platform-win32.cc.svn-base

Google浏览器V8内核代码

  static bool initialized = false;
  static TimeStamp init_time;
  static DWORD init_ticks;
  static const int kHundredNanosecondsPerSecond = 10000;
  static const int kMaxClockElapsedTime =
      60*60*24*kHundredNanosecondsPerSecond;  // 1 day

  // If we are uninitialized, we need to resync the clock.
  bool needs_resync = !initialized;

  // Get the current time.
  TimeStamp time_now;
  GetSystemTimeAsFileTime(&time_now.ft_);
  DWORD ticks_now = timeGetTime();

  // Check if we need to resync due to clock rollover.
  needs_resync |= ticks_now < init_ticks;

  // Check if we need to resync due to elapsed time.
  needs_resync |= (time_now.t_ - init_time.t_) > kMaxClockElapsedTime;

  // Resync the clock if necessary.
  if (needs_resync) {
    GetSystemTimeAsFileTime(&init_time.ft_);
    init_ticks = ticks_now = timeGetTime();
    initialized = true;
  }

  // Finally, compute the actual time.  Why is this so hard.
  DWORD elapsed = ticks_now - init_ticks;
  this->time_.t_ = init_time.t_ + (static_cast<int64_t>(elapsed) * 10000);
}


// Return the local timezone offset in milliseconds east of UTC. This
// takes into account whether daylight saving is in effect at the time.
int64_t Time::LocalOffset() {
  // Initialize timezone information, if needed.
  TzSet();

  // Convert timestamp to date/time components. These are now in UTC
  // format. NB: Please do not replace the following three calls with one
  // call to FileTimeToLocalFileTime(), because it does not handle
  // daylight saving correctly.
  SYSTEMTIME utc;
  FileTimeToSystemTime(&ft(), &utc);

  // Convert to local time, using timezone information.
  SYSTEMTIME local;
  SystemTimeToTzSpecificLocalTime(&tzinfo_, &utc, &local);

  // Convert local time back to a timestamp. This timestamp now
  // has a bias similar to the local timezone bias in effect
  // at the time of the original timestamp.
  Time localtime;
  SystemTimeToFileTime(&local, &localtime.ft());

  // The difference between the new local timestamp and the original
  // timestamp and is the local timezone offset.
  return localtime.Diff(this);
}


// Return whether or not daylight savings time is in effect at this time.
bool Time::InDST() {
  // Initialize timezone information, if needed.
  TzSet();

  // Determine if DST is in effect at the specified time.
  bool in_dst = false;
  if (tzinfo_.StandardDate.wMonth != 0 || tzinfo_.DaylightDate.wMonth != 0) {
    // Get the local timezone offset for the timestamp in milliseconds.
    int64_t offset = LocalOffset();

    // Compute the offset for DST. The bias parameters in the timezone info
    // are specified in minutes. These must be converted to milliseconds.
    int64_t dstofs = -(tzinfo_.Bias + tzinfo_.DaylightBias) * kMsPerMinute;

    // If the local time offset equals the timezone bias plus the daylight
    // bias then DST is in effect.
    in_dst = offset == dstofs;
  }

  return in_dst;
}


// Return the dalight savings time offset for this time.
int64_t Time::DaylightSavingsOffset() {
  return InDST() ? 60 * kMsPerMinute : 0;
}


// Returns a string identifying the current timezone for the
// timestamp taking into account daylight saving.
char* Time::LocalTimezone() {
  // Return the standard or DST time zone name based on whether daylight
  // saving is in effect at the given time.
  return InDST() ? dst_tz_name_ : std_tz_name_;
}


void OS::Setup() {
  // Seed the random number generator.
  // Convert the current time to a 64-bit integer first, before converting it
  // to an unsigned. Going directly can cause an overflow and the seed to be
  // set to all ones. The seed will be identical for different instances that
  // call this setup code within the same millisecond.
  uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
  srand(static_cast<unsigned int>(seed));
}


// Returns the accumulated user time for thread.
int OS::GetUserTime(uint32_t* secs,  uint32_t* usecs) {
  FILETIME dummy;
  uint64_t usertime;

  // Get the amount of time that the thread has executed in user mode.
  if (!GetThreadTimes(GetCurrentThread(), &dummy, &dummy, &dummy,
                      reinterpret_cast<FILETIME*>(&usertime))) return -1;

  // Adjust the resolution to micro-seconds.
  usertime /= 10;

  // Convert to seconds and microseconds
  *secs = static_cast<uint32_t>(usertime / 1000000);
  *usecs = static_cast<uint32_t>(usertime % 1000000);
  return 0;
}


// Returns current time as the number of milliseconds since
// 00:00:00 UTC, January 1, 1970.
double OS::TimeCurrentMillis() {
  Time t;
  t.SetToCurrentTime();
  return t.ToJSTime();
}

// Returns the tickcounter based on timeGetTime.
int64_t OS::Ticks() {
  return timeGetTime() * 1000;  // Convert to microseconds.
}


// Returns a string identifying the current timezone taking into
// account daylight saving.
char* OS::LocalTimezone(double time) {
  return Time(time).LocalTimezone();
}


// Returns the local time offset in milliseconds east of UTC without
// taking daylight savings time into account.
double OS::LocalTimeOffset() {
  // Use current time, rounded to the millisecond.
  Time t(TimeCurrentMillis());
  // Time::LocalOffset inlcudes any daylight savings offset, so subtract it.
  return static_cast<double>(t.LocalOffset() - t.DaylightSavingsOffset());
}


// Returns the daylight savings offset in milliseconds for the given
// time.
double OS::DaylightSavingsOffset(double time) {
  int64_t offset = Time(time).DaylightSavingsOffset();
  return static_cast<double>(offset);
}


// ----------------------------------------------------------------------------
// Win32 console output.
//
// If a Win32 application is linked as a console application it has a normal
// standard output and standard error. In this case normal printf works fine
// for output. However, if the application is linked as a GUI application,
// the process doesn't have a console, and therefore (debugging) output is lost.
// This is the case if we are embedded in a windows program (like a browser).
// In order to be able to get debug output in this case the the debugging
// facility using OutputDebugString. This output goes to the active debugger
// for the process (if any). Else the output can be monitored using DBMON.EXE.

enum OutputMode {
  UNKNOWN,  // Output method has not yet been determined.
  CONSOLE,  // Output is written to stdout.
  ODS       // Output is written to debug facility.
};

static OutputMode output_mode = UNKNOWN;  // Current output mode.


// Determine if the process has a console for output.
static bool HasConsole() {
  // Only check the first time. Eventual race conditions are not a problem,
  // because all threads will eventually determine the same mode.
  if (output_mode == UNKNOWN) {
    // We cannot just check that the standard output is attached to a console
    // because this would fail if output is redirected to a file. Therefore we
    // say that a process does not have an output console if either the
    // standard output handle is invalid or its file type is unknown.
    if (GetStdHandle(STD_OUTPUT_HANDLE) != INVALID_HANDLE_VALUE &&
        GetFileType(GetStdHandle(STD_OUTPUT_HANDLE)) != FILE_TYPE_UNKNOWN)
      output_mode = CONSOLE;
    else
      output_mode = ODS;
  }
  return output_mode == CONSOLE;
}


static void VPrintHelper(FILE* stream, const char* format, va_list args) {
  if (HasConsole()) {
    vfprintf(stream, format, args);
  } else {
    // It is important to use safe print here in order to avoid
    // overflowing the buffer. We might truncate the output, but this
    // does not crash.
    EmbeddedVector<char, 4096> buffer;
    OS::VSNPrintF(buffer, format, args);
    OutputDebugStringA(buffer.start());
  }
}


FILE* OS::FOpen(const char* path, const char* mode) {
  FILE* result;
  if (fopen_s(&result, path, mode) == 0) {
    return result;
  } else {
    return NULL;
  }
}


// Print (debug) message to console.
void OS::Print(const char* format, ...) {
  va_list args;
  va_start(args, format);
  VPrint(format, args);
  va_end(args);
}


void OS::VPrint(const char* format, va_list args) {
  VPrintHelper(stdout, format, args);
}


// Print error message to console.
void OS::PrintError(const char* format, ...) {
  va_list args;
  va_start(args, format);
  VPrintError(format, args);
  va_end(args);
}


void OS::VPrintError(const char* format, va_list args) {
  VPrintHelper(stderr, format, args);
}


int OS::SNPrintF(Vector<char> str, const char* format, ...) {
  va_list args;
  va_start(args, format);
  int result = VSNPrintF(str, format, args);
  va_end(args);
  return result;
}


int OS::VSNPrintF(Vector<char> str, const char* format, va_list args) {
  int n = _vsnprintf_s(str.start(), str.length(), _TRUNCATE, format, args);
  // Make sure to zero-terminate the string if the output was
  // truncated or if there was an error.
  if (n < 0 || n >= str.length()) {
    str[str.length() - 1] = '\0';
    return -1;
  } else {
    return n;
  }
}


void OS::StrNCpy(Vector<char> dest, const char* src, size_t n) {
  int result = strncpy_s(dest.start(), dest.length(), src, n);
  USE(result);
  ASSERT(result == 0);
}


void OS::WcsCpy(Vector<wchar_t> dest, const wchar_t* src) {
  int result = wcscpy_s(dest.start(), dest.length(), src);
  USE(result);
  ASSERT(result == 0);
}


char *OS::StrDup(const char* str) {
  return _strdup(str);
}


// We keep the lowest and highest addresses mapped as a quick way of
// determining that pointers are outside the heap (used mostly in assertions
// and verification).  The estimate is conservative, ie, not all addresses in
// 'allocated' space are actually allocated to our heap.  The range is
// [lowest, highest), inclusive on the low and and exclusive on the high end.
static void* lowest_ever_allocated = reinterpret_cast<void*>(-1);
static void* highest_ever_allocated = reinterpret_cast<void*>(0);


static void UpdateAllocatedSpaceLimits(void* address, int size) {
  lowest_ever_allocated = Min(lowest_ever_allocated, address);
  highest_ever_allocated =
      Max(highest_ever_allocated,
          reinterpret_cast<void*>(reinterpret_cast<char*>(address) + size));
}


bool OS::IsOutsideAllocatedSpace(void* pointer) {
  if (pointer < lowest_ever_allocated || pointer >= highest_ever_allocated)
    return true;
  // Ask the Windows API
  if (IsBadWritePtr(pointer, 1))
    return true;
  return false;
}


// Get the system's page size used by VirtualAlloc() or the next power
// of two. The reason for always returning a power of two is that the
// rounding up in OS::Allocate expects that.
static size_t GetPageSize() {
  static size_t page_size = 0;
  if (page_size == 0) {
    SYSTEM_INFO info;
    GetSystemInfo(&info);
    page_size = RoundUpToPowerOf2(info.dwPageSize);
  }
  return page_size;
}


// The allocation alignment is the guaranteed alignment for
// VirtualAlloc'ed blocks of memory.
size_t OS::AllocateAlignment() {
  static size_t allocate_alignment = 0;
  if (allocate_alignment == 0) {
    SYSTEM_INFO info;
    GetSystemInfo(&info);
    allocate_alignment = info.dwAllocationGranularity;
  }
  return allocate_alignment;
}


void* OS::Allocate(const size_t requested,
                   size_t* allocated,
                   bool executable) {
  // VirtualAlloc rounds allocated size to page size automatically.
  size_t msize = RoundUp(requested, GetPageSize());

  // Windows XP SP2 allows Data Excution Prevention (DEP).
  int prot = executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
  LPVOID mbase = VirtualAlloc(NULL, msize, MEM_COMMIT | MEM_RESERVE, prot);
  if (mbase == NULL) {
    LOG(StringEvent("OS::Allocate", "VirtualAlloc failed"));
    return NULL;
  }

  ASSERT(IsAligned(reinterpret_cast<size_t>(mbase), OS::AllocateAlignment()));

  *allocated = msize;
  UpdateAllocatedSpaceLimits(mbase, msize);
  return mbase;
}


void OS::Free(void* buf, const size_t length) {
  // TODO(1240712): VirtualFree has a return value which is ignored here.
  VirtualFree(buf, 0, MEM_RELEASE);
  USE(length);
}


void OS::Sleep(int milliseconds) {
  ::Sleep(milliseconds);
}


void OS::Abort() {
  // Redirect to windows specific abort to ensure
  // collaboration with sandboxing.