Date: Sat, 5 Sep 1998 11:16:49 -0700 (PDT) From: Matthew Dillon <dillon@backplane.com> To: Doug Rabson <dfr@nlsystems.com> Cc: "Andrey A. Chernov" <ache@nagual.pp.ru>, John Birrell <jb@FreeBSD.ORG>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/lib/libc/gen sleep.c Message-ID: <199809051816.LAA22705@apollo.backplane.com> References: <Pine.BSF.4.01.9809051454130.360-100000@herring.nlsystems.com>
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The sleep code is totally broken in regards to its comparisons. The
argument is an unsigned int, but values are stored in time_t which is
currently a signed long. The code, as it stands, is not clean if either
time_t changes from signed to unsigned, or if time_t changes from a 32 bit
value to a 64 bit value. Since there is no harm in doing multiple
sleeps, why not just fix the code? We no tv_sec must be at least large
enough to hold INT_MAX, so:
unsigned int
sleep(seconds)
unsigned int seconds;
{
while (seconds != 0) {
struct timespec time_to_sleep;
struct timespec time_remaining;
time_to_sleep.tv_sec = (seconds > INT_MAX) ? INT_MAX : seconds;
time_to_sleep.tv_nsec = 0;
if (nanosleep(&time_to_sleep, &time_remaining) == -1) {
/*
* time_remaining only valid if EINTR, else assume no
* time elapsed.
*/
if (errno == EINTR)
seconds -= time_to_sleep.tv_sec - time_remaining.tv_sec;
if (time_remaining.tv_nsec)
++seconds;
break;
}
seconds -= time_to_sleep.tv_sec;
}
return(seconds);
}
-Matt
Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet
Communications & God knows what else.
<dillon@backplane.com> (Please include original email in any response)
:> > Modified files:
:> > lib/libc/gen sleep.c
:> > Log:
:> > Use INT_MAX instead of LONG_MAX since the variable being compared
:> > is an int, not a long.
:>
:>
:> Please back it out, the test covers the case when
:> sizeof(unsigned) == sizeof(long) and prevents to overflow signed long with
:> unsigned value.
:
:Something needs to change here. LONG_MAX is too big to compare against an
:int and generates a warning on the alpha. Maybe compare against UINT_MAX?
:
:--
:Doug Rabson Mail: dfr@nlsystems.com
:Nonlinear Systems Ltd. Phone: +44 181 951 1891
Fax: +44 181 381 1039
: Fax: +44 181 381 1039
:
:
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