EDK: Add handle rights checking to the various entrypoints.

mojo/edk/system/core.h

Index: mojo/edk/system/core.h
diff --git a/mojo/edk/system/core.h b/mojo/edk/system/core.h
index 18ad059ecce4cfeec4dad196b23836fc655b43b2..fbb289cb276874a0f34b871f6972e299cd298aa7 100644
--- a/mojo/edk/system/core.h
+++ b/mojo/edk/system/core.h
@@ -9,6 +9,7 @@
 
 #include <functional>
 
+#include "mojo/edk/system/entrypoint_class.h"
 #include "mojo/edk/system/handle.h"
 #include "mojo/edk/system/handle_table.h"
 #include "mojo/edk/system/mapping_table.h"
@@ -55,19 +56,43 @@ class Core {
   // if the handle table is full.
   MojoHandle AddHandle(Handle&& h);
 
-  // Looks up the dispatcher for the given handle value. On success, gets the
-  // dispatcher for a given handle value. On failure, returns an appropriate
-  // result and leaves |dispatcher| alone), namely
-  // |MOJO_RESULT_INVALID_ARGUMENT| if the handle value is invalid or
-  // |MOJO_RESULT_BUSY| if the handle is marked as busy.
+  // Gets the handle for the given handle value. On success, returns
+  // |MOJO_RESULT_OK| (and sets |*h|). On failure, returns an appropriate result
+  // (and leaves |*h| alone), namely |MOJO_RESULT_INVALID_ARGUMENT| if the
+  // handle value is invalid or |MOJO_RESULT_BUSY| if the handle is marked as
+  // busy.
+  MojoResult GetHandle(MojoHandle handle, Handle* h);
+  // TODO(vtl): Remove this.
   MojoResult GetDispatcher(MojoHandle handle,
                            util::RefPtr<Dispatcher>* dispatcher);
 
+  // TODO(vtl): Convert this to |GetAndRemoveHandle()|.
   // Like |GetDispatcher()|, but on success also removes the handle from the
   // handle table.
   MojoResult GetAndRemoveDispatcher(MojoHandle handle,
                                     util::RefPtr<Dispatcher>* dispatcher);
 
+  // Gets the dispatcher for the given handle value, which must have (all of)
+  // the rights in |required_handle_rights|.
+  //
+  // On success, returns |MOJO_RESULT_OK| and sets |*dispatcher| appropriately.
+  // On failure, returns:
+  //   - |MOJO_RESULT_INVALID_ARGUMENT| if there's no handle for the given
+  //     handle value (or the handle value was |MOJO_HANDLE_INVALID|),
+  //   - |MOJO_RESULT_BUSY| if the handle is marked as busy,
+  //   - |MOJO_RESULT_PERMISSION_DENIED| if the handle does not have the
+  //     required rights *and* the dispatcher supports the specified
+  //     |entrypoint_class|, or
+  //   - |MOJO_RESULT_INVALID_ARGUMENT| if the handle does not have the required
+  //     rights *but* the dispatcher does not support |entrypoint_class|.
+  // (Warning: if the handle has the required rights, then its dispatcher will
+  // be returned even if the dispatcher does not support |entrypoint_class|.)
+  MojoResult GetDispatcherAndCheckRights(
+      MojoHandle handle_value,
+      MojoHandleRights required_handle_rights,
+      EntrypointClass entrypoint_class,
+      util::RefPtr<Dispatcher>* dispatcher);
+
   // Watches on the given handle for the given signals, calling |callback| when
   // a signal is satisfied or when all signals become unsatisfiable. |callback|
   // must satisfy stringent requirements -- see |Awakable::Awake()| in