The new ipc subsystem

[paraslash.git] / ipc.c

diff --git a/ipc.c b/ipc.c
new file mode 100644 (file)
index 0000000..9ae2b3a
--- /dev/null
+++ b/ipc.c
@@ -0,0 +1,105 @@
+#include "para.h"
+#include "error.h"
+#include "ipc.h"
+#include <sys/ipc.h>
+#include <sys/shm.h>
+
+
+int mutex_new(void)
+{
+       int ret = semget(IPC_PRIVATE, 1, IPC_CREAT | 0666);
+       return ret < 0?  -E_SEM_GET : ret;
+}
+
+int mutex_remove(int id)
+{
+       int ret = semctl(id, 0, IPC_RMID);
+       return ret < 0? -E_SEM_REMOVE : 1;
+}
+
+static void para_semop(int id, struct sembuf *sops, int num)
+{
+       if (semop(id, sops, num) >= 0)
+               return;
+       PARA_WARNING_LOG("semop failed (%s), retrying\n", strerror(errno));
+       while (semop(id, sops, num) < 0)
+               ; /* nothing */
+}
+
+/**
+ * lock the given mutex
+ *
+ * \sa semop(2), struct misc_meta_data
+ */
+void mutex_lock(int id)
+{
+       struct sembuf sops[2] = {
+               {
+                       .sem_num = 0,
+                       .sem_op = 0,
+                       .sem_flg = SEM_UNDO
+               },
+               {
+                       .sem_num = 0,
+                       .sem_op = 1,
+                       .sem_flg = SEM_UNDO
+               }
+       };
+       para_semop(id, sops, 2);
+}
+
+/**
+ * unlock a mutex
+ *
+ * \sa semop(2), struct misc_meta_data
+ */
+void mutex_unlock(int id)
+{
+       struct sembuf sops[1] = {
+               {
+                       .sem_num = 0,
+                       .sem_op = -1,
+                       .sem_flg = SEM_UNDO
+               },
+       };
+       para_semop(id, sops, 1);
+}
+
+/**
+ * create a new shared memory area of given size
+ * 
+ * \sa shmget(2)
+ */
+int shm_new(size_t size)
+{
+       int ret = shmget(IPC_PRIVATE, size, IPC_CREAT | IPC_EXCL | 0600);
+       return ret < 0 ? -E_SHM_GET : ret;
+}
+
+/**
+ * destroy the given shared memory area
+ * \sa shmctl(2)
+ **/
+int shm_destroy(int id)
+{
+       struct shmid_ds shm_desc;
+       int ret = shmctl(id, IPC_RMID, &shm_desc);
+       return ret < 0? -E_SHM_DESTROY : ret;
+}
+
+/**
+ * attach a shared memory area
+ *
+ * \sa semop(2)
+ */
+void *shm_attach(int id, enum shm_attach_mode mode)
+{
+       if (mode == ATTACH_RW)
+               return shmat(id, NULL, 0);
+       return shmat(id, NULL, SHM_RDONLY);
+}
+int shm_detach(void *addr)
+{
+       int ret = shmdt(addr);
+       return ret < 0? -E_SHM_DETACH : 1;
+}