Record.check_field: sig_name strings may contain whitespace.

It is permitted and not unheard of for signal name strings to contain
space characters.  This should be allowed, provided that the string
does not start or end with a space.  All control characters should be
disallowed.

Author: Benjamin Moody

wfdb/io/record.py

@@ -520,9 +520,15 @@ def check_field(self, field, required_channels="all"):
                             "block_size values must be non-negative integers"
                         )
                 elif field == "sig_name":
-                    if re.search(r"\s", item[ch]):
+                    if item[ch][:1].isspace() or item[ch][-1:].isspace():
+                        raise ValueError(
+                            "sig_name strings may not begin or end with "
+                            "whitespace."
+                        )
+                    if re.search(r"[\x00-\x1f\x7f-\x9f]", item[ch]):
                         raise ValueError(
-                            "sig_name strings may not contain whitespaces."
+                            "sig_name strings may not contain "
+                            "control characters."
                         )
                     if len(set(item)) != len(item):
                         raise ValueError("sig_name strings must be unique.")