Fixed #11158 - get_image_dimensions very slow/incorrect after 1 call

Thanks to kua for the report, and to kua, SmileyChris and SAn for the patch



git-svn-id: http://code.djangoproject.com/svn/django/trunk@13715 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/files/images.py

@@ -23,23 +23,26 @@ class ImageFile(File):
         if not hasattr(self, '_dimensions_cache'):
             close = self.closed
             self.open()
-            self._dimensions_cache = get_image_dimensions(self)
-            if close:
-                self.close()
+            self._dimensions_cache = get_image_dimensions(self, close=close)
         return self._dimensions_cache
 
-def get_image_dimensions(file_or_path):
-    """Returns the (width, height) of an image, given an open file or a path."""
+def get_image_dimensions(file_or_path, close=False):
+    """
+    Returns the (width, height) of an image, given an open file or a path.  Set
+    'close' to True to close the file at the end if it is initially in an open
+    state.
+    """
     # Try to import PIL in either of the two ways it can end up installed.
     try:
         from PIL import ImageFile as PILImageFile
     except ImportError:
         import ImageFile as PILImageFile
-        
+
     p = PILImageFile.Parser()
-    close = False
     if hasattr(file_or_path, 'read'):
         file = file_or_path
+        file_pos = file.tell()
+        file.seek(0)
     else:
         file = open(file_or_path, 'rb')
         close = True
@@ -55,3 +58,5 @@ def get_image_dimensions(file_or_path):
     finally:
         if close:
             file.close()
+        else:
+            file.seek(file_pos)