Move header length check into cython-code

src/eventio/base.py

@@ -161,7 +161,7 @@ def check_size_or_raise(data, expected_length, zero_ok=True):
         else:
             raise EOFError('File seems to be truncated')
 
-    if length < expected_length:
+    elif length < expected_length:
         raise EOFError('File seems to be truncated')
 
 
@@ -186,12 +186,6 @@ def read_header(byte_stream, offset, toplevel=False):
     '''
 
     header_bytes = byte_stream.read(constants.OBJECT_HEADER_SIZE)
-    check_size_or_raise(
-        header_bytes,
-        constants.OBJECT_HEADER_SIZE,
-        zero_ok=False,
-    )
-
     header = parse_header_bytes(header_bytes, toplevel=toplevel)
 
     if header.extended:

src/eventio/header.pyx

@@ -122,6 +122,11 @@ cpdef ObjectHeader parse_header_bytes(const uint8_t[:] header_bytes, bint toplev
     cdef bint only_subobjects
     cdef uint64_t length
 
+    if len(header_bytes) != OBJECT_HEADER_SIZE:
+        # for backwards compatibility, we raise the same error as before.
+        # more appropriate for this free function would be something like
+        # raise ValueError("header_bytes size must be 12")
+        raise EOFError('File seems to be truncated')
 
     type_int = unpack_uint32(header_bytes[0:4])
     type_, version, user, extended = parse_type_field(type_int)