Improve python searching logic in buildscripts.

Make it possible to override PYTHON_VERSION when invoking cmake.

Signed-off-by: Maksym Chukhrii <[email protected]>

CMakeLists.txt

@@ -215,26 +215,38 @@ if (NOT HAVE_WORKING_WERROR)
 endif()
 
 # Use Python modules based on CMake version for backward compatibility
-set(CYTHON_EXECUTABLE "")
 if (${CMAKE_VERSION} VERSION_LESS "3.12")
- # Look for Python. We prefer some variant of python 3 if the system has it
- FIND_PACKAGE(PythonInterp 3 QUIET)
- if (PythonInterp_FOUND)
- # pyverbs can only use python3:
- if (NOT NO_PYVERBS)
- FIND_PACKAGE(cython)
- endif()
- else()
- # But we still must have python (be it 2) for the build process
- FIND_PACKAGE(PythonInterp REQUIRED)
- endif()
-else()
- # FindPython looks preferably for Python3. If not found, version 2 is searched
- FIND_PACKAGE(Python COMPONENTS Interpreter REQUIRED)
- set(PYTHON_EXECUTABLE ${Python_EXECUTABLE})
- if (NOT NO_PYVERBS AND Python_VERSION_MAJOR EQUAL 3)
+ FIND_PACKAGE(PythonInterp REQUIRED)
+ FIND_PACKAGE(PythonLibs ${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR} EXACT)
+elseif (${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.12")
+ set(Python_EXECUTABLE ${PYTHON_EXECUTABLE})
+ FIND_PACKAGE(Python 3 REQUIRED COMPONENTS Interpreter OPTIONAL_COMPONENTS Development)
+ set(PYTHON_EXECUTABLE ${Python_EXECUTABLE})
+ if(Python_Development_FOUND)
+ set(PYTHONLIBS_FOUND ${Python_Development_FOUND})
+ set(PYTHON_LIBRARIES ${Python_LIBRARIES})
+ set(PYTHON_INCLUDE_DIRS ${Python_INCLUDE_DIRS})
+ endif()
+endif()
+
+set(CYTHON_EXECUTABLE "")
+if(NOT NO_PYVERBS AND PYTHONLIBS_FOUND)
+ execute_process(COMMAND "${PYTHON_EXECUTABLE}" -c
+ "import sysconfig; print(sysconfig.get_path(\"platlib\"))"
+ OUTPUT_VARIABLE py_path)
+ string(STRIP ${py_path} py_path)
+ set(CMAKE_INSTALL_PYTHON_ARCH_LIB "${py_path}"
+ CACHE PATH "Location for architecture specific python libraries")
+
+ # See PEP3149
+ execute_process(COMMAND "${PYTHON_EXECUTABLE}" -c
+ "import sysconfig; x = sysconfig.get_config_var(\"EXT_SUFFIX\"); print(x if x else '.so')"
+ OUTPUT_VARIABLE py_path)
+ string(STRIP ${py_path} CMAKE_PYTHON_SO_SUFFIX)
+
  FIND_PACKAGE(cython)
- endif()
+elseif(NOT NO_PYVERBS AND NOT PYTHONLIBS_FOUND)
+ message(WARNING "pyverbs build requested but python development files not found")
 endif()
 
 find_program(SYSTEMCTL_BIN systemctl HINTS "/usr/bin" "/bin")
@@ -451,38 +463,6 @@ else()
  set(HAVE_FULL_SYMBOL_VERSIONS 1)
 endif()
 
-# A cython & python-devel installation that matches our selected interpreter.
-
-if (CYTHON_EXECUTABLE)
- # cmake has really bad logic here, if PythonIterp has been run it tries to
- # find a matching -devel installation but will happily return a non-matching
- # one too. We need them both to match exactly to guarantee cython does the
- # right thing.
- if (${CMAKE_VERSION} VERSION_LESS "3.12")
- FIND_PACKAGE(PythonLibs ${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}
- EXACT REQUIRED)
- else()
- FIND_PACKAGE(Python ${Python_VERSION_MAJOR}.${Python_VERSION_MINOR}
- EXACT COMPONENTS Development REQUIRED)
- set(PYTHON_LIBRARIES ${Python_LIBRARIES})
- set(PYTHON_INCLUDE_DIRS ${Python_INCLUDE_DIRS})
- endif()
-
- # Get a default installation path
- execute_process(COMMAND "${PYTHON_EXECUTABLE}" -c
- "import sysconfig; print(sysconfig.get_path(\"platlib\"))"
- OUTPUT_VARIABLE py_path)
- string(STRIP ${py_path} py_path)
- set(CMAKE_INSTALL_PYTHON_ARCH_LIB "${py_path}"
- CACHE PATH "Location for architecture specific python libraries")
-
- # See PEP3149
- execute_process(COMMAND "${PYTHON_EXECUTABLE}" -c
- "import sysconfig; x = sysconfig.get_config_var(\"EXT_SUFFIX\"); print(x if x else '.so')"
- OUTPUT_VARIABLE py_path)
- string(STRIP ${py_path} CMAKE_PYTHON_SO_SUFFIX)
-endif()
-
 set(NO_MAN_PAGES "OFF" CACHE BOOL "Disable build/install of man pages")
 if (NOT NO_MAN_PAGES)
  # Look for pandoc and rst2man for making manual pages