address CRs

Author: SchrodingerZhu

libc/hdr/time_macros.h

@@ -19,4 +19,10 @@
 
 #endif // LLVM_LIBC_FULL_BUILD
 
+// TODO: For now, on windows, let's always include the extension header.
+// We will need to decide how to export this header.
+#ifdef _WIN32
+#include "include/llvm-libc-macros/windows/time-macros-ext.h"
+#endif // _WIN32
+
 #endif // LLVM_LIBC_HDR_TIME_MACROS_H

libc/hdr/types/clockid_t.h

@@ -9,7 +9,8 @@
 #ifndef LLVM_LIBC_HDR_TYPES_CLOCKID_T_H
 #define LLVM_LIBC_HDR_TYPES_CLOCKID_T_H
 
-#if defined(LIBC_FULL_BUILD) || defined(_MSC_VER)
+// TODO: we will need to decide how to export extension to windows.
+#if defined(LIBC_FULL_BUILD) || defined(_WIN32)
 
 #include "include/llvm-libc-types/clockid_t.h"
 

libc/src/__support/time/windows/CMakeLists.txt

@@ -13,4 +13,5 @@ add_object_library(
     libc.src.__support.error_or
     libc.src.__support.OSUtil.osutil
     libc.src.__support.CPP.atomic
+    libc.src.__support.CPP.limits
 )

libc/src/__support/time/windows/clock_gettime.cpp

@@ -6,26 +6,29 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/__support/time/clock_gettime.h"
-#include "include/llvm-libc-macros/windows/time-macros-ext.h"
+#include "hdr/time_macros.h"
+
 #include "src/__support/CPP/atomic.h"
 #include "src/__support/CPP/bit.h"
+#include "src/__support/CPP/limits.h"
+#include "src/__support/macros/optimization.h"
+#include "src/__support/time/clock_gettime.h"
 #include "src/__support/time/units.h"
-#include <Windows.h>
 
-#ifdef __clang__
-#define UNINITIALIZED [[clang::uninitialized]]
-#else
-#define UNINITIALIZED
-#endif
+#define WIN32_LEAN_AND_MEAN
+#define NOMINMAX
+#include <Windows.h>
 
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 static long long get_ticks_per_second() {
   static cpp::Atomic<long long> frequency = 0;
+  // Relaxed ordering is enough. It is okay to record the frequency multiple
+  // times. The store operation itself is atomic and the value must propagate
+  // as required by cache coherence.
   auto freq = frequency.load(cpp::MemoryOrder::RELAXED);
   if (!freq) {
-    UNINITIALIZED LARGE_INTEGER buffer;
+    [[clang::uninitialized]] LARGE_INTEGER buffer;
     // On systems that run Windows XP or later, the function will always
     // succeed and will thus never return zero.
     ::QueryPerformanceFrequency(&buffer);
@@ -37,6 +40,8 @@ static long long get_ticks_per_second() {
 
 ErrorOr<int> clock_gettime(clockid_t clockid, timespec *ts) {
   using namespace time_units;
+  constexpr long long SEC_LIMIT =
+      cpp::numeric_limits<decltype(ts->tv_sec)>::max();
   ErrorOr<int> ret = 0;
   switch (clockid) {
   default:
@@ -48,14 +53,18 @@ ErrorOr<int> clock_gettime(clockid_t clockid, timespec *ts) {
     // https://learn.microsoft.com/en-us/windows/win32/sysinfo/acquiring-high-resolution-time-stamps
     // Is the performance counter monotonic (non-decreasing)?
     // Yes. QPC does not go backward.
-    UNINITIALIZED LARGE_INTEGER buffer;
+    [[clang::uninitialized]] LARGE_INTEGER buffer;
     // On systems that run Windows XP or later, the function will always
     // succeed and will thus never return zero.
     ::QueryPerformanceCounter(&buffer);
     long long freq = get_ticks_per_second();
     long long ticks = buffer.QuadPart;
     long long tv_sec = ticks / freq;
     long long tv_nsec = (ticks % freq) * 1_s_ns / freq;
+    if (LIBC_UNLIKELY(tv_sec > SEC_LIMIT)) {
+      ret = cpp::unexpected(EOVERFLOW);
+      break;
+    }
     ts->tv_sec = static_cast<decltype(ts->tv_sec)>(tv_sec);
     ts->tv_nsec = static_cast<decltype(ts->tv_nsec)>(tv_nsec);
     break;
@@ -65,17 +74,27 @@ ErrorOr<int> clock_gettime(clockid_t clockid, timespec *ts) {
     // GetSystemTimePreciseAsFileTime
     // This function is best suited for high-resolution time-of-day
     // measurements, or time stamps that are synchronized to UTC
-    UNINITIALIZED FILETIME file_time;
-    UNINITIALIZED ULARGE_INTEGER time;
+    [[clang::uninitialized]] FILETIME file_time;
+    [[clang::uninitialized]] ULARGE_INTEGER time;
     ::GetSystemTimePreciseAsFileTime(&file_time);
     time.LowPart = file_time.dwLowDateTime;
     time.HighPart = file_time.dwHighDateTime;
 
     // adjust to POSIX epoch (from Jan 1, 1601 to Jan 1, 1970)
     constexpr unsigned long long HNS_PER_SEC = 1_s_ns / 100ULL;
+    constexpr unsigned long long POSIX_TIME_SHIFT =
+        (11644473600ULL * HNS_PER_SEC);
+    if (LIBC_UNLIKELY(POSIX_TIME_SHIFT > time.QuadPart)) {
+      ret = cpp::unexpected(EOVERFLOW);
+      break;
+    }
     time.QuadPart -= (11644473600ULL * HNS_PER_SEC);
     unsigned long long tv_sec = time.QuadPart / HNS_PER_SEC;
     unsigned long long tv_nsec = (time.QuadPart % HNS_PER_SEC) * 100ULL;
+    if (LIBC_UNLIKELY(tv_sec > SEC_LIMIT)) {
+      ret = cpp::unexpected(EOVERFLOW);
+      break;
+    }
     ts->tv_sec = static_cast<decltype(ts->tv_sec)>(tv_sec);
     ts->tv_nsec = static_cast<decltype(ts->tv_nsec)>(tv_nsec);
     break;

libc/src/time/time.cpp

@@ -13,12 +13,8 @@
 #include "src/errno/libc_errno.h"
 #include "src/time/time_func.h"
 
-#ifdef _MSC_VER
-#include "include/llvm-libc-macros/windows/time-macros-ext.h"
-#endif
-
 namespace LIBC_NAMESPACE_DECL {
-LLVM_LIBC_FUNCTION(time_t, time, (time_t * tp)) {
+LLVM_LIBC_FUNCTION(time_t, time, (time_t *tp)) {
   struct timespec ts;
   auto result = internal::clock_gettime(CLOCK_REALTIME, &ts);
   if (!result.has_value()) {