diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/lib/krb5/os/c_ustime.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/src/lib/krb5/os/c_ustime.c b/src/lib/krb5/os/c_ustime.c index 3dabe801bb..d374b13478 100644 --- a/src/lib/krb5/os/c_ustime.c +++ b/src/lib/krb5/os/c_ustime.c @@ -83,6 +83,11 @@ krb5_crypto_us_timeofday(krb5_int32 *seconds, krb5_int32 *microseconds) if (err) return err; + /* It would probably be more efficient to remove this mutex and use + thread-local storage for last_time. But that could result in + different threads getting the same value for time, which may be + a technical violation of spec. */ + err = k5_mutex_lock(&krb5int_us_time_mutex); if (err) return err; @@ -94,16 +99,24 @@ krb5_crypto_us_timeofday(krb5_int32 *seconds, krb5_int32 *microseconds) On Windows, where we get millisecond accuracy currently, that's quite likely. On UNIX, it appears that we always get new microsecond values, so this case should never trigger. */ - if ((now.sec == last_time.sec) && (now.usec <= last_time.usec)) { - /* Same as last time??? */ + + /* Check for case where previously usec rollover caused bump in sec, + putting now.sec in the past. But don't just use '<' because we + need to properly handle the case where the administrator intentionally + adjusted time backwards. */ + if ((now.sec == last_time.sec-1) || + ((now.sec == last_time.sec) && (now.usec <= last_time.usec))) { + /* Correct 'now' to be exactly one microsecond later than 'last_time'. + Note that _because_ we perform this hack, 'now' may be _earlier_ + than 'last_time', even though the system time is monotonically + increasing. */ + + now.sec = last_time.sec; now.usec = ++last_time.usec; if (now.usec >= 1000000) { ++now.sec; now.usec = 0; } - /* For now, we're not worrying about the case of enough - returns of the same value that we roll over now.sec, and - the next call still gets the previous now.sec value. */ } last_time.sec = now.sec; /* Remember for next time */ last_time.usec = now.usec; |