base: make CAP session upgradeable

* Introduce 'Out_of_metadata' exception for capability allocation

Ref #1443

repos/base-foc/src/core/include/cap_session_component.h

@@ -26,6 +26,8 @@ namespace Genode {
 
 			Cap_session_component(Allocator *md_alloc, const char *args) {}
 
+			void upgrade_ram_quota(size_t ram_quota) { }
+
 			Native_capability alloc(Native_capability ep);
 
 			void free(Native_capability cap);

repos/base-linux/src/core/include/cap_session_component.h

@@ -36,6 +36,8 @@ namespace Genode {
 
 			Cap_session_component(Allocator *md_alloc, const char *args) {}
 
+			void upgrade_ram_quota(size_t ram_quota) { }
+
 			Native_capability alloc(Native_capability ep)
 			{
 				Lock::Guard lock_guard(_lock());

repos/base-nova/src/core/include/cap_session_component.h

@@ -62,6 +62,8 @@ namespace Genode {
 				}
 			}
 
+			void upgrade_ram_quota(size_t ram_quota) { }
+
 			Native_capability alloc(Native_capability ep, addr_t entry,
 			                        addr_t mtd)
 			{

repos/base-sel4/src/core/include/cap_session_component.h

@@ -24,6 +24,8 @@ struct Genode::Cap_session_component : Rpc_object<Cap_session>
 {
 	Cap_session_component(Allocator *md_alloc, const char *args) {}
 
+	void upgrade_ram_quota(size_t ram_quota) { }
+
 	Native_capability alloc(Native_capability ep);
 
 	void free(Native_capability cap);

repos/base/include/cap_session/cap_session.h

@@ -18,6 +18,7 @@
 #ifndef _INCLUDE__CAP_SESSION__CAP_SESSION_H_
 #define _INCLUDE__CAP_SESSION__CAP_SESSION_H_
 
+#include <base/exception.h>
 #include <base/native_types.h>
 #include <session/session.h>
 
@@ -26,6 +27,8 @@ namespace Genode { struct Cap_session; }
 
 struct Genode::Cap_session : Session
 {
+	class Out_of_metadata : public Exception { };
+
 	static const char *service_name() { return "CAP"; }
 
 	virtual ~Cap_session() { }
@@ -35,6 +38,8 @@ struct Genode::Cap_session : Session
 	 *
 	 * \param ep  entry point that will use this capability
 	 *
+	 * \throw Out_of_metadata  if meta-data backing store is exhausted
+	 *
 	 * \return new userland capability
 	 */
 	virtual Native_capability alloc(Native_capability ep) = 0;
@@ -51,7 +56,8 @@ struct Genode::Cap_session : Session
 	 ** RPC declaration **
 	 *********************/
 
-	GENODE_RPC(Rpc_alloc, Native_capability, alloc, Native_capability);
+	GENODE_RPC_THROW(Rpc_alloc, Native_capability, alloc,
+	                 GENODE_TYPE_LIST(Out_of_metadata), Native_capability);
 	GENODE_RPC(Rpc_free, void, free, Native_capability);
 	GENODE_RPC_INTERFACE(Rpc_alloc, Rpc_free);
 };

repos/base/src/core/include/cap_root.h

@@ -33,6 +33,13 @@ namespace Genode {
 			Cap_session_component *_create_session(const char *args) {
 				return new (md_alloc()) Cap_session_component(_md_alloc, args); }
 
+			void _upgrade_session(Cap_session_component *c, const char *args)
+			{
+				size_t ram_quota =
+					Arg_string::find_arg(args, "ram_quota").ulong_value(0);
+				c->upgrade_ram_quota(ram_quota);
+			}
+
 		public:
 
 			/**

repos/base/src/core/include/cap_session_component.h

@@ -36,6 +36,8 @@ namespace Genode {
 
 			Cap_session_component(Allocator *md_alloc, const char *args) {}
 
+			void upgrade_ram_quota(size_t ram_quota) { }
+
 			Native_capability alloc(Native_capability ep)
 			{
 				Lock::Guard lock_guard(_lock());