From 057cd06c19875bcf8b5d34d41d92a8abdb856b7c Mon Sep 17 00:00:00 2001
From: Kleis Auke Wolthuizen <github@kleisauke.nl>
Date: Fri, 11 Mar 2022 21:11:24 +0100
Subject: [PATCH] Remove LCMS mutex (#112)

* Remove LCMS mutex

Requires mm2/Little-CMS@a35bacd, which is released in LCMS v2.11.

* Use a threadsafe alternative of gmtime in LCMS

Requires mm2/Little-CMS@68ee2ff, which is released in LCMS v2.13.

LCMS submodule was updated to version 2.13.1 instead.
---
 lib/jxl/enc_color_management.cc |   15 +++++++++++++++
 third_party/CMakeLists.txt      |    2 +-
 third_party/lcms2.cmake         |   14 --------------
 3 files changed, 16 insertions(+), 15 deletions(-)

Index: libjxl-0.8.1/lib/jxl/enc_color_management.cc
===================================================================
--- libjxl-0.8.1.orig/lib/jxl/enc_color_management.cc
+++ libjxl-0.8.1/lib/jxl/enc_color_management.cc
@@ -18,6 +18,7 @@
 #include <array>
 #include <atomic>
 #include <memory>
+#include <mutex>
 #include <string>
 #include <utility>
 
@@ -308,6 +309,14 @@ int DoColorSpaceTransform(void* t, size_
 // Define to 1 on OS X as a workaround for older LCMS lacking MD5.
 #define JXL_CMS_OLD_VERSION 0
 
+// cms functions (even *THR) are not thread-safe, except cmsDoTransform.
+// To ensure all functions are covered without frequent lock-taking nor risk of
+// recursive lock, we lock in the top-level APIs.
+static std::mutex& LcmsMutex() {
+  static std::mutex m;
+  return m;
+}
+
 #if JPEGXL_ENABLE_SKCMS
 
 JXL_MUST_USE_RESULT CIExy CIExyFromXYZ(const float XYZ[3]) {
@@ -871,6 +880,9 @@ bool ApplyCICP(const uint8_t color_prima
 
 }  // namespace
 
+// All functions that call lcms directly (except ColorSpaceTransform::Run) must
+// lock LcmsMutex().
+
 Status ColorEncoding::SetFieldsFromICC() {
   // In case parsing fails, mark the ColorEncoding as invalid.
   SetColorSpace(ColorSpace::kUnknown);
@@ -917,6 +929,7 @@ Status ColorEncoding::SetFieldsFromICC()
   DetectTransferFunction(profile, this);
 #else  // JPEGXL_ENABLE_SKCMS
 
+  std::lock_guard<std::mutex> guard(LcmsMutex());
   const cmsContext context = GetContext();
 
   Profile profile;
@@ -984,6 +997,7 @@ void JxlCmsDestroy(void* cms_data) {
   if (cms_data == nullptr) return;
   JxlCms* t = reinterpret_cast<JxlCms*>(cms_data);
 #if !JPEGXL_ENABLE_SKCMS
+  std::lock_guard<std::mutex> guard(LcmsMutex());
   TransformDeleter()(t->lcms_transform);
 #endif
   delete t;
@@ -1020,6 +1034,7 @@ void* JxlCmsInit(void* init_data, size_t
     return nullptr;
   }
 #else   // JPEGXL_ENABLE_SKCMS
+  std::lock_guard<std::mutex> guard(LcmsMutex());
   const cmsContext context = GetContext();
   Profile profile_src, profile_dst;
   if (!DecodeProfile(context, c_src.ICC(), &profile_src)) {
Index: libjxl-0.8.1/third_party/CMakeLists.txt
===================================================================
--- libjxl-0.8.1.orig/third_party/CMakeLists.txt
+++ libjxl-0.8.1/third_party/CMakeLists.txt
@@ -111,7 +111,7 @@ if (JPEGXL_ENABLE_SKCMS OR JPEGXL_ENABLE
 endif ()
 if (JPEGXL_ENABLE_VIEWERS OR NOT JPEGXL_ENABLE_SKCMS)
   if( NOT EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/lcms/.git" OR JPEGXL_FORCE_SYSTEM_LCMS2 )
-    find_package(LCMS2 2.13)
+    find_package(LCMS2 2.10)
     if ( NOT LCMS2_FOUND )
       message(FATAL_ERROR "Please install lcms2 or run git submodule update --init")
     endif ()
Index: libjxl-0.8.1/third_party/lcms2.cmake
===================================================================
--- libjxl-0.8.1.orig/third_party/lcms2.cmake
+++ libjxl-0.8.1/third_party/lcms2.cmake
@@ -60,18 +60,4 @@ target_compile_definitions(lcms2
 target_compile_definitions(lcms2
   PUBLIC "-DCMS_NO_REGISTER_KEYWORD=1")
 
-# Ensure that a thread safe alternative of gmtime is used in LCMS
-include(CheckSymbolExists)
-check_symbol_exists(gmtime_r "time.h" HAVE_GMTIME_R)
-if (HAVE_GMTIME_R)
-  target_compile_definitions(lcms2
-    PUBLIC "-DHAVE_GMTIME_R=1")
-else()
-  check_symbol_exists(gmtime_s "time.h" HAVE_GMTIME_S)
-  if (HAVE_GMTIME_S)
-    target_compile_definitions(lcms2
-      PUBLIC "-DHAVE_GMTIME_S=1")
-  endif()
-endif()
-
 set_property(TARGET lcms2 PROPERTY POSITION_INDEPENDENT_CODE ON)