libvips
diff --git a/‎pyvips/decls.py
Lines changed: 3 additions & 0 deletions b/‎pyvips/decls.py
Lines changed: 3 additions & 0 deletions
diff --git a/‎pyvips/gvalue.py
Lines changed: 2 additions & 4 deletions b/‎pyvips/gvalue.py
Lines changed: 2 additions & 4 deletions
diff --git a/‎pyvips/pyvips_build.py
Lines changed: 12 additions & 0 deletions b/‎pyvips/pyvips_build.py
Lines changed: 12 additions & 0 deletions
diff --git a/‎setup.py
Lines changed: 5 additions & 4 deletions b/‎setup.py
Lines changed: 5 additions & 4 deletions
@@ -53,6 +53,9 @@ def cdefs(features):
         void* g_malloc (size_t size);
         void g_free (void* data);
 
+        // not what's in the headers, but see the comment in pyvips_build.py
+        int vips_free (void* a, void* b);
+
         void vips_leak_set (int leak);
 
         char* vips_path_filename7 (const char* path);
 
@@ -188,10 +188,8 @@ def set(self, value):
             # can own
             memory = glib_lib.g_malloc(len(value))
             ffi.memmove(memory, value, len(value))
-            free_fn = ffi.cast('VipsCallbackFn', glib_lib.g_free)
-
             vips_lib.vips_value_set_blob(self.gvalue,
-                                         free_fn, memory, len(value))
+                                         vips_lib.vips_free, memory, len(value))
         else:
             raise Error('unsupported gtype for set {0}, fundamental {1}'.
                         format(type_name(gtype), type_name(fundamental)))
@@ -269,7 +267,7 @@ def get(self):
         elif gtype == GValue.blob_type:
             psize = ffi.new('size_t *')
             array = vips_lib.vips_value_get_blob(self.gvalue, psize)
-            buf = ffi.cast("char*", array)
+            buf = ffi.cast('char*', array)
 
             result = ffi.unpack(buf, psize[0])
         else:
 
@@ -10,9 +10,21 @@
 
 ffibuilder = FFI()
 
+# this is very hacky ... cffi in API mode won't let us cast function pointers,
+# so we can't pass vips_free() as a vipsCallbackFn, which we need to be able to
+# do when we set a blob
+# 
+# to fix this, we rename vips_free during the vips header load as
+# real_vips_free, then declare a fake type ourselves that decl.py then hooks up
+# to
+
 ffibuilder.set_source("_libvips",
     r""" 
+        #define vips_free real_vips_free
         #include <vips/vips.h>
+        #undef vips_free
+
+        extern VipsCallbackFn vips_free;
     """, 
     **pkgconfig.parse('vips'))
 
 
@@ -21,23 +21,24 @@
 setup_deps = [
     'cffi>=1.0.0',
     'pytest-runner',
-    'pkgconfig'
+    'pkgconfig',
 ]
 
 install_deps = [
     'cffi>=1.0.0',
-    'pkgconfig'
+    'pkgconfig',
 ]
 
 test_deps = [
+    'cffi>=1.0.0',
     'pytest',
     'pytest-catchlog',
-    'pytest-flake8'
+    'pytest-flake8',
 ]
 
 extras = {
     'test': test_deps,
-    'doc': ['sphinx', 'sphinx_rtd_theme']
+    'doc': ['sphinx', 'sphinx_rtd_theme'],
 }
 
 import sys