Thumbnail keeps reference to Exif data

This reduces the risk of a segfault if the exif data (and hence image) gets deleted.
jim-easterbrook · Nov 29, 2023 · 1a7dd16 · 1a7dd16
1 parent 1cac464
commit 1a7dd16
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Showing 5 changed files with 36 additions and 0 deletions.
diff --git a/src/interface/exif.i b/src/interface/exif.i
@@ -30,6 +30,15 @@
 %import "metadatum.i"
 %import "tags.i"
 
+// ExifThumb keeps a reference to the ExifData it uses
+%typemap(ret) Exiv2::ExifThumb* %{
+    if ($result != Py_None) {
+        if (PyObject_SetAttrString($result, "_refers_to", swig_obj[0])) {
+            SWIG_fail;
+        }
+    }
+%}
+
 #if EXIV2_VERSION_HEX < 0x001c0000
 INPUT_BUFFER_RO(const Exiv2::byte* buf, long size)
 #else

diff --git a/src/swig-0_27_0/exif_wrap.cxx b/src/swig-0_27_0/exif_wrap.cxx
@@ -9369,6 +9369,13 @@ SWIGINTERN int _wrap_new_ExifThumb(PyObject *self, PyObject *args, PyObject *kwa
     }
   }
   resultobj = SWIG_NewPointerObj(SWIG_as_voidptr(result), SWIGTYPE_p_Exiv2__ExifThumb, SWIG_BUILTIN_INIT |  0 );
+
+  if (resultobj != Py_None) {
+    if (PyObject_SetAttrString(resultobj, "_refers_to", swig_obj[0])) {
+      SWIG_fail;
+    }
+  }
+
   return resultobj == Py_None ? -1 : 0;
 fail:
   return -1;

diff --git a/src/swig-0_27_4/exif_wrap.cxx b/src/swig-0_27_4/exif_wrap.cxx
@@ -9369,6 +9369,13 @@ SWIGINTERN int _wrap_new_ExifThumb(PyObject *self, PyObject *args, PyObject *kwa
     }
   }
   resultobj = SWIG_NewPointerObj(SWIG_as_voidptr(result), SWIGTYPE_p_Exiv2__ExifThumb, SWIG_BUILTIN_INIT |  0 );
+
+  if (resultobj != Py_None) {
+    if (PyObject_SetAttrString(resultobj, "_refers_to", swig_obj[0])) {
+      SWIG_fail;
+    }
+  }
+
   return resultobj == Py_None ? -1 : 0;
 fail:
   return -1;

diff --git a/src/swig-0_28_0/exif_wrap.cxx b/src/swig-0_28_0/exif_wrap.cxx
@@ -9803,6 +9803,13 @@ SWIGINTERN int _wrap_new_ExifThumb(PyObject *self, PyObject *args, PyObject *kwa
     }
   }
   resultobj = SWIG_NewPointerObj(SWIG_as_voidptr(result), SWIGTYPE_p_Exiv2__ExifThumb, SWIG_BUILTIN_INIT |  0 );
+
+  if (resultobj != Py_None) {
+    if (PyObject_SetAttrString(resultobj, "_refers_to", swig_obj[0])) {
+      SWIG_fail;
+    }
+  }
+
   return resultobj == Py_None ? -1 : 0;
 fail:
   return -1;

diff --git a/tests/test_exif.py b/tests/test_exif.py
@@ -201,6 +201,12 @@ def test_ref_counts(self):
         self.assertEqual(sys.getrefcount(self.image), 2)
         data = self.image.exifData()
         self.assertEqual(sys.getrefcount(self.image), 3)
+        # thumbnail keeps a reference to exifData
+        self.assertEqual(sys.getrefcount(data), 2)
+        thumb = exiv2.ExifThumb(data)
+        self.assertEqual(sys.getrefcount(data), 3)
+        del thumb
+        self.assertEqual(sys.getrefcount(data), 2)
         # iterator keeps a reference to data
         self.assertEqual(sys.getrefcount(data), 2)
         b = data.begin()