Fixed GEOS & GDAL C function prototypes to explicitly use a subclass …

…of `c_char_p` as the return type on routines that return strings. This prevents crashes on some 64-bit platforms, like FreeBSD. Thanks to wilsaj for discovering the problem. Refs #9747.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11205 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/gdal/prototypes/generation.py

@@ -8,6 +8,9 @@
     check_arg_errcode, check_errcode, check_geom, check_geom_offset, \
     check_pointer, check_srs, check_str_arg, check_string, check_const_string
 
+class gdal_char_p(c_char_p):
+    pass
+
 def double_output(func, argtypes, errcheck=False, strarg=False):
     "Generates a ctypes function that returns a double value."
     func.argtypes = argtypes
@@ -77,9 +80,9 @@ def string_output(func, argtypes, offset=-1, str_result=False):
     """
     func.argtypes = argtypes
     if str_result:
-        # String is the result, don't explicitly define
-        # the argument type so we can get the pointer.
-        pass
+        # Use subclass of c_char_p so the error checking routine
+        # can free the memory at the pointer's address.
+        func.restype = gdal_char_p
     else:
         # Error code is returned
         func.restype = c_int

django/contrib/gis/geos/prototypes/topology.py

@@ -10,6 +10,7 @@
 from ctypes import c_char_p, c_double, c_int
 from django.contrib.gis.geos.libgeos import lgeos, GEOM_PTR, GEOS_PREPARE
 from django.contrib.gis.geos.prototypes.errcheck import check_geom, check_string
+from django.contrib.gis.geos.prototypes.geom import geos_char_p
 
 def topology(func, *args):
     "For GEOS unary topology functions."
@@ -38,6 +39,7 @@ def topology(func, *args):
 # GEOSRelate returns a string, not a geometry.
 geos_relate = lgeos.GEOSRelate
 geos_relate.argtypes = [GEOM_PTR, GEOM_PTR]
+geos_relate.restype = geos_char_p
 geos_relate.errcheck = check_string
 
 # Routines only in GEOS 3.1+