From 4ac10c4a9d47e6aea5f05bcf0127cb72c659303f Mon Sep 17 00:00:00 2001
From: Castor215 <132155746+Castor215@users.noreply.github.com>
Date: Sun, 22 Oct 2023 00:10:02 +0100
Subject: [PATCH] externals: allow users to use system Zstandard (#7083)

---
 externals/CMakeLists.txt                      | 20 ++++++++++++++-----
 .../cmake-modules/CitraHandleSystemLibs.cmake |  3 +++
 src/common/CMakeLists.txt                     |  2 +-
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/externals/CMakeLists.txt b/externals/CMakeLists.txt
index c86981f030..69f4f31078 100644
--- a/externals/CMakeLists.txt
+++ b/externals/CMakeLists.txt
@@ -211,11 +211,21 @@ if (ENABLE_LIBUSB AND NOT USE_SYSTEM_LIBUSB)
 endif()
 
 # Zstandard
-set(ZSTD_LEGACY_SUPPORT OFF)
-set(ZSTD_BUILD_PROGRAMS OFF)
-set(ZSTD_BUILD_SHARED OFF)
-add_subdirectory(zstd/build/cmake EXCLUDE_FROM_ALL)
-target_include_directories(libzstd_static INTERFACE $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/externals/zstd/lib>)
+if(USE_SYSTEM_ZSTD)
+    find_package(zstd REQUIRED)
+    add_library(zstd INTERFACE)
+    if(TARGET zstd::libzstd_shared)
+        message(STATUS "Found system Zstandard")
+    endif()
+    target_link_libraries(zstd INTERFACE zstd::libzstd_shared)
+else()
+    set(ZSTD_LEGACY_SUPPORT OFF)
+    set(ZSTD_BUILD_PROGRAMS OFF)
+    set(ZSTD_BUILD_SHARED OFF)
+    add_subdirectory(zstd/build/cmake EXCLUDE_FROM_ALL)
+    target_include_directories(libzstd_static INTERFACE $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/externals/zstd/lib>)
+    add_library(zstd ALIAS libzstd_static)
+endif()
 
 # ENet
 add_subdirectory(enet)
diff --git a/externals/cmake-modules/CitraHandleSystemLibs.cmake b/externals/cmake-modules/CitraHandleSystemLibs.cmake
index 4166e201b3..cbb80687d9 100644
--- a/externals/cmake-modules/CitraHandleSystemLibs.cmake
+++ b/externals/cmake-modules/CitraHandleSystemLibs.cmake
@@ -18,6 +18,7 @@ option(USE_SYSTEM_INIH "Use the system inih (instead of the bundled one)" OFF)
 option(USE_SYSTEM_FDK_AAC_HEADERS "Use the system fdk-aac headers (instead of the bundled one)" OFF)
 option(USE_SYSTEM_FFMPEG_HEADERS "Use the system FFmpeg headers (instead of the bundled one)" OFF)
 option(USE_SYSTEM_GLSLANG "Use the system glslang and SPIR-V libraries (instead of the bundled ones)" OFF)
+option(USE_SYSTEM_ZSTD "Use the system Zstandard library (instead of the bundled one)" OFF)
 
 # Qt and MoltenVK are handled separately
 CMAKE_DEPENDENT_OPTION(DISABLE_SYSTEM_SDL2 "Disable system SDL2" OFF "USE_SYSTEM_LIBS" OFF)
@@ -35,6 +36,7 @@ CMAKE_DEPENDENT_OPTION(DISABLE_SYSTEM_INIH "Disable system inih" OFF "USE_SYSTEM
 CMAKE_DEPENDENT_OPTION(DISABLE_SYSTEM_FDK_AAC_HEADERS "Disable system fdk_aac" OFF "USE_SYSTEM_LIBS" OFF)
 CMAKE_DEPENDENT_OPTION(DISABLE_SYSTEM_FFMPEG_HEADERS "Disable system ffmpeg" OFF "USE_SYSTEM_LIBS" OFF)
 CMAKE_DEPENDENT_OPTION(DISABLE_SYSTEM_GLSLANG "Disable system glslang" OFF "USE_SYSTEM_LIBS" OFF)
+CMAKE_DEPENDENT_OPTION(DISABLE_SYSTEM_ZSTD "Disable system Zstandard" OFF "USE_SYSTEM_LIBS" OFF)
 
 set(LIB_VAR_LIST
     SDL2
@@ -52,6 +54,7 @@ set(LIB_VAR_LIST
     FDK_AAC_HEADERS
     FFMPEG_HEADERS
     GLSLANG
+    ZSTD
     )
 
 # First, check that USE_SYSTEM_XXX is not used with USE_SYSTEM_LIBS
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index e2ee678355..74a22e6b05 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -174,7 +174,7 @@ endif()
 create_target_directory_groups(citra_common)
 
 target_link_libraries(citra_common PUBLIC fmt library-headers microprofile Boost::boost Boost::serialization Boost::iostreams)
-target_link_libraries(citra_common PRIVATE libzstd_static)
+target_link_libraries(citra_common PRIVATE zstd)
 
 if ("x86_64" IN_LIST ARCHITECTURE)
     target_link_libraries(citra_common PRIVATE xbyak)