[#145] Identify libpython soname at configure-time

Author: SwooshyCueb

CMakeLists.txt

@@ -41,6 +41,37 @@ find_package(OpenSSL REQUIRED COMPONENTS Crypto SSL)
 find_package(nlohmann_json "3.6.1" REQUIRED)
 find_package(Python "${IRODS_PYTHON_VERSION}" REQUIRED COMPONENTS Development)
 
+if (NOT IRODS_PYTHON_SONAME)
+  get_target_property(IRODS_PYTHON_SONAME Python::Python IMPORTED_SONAME)
+  if (NOT IRODS_PYTHON_SONAME)
+    get_target_property(__PYTHON_IMPORTED_LOCATION Python::Python IMPORTED_LOCATION)
+    if (__PYTHON_IMPORTED_LOCATION)
+      if (IS_SYMLINK "${__PYTHON_IMPORTED_LOCATION}")
+        file(READ_SYMLINK "${__PYTHON_IMPORTED_LOCATION}" __PYTHON_LIBRARY_PATH)
+      else()
+        set(__PYTHON_LIBRARY_PATH "${__PYTHON_IMPORTED_LOCATION}")
+      endif()
+      get_filename_component(IRODS_PYTHON_SONAME "${__PYTHON_LIBRARY_PATH}" NAME)
+    else()
+      # We might be able to use python-config before falling back to guessing like this.
+      if (Python_VERSION_MAJOR EQUAL "3" AND Python_VERSION_MINOR LESS "8")
+        set(__PYTHON_VERSION_SUFFIX "m")
+      else()
+        set(__PYTHON_VERSION_SUFFIX "")
+      endif()
+      set(IRODS_PYTHON_SONAME "${CMAKE_SHARED_LIBRARY_PREFIX}python${Python_VERSION_MAJOR}.${Python_VERSION_MINOR}${__PYTHON_VERSION_SUFFIX}${CMAKE_SHARED_LIBRARY_SUFFIX}.1.0")
+    endif()
+  endif()
+  message("Python SONAME detected as ${IRODS_PYTHON_SONAME}")
+endif()
+
+file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/include/irods/private/re/python")
+configure_file(
+  "${CMAKE_CURRENT_SOURCE_DIR}/include/irods/private/re/python/config.hpp.in"
+  "${CMAKE_CURRENT_BINARY_DIR}/include/irods/private/re/python/config.hpp"
+  @ONLY
+)
+
 set(
   PLUGIN
   irods_rule_engine_plugin-python
@@ -154,6 +185,7 @@ target_include_directories(
   ${PLUGIN}
   PRIVATE
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>
   ${IRODS_INCLUDE_DIRS}
   ${IRODS_EXTERNALS_FULLPATH_BOOST}/include
   ${IRODS_EXTERNALS_FULLPATH_FMT}/include

include/irods/private/re/python/config.hpp.in

@@ -0,0 +1,9 @@
+#ifndef IRODS_RE_PYTHON_CONFIG_HPP
+#define IRODS_RE_PYTHON_CONFIG_HPP
+
+// include this first to fix macro redef warnings
+#include <pyconfig.h>
+
+#cmakedefine IRODS_PYTHON_SONAME "@IRODS_PYTHON_SONAME"
+
+#endif // IRODS_RE_PYTHON_CONFIG_HPP

src/main.cpp

@@ -35,6 +35,7 @@
 #include <irods/rsExecMyRule.hpp>
 
 #include "irods/private/re/python.hpp"
+#include "irods/private/re/python/config.hpp"
 
 #include <patchlevel.h>
 #pragma GCC diagnostic push
@@ -314,19 +315,14 @@ namespace
 
 irods::error start(irods::default_re_ctx&, const std::string& _instance_name)
 {
-	// TODO Enable config-selectable Python version
-#if PY_VERSION_HEX < 0x03000000
-	void* p = dlopen(
-		"libpython2.7.so",
-		RTLD_LAZY | RTLD_GLOBAL); // https://mail.python.org/pipermail/new-bugs-announce/2008-November/003322.html
-#else
-	void* p =
-		dlopen("libpython3.6m.so.1.0", RTLD_LAZY | RTLD_GLOBAL); // Kludge for bionic; proper solution forthcoming.
-#endif
+#ifdef IRODS_PYTHON_SONAME
+	// Force python library to be loaded
+	void* p = dlopen(IRODS_PYTHON_SONAME, RTLD_LAZY | RTLD_GLOBAL);
 	rodsLog(LOG_DEBUG, "dlopen returned: [%p]", p);
 	if (!p) {
 		rodsLog(LOG_DEBUG, "dlerror gives : [%s]", dlerror());
 	}
+#endif
 
 	try {
 #if PY_VERSION_HEX < 0x03000000