native_client_sdk/src/libraries/ppapi_stub/ppapi_main.c

   1 /*
   2  * Copyright (c) 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 <pthread.h>
   8
   9 #include "irt_syscalls.h"
  10 #include "ppapi/c/pp_module.h"
  11 #include "ppapi/c/ppp.h"
  12
  13 struct PP_StartFunctions {
  14   int32_t (*PPP_InitializeModule)(PP_Module module_id,
  15                                   PPB_GetInterface get_browser_interface);
  16   void (*PPP_ShutdownModule)();
  17   const void* (*PPP_GetInterface)(const char* interface_name);
  18 };
  19
  20 struct PP_ThreadFunctions {
  21   /*
  22    * This is a cut-down version of pthread_create()/pthread_join().
  23    * We omit thread creation attributes and the thread's return value.
  24    *
  25    * We use uintptr_t as the thread ID type because pthread_t is not
  26    * part of the stable ABI; a user thread library might choose an
  27    * arbitrary size for its own pthread_t.
  28    */
  29   int (*thread_create)(uintptr_t* tid,
  30                        void (*func)(void* thread_argument),
  31                        void* thread_argument);
  32   int (*thread_join)(uintptr_t tid);
  33 };
  34
  35 #define NACL_IRT_PPAPIHOOK_v0_1 "nacl-irt-ppapihook-0.1"
  36 struct nacl_irt_ppapihook {
  37   int (*ppapi_start)(const struct PP_StartFunctions*);
  38   void (*ppapi_register_thread_creator)(const struct PP_ThreadFunctions*);
  39 };
  40
  41
  42 static int thread_create(uintptr_t *tid,
  43                          void (*func)(void *thread_argument),
  44                          void *thread_argument) {
  45   /*
  46    * We know that newlib and glibc use a small pthread_t type, so we
  47    * do not need to wrap pthread_t values.
  48    */
  49   return pthread_create((pthread_t *) tid, NULL,
  50                         (void *(*)(void *thread_argument)) func,
  51                         thread_argument);
  52 }
  53
  54 static int thread_join(uintptr_t tid) {
  55   return pthread_join((pthread_t) tid, NULL);
  56 }
  57
  58 /*
  59  * These are dangling references to functions that the application must define.
  60  */
  61 static const struct PP_StartFunctions ppapi_app_start_callbacks = {
  62   PPP_InitializeModule,
  63   PPP_ShutdownModule,
  64   PPP_GetInterface
  65 };
  66
  67 const static struct PP_ThreadFunctions thread_funcs = {
  68   thread_create,
  69   thread_join
  70 };
  71
  72 static void fatal_error(const char *message) {
  73   write(2, message, strlen(message));
  74   _exit(127);
  75 }
  76
  77 /*
  78  * We cannot tell at link time whether the application uses PPB_Audio,
  79  * because of the way that PPAPI is defined via runtime interface
  80  * query rather than a set of static functions.  This means that we
  81  * register the audio thread functions unconditionally.  This adds the
  82  * small overhead of pulling in pthread_create() even if the
  83  * application does not use PPB_Audio or libpthread.
  84  *
  85  * If an application developer wants to avoid that cost, they can
  86  * override this function with an empty definition.
  87  */
  88 void __nacl_register_thread_creator(const struct nacl_irt_ppapihook *hooks) {
  89   hooks->ppapi_register_thread_creator(&thread_funcs);
  90 }
  91
  92 int PpapiPluginStart(const struct PP_StartFunctions *funcs) {
  93   struct nacl_irt_ppapihook hooks;
  94   if (sizeof(hooks) != __nacl_irt_query(NACL_IRT_PPAPIHOOK_v0_1,
  95                                         &hooks, sizeof(hooks))) {
  96     fatal_error("PpapiPluginStart: PPAPI hooks not found\n");
  97   }
  98
  99   __nacl_register_thread_creator(&hooks);
 100   return hooks.ppapi_start(funcs);
 101 }
 102
 103
 104 /*
 105  * The application's main (or the one supplied in this library) calls this
 106  * to start the PPAPI world.
 107  */
 108 int PpapiPluginMain(void) {
 109   return PpapiPluginStart(&ppapi_app_start_callbacks);
 110 }