Anders Kaseorg
e52d22b6da
A Darwin PPC 32-bit user observes huge values numer == 1000000000 and denom == 18431683 returned from mach_timebase_info(). For these values, mach_absolute_time() * numer overflows uint64_t every 1000.82 seconds, and 1000000 * denom always overflows uint32_t, with the effect of making time run backwards at -11190660 times its usual speed. This bug was masked on Darwin x86 64-bit, where numer == denom == 1. Fix it by doing the conversion with double arithmetic instead. Closes #479. Signed-off-by: Anders Kaseorg <andersk@mit.edu>
102 lines
3.0 KiB
C++
102 lines
3.0 KiB
C++
/*
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Mosh: the mobile shell
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Copyright 2012 Keith Winstein
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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In addition, as a special exception, the copyright holders give
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permission to link the code of portions of this program with the
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OpenSSL library under certain conditions as described in each
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individual source file, and distribute linked combinations including
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the two.
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You must obey the GNU General Public License in all respects for all
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of the code used other than OpenSSL. If you modify file(s) with this
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exception, you may extend this exception to your version of the
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file(s), but you are not obligated to do so. If you do not wish to do
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so, delete this exception statement from your version. If you delete
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this exception statement from all source files in the program, then
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also delete it here.
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*/
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#include "config.h"
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#include "timestamp.h"
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#include <errno.h>
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#if HAVE_CLOCK_GETTIME
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#include <time.h>
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#elif HAVE_MACH_ABSOLUTE_TIME
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#include <mach/mach_time.h>
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#elif HAVE_GETTIMEOFDAY
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#include <sys/time.h>
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#include <stdio.h>
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#endif
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static uint64_t millis_cache = -1;
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uint64_t frozen_timestamp( void )
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{
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if ( millis_cache == uint64_t( -1 ) ) {
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freeze_timestamp();
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}
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return millis_cache;
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}
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void freeze_timestamp( void )
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{
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#if HAVE_CLOCK_GETTIME
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struct timespec tp;
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if ( clock_gettime( CLOCK_MONOTONIC, &tp ) < 0 ) {
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/* did not succeed */
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} else {
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uint64_t millis = tp.tv_nsec / 1000000;
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millis += uint64_t( tp.tv_sec ) * 1000;
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millis_cache = millis;
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return;
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}
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#elif HAVE_MACH_ABSOLUTE_TIME
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static mach_timebase_info_data_t s_timebase_info;
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static double absolute_to_millis;
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if (s_timebase_info.denom == 0) {
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mach_timebase_info(&s_timebase_info);
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absolute_to_millis = 1e-6 * s_timebase_info.numer / s_timebase_info.denom;
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}
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// NB: mach_absolute_time() returns "absolute time units"
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// We need to apply a conversion to get milliseconds.
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millis_cache = mach_absolute_time() * absolute_to_millis;
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return;
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#elif HAVE_GETTIMEOFDAY
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// NOTE: If time steps backwards, timeouts may be confused.
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struct timeval tv;
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if ( gettimeofday(&tv, NULL) ) {
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perror( "gettimeofday" );
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} else {
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uint64_t millis = tv.tv_usec / 1000;
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millis += uint64_t( tv.tv_sec ) * 1000;
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millis_cache = millis;
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return;
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}
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#else
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# error "Don't know how to get a timestamp on this platform"
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#endif
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}
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