Merge pull request #5515 from mdboom/png-fishiness

tacaswell · tacaswell · commit 3814c7782380 · 2015-11-20T17:35:13.000-05:00
Fix some theoretical problems with png reading
diff --git a/lib/matplotlib/backends/backend_agg.py b/lib/matplotlib/backends/backend_agg.py
@@ -525,6 +525,7 @@ def print_png(self, filename_or_obj, *args, **kwargs):
             close = True
         else:
             close = False
+
         try:
             _png.write_png(renderer._renderer, filename_or_obj, self.figure.dpi)
         finally:
diff --git a/lib/matplotlib/image.py b/lib/matplotlib/image.py
@@ -1279,8 +1279,8 @@ def pilread(fname):
             from PIL import Image
         except ImportError:
             return None
-        image = Image.open(fname)
-        return pil_to_array(image)
+        with Image.open(fname) as image:
+            return pil_to_array(image)
 
     handlers = {'png': _png.read_png, }
     if format is None:
diff --git a/src/_png.cpp b/src/_png.cpp
@@ -241,10 +241,12 @@ static void _read_png_data(PyObject *py_file_obj, png_bytep data, png_size_t len
     Py_ssize_t bufflen;
     if (read_method) {
         result = PyObject_CallFunction(read_method, (char *)"i", length);
-    }
-    if (PyBytes_AsStringAndSize(result, &buffer, &bufflen) == 0) {
-        if (bufflen == (Py_ssize_t)length) {
-            memcpy(data, buffer, length);
+        if (PyBytes_AsStringAndSize(result, &buffer, &bufflen) == 0) {
+            if (bufflen == (Py_ssize_t)length) {
+                memcpy(data, buffer, length);
+            } else {
+                PyErr_SetString(PyExc_IOError, "read past end of file");
+            }
         }
     }
     Py_XDECREF(read_method);
