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-rw-r--r--src/cmdline.c118
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;