diff options
| -rw-r--r-- | src/semaphore.c | 183 |
1 files changed, 174 insertions, 9 deletions
diff --git a/src/semaphore.c b/src/semaphore.c index 5447c82..8c9f099 100644 --- a/src/semaphore.c +++ b/src/semaphore.c @@ -2,6 +2,7 @@ #include <stdio.h> #include <time.h> #include <errno.h> +#include <string.h> #include <sys/ipc.h> #include <sys/sem.h> @@ -16,17 +17,26 @@ union semun { #endif +#define P 0 +#define Q 1 +#define N 2 + +#define SEMAPHORES 3 + + char *argv0; -int main(int argc, char *argv[]) +static int +create_semaphores(void) { key_t key; - int id = -1; + int id = -1, saved_errno; + union semun values; - (void) argc; - argv0 = *argv; + values.array = NULL; + /* Create semaphore array. */ srand(time(NULL)); for (;;) { double r = (double)rand(); @@ -35,24 +45,179 @@ int main(int argc, char *argv[]) key = (key_t)r + 1; if (key == IPC_PRIVATE) continue; - id = semget(key, 3, IPC_CREAT | IPC_EXCL | 0600); + id = semget(key, SEMAPHORES, IPC_CREAT | IPC_EXCL | 0600); if (id != -1) break; if ((errno != EEXIST) && (errno != EINTR)) goto fail; } - printf("key:%zx, id:%i\n", (size_t)key, id); - - if (semctl(id, 0, IPC_RMID) == -1) + /* Initialise the array. */ + values.array = calloc(SEMAPHORES, sizeof(unsigned short)); + if (values.array == NULL) 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: - perror(argv0); + saved_errno = errno; if ((id != -1) && (semctl(id, 0, IPC_RMID) == -1)) perror(argv0); + free(values.array); + errno = saved_errno; + return -1; +} + + +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; +} + + +static int +acquire_semaphore(key_t key, int semaphore, int delta) +{ + 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 = 0; + + return semop(id, &op, 1); +} + + +static int +release_semaphore(key_t key, int semaphore, int delta) +{ + 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 = 0; + + return semop(id, &op, 1); +} + + +static int +zero_semaphore(key_t key, int semaphore) +{ + struct sembuf op; + int id; + + id = semget(key, SEMAPHORES, 0600); + if (id == -1) + return -1; + + op.sem_op = 0; + op.sem_num = semaphore; + op.sem_flg = 0; + + return semop(id, &op, 1); +} + + +static int +read_semaphore(key_t key, int semaphore, int *z, int *n, int *v) +{ + struct sembuf op; + int id, r; + + id = semget(key, SEMAPHORES, 0600); + if (id == -1) + return -1; + + if (r = semctl(id, semaphore, GETZCNT), r == -1) + return -1; + if (z) + *z = r; + + if (r = semctl(id, semaphore, GETNCNT), r == -1) + return -1; + if (n) + *n = r; + + if (r = semctl(id, semaphore, GETVAL), r == -1) + return -1; + if (v) + *v = r; + + return 0; +} + + +int +main(int argc, char *argv[]) +{ + int r = -1, saved_errno, value; + key_t key = argc > 2 ? (key_t)atoll(argv[2]) : 0; + + argv0 = *argv; + + if (!strcmp(argv[1], "create")) { + r = create_semaphores(); + } else if (!strcmp(argv[1], "remove")) { + r = remove_semaphores(key); + } else if (!strcmp(argv[1], "pick-up")) { + r = release_semaphore(key, N, 1); + } else if (!strcmp(argv[1], "hang-up")) { + r = acquire_semaphore(key, N, 1); + } else if (!strcmp(argv[1], "listen")) { + r = acquire_semaphore(key, Q, 1); + if (r) { + saved_errno = errno; + r = release_semaphore(key, P, 1); + if (r) + perror(argv0); + errno = saved_errno; + goto fail; + } + printf("read here\n"); + r = release_semaphore(key, P, 1); + } else if (!strcmp(argv[1], "speak")) { + printf("write here\n"); + r = read_semaphore(key, N, NULL, NULL, &value); + if (r) + goto fail; + r = release_semaphore(key, Q, value); + if (r) + goto fail; + r = acquire_semaphore(key, P, value); + } else + return 2; + + if (r) + goto fail; + return 0; + +fail: + perror(argv0); return 1; } |