc < 2) {
printf("usage: sync [number readers] [number writers]\n");
exit(1);
}
n_read = atoi(argv[1]);
n_write = atoi(argv[2]);
if ((shmid = shmget(52, 1<<14, IPC_CREAT | 0666)) == -1){
perror("shmget: shmget failed");
exit(1);
}
if ((mem = shmat(shmid, NULL, 0)) == (char *) -1) {
perror("shmat");
exit(1);
}
printf("Sshmid: %x\n", shmid);
signal(SIGQUIT, quit);
for (i = 0; i < 1<<14; i++) {
*(mem + i) = 0x30;
}
if ((semid = semget(shmid, NSEM, 0666 | IPC_CREAT)) == -1) {
perror("Ssemget: ");
exit(1);
}
semarg.val = 1;
for (i = 0; i < NSEM; i++) {
if ((semctl(semid, i, SETVAL, semarg)) == -1) {
perror("semctl: ");
exit(1);
}
}
arg_r = malloc(sizeof(char*) * 3);
arg_w = malloc(sizeof(char*) * 3);
*arg_r = malloc(sizeof(char) * 10);
*arg_w = malloc(sizeof(char) * 10);
*(arg_r + 1) = malloc(sizeof(char) * 50);
*(arg_w + 1) = malloc(sizeof(char) * 50);
*arg_r = "reader";
*arg_w = "writer";
*(arg_r + 2) = NULL;
*(arg_w + 2) = NULL;
for (i = 0; i < n_read; i++){
sprintf(*(arg_r + 1), "%d", i);
if (pid = fork()) {
/* printf("starting reader %d...\n", i); */
} else {
int ret = execv("./reader", arg_r);
printf("exec retern %d", ret);
}
}
for (i = 0; i < n_write; i++) {
sprintf(*(arg_w + 1), "%d", i);
if (pid = fork()) {
/* printf("starting writer %d...\n", i); */
} else {
execvp("./writer", arg_w);
}
}
shmdt(mem);
printf("sync done...\n");
/* TODO
* why is this returning 8
*/
for (i = 0; i < (n_write + n_read); i++) {
wait(&w);
printf("\nReturned with code:%d\n", WEXITSTATUS(w));
}
quit();
}
|
