From 85c8e289735d9d2f1d8ab3605522bf2cf346cd96 Mon Sep 17 00:00:00 2001
From: Tushar Maheshwari <tushar27192@gmail.com>
Date: Wed, 16 Jun 2021 01:17:56 +0530
Subject: [PATCH 1/2] Enable generator tests on Windows CI

- Reduce included windows headers
- Reduce scope of time-generator dependencies
---
 CMakeLists.txt |  6 ++++++
 appveyor.yml   |  3 ++-
 include/uuid.h | 31 ++++++++++---------------------
 3 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 65df943..fffb92c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake")
 
 option(UUID_BUILD_TESTS "Build the unit tests" ON)
 option(UUID_SYSTEM_GENERATOR "Enable operating system uuid generator" OFF)
+option(UUID_TIME_GENERATOR "Enable experimental time-based uuid generator" OFF)
 option(UUID_USING_CXX20_SPAN "Using span from std instead of gsl" OFF)
 
 # Library target
@@ -29,6 +30,11 @@ if (UUID_SYSTEM_GENERATOR)
     endif ()
 endif ()
 
+# Using time-based generator
+if (UUID_TIME_GENERATOR)
+    target_compile_definitions(${PROJECT_NAME} INTERFACE UUID_TIME_GENERATOR)
+endif()
+
 # Using span from std
 if (NOT UUID_USING_CXX20_SPAN)
     target_include_directories(${PROJECT_NAME} INTERFACE
diff --git a/appveyor.yml b/appveyor.yml
index 32525d3..b156d56 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -9,13 +9,14 @@ environment:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       CMAKE_GENERATOR: Visual Studio 15 2017
       CMAKE_GENERATOR_PLATFORM: x64
+      CMAKE_CLI_FLAGS: -DUUID_SYSTEM_GENERATOR=ON -DUUID_TIME_GENERATOR=ON
 
 init:
   - cmake --version
   - msbuild /version
 
 before_build:
-  - cmake -S . -B build
+  - cmake %CMAKE_CLI_FLAGS% -S . -B build
   - cd build
 
 build_script:
diff --git a/include/uuid.h b/include/uuid.h
index 3eb90c8..5adfdeb 100644
--- a/include/uuid.h
+++ b/include/uuid.h
@@ -17,23 +17,16 @@
 #include <atomic>
 #include <span>
 
-#if defined(UUID_TIME_GENERATOR) || defined(UUID_SYSTEM_GENERATOR)
 #ifdef _WIN32
-#ifndef WIN32_LEAN_AND_MEAN
-#define WIN32_LEAN_AND_MEAN
-#endif
-#ifndef NOMINMAX
-#define NOMINMAX
-#endif
 
 #ifdef UUID_SYSTEM_GENERATOR
 #include <objbase.h>
 #endif
 
-#include <windows.h>
-#include <intrin.h>       
+#ifdef UUID_TIME_GENERATOR
 #include <iphlpapi.h> 
 #pragma comment(lib, "IPHLPAPI.lib")
+#endif
 
 #elif defined(__linux__) || defined(__unix__)
 
@@ -47,7 +40,6 @@
 #include <CoreFoundation/CFUUID.h>
 #endif
 
-#endif
 #endif
 
 namespace uuids
@@ -278,10 +270,6 @@ namespace uuids
          size_t m_blockByteIndex;
          size_t m_byteCount;
       };
-
-      static std::mt19937 clock_gen(std::random_device{}());
-      static std::uniform_int_distribution<short> clock_dis{ -32768, 32767 };
-      static std::atomic_short clock_sequence = clock_dis(clock_gen);
    }
 
    // --------------------------------------------------------------------------------------------------------------------------
@@ -847,11 +835,15 @@ namespace uuids
          return ns / 100;
       }
 
-   public:
-      uuid_time_generator()
+      static short get_clock_sequence()
       {
+         static std::mt19937 clock_gen(std::random_device{}());
+         static std::uniform_int_distribution<short> clock_dis{ -32768, 32767 };
+         static std::atomic_short clock_sequence = clock_dis(clock_gen);
+         return clock_sequence++;
       }
 
+   public:
       uuid operator()()
       {
          if (get_mac_address())
@@ -860,12 +852,9 @@ namespace uuids
 
             auto tm = get_time_intervals();
 
-            short clock_seq = detail::clock_sequence++;
-
-            clock_seq &= 0x3FFF;
+            short clock_seq = get_clock_sequence();
 
             auto ptm = reinterpret_cast<uuids::uuid::value_type*>(&tm);
-            ptm[0] &= 0x0F;
 
             memcpy(&data[0], ptm + 4, 4);
             memcpy(&data[4], ptm + 2, 2);
@@ -878,7 +867,7 @@ namespace uuids
             data[8] |= 0x80;
 
             // version must be 0b0001xxxx
-            data[6] &= 0x5F;
+            data[6] &= 0x1F;
             data[6] |= 0x10;
 
             memcpy(&data[10], &device_address.value()[0], 6);

From 1562616dab012e71d12b10a0046e240de50504fe Mon Sep 17 00:00:00 2001
From: Tushar Maheshwari <tushar27192@gmail.com>
Date: Fri, 25 Jun 2021 01:10:48 +0530
Subject: [PATCH 2/2] fix short overflow UB

---
 include/uuid.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/uuid.h b/include/uuid.h
index 5adfdeb..0752e7f 100644
--- a/include/uuid.h
+++ b/include/uuid.h
@@ -835,11 +835,11 @@ namespace uuids
          return ns / 100;
       }
 
-      static short get_clock_sequence()
+      static unsigned short get_clock_sequence()
       {
          static std::mt19937 clock_gen(std::random_device{}());
-         static std::uniform_int_distribution<short> clock_dis{ -32768, 32767 };
-         static std::atomic_short clock_sequence = clock_dis(clock_gen);
+         static std::uniform_int_distribution<unsigned short> clock_dis;
+         static std::atomic_ushort clock_sequence = clock_dis(clock_gen);
          return clock_sequence++;
       }
 
@@ -852,7 +852,7 @@ namespace uuids
 
             auto tm = get_time_intervals();
 
-            short clock_seq = get_clock_sequence();
+            auto clock_seq = get_clock_sequence();
 
             auto ptm = reinterpret_cast<uuids::uuid::value_type*>(&tm);
 
@@ -860,7 +860,7 @@ namespace uuids
             memcpy(&data[4], ptm + 2, 2);
             memcpy(&data[6], ptm, 2);
 
-            memcpy(&data[8], reinterpret_cast<uuids::uuid::value_type*>(&clock_seq), 2);
+            memcpy(&data[8], &clock_seq, 2);
 
             // variant must be 0b10xxxxxx
             data[8] &= 0xBF;