X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=ipc.c;fp=ipc.c;h=9ae2b3a09d1e1d98617e4502c16f7af2f0f54742;hb=bad57eee70cdca87e8ba1af08d4e2ef6d2878620;hp=0000000000000000000000000000000000000000;hpb=c589157169366fa47f2041cfe52e7019fbc19b35;p=paraslash.git

diff --git a/ipc.c b/ipc.c
new file mode 100644
index 00000000..9ae2b3a0
--- /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;
+}