static nsresult
LoadGtkModule(GnomeAccessibilityModule& aModule)
{
    NS_ENSURE_ARG(aModule.libName);

    if (!(aModule.lib = PR_LoadLibrary(aModule.libName))) {

        MAI_LOG_DEBUG(("Fail to load lib: %s in default path\n", aModule.libName));

        //try to load the module with "gtk-2.0/modules" appended
        char *curLibPath = PR_GetLibraryPath();
        nsCAutoString libPath(curLibPath);
#if defined(LINUX) && defined(__x86_64__)
        libPath.Append(":/usr/lib64:/usr/lib");
#else
        libPath.Append(":/usr/lib");
#endif
        MAI_LOG_DEBUG(("Current Lib path=%s\n", libPath.get()));
        PR_FreeLibraryName(curLibPath);

        PRInt16 loc1 = 0, loc2 = 0;
        PRInt16 subLen = 0;
        while (loc2 >= 0) {
            loc2 = libPath.FindChar(':', loc1);
            if (loc2 < 0)
                subLen = libPath.Length() - loc1;
            else
                subLen = loc2 - loc1;
            nsCAutoString sub(Substring(libPath, loc1, subLen));
            sub.Append("/gtk-2.0/modules/");
            sub.Append(aModule.libName);
            aModule.lib = PR_LoadLibrary(sub.get());
            if (aModule.lib) {
                MAI_LOG_DEBUG(("Ok, load %s from %s\n", aModule.libName, sub.get()));
                break;
            }
            loc1 = loc2+1;
        }
        if (!aModule.lib) {
            MAI_LOG_DEBUG(("Fail to load %s\n", aModule.libName));
            return NS_ERROR_FAILURE;
        }
    }

    //we have loaded the library, try to get the function ptrs
    if (!(aModule.init = PR_FindFunctionSymbol(aModule.lib,
                                               aModule.initName)) ||
        !(aModule.shutdown = PR_FindFunctionSymbol(aModule.lib,
                                                   aModule.shutdownName))) {

        //fail, :(
        MAI_LOG_DEBUG(("Fail to find symbol %s in %s",
                       aModule.init ? aModule.shutdownName : aModule.initName,
                       aModule.libName));
        PR_UnloadLibrary(aModule.lib);
        aModule.lib = NULL;
        return NS_ERROR_FAILURE;
    }
    return NS_OK;
}

static void Initialize()
{
    if (!GDK_IS_X11_DISPLAY(gdk_display_get_default()))
        return;

    // This will leak - See comments in ~nsIdleServiceGTK().
    PRLibrary* xsslib = PR_LoadLibrary("libXss.so.1");
    if (!xsslib) // ouch.
    {
#ifdef PR_LOGGING
        PR_LOG(sIdleLog, PR_LOG_WARNING, ("Failed to find libXss.so!\n"));
#endif
        return;
    }

    _XSSQueryExtension = (_XScreenSaverQueryExtension_fn)
        PR_FindFunctionSymbol(xsslib, "XScreenSaverQueryExtension");
    _XSSAllocInfo = (_XScreenSaverAllocInfo_fn)
        PR_FindFunctionSymbol(xsslib, "XScreenSaverAllocInfo");
    _XSSQueryInfo = (_XScreenSaverQueryInfo_fn)
        PR_FindFunctionSymbol(xsslib, "XScreenSaverQueryInfo");
#ifdef PR_LOGGING
    if (!_XSSQueryExtension)
        PR_LOG(sIdleLog, PR_LOG_WARNING, ("Failed to get XSSQueryExtension!\n"));
    if (!_XSSAllocInfo)
        PR_LOG(sIdleLog, PR_LOG_WARNING, ("Failed to get XSSAllocInfo!\n"));
    if (!_XSSQueryInfo)
        PR_LOG(sIdleLog, PR_LOG_WARNING, ("Failed to get XSSQueryInfo!\n"));
#endif

    sInitialized = true;
}

static void
ProcessModule(const char *modulesDir, const char *fileName)
{
    int dLen = strlen(modulesDir);
    int fLen = strlen(fileName);

    char *buf = (char *) malloc(dLen + 1 + fLen + 1);
    memcpy(buf, modulesDir, dLen);
    buf[dLen] = kPathSep;
    memcpy(buf + dLen + 1, fileName, fLen);
    buf[dLen + 1 + fLen] = '\0';

    PRLibrary *lib = PR_LoadLibrary(buf);
    if (lib) {
        EntryPoint initFunc     = (EntryPoint) PR_FindFunctionSymbol(lib, kInitMethod);
        EntryPoint testFunc     = (EntryPoint) PR_FindFunctionSymbol(lib, kTestMethod);
        EntryPoint shutdownFunc = (EntryPoint) PR_FindFunctionSymbol(lib, kShutdownMethod);

        if (testFunc) {
            int rv = 0;
            if (initFunc)
                rv = initFunc();
            // don't run test case if init fails.
            if (rv == 0)
                 testFunc();
            if (shutdownFunc)
                shutdownFunc();
        }
        PR_UnloadLibrary(lib);
    }

    free(buf);
}

static nsresult
ensure_libgnomeui()
{
    // Attempt to get the libgnomeui symbol references. We do it this way so that stock icons from Init()
    // don't get held back by InitWithGnome()'s libgnomeui dependency.
    if (!gTriedToLoadGnomeLibs) {
        gLibGnomeUI = PR_LoadLibrary("libgnomeui-2.so.0");
        if (!gLibGnomeUI)
            return NS_ERROR_NOT_AVAILABLE;

        _gnome_init = (_GnomeInit_fn)PR_FindFunctionSymbol(gLibGnomeUI, "gnome_init_with_popt_table");
        _gnome_icon_theme_new = (_GnomeIconThemeNew_fn)PR_FindFunctionSymbol(gLibGnomeUI, "gnome_icon_theme_new");
        _gnome_icon_lookup = (_GnomeIconLookup_fn)PR_FindFunctionSymbol(gLibGnomeUI, "gnome_icon_lookup");

        if (!_gnome_init || !_gnome_icon_theme_new || !_gnome_icon_lookup) {
            PR_UnloadLibrary(gLibGnomeUI);
            gLibGnomeUI = nullptr;
            return NS_ERROR_NOT_AVAILABLE;
        }
    }

    if (!gLibGnomeUI)
        return NS_ERROR_NOT_AVAILABLE;

    return NS_OK;
}

void
nsApplicationAccessibleWrap::PreCreate()
{
    if (!sATKChecked) {
        sATKLib = PR_LoadLibrary(sATKLibName);
        if (sATKLib) {
            AtkGetTypeType pfn_atk_hyperlink_impl_get_type = (AtkGetTypeType) PR_FindFunctionSymbol(sATKLib, sATKHyperlinkImplGetTypeSymbol);
            if (pfn_atk_hyperlink_impl_get_type)
                g_atk_hyperlink_impl_type = pfn_atk_hyperlink_impl_get_type();

            AtkGetTypeType pfn_atk_socket_get_type;
            pfn_atk_socket_get_type = (AtkGetTypeType)
                                      PR_FindFunctionSymbol(sATKLib,
                                                            AtkSocketAccessible::sATKSocketGetTypeSymbol);
            if (pfn_atk_socket_get_type) {
                AtkSocketAccessible::g_atk_socket_type =
                  pfn_atk_socket_get_type();
                AtkSocketAccessible::g_atk_socket_embed = (AtkSocketEmbedType)
                  PR_FindFunctionSymbol(sATKLib,
                                        AtkSocketAccessible
                                          ::sATKSocketEmbedSymbol);
            AtkSocketAccessible::gCanEmbed =
              AtkSocketAccessible::g_atk_socket_type != G_TYPE_INVALID &&
              AtkSocketAccessible::g_atk_socket_embed;
            }
        }
        sATKChecked = PR_TRUE;
    }
}

static PRStatus
ssl_InitCngFunctions(void)
{
    SECStatus rv;

    ncrypt_library = PR_LoadLibrary("ncrypt.dll");
    if (ncrypt_library == NULL)
        goto loser;

    pNCryptFreeObject = (NCryptFreeObjectFunc)PR_FindFunctionSymbol(
        ncrypt_library, "NCryptFreeObject");
    if (pNCryptFreeObject == NULL)
        goto loser;

    pNCryptSignHash = (NCryptSignHashFunc)PR_FindFunctionSymbol(
        ncrypt_library, "NCryptSignHash");
    if (pNCryptSignHash == NULL)
        goto loser;

    rv = NSS_RegisterShutdown(ssl_ShutdownCngFunctions, NULL);
    if (rv != SECSuccess)
        goto loser;

    return PR_SUCCESS;

loser:
    pNCryptSignHash = NULL;
    pNCryptFreeObject = NULL;
    if (ncrypt_library) {
        PR_UnloadLibrary(ncrypt_library);
        ncrypt_library = NULL;
    }

    return PR_FAILURE;
}

GMPErr
ChromiumCDMAdapter::GMPInit(const GMPPlatformAPI* aPlatformAPI)
{
  GMP_LOG("ChromiumCDMAdapter::GMPInit");
  sPlatform = aPlatformAPI;
  if (!mLib) {
    return GMPGenericErr;
  }

#ifdef MOZILLA_OFFICIAL
  // Note: we must call the VerifyCdmHost_0 function if it's present before
  // we call the initialize function.
  auto verify = reinterpret_cast<decltype(::VerifyCdmHost_0)*>(
    PR_FindFunctionSymbol(mLib, STRINGIFY(VerifyCdmHost_0)));
  if (verify) {
    nsTArray<cdm::HostFile> files;
    for (HostFileData& hostFile : mHostFiles) {
      files.AppendElement(TakeToCDMHostFile(hostFile));
    }
    bool result = verify(files.Elements(), files.Length());
    GMP_LOG("%s VerifyCdmHost_0 returned %d", __func__, result);
  }
#endif

  auto init = reinterpret_cast<decltype(::INITIALIZE_CDM_MODULE)*>(
    PR_FindFunctionSymbol(mLib, STRINGIFY(INITIALIZE_CDM_MODULE)));
  if (!init) {
    return GMPGenericErr;
  }

  GMP_LOG(STRINGIFY(INITIALIZE_CDM_MODULE) "()");
  init();

  return GMPNoErr;
}

bool
GMPChild::LoadPluginLibrary(const std::string& aPluginPath)
{
  nsDependentCString pluginPath(aPluginPath.c_str());

  nsCOMPtr<nsIFile> libFile;
  nsresult rv = NS_NewNativeLocalFile(pluginPath, true, getter_AddRefs(libFile));
  if (NS_FAILED(rv)) {
    return false;
  }

  nsAutoString leafName;
  if (NS_FAILED(libFile->GetLeafName(leafName))) {
    return false;
  }
  nsAutoString baseName(Substring(leafName, 4, leafName.Length() - 1));

#if defined(XP_MACOSX)
  nsAutoString binaryName = NS_LITERAL_STRING("lib") + baseName + NS_LITERAL_STRING(".dylib");
#elif defined(OS_POSIX)
  nsAutoString binaryName = NS_LITERAL_STRING("lib") + baseName + NS_LITERAL_STRING(".so");
#elif defined(XP_WIN)
  nsAutoString binaryName =                            baseName + NS_LITERAL_STRING(".dll");
#else
#error not defined
#endif
  libFile->AppendRelativePath(binaryName);

  nsAutoCString nativePath;
  libFile->GetNativePath(nativePath);
  mLib = PR_LoadLibrary(nativePath.get());
  if (!mLib) {
    return false;
  }

  GMPInitFunc initFunc = reinterpret_cast<GMPInitFunc>(PR_FindFunctionSymbol(mLib, "GMPInit"));
  if (!initFunc) {
    return false;
  }

  auto platformAPI = new GMPPlatformAPI();
  InitPlatformAPI(*platformAPI);

  if (initFunc(platformAPI) != GMPNoErr) {
    return false;
  }

  mGetAPIFunc = reinterpret_cast<GMPGetAPIFunc>(PR_FindFunctionSymbol(mLib, "GMPGetAPI"));
  if (!mGetAPIFunc) {
    return false;
  }

  return true;
}

NS_IMETHODIMP
nsSound::Init()
{
    // This function is designed so that no library is compulsory, and
    // one library missing doesn't cause the other(s) to not be used.
    if (mInited) 
        return NS_OK;

    mInited = true;

    if (!libcanberra) {
        libcanberra = PR_LoadLibrary("libcanberra.so.0");
        if (libcanberra) {
            ca_context_create = (ca_context_create_fn) PR_FindFunctionSymbol(libcanberra, "ca_context_create");
            if (!ca_context_create) {
                PR_UnloadLibrary(libcanberra);
                libcanberra = nullptr;
            } else {
                // at this point we know we have a good libcanberra library
                ca_context_destroy = (ca_context_destroy_fn) PR_FindFunctionSymbol(libcanberra, "ca_context_destroy");
                ca_context_play = (ca_context_play_fn) PR_FindFunctionSymbol(libcanberra, "ca_context_play");
                ca_context_change_props = (ca_context_change_props_fn) PR_FindFunctionSymbol(libcanberra, "ca_context_change_props");
                ca_proplist_create = (ca_proplist_create_fn) PR_FindFunctionSymbol(libcanberra, "ca_proplist_create");
                ca_proplist_destroy = (ca_proplist_destroy_fn) PR_FindFunctionSymbol(libcanberra, "ca_proplist_destroy");
                ca_proplist_sets = (ca_proplist_sets_fn) PR_FindFunctionSymbol(libcanberra, "ca_proplist_sets");
                ca_context_play_full = (ca_context_play_full_fn) PR_FindFunctionSymbol(libcanberra, "ca_context_play_full");
            }
        }
    }

    return NS_OK;
}

GMPErr
WidevineAdapter::GMPInit(const GMPPlatformAPI* aPlatformAPI)
{
#ifdef ENABLE_WIDEVINE_LOG
  if (getenv("GMP_LOG_FILE")) {
    // Clear log file.
    FILE* f = fopen(getenv("GMP_LOG_FILE"), "w");
    if (f) {
      fclose(f);
    }
  }
#endif

  sPlatform = aPlatformAPI;
  if (!mLib) {
    return GMPGenericErr;
  }

  auto init = reinterpret_cast<decltype(::INITIALIZE_CDM_MODULE)*>(
    PR_FindFunctionSymbol(mLib, STRINGIFY(INITIALIZE_CDM_MODULE)));
  if (!init) {
    return GMPGenericErr;
  }

  Log(STRINGIFY(INITIALIZE_CDM_MODULE)"()");
  init();

  return GMPNoErr;
}

PRFuncPtr
GLLibraryLoader::LookupSymbol(PRLibrary *lib,
                              const char *sym,
                              PlatformLookupFunction lookupFunction)
{
    PRFuncPtr res = 0;

    // try finding it in the library directly, if we have one
    if (lib) {
        res = PR_FindFunctionSymbol(lib, sym);
    }

    // then try looking it up via the lookup symbol
    if (!res && lookupFunction) {
        res = lookupFunction(sym);
    }

    // finally just try finding it in the process
    if (!res) {
        PRLibrary *leakedLibRef;
        res = PR_FindFunctionSymbolAndLibrary(sym, &leakedLibRef);
    }

    return res;
}

nsresult
PluginPRLibrary::NP_Initialize(NPNetscapeFuncs* bFuncs,
			       NPPluginFuncs* pFuncs, NPError* error)
{
  JNIEnv* env = GetJNIForThread();
  if (!env)
    return NS_ERROR_FAILURE;

  if (mNP_Initialize) {
    *error = mNP_Initialize(bFuncs, pFuncs, env);
  } else {
    NP_InitializeFunc pfNP_Initialize = (NP_InitializeFunc)
      PR_FindFunctionSymbol(mLibrary, "NP_Initialize");
    if (!pfNP_Initialize)
      return NS_ERROR_FAILURE;
    *error = pfNP_Initialize(bFuncs, pFuncs, env);
  }

  // Save pointers to functions that get called through PluginLibrary itself.
  mNPP_New = pFuncs->newp;
  mNPP_GetValue = pFuncs->getvalue;
  mNPP_ClearSiteData = pFuncs->clearsitedata;
  mNPP_GetSitesWithData = pFuncs->getsiteswithdata;
  return NS_OK;
}

NS_IMETHODIMP
nsSound::Init()
{
    /* we don't need to do esd_open_sound if we are only going to play files
       but we will if we want to do things like streams, etc
    */
    if (mInited) 
        return NS_OK;
    if (elib) 
        return NS_OK;

    EsdOpenSoundType EsdOpenSound;

    elib = PR_LoadLibrary("libesd.so.0");
    if (!elib) return NS_ERROR_NOT_AVAILABLE;

    EsdOpenSound = (EsdOpenSoundType) PR_FindFunctionSymbol(elib, "esd_open_sound");

    if (!EsdOpenSound)
        return NS_ERROR_FAILURE;

    esdref = (*EsdOpenSound)("localhost");

    if (!esdref)
        return NS_ERROR_FAILURE;

    mInited = PR_TRUE;

    return NS_OK;
}

// Gets shell version as packed 64 bit int
PRUint64 nsDragService::GetShellVersion()
{
  PRUint64 lVersion = LL_INIT(0, 0);
  PRUint64 lMinor = lVersion;

  // shell32.dll should be loaded already, so we ae not actually loading the library here
  PRLibrary *libShell = PR_LoadLibrary("shell32.dll");
  if (libShell == NULL)
    return lVersion;

  do
  {
    DLLGETVERSIONPROC versionProc = NULL;
    versionProc = (DLLGETVERSIONPROC)PR_FindFunctionSymbol(libShell, "DllGetVersion");
    if (versionProc == NULL)
      break;

    DLLVERSIONINFO versionInfo;
    ::ZeroMemory(&versionInfo, sizeof(DLLVERSIONINFO));
    versionInfo.cbSize = sizeof(DLLVERSIONINFO);
    if (FAILED(versionProc(&versionInfo)))
      break;

    // why is this?
    LL_UI2L(lVersion, versionInfo.dwMajorVersion);
    LL_SHL(lVersion, lVersion, 32);
    LL_UI2L(lMinor, versionInfo.dwMinorVersion);
    LL_OR2(lVersion, lMinor);
  } while (false);

  PR_UnloadLibrary(libShell);
  libShell = NULL;

  return lVersion;
}

gfxFT2LockedFace::CharVariantFunction
gfxFT2LockedFace::FindCharVariantFunction()
{
    // This function is available from FreeType 2.3.6 (June 2008).
    PRLibrary *lib = nsnull;
    CharVariantFunction function =
        reinterpret_cast<CharVariantFunction>
        (PR_FindFunctionSymbolAndLibrary("FT_Face_GetCharVariantIndex", &lib));
    if (!lib) {
        return nsnull;
    }

    FT_Int major;
    FT_Int minor;
    FT_Int patch;
    FT_Library_Version(mFace->glyph->library, &major, &minor, &patch);

    // Versions 2.4.0 to 2.4.3 crash if configured with
    // FT_CONFIG_OPTION_OLD_INTERNALS.  Presence of the symbol FT_Alloc
    // indicates FT_CONFIG_OPTION_OLD_INTERNALS.
    if (major == 2 && minor == 4 && patch < 4 &&
        PR_FindFunctionSymbol(lib, "FT_Alloc")) {
        function = nsnull;
    }

    // Decrement the reference count incremented in
    // PR_FindFunctionSymbolAndLibrary.
    PR_UnloadLibrary(lib);

    return function;
}

nsSound::~nsSound()
{
    /* see above comment */
    if (esdref != -1) {
        EsdCloseType EsdClose = (EsdCloseType) PR_FindFunctionSymbol(elib, "esd_close");
        if (EsdClose)
            (*EsdClose)(esdref);
        esdref = -1;
    }
}

static void Initialize()
{
    sInitialized = true;

#if !defined(MOZ_PLATFORM_MAEMO) && defined(MOZ_X11)
    // This will leak - See comments in ~nsIdleServiceQt().
    PRLibrary* xsslib = PR_LoadLibrary("libXss.so.1");
    if (!xsslib) {
        return;
    }

    _XSSQueryExtension = (_XScreenSaverQueryExtension_fn)
        PR_FindFunctionSymbol(xsslib, "XScreenSaverQueryExtension");
    _XSSAllocInfo = (_XScreenSaverAllocInfo_fn)
        PR_FindFunctionSymbol(xsslib, "XScreenSaverAllocInfo");
    _XSSQueryInfo = (_XScreenSaverQueryInfo_fn)
        PR_FindFunctionSymbol(xsslib, "XScreenSaverQueryInfo");
#endif
}

 void GMPSetNodeId(const char* aNodeId, uint32_t aLength) override
 {
   if (!mLib) {
     return;
   }
   GMPSetNodeIdFunc setNodeIdFunc = reinterpret_cast<GMPSetNodeIdFunc>(PR_FindFunctionSymbol(mLib, "GMPSetNodeId"));
   if (setNodeIdFunc) {
     setNodeIdFunc(aNodeId, aLength);
   }
 }

 GMPErr GMPInit(const GMPPlatformAPI* aPlatformAPI) override
 {
   if (!mLib) {
     return GMPGenericErr;
   }
   GMPInitFunc initFunc = reinterpret_cast<GMPInitFunc>(PR_FindFunctionSymbol(mLib, "GMPInit"));
   if (!initFunc) {
     return GMPNotImplementedErr;
   }
   return initFunc(aPlatformAPI);
 }

 void GMPShutdown() override
 {
   if (mLib) {
     GMPShutdownFunc shutdownFunc = reinterpret_cast<GMPShutdownFunc>(PR_FindFunctionSymbol(mLib, "GMPShutdown"));
     if (shutdownFunc) {
       shutdownFunc();
     }
     PR_UnloadLibrary(mLib);
     mLib = nullptr;
   }
 }