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      1 /*
      2  * Copyright 2014 The Chromium Authors. All rights reserved.
      3  * Use of this source code is governed by a BSD-style license that can be
      4  * found in the LICENSE file.
      5  */
      6 
      7 #include "ppapi/native_client/src/untrusted/pnacl_irt_shim/irt_shim_ppapi.h"
      8 
      9 #include "native_client/src/untrusted/irt/irt.h"
     10 #include "ppapi/nacl_irt/public/irt_ppapi.h"
     11 #include "ppapi/native_client/src/untrusted/pnacl_irt_shim/pnacl_shim.h"
     12 #include "ppapi/nacl_irt/plugin_main.h"
     13 
     14 /*
     15  * Defines a version of the version irt_ppapi_start and of the irt_ppapihook
     16  * that returns a shimmed GetInterface for PNaCl.
     17  *
     18  * The hook will be linked into the IRT but it is considered unstable.
     19  * Stable nexes should not use that IRT hook (and a filter prevents
     20  * it from being used). Instead PNaCl nexes should embed the
     21  * irt_shim_ppapi_start and the shim functions directly into the nexe
     22  * for ABI stability.
     23  */
     24 
     25 static struct PP_StartFunctions g_user_start_functions;
     26 
     27 static int32_t shim_PPPInitializeModule(PP_Module module_id,
     28                                         PPB_GetInterface get_browser_intf) {
     29   /* Record the original PPB_GetInterface and provide a shimmed one. */
     30   __set_real_Pnacl_PPBGetInterface(get_browser_intf);
     31   return (*g_user_start_functions.PPP_InitializeModule)(
     32       module_id,
     33       &__Pnacl_PPBGetInterface);
     34 }
     35 
     36 static void shim_PPPShutdownModule(void) {
     37   (*g_user_start_functions.PPP_ShutdownModule)();
     38 }
     39 
     40 #ifdef PNACL_SHIM_AOT
     41  /*
     42   * This will be discovered and set by the shim, since we cannot link
     43   * against the IRT directly in the AOT library.
     44   */
     45 int (*real_irt_ppapi_start)(const struct PP_StartFunctions *) = NULL;
     46 #else
     47  /*
     48   * Otherwise, when linking directly into the IRT, we can refer to the
     49   * real irt_ppapi_start from irt_ppapi.
     50   */
     51 extern int irt_ppapi_start(const struct PP_StartFunctions *);
     52 static int (* const real_irt_ppapi_start)(const struct PP_StartFunctions *) =
     53     &irt_ppapi_start;
     54 #endif
     55 
     56 int irt_shim_ppapi_start(const struct PP_StartFunctions *funcs) {
     57   g_user_start_functions = *funcs;
     58   /*
     59    * Record the original PPP_GetInterface and provide a shimmed one
     60    * via wrapped_ppapi_methods.
     61    */
     62   const struct PP_StartFunctions wrapped_ppapi_methods = {
     63     shim_PPPInitializeModule,
     64     shim_PPPShutdownModule,
     65     __Pnacl_PPPGetInterface
     66   };
     67   __set_real_Pnacl_PPPGetInterface(g_user_start_functions.PPP_GetInterface);
     68   /*
     69    * Invoke the IRT's ppapi_start interface with the wrapped interface.
     70    */
     71   return (*real_irt_ppapi_start)(&wrapped_ppapi_methods);
     72 }
     73 
     74 #ifndef PNACL_SHIM_AOT
     75 const struct nacl_irt_ppapihook nacl_irt_ppapihook_pnacl_private = {
     76   irt_shim_ppapi_start,
     77   PpapiPluginRegisterThreadCreator,
     78 };
     79 #endif
     80