Fix empty files being considered valid WARCs

warc-tiny

@@ -130,6 +130,7 @@ class EndOfRecord(Event):
 class WARCParsingIssue(enum.Enum):
 	TRUNCATED_FILE = enum.auto()
 	MALFORMED_HTTP_RECORD = enum.auto()
+	EMPTY_FILE = enum.auto()
 
 
 class WARCParsingIssueEvent(Event):
@@ -157,6 +158,7 @@ def iter_warc(f):
 
 	with open_warc(f) as fp:
 		buf = b''
+		isEmpty = True
 		while True:
 			# Read WARC header
 			while b'\r\n\r\n' not in buf:
@@ -168,7 +170,11 @@ def iter_warc(f):
 					break
 				buf += d
 			if not buf:
+				if isEmpty:
+					print('Error: empty file', file = sys.stderr)
+					yield WARCParsingIssueEvent(WARCParsingIssue.EMPTY_FILE)
 				break
+			isEmpty = False
 			assert b'\r\n\r\n' in buf
 			warcHeaderBuf, buf = buf.split(b'\r\n\r\n', 1)
 			assert warcHeaderBuf.startswith(b'WARC/1.0\r\n') or warcHeaderBuf.startswith(b'WARC/1.1\r\n')