system/freebsd-src
system/freebsd-src
1
0
Fork 0
mirror of https://github.com/freebsd/freebsd-src synced 2024-07-22 10:48:02 +00:00
Code Issues Actions 2 Packages Projects Releases Wiki Activity

fattime: fix fattime to timespec conversion of dates beyond 2106-02-06

Browse source 
It turns out that the only conversion issue was in fattime2timespec, where
multiplying the number of seconds in a day by the number of days overflowed
32-bit unsigned int for dates beyond 2106-02-07 06:28:15.

Casting one of the multiplicands as time_t forces a 64-bit multiplication on
systems where time_t is 64-bits and produces no binary changes on the one
remaining system with 32-bit time_t (namely i386).

Since the code is now tested & fixed, this change removes the fixme comments.

Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D44755
This commit is contained in:
Josef 'Jeff' Sipek 2024-04-29 09:40:31 -04:00 committed by Toomas Soome
parent 9d1396c346
commit 0fe60dc655
1 changed files with 3 additions and 14 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

17
sys/kern/subr_fattime.c
View file

@ -63,11 +63,6 @@
* FAT timestamps have 7 bits for the year and starts at 1980, so
* they can represent up to 2107 which means that the non-leap-year
* 2100 must be handled.
*
* XXX: As long as time_t is 32 bits this is not relevant or easily
* XXX: testable. Revisit when time_t grows bigger.
* XXX: grepfodder: 64 bit time_t, y2100, y2.1k, 2100, leap year
*
*/
#include <sys/param.h>
@ -165,10 +160,7 @@ timespec2fattime(const struct timespec *tsp, int utc, uint16_t *ddp,
} else {
t2 -= T1980;
/*
* 2100 is not a leap year.
* XXX: a 32 bit time_t can not get us here.
*/
/* 2100 is not a leap year */
if (t2 >= ((2100 - 1980) / 4 * LYC + FEB))
t2++;
@ -242,17 +234,14 @@ fattime2timespec(unsigned dd, unsigned dt, unsigned dh, int utc,
/* Month offset from leap-year cycle */
day += daytab[(dd >> 5) & 0x3f];
/*
* 2100 is not a leap year.
* XXX: a 32 bit time_t can not get us here.
*/
/* 2100 is not a leap year */
if (day >= ((2100 - 1980) / 4 * LYC + FEB))
day--;
/* Align with time_t epoch */
day += T1980;
tsp->tv_sec += DAY * day;
tsp->tv_sec += (time_t) DAY * day;
if (!utc)
tsp->tv_sec += utc_offset();
}