dokan_fuse: Add libfuse-compatible pkg-config

Generate a pkg-config-file that can be used as a drop-in "replacement"
for libfuse, i.e.
$ pkg-config --libs --cflags fuse
will return the dokanfuse-flags.

Closes dokan-dev#338.

dokan_fuse/CMakeLists.txt

@@ -14,6 +14,30 @@ include_directories(
     ${CMAKE_CURRENT_SOURCE_DIR}/../sys
 )
 
+# Defining helper-function to deal with setups that manually set an
+# absolute path for CMAKE_INSTALL_(LIB|INCLUDE)DIR...
+# We could also just make all paths absolute, but this way the
+# pkg-config-file is more human-readable and pkg-config may be able to deal
+# with varying prefixes.
+# CMake does not have a ternary operator for generator expressions, so this
+# looks more complicated than it is.
+function ( make_pkg_config_absolute out_path in_path )
+    if(IS_ABSOLUTE "${${in_path}}")
+        set(${out_path} "${${in_path}}" PARENT_SCOPE)
+    else()
+        set(${out_path} "\${prefix}/${${in_path}}" PARENT_SCOPE)
+    endif()
+endfunction()
+
+set(pkg_config_file "${CMAKE_CURRENT_BINARY_DIR}/fuse.pc")
+make_pkg_config_absolute(PKG_CONFIG_LIBDIR CMAKE_INSTALL_LIBDIR)
+make_pkg_config_absolute(PKG_CONFIG_INCLUDEDIR CMAKE_INSTALL_INCLUDEDIR)
+CONFIGURE_FILE(
+    "${CMAKE_CURRENT_SOURCE_DIR}/pkg-config.pc.in"
+    ${pkg_config_file}
+    @ONLY
+)
+
 file(GLOB sources src/*.cpp src/*.c src/*.rc)
 set(install_headers
     include/fuse.h
@@ -30,6 +54,7 @@ add_library(dokanfuse1 SHARED ${sources})
 
 INSTALL(FILES ${install_headers} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/fuse/)
 INSTALL(FILES ${compat_headers} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+INSTALL(FILES ${pkg_config_file} DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
 INSTALL(TARGETS dokanfuse1
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}

dokan_fuse/pkg-config.pc.in

@@ -0,0 +1,13 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+exec_prefix=${prefix}
+libdir=@PKG_CONFIG_LIBDIR@
+includedir=@PKG_CONFIG_INCLUDEDIR@
+
+Name: Dokan FUSE
+Description: FUSE-API compatibility library for the Dokan user mode filesystem driver for Windows
+# Dokan FUSE provides compatibility with libfuse 2.6.x.
+# The corresponding libfuse-version is therefore reported instead of the Dokan FUSE-version
+Version: 2.6.0
+URL: https://dokan-dev.github.io
+Libs: -L${libdir} -l@PROJECT_NAME@
+Cflags: -I${includedir} -D_FILE_OFFSET_BITS=64