Implement ioctl-alike communication

[lttng-ust.git] / libust / lttng-ust-abi.c

diff --git a/libust/lttng-ust-abi.c b/libust/lttng-ust-abi.c
index dca010c9f97353c68011eac4cab506f23d089804..5f4ba8916da496c0f0b0f5867a996e13fa9b39e1 100644 (file)
--- a/libust/lttng-ust-abi.c
+++ b/libust/lttng-ust-abi.c
@@ -37,13 +37,6 @@
  * by the caller.
  */
 
-struct obj;
-
-struct objd_ops {
-       long (*cmd)(int objd, unsigned int cmd, unsigned long arg);
-       int (*release)(int objd);
-};
-
 struct obj {
        union {
                struct {
@@ -100,7 +93,8 @@ int objd_alloc(void *private_data, const struct objd_ops *ops)
 end:
        obj->u.s.private_data = private_data;
        obj->u.s.ops = ops;
-       obj->u.s.f_count = 1;
+       obj->u.s.f_count = 2;   /* count == 1 : object is allocated */
+                               /* count == 2 : allocated + hold ref */
        return obj - objd_table.array;
 }
 
@@ -109,6 +103,8 @@ struct obj *_objd_get(int id)
 {
        if (id >= objd_table.len)
                return NULL;
+       if (!objd_table.array[id].u.s.f_count)
+               return NULL;
        return &objd_table.array[id];
 }
 
@@ -128,11 +124,12 @@ void objd_set_private(int id, void *private_data)
        obj->u.s.private_data = private_data;
 }
 
-static
 const struct objd_ops *objd_ops(int id)
 {
        struct obj *obj = _objd_get(id);
-       assert(obj);
+
+       if (!obj)
+               return NULL;
        return obj->u.s.ops;
 }
 
@@ -144,6 +141,8 @@ void objd_free(int id)
        assert(obj);
        obj->u.freelist_next = objd_table.freelist_head;
        objd_table.freelist_head = obj - objd_table.array;
+       assert(obj->u.s.f_count == 1);
+       obj->u.s.f_count = 0;   /* deallocated */
 }
 
 static
@@ -159,9 +158,13 @@ int objd_unref(int id)
 
        if (!obj)
                return -EINVAL;
-       if (!(--obj->u.s.f_count)) {
+       if (obj->u.s.f_count == 1) {
+               ERR("Reference counting error\n");
+               return -EINVAL;
+       }
+       if ((--obj->u.s.f_count) == 1) {
                const struct objd_ops *ops = objd_ops(id);
-
+               
                if (ops->release)
                        ops->release(id);
                objd_free(id);
@@ -172,6 +175,18 @@ int objd_unref(int id)
 static
 void objd_table_destroy(void)
 {
+       int i;
+
+       for (i = 0; i < objd_table.allocated_len; i++) {
+               struct obj *obj = _objd_get(i);
+               const struct objd_ops *ops;
+
+               if (!obj)
+                       continue;
+               ops = obj->u.s.ops;
+               if (ops->release)
+                       ops->release(i);
+       }
        free(objd_table.array);
 }
 
@@ -191,6 +206,15 @@ enum channel_type {
        METADATA_CHANNEL,
 };
 
+int lttng_abi_create_root_handle(void)
+{
+       int root_handle;
+
+       root_handle = objd_alloc(NULL, &lttng_ops);
+       assert(root_handle == 0);
+       return root_handle;
+}
+
 int lttng_abi_create_session(void)
 {
        struct ltt_session *session;
@@ -333,7 +357,6 @@ create_error:
        return;         /* not allowed to return error */
 }
 
-static
 int lttng_abi_create_channel(int session_objd,
                             struct lttng_ust_channel *chan_param,
                             enum channel_type channel_type)