diff options
| -rw-r--r-- | src/cmdline.c | 118 |
1 files changed, 43 insertions, 75 deletions
diff --git a/src/cmdline.c b/src/cmdline.c index a1ebafe..9d1135b 100644 --- a/src/cmdline.c +++ b/src/cmdline.c @@ -28,8 +28,21 @@ union semun { #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) @@ -85,6 +98,7 @@ create_shared_memory(void) int id = -1, saved_errno; struct shmid_ds _info; + /* Create shared memory. */ for (;;) { double r = (double)rand(); r /= (double)RAND_MAX + 1; @@ -115,90 +129,52 @@ static int remove_semaphores(key_t key) { int id = semget(key, SEMAPHORES, 0600); - - if (id == -1) - return -1; - - if (semctl(id, 0, IPC_RMID) == -1) - return -1; - - return 0; + return ((id == -1) || (semctl(id, 0, IPC_RMID) == -1)) ? -1 : 0; } static int remove_shared_memory(key_t key) { - int id = shmget(key, MEMORY_SIZE, 0600); struct shmid_ds _info; - - if (id == -1) - return -1; - - if (shmctl(id, IPC_RMID, &_info) == -1) - return -1; - - return 0; + int id = shmget(key, MEMORY_SIZE, 0600); + return ((id == -1) || (shmctl(sem_id, IPC_RMID, &_info) == -1)) ? -1 : 0; } static int -semaphore_op(key_t key, int semaphore, int delta, int undo) +semaphore_op(int semaphore, int delta, int undo) { struct sembuf op; - int id; - - id = semget(key, SEMAPHORES, 0600); - if (id == -1) - return -1; - op.sem_op = delta; op.sem_num = semaphore; op.sem_flg = undo * SEM_UNDO; - - return semop(id, &op, 1); + return semop(sem_id, &op, 1); } -#define acquire_semaphore(key, semaphore, delta, undo) semaphore_op(key, semaphore, -delta, undo) -#define release_semaphore(key, semaphore, delta, undo) semaphore_op(key, semaphore, +delta, undo) -#define zero_semaphore(key, semaphore) semaphore_op(key, semaphore, 0, 0) - - static int -write_semaphore(key_t key, int semaphore, int value) +write_semaphore(int semaphore, int value) { union semun semval; - int id; - - id = semget(key, SEMAPHORES, 0600); - if (id == -1) - return -1; - semval.val = value; - return semctl(id, semaphore, SETVAL, semval); + return semctl(sem_id, semaphore, SETVAL, semval); } + static int read_shared_memory(key_t key, char *message) { int id, saved_errno; void *address = NULL; - id = shmget(key, MEMORY_SIZE, 0600); - if (id == -1) - goto fail; - + t(shmget(key, MEMORY_SIZE, 0600)); address = shmat(id, NULL, SHM_RDONLY); if ((address == (void *)-1) || !address) goto fail; - strncpy(message, address, MEMORY_SIZE); - - if (shmdt(address) == -1) - goto fail; - + t(shmdt(address)); return 0; fail: @@ -216,19 +192,12 @@ write_shared_memory(key_t key, const char *message) int id, saved_errno; void *address = NULL; - id = shmget(key, MEMORY_SIZE, 0600); - if (id == -1) - goto fail; - + 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)); - - if (shmdt(address) == -1) - goto fail; - + t(shmdt(address)); return 0; fail: @@ -240,13 +209,10 @@ fail: } -#define t(inst) if (r = inst, r) goto fail - - int main(int argc, char *argv[]) { - int r = -1, saved_errno, value; + int saved_errno, value; 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"; @@ -261,29 +227,31 @@ main(int argc, char *argv[]) } else if (!strcmp(argv[1], "remove")) { t(remove_semaphores(key_sem)); - t(remove_shared_memory(key_sem)); + t(remove_shared_memory(key_shm)); } else if (!strcmp(argv[1], "listen")) { - t(release_semaphore(key_sem, S, 1, 1)); + t(open_semaphore(key_sem)); + t(release_semaphore(S, 1, 1)); for (;;) { - t(release_semaphore(key_sem, Q, 1, 0)); - t(zero_semaphore(key_sem, Q)); + 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(key_sem, W, 1, 1)); - t(acquire_semaphore(key_sem, S, 1, 1)); - t(zero_semaphore(key_sem, S)); - t(release_semaphore(key_sem, S, 1, 1)); - t(acquire_semaphore(key_sem, W, 1, 1)); + 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(acquire_semaphore(key_sem, X, 1, 1)); - t(zero_semaphore(key_sem, W)); + 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(key_sem, Q, 0)); - t(zero_semaphore(key_sem, S)); - t(release_semaphore(key_sem, X, 1, 1)); + t(write_semaphore(Q, 0)); + t(zero_semaphore(S)); + t(release_semaphore(X, 1, 1)); } else return 2; |