Changeset 01900b6 in mainline for uspace/lib/c/generic/ns.c

Timestamp:

2020-01-21T15:10:26Z (4 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

51da086

Parents:

f8fb03b

Message:

Use an optional output argument instead of errno to propagate the error

The use of errno is troublesome in all other than top-level library
functions since the value in errno might get overwritten by subsequent
inner calls on the error path (e.g. cleanup, deallocation, etc.). The
optional output argument makes it possible to explicitly ignore the
error code if it is not needed, but still to pass it reliably back to
the original caller.

This change affecs async_connect_me_to(),
async_connect_me_to_blocking(), async_connect_kbox(), service_connect(),
service_connect_blocking() and loader_connect().

File:

• uspace/lib/c/generic/ns.c (modified) (9 diffs)

uspace/lib/c/generic/ns.c

@@ -49 +49 @@
     async_port_handler_t handler, void *data)
 {
-        async_sess_t *sess = ns_session_get();
-        if (sess == NULL)
-                return EIO;
+        errno_t rc;
+        async_sess_t *sess = ns_session_get(&rc);
+        if (sess == NULL)
+                return rc;
 
         port_id_t port;
-        errno_t rc = async_create_port(iface, handler, data, &port);
+        rc = async_create_port(iface, handler, data, &port);
         if (rc != EOK)
                 return rc;
@@ -81 +82 @@
         async_set_fallback_port_handler(handler, data);
 
-        async_sess_t *sess = ns_session_get();
-        if (sess == NULL)
-                return EIO;
+        errno_t rc;
+        async_sess_t *sess = ns_session_get(&rc);
+        if (sess == NULL)
+                return rc;
 
         async_exch_t *exch = async_exchange_begin(sess);
@@ -89 +91 @@
         ipc_call_t answer;
         aid_t req = async_send_1(exch, NS_REGISTER_BROKER, service, &answer);
-        errno_t rc = async_connect_to_me(exch, INTERFACE_ANY, service, 0);
+        rc = async_connect_to_me(exch, INTERFACE_ANY, service, 0);
 
         async_exchange_end(exch);
@@ -103 +105 @@
 }
 
-async_sess_t *service_connect(service_t service, iface_t iface, sysarg_t arg3)
-{
-        async_sess_t *sess = ns_session_get();
+/** Connect to a singleton service.
+ *
+ * @param service Singleton service ID.
+ * @param iface   Interface to connect to.
+ * @param arg3    Custom connection argument.
+ * @param rc      Placeholder for return code. Unused if NULL.
+ *
+ * @return New session on success or NULL on error.
+ *
+ */
+async_sess_t *service_connect(service_t service, iface_t iface, sysarg_t arg3,
+    errno_t *rc)
+{
+        async_sess_t *sess = ns_session_get(rc);
         if (sess == NULL)
                 return NULL;
@@ -114 +127 @@
 
         async_sess_t *csess =
-            async_connect_me_to(exch, iface, service, arg3);
+            async_connect_me_to(exch, iface, service, arg3, rc);
         async_exchange_end(exch);
 
@@ -130 +143 @@
 }
 
+/** Wait and connect to a singleton service.
+ *
+ * @param service Singleton service ID.
+ * @param iface   Interface to connect to.
+ * @param arg3    Custom connection argument.
+ * @param rc      Placeholder for return code. Unused if NULL.
+ *
+ * @return New session on success or NULL on error.
+ *
+ */
 async_sess_t *service_connect_blocking(service_t service, iface_t iface,
-    sysarg_t arg3)
-{
-        async_sess_t *sess = ns_session_get();
+    sysarg_t arg3, errno_t *rc)
+{
+        async_sess_t *sess = ns_session_get(rc);
         if (sess == NULL)
                 return NULL;
@@ -139 +162 @@
         async_exch_t *exch = async_exchange_begin(sess);
         async_sess_t *csess =
-            async_connect_me_to_blocking(exch, iface, service, arg3);
+            async_connect_me_to_blocking(exch, iface, service, arg3, rc);
         async_exchange_end(exch);
 
@@ -157 +180 @@
 errno_t ns_ping(void)
 {
-        async_sess_t *sess = ns_session_get();
+        errno_t rc;
+        async_sess_t *sess = ns_session_get(&rc);
+        if (sess == NULL)
+                return rc;
+
+        async_exch_t *exch = async_exchange_begin(sess);
+        rc = async_req_0_0(exch, NS_PING);
+        async_exchange_end(exch);
+
+        return rc;
+}
+
+errno_t ns_intro(task_id_t id)
+{
+        errno_t rc;
+        async_sess_t *sess = ns_session_get(&rc);
         if (sess == NULL)
                 return EIO;
 
         async_exch_t *exch = async_exchange_begin(sess);
-        errno_t rc = async_req_0_0(exch, NS_PING);
-        async_exchange_end(exch);
-
-        return rc;
-}
-
-errno_t ns_intro(task_id_t id)
-{
-        async_exch_t *exch;
-        async_sess_t *sess = ns_session_get();
-        if (sess == NULL)
-                return EIO;
-
-        exch = async_exchange_begin(sess);
-        errno_t rc = async_req_2_0(exch, NS_ID_INTRO, LOWER32(id), UPPER32(id));
-        async_exchange_end(exch);
-
-        return rc;
-}
-
-async_sess_t *ns_session_get(void)
+        rc = async_req_2_0(exch, NS_ID_INTRO, LOWER32(id), UPPER32(id));
+        async_exchange_end(exch);
+
+        return rc;
+}
+
+async_sess_t *ns_session_get(errno_t *rc)
 {
         async_exch_t *exch;
@@ -188 +212 @@
         if (sess_ns == NULL) {
                 exch = async_exchange_begin(&session_ns);
-                sess_ns = async_connect_me_to(exch, 0, 0, 0);
+                sess_ns = async_connect_me_to(exch, 0, 0, 0, rc);
                 async_exchange_end(exch);
                 if (sess_ns == NULL)