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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 //
      5 #include "base/win/event_trace_provider.h"
      6 #include <windows.h>
      7 #include <cguid.h>
      8 
      9 namespace base {
     10 namespace win {
     11 
     12 TRACE_GUID_REGISTRATION EtwTraceProvider::obligatory_guid_registration_ = {
     13   &GUID_NULL,
     14   NULL
     15 };
     16 
     17 EtwTraceProvider::EtwTraceProvider(const GUID& provider_name)
     18     : provider_name_(provider_name), registration_handle_(NULL),
     19       session_handle_(NULL), enable_flags_(0), enable_level_(0) {
     20 }
     21 
     22 EtwTraceProvider::EtwTraceProvider()
     23     : provider_name_(GUID_NULL), registration_handle_(NULL),
     24       session_handle_(NULL), enable_flags_(0), enable_level_(0) {
     25 }
     26 
     27 EtwTraceProvider::~EtwTraceProvider() {
     28   Unregister();
     29 }
     30 
     31 ULONG EtwTraceProvider::EnableEvents(void* buffer) {
     32   session_handle_ = ::GetTraceLoggerHandle(buffer);
     33   if (NULL == session_handle_) {
     34     return ::GetLastError();
     35   }
     36 
     37   enable_flags_ = ::GetTraceEnableFlags(session_handle_);
     38   enable_level_ = ::GetTraceEnableLevel(session_handle_);
     39 
     40   // Give subclasses a chance to digest the state change.
     41   OnEventsEnabled();
     42 
     43   return ERROR_SUCCESS;
     44 }
     45 
     46 ULONG EtwTraceProvider::DisableEvents() {
     47   // Give subclasses a chance to digest the state change.
     48   OnEventsDisabled();
     49 
     50   enable_level_ = 0;
     51   enable_flags_ = 0;
     52   session_handle_ = NULL;
     53 
     54   PostEventsDisabled();
     55 
     56   return ERROR_SUCCESS;
     57 }
     58 
     59 ULONG EtwTraceProvider::Callback(WMIDPREQUESTCODE request, void* buffer) {
     60   switch (request) {
     61     case WMI_ENABLE_EVENTS:
     62       return EnableEvents(buffer);
     63     case WMI_DISABLE_EVENTS:
     64       return DisableEvents();
     65     default:
     66       return ERROR_INVALID_PARAMETER;
     67   }
     68   // Not reached.
     69 }
     70 
     71 ULONG WINAPI EtwTraceProvider::ControlCallback(WMIDPREQUESTCODE request,
     72     void* context, ULONG *reserved, void* buffer) {
     73   EtwTraceProvider *provider = reinterpret_cast<EtwTraceProvider*>(context);
     74 
     75   return provider->Callback(request, buffer);
     76 }
     77 
     78 ULONG EtwTraceProvider::Register() {
     79   if (provider_name_ == GUID_NULL)
     80     return ERROR_INVALID_NAME;
     81 
     82   return ::RegisterTraceGuids(ControlCallback, this, &provider_name_,
     83       1, &obligatory_guid_registration_, NULL, NULL, &registration_handle_);
     84 }
     85 
     86 ULONG EtwTraceProvider::Unregister() {
     87   // If a session is active, notify subclasses that it's going away.
     88   if (session_handle_ != NULL)
     89     DisableEvents();
     90 
     91   ULONG ret = ::UnregisterTraceGuids(registration_handle_);
     92 
     93   registration_handle_ = NULL;
     94 
     95   return ret;
     96 }
     97 
     98 ULONG EtwTraceProvider::Log(const EtwEventClass& event_class,
     99     EtwEventType type, EtwEventLevel level, const char *message) {
    100   if (NULL == session_handle_ || enable_level_ < level)
    101     return ERROR_SUCCESS;  // No one listening.
    102 
    103   EtwMofEvent<1> event(event_class, type, level);
    104 
    105   event.fields[0].DataPtr = reinterpret_cast<ULONG64>(message);
    106   event.fields[0].Length = message ?
    107       static_cast<ULONG>(sizeof(message[0]) * (1 + strlen(message))) : 0;
    108 
    109   return ::TraceEvent(session_handle_, &event.header);
    110 }
    111 
    112 ULONG EtwTraceProvider::Log(const EtwEventClass& event_class,
    113     EtwEventType type, EtwEventLevel level, const wchar_t *message) {
    114   if (NULL == session_handle_ || enable_level_ < level)
    115     return ERROR_SUCCESS;  // No one listening.
    116 
    117   EtwMofEvent<1> event(event_class, type, level);
    118 
    119   event.fields[0].DataPtr = reinterpret_cast<ULONG64>(message);
    120   event.fields[0].Length = message ?
    121       static_cast<ULONG>(sizeof(message[0]) * (1 + wcslen(message))) : 0;
    122 
    123   return ::TraceEvent(session_handle_, &event.header);
    124 }
    125 
    126 ULONG EtwTraceProvider::Log(EVENT_TRACE_HEADER* event) {
    127   if (enable_level_ < event->Class.Level)
    128     return ERROR_SUCCESS;
    129 
    130   return ::TraceEvent(session_handle_, event);
    131 }
    132 
    133 }  // namespace win
    134 }  // namespace base
    135