fix cmake build when using fetch content

Author: ITotalJustice

CMakeLists.txt

@@ -31,7 +31,62 @@ project(libusbhsfs
 option(USBHSFS_GPL "ext4 and ntfs support" OFF)
 option(USBHSFS_EXAMPLES "build examples" OFF)
 
-add_subdirectory(source)
+add_library(libusbhsfs
+    source/usbhsfs_drive.c
+    source/usbhsfs_log.c
+    source/usbhsfs_manager.c
+    source/usbhsfs_mount.c
+    source/usbhsfs_request.c
+    source/usbhsfs_scsi.c
+    source/usbhsfs_utils.c
+)
+
+target_include_directories(libusbhsfs PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include)
+
+# fatfs stuff
+target_sources(libusbhsfs PRIVATE
+    source/fatfs/diskio.c
+    source/fatfs/ff_dev.c
+    source/fatfs/ff.c
+    source/fatfs/ffsystem.c
+    source/fatfs/ffunicode.c
+)
+
+# sxos stuff
+target_sources(libusbhsfs PRIVATE
+    source/sxos/usbfs_dev.c
+    source/sxos/usbfs.c
+)
+
+if (USBHSFS_GPL)
+    target_sources(libusbhsfs PRIVATE
+        source/lwext4/ext_dev.c
+        source/lwext4/ext_disk_io.c
+        source/lwext4/ext.c
+
+        source/ntfs-3g/ntfs_dev.c
+        source/ntfs-3g/ntfs_disk_io.c
+        source/ntfs-3g/ntfs.c
+    )
+
+    find_library(ntfs_3g_lib ntfs-3g)
+    find_path(ntfs_3g_inc ntfs-3g)
+
+    find_library(lwext4_lib lwext4)
+    find_path(lwext4_inc ext4.h)
+
+    if (NOT ntfs-3g_lib OR NOT ntfs-3g_inc)
+        message(FATAL_ERROR "ntfs-3g is not installed!")
+    endif()
+
+    if (NOT lwext4_lib OR NOT lwext4_inc)
+        message(FATAL_ERROR "lwext4 is not installed!")
+    endif()
+
+    target_link_libraries(libusbhsfs PRIVATE ${ntfs_3g_lib} ${lwext4_lib})
+    target_include_directories(libusbhsfs PRIVATE ${ntfs_3g_inc} ${lwext4_inc})
+    target_compile_definitions(libusbhsfs PRIVATE GPL_BUILD)
+endif()
 
 if (USBHSFS_EXAMPLES)
     add_subdirectory(example_callback)