info file export soname and fix for windows w/ py < 3.8

src/setuptools_dso/dsocmd.py

@@ -412,17 +412,37 @@ class build_dso(dso2libmixin, Command):
                 file.write(
                     textwrap.dedent(
                         """
-                    import os.path
-                    import sys
-                    dir = os.path.dirname(__file__)
-                    if sys.platform == 'win32':
-                        os.add_dll_directory(dir)
+                    # generated by setuptools_dso
+                    import sys, os
+
+                    # on windows, extend DLL search path to include
+                    # the directory containing this file
+                    def fixpath():
+                        libdir = os.path.dirname(__file__)
+
+                        if hasattr(os, 'add_dll_directory'): # py >= 3.8
+                            os.add_dll_directory(libdir)
+
+                        elif sys.platform == "win32":
+                            path = os.environ.get('PATH', '').split(os.pathsep)
+                            path.append(libdir)
+                            os.environ['PATH'] = os.pathsep.join(path)
+
+                    fixpath()
+                    del fixpath
+
                     dsoname = {dsoname!r}
                     libname = {libname!r}
+                    soname = {soname!r}
+                    dir = os.path.dirname(__file__)
                     filename = os.path.join(dir, libname)
-                    __all__ = ("dsoname", "libname", "filename")
+                    sofilename = os.path.join(dir, soname)
+                    del dir
+                    __all__ = ("dsoname", "libname", "soname", "filename", "sofilename")
                     """
-                    ).format(dsoname=dso.name, libname=self._name2libname(dso))
+                    ).format(dsoname=dso.name,
+                             libname=self._name2libname(dso),
+                             soname=self._name2libname(dso, so=True))
                 )
 
         if self.inplace: