From f28dc743d653df245fb074ecfaf3befa54859dc4 Mon Sep 17 00:00:00 2001
From: King_DuckZ <king_duckz@gmx.com>
Date: Mon, 4 Aug 2014 18:57:14 +0200
Subject: [PATCH] Use the system's PhysFS if present.

Also add an option to allow the user to override this and force the use of the supplied library.
Pass -DWITH_BUILTIN_PHYSFS=on to cmake to force using the supplied library.
---
 CMakeLists.txt | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d7aa40b..6509b17 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,11 +5,24 @@ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wextra -pedantic -Wcon
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -std=c++11 -Wall -Wextra -pedantic -Wconversion")
 set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -std=c++11 -Wall -Wextra -pedantic -Wconversion")
 
+option(WITH_BUILTIN_PHYSFS "Force using the version of PhysFS accompanying the code even if a system library is available" OFF)
+
 include(FindPkgConfig)
 PKG_SEARCH_MODULE(SDL2 REQUIRED sdl2)
 
 find_package(PNG REQUIRED)
 find_package(Boost 1.55.0 REQUIRED)
+if (NOT WITH_BUILTIN_PHYSFS)
+	find_package(PhysFS 2.0.3)
+endif()
+
+if (PHYSFS_FOUND)
+	message(STATUS "Using system's PhysFS, set WITH_BUILTIN_PHYSFS to on to override this")
+else(PHYSFS_FOUND)
+	message(STATUS "Using internal PhysFS")
+	set(PHYSFS_INCLUDE_DIR "lib/physfs-2.0.3")
+	set(PHYSFS_LIBRARY "physfs")
+endif(PHYSFS_FOUND)
 
 add_definitions(
 	${PNG_DEFINITIONS}
@@ -27,7 +40,7 @@ include_directories(
 	src/movers
 	include
 	"${PROJECT_BINARY_DIR}"
-	lib/physfs-2.0.3
+	${PHYSFS_INCLUDE_DIR}
 )
 
 configure_file(
@@ -35,7 +48,9 @@ configure_file(
 	"${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.h"
 )
 
-add_subdirectory(lib/physfs-2.0.3)
+if (NOT PHYSFS_FOUND)
+	add_subdirectory(lib/physfs-2.0.3)
+endif(NOT PHYSFS_FOUND)
 
 add_executable(${PROJECT_NAME}
 	src/main.cpp
@@ -69,6 +84,6 @@ add_executable(${PROJECT_NAME}
 
 target_link_libraries(${PROJECT_NAME}
 	${SDL2_LIBRARIES}
-	physfs
+	${PHYSFS_LIBRARY}
 	${PNG_LIBRARIES}
 )