create semaphore array with random key

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/src/semaphore.c b/src/semaphore.c
new file mode 100644
index 0000000..5447c82
--- /dev/null
+++ b/src/semaphore.c
@@ -0,0 +1,58 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <time.h>
+#include <errno.h>
+
+#include <sys/ipc.h>
+#include <sys/sem.h>
+
+
+#ifdef _SEM_SEMUN_UNDEFINED
+union semun {
+	int val;
+	struct semid_ds *buf;
+	unsigned short *array;
+};
+#endif
+
+
+char *argv0;
+
+
+int main(int argc, char *argv[])
+{
+	key_t key;
+	int id = -1;
+
+	(void) argc;
+	argv0 = *argv;
+
+	srand(time(NULL));
+	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, 3, 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)
+		goto fail;
+
+	return 0;
+
+fail:
+	perror(argv0);
+	if ((id != -1) && (semctl(id, 0, IPC_RMID) == -1))
+		perror(argv0);
+	return 1;
+}
+