chrome/test/logging/win/mof_data_parser.h

   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 #ifndef CHROME_TEST_LOGGING_WIN_MOF_DATA_PARSER_H_
   6 #define CHROME_TEST_LOGGING_WIN_MOF_DATA_PARSER_H_
   7
   8 #include <stddef.h>
   9 #include <windows.h>
  10 #include <wmistr.h>
  11 #include <evntrace.h>
  12
  13 #include "base/basictypes.h"
  14 #include "base/strings/string_piece.h"
  15
  16 namespace logging_win {
  17
  18 // A parser for Mof data found in an EVENT_TRACE object as formatted by
  19 // Chromium-related classes.  Instances have an implicit cursor that scans the
  20 // data.  Callers invoke Read* methods to extract primitive data types values or
  21 // pointers to complex data types (arrays and strings).  In the latter case, the
  22 // pointers are only valid for the lifetime of the underlying event.
  23 class MofDataParser {
  24  public:
  25   explicit MofDataParser(const EVENT_TRACE* event);
  26
  27   bool ReadDWORD(DWORD* value) {
  28     return ReadPrimitive(value);
  29   }
  30
  31   bool ReadInt(int* value) {
  32     return ReadPrimitive(value);
  33   }
  34
  35   bool ReadPointer(intptr_t* value) {
  36     return ReadPrimitive(value);
  37   }
  38
  39   // Populates |values| with a pointer to an array of |size| pointer-sized
  40   // values in the data.
  41   bool ReadPointerArray(DWORD size, const intptr_t** values) {
  42     return ReadPrimitiveArray(size, values);
  43   }
  44
  45   // Populates |value| with a pointer to an arbitrary data structure at the
  46   // current position.
  47   template<typename T> bool ReadStructure(const T** value) {
  48     if (length_ < sizeof(**value))
  49       return false;
  50     *value = reinterpret_cast<const T*>(scan_);
  51     Advance(sizeof(**value));
  52     return true;
  53   }
  54
  55   // Sets |value| such that it points to the string in the data at the current
  56   // position.  A trailing newline, if present, is not included in the returned
  57   // piece.  The returned piece is not null-terminated.
  58   bool ReadString(base::StringPiece* value);
  59
  60   bool empty() { return length_ == 0; }
  61
  62  private:
  63   void Advance(size_t num_bytes) {
  64     scan_ += num_bytes;
  65     length_ -= num_bytes;
  66   }
  67
  68   template<typename T> bool ReadPrimitive(T* value) {
  69     if (length_ < sizeof(*value))
  70       return false;
  71     *value = *reinterpret_cast<const T*>(scan_);
  72     Advance(sizeof(*value));
  73     return true;
  74   }
  75
  76   template<typename T> bool ReadPrimitiveArray(DWORD size, const T** values) {
  77     if (length_ < sizeof(**values) * size)
  78       return false;
  79     *values = reinterpret_cast<const T*>(scan_);
  80     Advance(sizeof(**values) * size);
  81     return true;
  82   }
  83
  84   const uint8* scan_;
  85   uint32 length_;
  86 };
  87
  88 }  // namespace logging_win
  89
  90 #endif  // CHROME_TEST_LOGGING_WIN_MOF_DATA_PARSER_H_