text: // Copyright 2015 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include <windows.h>
  #include <stddef.h>
  #include <time.h>
  
  #include "base/files/file_path.h"
  #include "base/strings/stringprintf.h"
  #include "chrome/tools/crash_service/caps/logger_win.h"
  #include "components/version_info/version_info_values.h"
  
  namespace {
  // Every message has this structure:
  // <index>~ <tick_count> <message> ~\n"
  const char kMessageHeader[] = "%03d~ %08x %s ~\n";
  
  // Do not re-order these messages. Only add at the end.
  const char* kMessages[] {
    "start pid(%lu) version(%s) time(%s)",                    // 0
    "exit pid(%lu) time(%s)",                                 // 1
    "instance found",                                         // 2
  };
  
  bool WriteLogLine(HANDLE file, const std::string& txt) {
    if (txt.empty())
      return true;
    DWORD written;
    auto rc = ::WriteFile(file, txt.c_str(),
                          static_cast<DWORD>(txt.size()),
                          &written,
                          nullptr);
    return (rc == TRUE);
  }
  
  // Uses |kMessages| at |index| above to write to disk a formatted log line.
  bool WriteFormattedLogLine(HANDLE file, size_t index, ...) {
    va_list ap;
    va_start(ap, index);
    auto fmt = base::StringPrintf(
        kMessageHeader, index, ::GetTickCount(), kMessages[index]);
    auto msg = base::StringPrintV(fmt.c_str(), ap);
    auto rc = WriteLogLine(file, msg.c_str());
    va_end(ap);
    return rc;
  }
  
  // Returns the current time and date formatted in standard C style.
  std::string DateTime() {
    time_t current_time = 0;
    time(&current_time);
    struct tm local_time = {0};
    char time_buf[26] = {0};
    localtime_s(&local_time, &current_time);
    asctime_s(time_buf, &local_time);
    time_buf[24] = '\0';
    return time_buf;
  }
  
  }  // namespace
  
  namespace caps {
  
  Logger::Logger(const base::FilePath& path) : file_(INVALID_HANDLE_VALUE) {
    auto logfile = path.Append(L"caps_log.txt");
    // Opening a file like so allows atomic appends, but can't be used
    // for anything else.
    DWORD kShareAll = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
    file_ = ::CreateFile(logfile.value().c_str(),
                         FILE_APPEND_DATA, kShareAll,
                         nullptr,
                         OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL,
                         nullptr);
    if (file_ == INVALID_HANDLE_VALUE)
      return;
    WriteFormattedLogLine(
        file_, 0, ::GetCurrentProcessId(), PRODUCT_VERSION, DateTime().c_str());
  }
  
  Logger::~Logger() {
    if (file_ != INVALID_HANDLE_VALUE) {
      WriteFormattedLogLine(
          file_, 1, ::GetCurrentProcessId(), DateTime().c_str());
      ::CloseHandle(file_);
    }
  }
  
  }  // namespace caps
  
  