User cmake helper for finding LZ4

Author: joto

cmake/FindLZ4.cmake

@@ -0,0 +1,38 @@
+find_path(LZ4_INCLUDE_DIR
+  NAMES lz4.h
+  DOC "lz4 include directory")
+mark_as_advanced(LZ4_INCLUDE_DIR)
+find_library(LZ4_LIBRARY
+  NAMES lz4 liblz4
+  DOC "lz4 library")
+mark_as_advanced(LZ4_LIBRARY)
+
+if (LZ4_INCLUDE_DIR)
+  file(STRINGS "${LZ4_INCLUDE_DIR}/lz4.h" _lz4_version_lines
+    REGEX "#define[ \t]+LZ4_VERSION_(MAJOR|MINOR|RELEASE)")
+  string(REGEX REPLACE ".*LZ4_VERSION_MAJOR *\([0-9]*\).*" "\\1" _lz4_version_major "${_lz4_version_lines}")
+  string(REGEX REPLACE ".*LZ4_VERSION_MINOR *\([0-9]*\).*" "\\1" _lz4_version_minor "${_lz4_version_lines}")
+  string(REGEX REPLACE ".*LZ4_VERSION_RELEASE *\([0-9]*\).*" "\\1" _lz4_version_release "${_lz4_version_lines}")
+  set(LZ4_VERSION "${_lz4_version_major}.${_lz4_version_minor}.${_lz4_version_release}")
+  unset(_lz4_version_major)
+  unset(_lz4_version_minor)
+  unset(_lz4_version_release)
+  unset(_lz4_version_lines)
+endif ()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(LZ4
+  REQUIRED_VARS LZ4_LIBRARY LZ4_INCLUDE_DIR
+  VERSION_VAR LZ4_VERSION)
+
+if (LZ4_FOUND)
+  set(LZ4_INCLUDE_DIRS "${LZ4_INCLUDE_DIR}")
+  set(LZ4_LIBRARIES "${LZ4_LIBRARY}")
+
+  if (NOT TARGET LZ4::LZ4)
+    add_library(LZ4::LZ4 UNKNOWN IMPORTED)
+    set_target_properties(LZ4::LZ4 PROPERTIES
+      IMPORTED_LOCATION "${LZ4_LIBRARY}"
+      INTERFACE_INCLUDE_DIRECTORIES "${LZ4_INCLUDE_DIR}")
+  endif ()
+endif ()

cmake/FindOsmium.cmake

@@ -118,21 +118,20 @@ if(Osmium_USE_PBF)
     find_package(Protozero 1.6.3)
 
     if(Osmium_USE_LZ4)
-        find_path(LZ4_INCLUDE_DIR NAMES lz4.h REQUIRED)
-        find_library(LZ4_LIBRARY NAMES lz4 REQUIRED)
+        find_package(LZ4 REQUIRED)
         add_definitions(-DOSMIUM_WITH_LZ4)
     endif()
 
     list(APPEND OSMIUM_EXTRA_FIND_VARS ZLIB_FOUND Threads_FOUND PROTOZERO_INCLUDE_DIR)
     if(ZLIB_FOUND AND Threads_FOUND AND PROTOZERO_FOUND)
         list(APPEND OSMIUM_PBF_LIBRARIES
             ${ZLIB_LIBRARIES}
-            ${LZ4_LIBRARY}
+            ${LZ4_LIBRARIES}
             ${CMAKE_THREAD_LIBS_INIT}
         )
         list(APPEND OSMIUM_INCLUDE_DIRS
             ${ZLIB_INCLUDE_DIR}
-            ${LZ4_INCLUDE_DIR}
+            ${LZ4_INCLUDE_DIRS}
             ${PROTOZERO_INCLUDE_DIR}
         )
     else()