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#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <errno.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#ifdef _SEM_SEMUN_UNDEFINED
union semun {
int val;
struct semid_ds *buf;
unsigned short *array;
};
#endif
#define S 0
#define W 1
#define X 2
#define Q 3
#define SEMAPHORES 4
#define MEMORY_SIZE (2 * 1024)
#define open_semaphore(key) ((sem_id = semget(key, SEMAPHORES, 0600)) == -1 ? -1 : 0)
#define acquire_semaphore(semaphore, delta, undo) semaphore_op(semaphore, -delta, undo)
#define release_semaphore(semaphore, delta, undo) semaphore_op(semaphore, +delta, undo)
#define zero_semaphore(semaphore) semaphore_op(semaphore, 0, 0)
#define t(inst) if ((inst) == -1) goto fail
char *argv0;
static int sem_id = -1;
static int
create_semaphores(void)
{
key_t key;
int id = -1, saved_errno;
union semun values;
values.array = NULL;
/* Create semaphore array. */
for (;;) {
double r = (double)rand();
r /= (double)RAND_MAX + 1;
r *= (1 << (8 * sizeof(key_t) - 2)) - 1;
key = (key_t)r + 1;
if (key == IPC_PRIVATE)
continue;
id = semget(key, SEMAPHORES, IPC_CREAT | IPC_EXCL | 0600);
if (id != -1)
break;
if ((errno != EEXIST) && (errno != EINTR))
goto fail;
}
/* Initialise the array. */
values.array = calloc(SEMAPHORES, sizeof(unsigned short));
values.array[X] = 1;
if (!values.array)
goto fail;
if (semctl(id, 0, SETALL, values.array) == -1)
goto fail;
free(values.array);
values.array = NULL;
printf("key:%zi(x%zx), id:%i\n", (ssize_t)key, (size_t)key, id);
return 0;
fail:
saved_errno = errno;
if ((id != -1) && (semctl(id, 0, IPC_RMID) == -1))
perror(argv0);
free(values.array);
errno = saved_errno;
return -1;
}
static int
create_shared_memory(void)
{
key_t key;
int id = -1, saved_errno;
struct shmid_ds _info;
/* Create shared memory. */
for (;;) {
double r = (double)rand();
r /= (double)RAND_MAX + 1;
r *= (1 << (8 * sizeof(key_t) - 2)) - 1;
key = (key_t)r + 1;
if (key == IPC_PRIVATE)
continue;
id = shmget(key, MEMORY_SIZE, IPC_CREAT | IPC_EXCL | 0600);
if (id != -1)
break;
if ((errno != EEXIST) && (errno != EINTR))
goto fail;
}
printf("key:%zi(x%zx), id:%i\n", (ssize_t)key, (size_t)key, id);
return 0;
fail:
saved_errno = errno;
if ((id != -1) && (shmctl(id, IPC_RMID, &_info) == -1))
perror(argv0);
errno = saved_errno;
return -1;
}
static int
remove_semaphores(key_t key)
{
int id = semget(key, SEMAPHORES, 0600);
return ((id == -1) || (semctl(id, 0, IPC_RMID) == -1)) ? -1 : 0;
}
static int
remove_shared_memory(key_t key)
{
struct shmid_ds _info;
int id = shmget(key, MEMORY_SIZE, 0600);
return ((id == -1) || (shmctl(sem_id, IPC_RMID, &_info) == -1)) ? -1 : 0;
}
static int
semaphore_op(int semaphore, int delta, int undo)
{
struct sembuf op;
op.sem_op = delta;
op.sem_num = semaphore;
op.sem_flg = undo * SEM_UNDO;
return semop(sem_id, &op, 1);
}
static int
write_semaphore(int semaphore, int value)
{
union semun semval;
semval.val = value;
return semctl(sem_id, semaphore, SETVAL, semval);
}
static int
read_shared_memory(key_t key, char *message)
{
int id, saved_errno;
void *address = NULL;
t(shmget(key, MEMORY_SIZE, 0600));
address = shmat(id, NULL, SHM_RDONLY);
if ((address == (void *)-1) || !address)
goto fail;
strncpy(message, address, MEMORY_SIZE);
t(shmdt(address));
return 0;
fail:
saved_errno = errno;
if (address && (shmdt(address) == -1))
perror(argv0);
errno = saved_errno;
return -1;
}
static int
write_shared_memory(key_t key, const char *message)
{
int id, saved_errno;
void *address = NULL;
t(id = shmget(key, MEMORY_SIZE, 0600));
address = shmat(id, NULL, 0);
if ((address == (void *)-1) || !address)
goto fail;
memcpy(address, message, (strlen(message) + 1) * sizeof(char));
t(shmdt(address));
return 0;
fail:
saved_errno = errno;
if (address && (shmdt(address) == -1))
perror(argv0);
errno = saved_errno;
return -1;
}
int
main(int argc, char *argv[])
{
int saved_errno;
key_t key_sem = argc > 2 ? (key_t)atoll(argv[2]) : 0;
key_t key_shm = argc > 3 ? (key_t)atoll(argv[3]) : 0;
const char *message = argc > 4 ? argv[4] : "default message";
char read_message[MEMORY_SIZE];
argv0 = *argv;
if (!strcmp(argv[1], "create")) {
srand(time(NULL));
t(create_semaphores());
t(create_shared_memory());
} else if (!strcmp(argv[1], "remove")) {
t(remove_semaphores(key_sem));
t(remove_shared_memory(key_shm));
} else if (!strcmp(argv[1], "listen")) {
t(open_semaphore(key_sem));
t(release_semaphore(S, 1, 1));
for (;;) {
t(release_semaphore(Q, 1, 0));
t(zero_semaphore(Q));
t(read_shared_memory(key_shm, read_message));
printf("%s\n", read_message);
t(release_semaphore(W, 1, 1));
t(acquire_semaphore(S, 1, 1));
t(zero_semaphore(S));
t(release_semaphore(S, 1, 1));
t(acquire_semaphore(W, 1, 1));
}
} else if (!strcmp(argv[1], "broadcast")) {
t(open_semaphore(key_sem));
t(acquire_semaphore(X, 1, 1));
t(zero_semaphore(W));
t(write_shared_memory(key_shm, message));
t(write_semaphore(Q, 0));
t(zero_semaphore(S));
t(release_semaphore(X, 1, 1));
} else
return 2;
return 0;
fail:
perror(argv0);
return 1;
}
#undef t
|
