--- a/bin/ix.py	Fri Apr 16 18:28:00 2021 +0000
+++ b/bin/ix.py	Sun Apr 18 17:03:45 2021 +0000
@@ -17,52 +17,70 @@
     FOO=argparse.RawDescriptionHelpFormatter.format_help(self)
     return HACK_USAGE.sub('\n             [ ( -x | length offset filename ) ]',
                           FOO)
-  
-parser = argparse.ArgumentParser(
-  description='''Extract records from warc files given length, offset and file triples.
-Input one triple on command line, or
-triples from stdin as tab-delimited lines
-or complete cdx index lines.''',
-  epilog='''Note that if no output flag(s) is/are given,
-the whole WARC record will be output, more efficiently than
-would be the case if all three flags were given.''',
-  add_help=False,
-  conflict_handler='resolve',
-  formatter_class=HackFormat
-  )
-  
-parser.add_argument('--help',help='Show help',action='help')
-parser.add_argument('-d','--debug',help='Debug output',action='store_true')
-parser.add_argument('-w','--warc',help='output WARC headers',
-                    action='store_true')
-parser.add_argument('-h','--headers',help='output HTTP headers',
-                    action='store_true')
-parser.add_argument('-b','--body',help='output HTTP body',
-                    action='store_true')
-parser.add_argument('-c','--cmd',help='pipes each result thru CMD')
-sg=parser.add_mutually_exclusive_group()
-sg.add_argument('-x','--index',
-                    help='take lines of triples from a cdx index file as input',
-                    action='store_true')
-sg.add_argument('length',type=int,
-                help='length in bytes of gzipped record',
-                nargs='?')
-parser.add_argument('offset',type=int,
-                    help='start position in bytes of gzipped record',
-                    nargs='?')
-parser.add_argument('filename',
-                    help='name of gzipped Common Crawl WARC-format file',
-                    nargs='?',
-                    type=argparse.FileType('rb',0))
-# Hack the order of optional and positional in the help output
-parser._action_groups.sort(key=lambda g:g.title)
-#parser.print_help()
-pa=parser.parse_args(sys.argv[1:])
-# We have to enforce our own check..
-print(pa,file=sys.stderr)
-if pa.length is not None and (
-  pa.offset is None or pa.filename is None):
-  parser.error("length, offset and filename must all be supplied together")
-  
-buf=bytearray(1024*1024)
+
+def process(options,buf,file,offset,length):
+  whole=not (options.warc or options.headers or options.body)
+  if whole:
+    file.seek(offset)
+    bv=memoryview(buf)[:length]
+    nb=file.readinto(bv)
+    if nb!=length:
+      print("losing",file.name,name,length,nb,file=sys.stderr)
+      exit(1)
+    sys.stdout.buffer.write(bv)
+
+def main():
+  parser = argparse.ArgumentParser(
+    description='''Extract records from warc files given length, offset and file triples.
+  Input one triple on command line, or
+  triples from stdin as tab-delimited lines
+  or complete cdx index lines.''',
+    epilog='''Note that if no output flag(s) is/are given,
+  the whole WARC record will be output, more efficiently than
+  would be the case if all three flags were given.''',
+    add_help=False,
+    conflict_handler='resolve',
+    formatter_class=HackFormat
+    )
 
+  parser.add_argument('--help',help='Show help',action='help')
+  parser.add_argument('-d','--debug',help='Debug output',action='store_true')
+  parser.add_argument('-w','--warc',help='output WARC headers',
+                      action='store_true')
+  parser.add_argument('-h','--headers',help='output HTTP headers',
+                      action='store_true')
+  parser.add_argument('-b','--body',help='output HTTP body',
+                      action='store_true')
+  parser.add_argument('-c','--cmd',help='pipes each result thru CMD')
+  sg=parser.add_mutually_exclusive_group()
+  sg.add_argument('-x','--index',
+                      help='take lines of triples from a cdx index file as input',
+                      action='store_true')
+  sg.add_argument('length',type=int,
+                  help='length in bytes of gzipped record',
+                  nargs='?')
+  parser.add_argument('offset',type=int,
+                      help='start position in bytes of gzipped record',
+                      nargs='?')
+  parser.add_argument('filename',
+                      help='name of gzipped Common Crawl WARC-format file',
+                      nargs='?',
+                      type=argparse.FileType('rb',0))
+  # Hack the order of optional and positional in the help output
+  parser._action_groups.sort(key=lambda g:g.title)
+  #parser.print_help()
+  pa=parser.parse_args(sys.argv[1:])
+  print(pa,file=sys.stderr)
+  if pa.length is not None:
+    # We have to enforce our own check..
+    if pa.offset is None or pa.filename is None:
+      parser.error("length, offset and filename must all be supplied together")
+ 
+  buf=bytearray(1024*1024)
+
+  if pa.length is not None:
+    process(pa,buf,pa.filename,pa.offset,pa.length)
+    exit(0)
+
+if __name__ == "__main__":
+    main()