Commit d6b37d83 authored by Daniel Stenberg's avatar Daniel Stenberg
Browse files

curlx_tvdiff: handle 32bit time_t overflows 

On 32bit systems, make sure we don't overflow and return funky values
for very large time differences.

Reported-by: Anders Bakken

Closes #646
parent d202fbcc

lib/timeval.c

+10 −2
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 
 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.

 * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms
@@ -113,10 +113,18 @@ struct timeval curlx_tvnow(void) 
 * Make sure that the first argument is the more recent time, as otherwise

 * we'll get a weird negative time-diff back...

 *

 * Returns: the time difference in number of milliseconds.

 * Returns: the time difference in number of milliseconds. For large diffs it

 * returns 0x7fffffff on 32bit time_t systems.

 */

long curlx_tvdiff(struct timeval newer, struct timeval older)

{

#if SIZEOF_TIME_T < 8

  /* for 32bit time_t systems, add a precaution to avoid overflow for really

     big time differences */

  time_t diff = newer.tv_sec-older.tv_sec;

  if(diff >= (0x7fffffff/1000))

    return 0x7fffffff;

#endif

  return (newer.tv_sec-older.tv_sec)*1000+

    (long)(newer.tv_usec-older.tv_usec)/1000;

}