1 files changed, 73 insertions, 0 deletions
diff --git a/schulung_tools/ipc_shm/shm.c b/schulung_tools/ipc_shm/shm.c
new file mode 100644
index 0000000..777fe79
--- /dev/null
+++ b/schulung_tools/ipc_shm/shm.c
@@ -0,0 +1,73 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include "shm.h"
+
+#define SHARE_NAME "/ipc.shm"
+
+/* open and return a pointer to shared data */
+struct share_data *get_share(void)
+{
+	struct share_data *data;
+	int fd;
+
+	fd = shm_open(SHARE_NAME, O_RDWR, 0);
+	if (fd == -1)
+		return NULL;
+
+	data = mmap(NULL, sysconf(_SC_PAGESIZE), PROT_READ | PROT_WRITE,
+		    MAP_SHARED, fd, 0);
+	if (data == MAP_FAILED) {
+		close(fd);
+		return NULL;
+	}
+
+	close(fd);
+
+	return data;
+}
+
+/* initialize shared data */
+void init_share(struct share_data *data)
+{
+	pthread_mutexattr_t mattr;
+	pthread_condattr_t cattr;
+
+	pthread_mutexattr_init(&mattr);
+	pthread_mutexattr_setprotocol(&mattr, PTHREAD_PRIO_INHERIT);
+	pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
+	pthread_mutexattr_setrobust(&mattr, PTHREAD_MUTEX_ROBUST);
+	pthread_mutex_init(&data->m, &mattr);
+
+	pthread_condattr_init(&cattr);
+	pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
+	pthread_cond_init(&data->c, &cattr);
+}
+
+/* create a zero'd out file of size 1 page */
+int create_share(void)
+{
+	int ret;
+	int fd;
+
+	fd = shm_open(SHARE_NAME, O_CREAT|O_RDWR, S_IRUSR|S_IWUSR);
+	if (fd == -1)
+		return -1;
+
+	ret = ftruncate(fd, sysconf(_SC_PAGESIZE));
+
+	close(fd);
+
+	return ret;
+}
+
+/* remove the share */
+void remove_share(void)
+{
+	shm_unlink(SHARE_NAME);
+}