Incorporate shimming into the irt

src/untrusted/irt/irt_ppapi.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/shared/ppapi_proxy/ppruntime.h"
 #include "native_client/src/untrusted/irt/irt.h"
+#include "native_client/src/untrusted/irt/irt_interfaces.h"
 #include "native_client/src/untrusted/irt/irt_ppapi.h"
 #include "native_client/src/untrusted/irt/irt_private.h"
 
+#include "ppapi/generators/pnacl_shim.h"
+
 struct PP_StartFunctions g_pp_functions;
 
+/*
+ * PNaCl Shimming magic
+ * ====================
+ * Note: this could be simplified by changing the actual
+ * GetInterface functions for now we rely on some autogenerated files.
+ *
+ * Some background:
+ * pnacl has calling conventions which are slightly different from nacl-gcc.
+ * This only affect structure passing on x86-64 which is only used by Ppapi
+ * functions.
+ * There are two functions which are relevant:
+ * PPP_GetInterface and PPB_GetInterface.
+ * We interecept those functions, store the old version and then redirect
+ * to __Pnacl_PPPGetInterface and __Pnacl_PPBGetInterface.
+ */
+
+/* Holds the orginial PP_StartFunctions if shimming is enabled. */
+struct PP_StartFunctions g_pp_functions_non_shim;
+
+static int32_t PPPInitializeModule_cc_shim(PP_Module module_id,
+                                           PPB_GetInterface get_browser_intf) {
+  /* save old version of PPB_GetInterface */
+  __set_real_Pnacl_PPBGetInterface(get_browser_intf);

[Roland McGrath, 2012/08/06 23:32:24]

There's no reason to use __ names in any of this.

[Robert Muth (chromium), 2012/08/07 14:45:40]

I agree but the "__" code is generated by python scripts
in another repo so this change will have to be moved 
to another CL.

+  /* redirect to new version of PPB_GetInterface */
+  return g_pp_functions_non_shim.PPP_InitializeModule(
+    module_id, &__Pnacl_PPBGetInterface);
+}
+
+static void PPP_ShutdownModule_cc_shim() {
+  /* redirect to non-shimed version */
+  g_pp_functions_non_shim.PPP_ShutdownModule();
+}
+
+static const void *PPP_GetInterface_cc_shim(const char *interface_name) {
+  /* redirect to new version of PPP_GetInterface */
+  return __Pnacl_PPPGetInterface(interface_name);
+}
+
+struct PP_StartFunctions g_pp_functions_cc_shim = {
+  &PPPInitializeModule_cc_shim,
+  &PPP_ShutdownModule_cc_shim,
+  &PPP_GetInterface_cc_shim
+};
+
+/* register entry  points to untrusted pepper plugin  */
 static int irt_ppapi_start(const struct PP_StartFunctions *funcs) {
-  g_pp_functions = *funcs;
+  if (g_use_cc_shim) {
+    /* save old version of PPP_GetInterface */
+    __set_real_Pnacl_PPPGetInterface(funcs->PPP_GetInterface);
+    g_pp_functions_non_shim = *funcs;
+    g_pp_functions = g_pp_functions_cc_shim;
+  } else {
+    g_pp_functions = *funcs;
+  }
   g_is_main_thread = 1;
   return PpapiPluginMain();
 }
 
 int32_t PPP_InitializeModule(PP_Module module_id,
                              PPB_GetInterface get_browser_interface) {
   return g_pp_functions.PPP_InitializeModule(module_id, get_browser_interface);
 }
 
 void PPP_ShutdownModule() {
   g_pp_functions.PPP_ShutdownModule();
 }
 
 const void *PPP_GetInterface(const char *interface_name) {
   return g_pp_functions.PPP_GetInterface(interface_name);
 }
 
 /*
  * This overrides the definition in ppapi_proxy/plugin_threading.cc.
  * TODO(mseaborn): Remove this when PPAPI is only supported via the IRT.
  * See http://code.google.com/p/nativeclient/issues/detail?id=1691
  */
 void PpapiPluginRegisterDefaultThreadCreator() {
 }
 
 const struct nacl_irt_ppapihook nacl_irt_ppapihook = {
   irt_ppapi_start,
   PpapiPluginRegisterThreadCreator,
 };