hide decompressionbomb warnings, issue them as info to log

sigal/image.py

@@ -70,8 +70,11 @@ def generate_image(source, outname, settings, options=None):
         utils.copy(source, outname, symlink=settings['orig_link'])
         return
 
-    img = PILImage.open(source)
-    original_format = img.format
+    with warnings.catch_warnings(record = True) as caught_warnings:
+        img = PILImage.open(source)
+        original_format = img.format
+
+    _handle_caught_warnings(caught_warnings, source)
 
     if settings['copy_exif_data'] and settings['autorotate_images']:
         logger.warning("The 'autorotate_images' and 'copy_exif_data' settings "
@@ -120,8 +123,11 @@ def generate_thumbnail(source, outname, box, delay, fit=True, options=None):
     """Create a thumbnail image."""
 
     logger = logging.getLogger(__name__)
-    img = PILImage.open(source)
-    original_format = img.format
+    with warnings.catch_warnings(record = True) as caught_warnings:
+        img = PILImage.open(source)
+        original_format = img.format
+
+    _handle_caught_warnings(caught_warnings, source)
 
     if fit:
         img = ImageOps.fit(img, box, PILImage.ANTIALIAS)
@@ -170,7 +176,11 @@ def process_image(filepath, outpath, settings):
 def get_size(file_path):
     """Return image size (width and height)."""
     try:
-        im = PILImage.open(file_path)
+        with warnings.catch_warnings(record = True) as caught_warnings:
+            im = PILImage.open(file_path)
+
+        _handle_caught_warnings(caught_warnings, file_path)
+
     except (IOError, IndexError, TypeError, AttributeError) as e:
         logger = logging.getLogger(__name__)
         logger.error("Could not read size of %s due to %r", file_path, e)
@@ -191,7 +201,11 @@ def get_exif_data(filename):
         warnings.warn('Pillow 3.0.0 is broken with EXIF data, consider using '
                       'another version if you want to use EXIF data.')
 
-    img = PILImage.open(filename)
+    with warnings.catch_warnings(record = True) as caught_warnings:
+        img = PILImage.open(filename)
+
+    _handle_caught_warnings(caught_warnings, filename)
+
     try:
         exif = img._getexif() or {}
     except ZeroDivisionError:
@@ -312,3 +326,14 @@ def get_exif_tags(data):
                 }
 
     return simple
+
+
+def _handle_caught_warnings(caught_warnings, filename):
+    logger = logging.getLogger(__name__)
+    for warning in caught_warnings:
+        if warning.category == PILImage.DecompressionBombWarning:
+            logger.info('PILImage reported a possible DecompressionBomb'
+                         ' for file {}'.format(filename))
+        else:
+            warnings.showwarning(warning.message, warning.category,
+                                 warning.filename, warning.lineno)