fix: Extension upper casing

Author: tmathern

src/c2pa/c2pa.py

@@ -1258,7 +1258,8 @@ class Reader:
         'stream_error': "Error cleaning up stream: {}",
         'file_error': "Error cleaning up file: {}",
         'reader_cleanup_error': "Error cleaning up reader: {}",
-        'encoding_error': "Invalid UTF-8 characters in input: {}"
+        'encoding_error': "Invalid UTF-8 characters in input: {}",
+        'closed_error': "Reader is closed"
     }
 
     @classmethod
@@ -1411,7 +1412,7 @@ def __init__(self,
             # If stream is a string, treat it as a path and try to open it
 
             # format_or_path is a format
-            if format_or_path not in Reader.get_supported_mime_types():
+            if format_or_path.lower() not in Reader.get_supported_mime_types():
                 raise C2paError.NotSupported(
                     f"Reader does not support {format_or_path}")
 
@@ -1468,7 +1469,7 @@ def __init__(self,
         else:
             # format_or_path is a format string
             format_str = str(format_or_path)
-            if format_str not in Reader.get_supported_mime_types():
+            if format_str.lower() not in Reader.get_supported_mime_types():
                 raise C2paError.NotSupported(
                     f"Reader does not support {format_str}")
 
@@ -1528,8 +1529,10 @@ def _ensure_valid_state(self):
         Raises:
             C2paError: If the reader is closed or invalid
         """
-        if self._closed or not self._reader:
-            raise C2paError("Reader is closed")
+        if self._closed:
+            raise C2paError(Reader._ERROR_MESSAGES['closed_error'])
+        if not self._reader:
+            raise C2paError(Reader._ERROR_MESSAGES['closed_error'])
 
     def _cleanup_resources(self):
         """Internal cleanup method that releases native resources.
@@ -2391,7 +2394,7 @@ def _sign_internal(
         if not signer or not hasattr(signer, '_signer') or not signer._signer:
             raise C2paError("Invalid or closed signer")
 
-        if format not in Builder.get_supported_mime_types():
+        if format.lower() not in Builder.get_supported_mime_types():
             raise C2paError.NotSupported(
                 f"Builder does not support {format}")
 

tests/test_unit_tests.py

@@ -150,6 +150,15 @@ def test_read_dng_from_stream(self):
             # Just run and verify there is no crash
             json.loads(reader.json())
 
+    def test_read_dng_upper_case_from_stream(self):
+        test_path = os.path.join(self.data_dir, "C.dng")
+        with open(test_path, "rb") as file:
+            file_content = file.read()
+
+        with Reader("DNG", io.BytesIO(file_content)) as reader:
+            # Just run and verify there is no crash
+            json.loads(reader.json())
+
     def test_read_dng_file_from_path(self):
         test_path = os.path.join(self.data_dir, "C.dng")