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Prevent nanosleep from potentially overwriting sleep time

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suggested by Rene Zatvo
This commit is contained in:
Erik van der Kouwe 2010-01-07 19:25:18 +00:00
parent aac4b7923f
commit acc3c30855
1 changed files with 8 additions and 4 deletions
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12
lib/posix/_nanosleep.c
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@ -22,6 +22,7 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
{ {
struct timeval timeout, timestart = { 0, 0 }, timeend; struct timeval timeout, timestart = { 0, 0 }, timeend;
int errno_select, r; int errno_select, r;
struct timespec rqt;
/* check parameters */ /* check parameters */
if (!rqtp) if (!rqtp)
@ -32,6 +33,9 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
rqtp->tv_nsec >= NSEC_PER_SEC) rqtp->tv_nsec >= NSEC_PER_SEC)
return EINVAL; return EINVAL;
/* store *rqtp to make sure it is not overwritten */
rqt = *rqtp;
/* keep track of start time if needed */ /* keep track of start time if needed */
if (rmtp) if (rmtp)
{ {
@ -42,8 +46,8 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
} }
/* use select to wait */ /* use select to wait */
timeout.tv_sec = rqtp->tv_sec; timeout.tv_sec = rqt.tv_sec;
timeout.tv_usec = (rqtp->tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC; timeout.tv_usec = (rqt.tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC;
r = select(0, NULL, NULL, NULL, &timeout); r = select(0, NULL, NULL, NULL, &timeout);
/* return remaining time only if requested */ /* return remaining time only if requested */
@ -59,8 +63,8 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
errno = errno_select; errno = errno_select;
/* compute remaining time */ /* compute remaining time */
rmtp->tv_sec = rqtp->tv_sec - (timeend.tv_sec - timestart.tv_sec); rmtp->tv_sec = rqt.tv_sec - (timeend.tv_sec - timestart.tv_sec);
rmtp->tv_nsec = rqtp->tv_nsec - (timeend.tv_usec - timestart.tv_usec) * NSEC_PER_USEC; rmtp->tv_nsec = rqt.tv_nsec - (timeend.tv_usec - timestart.tv_usec) * NSEC_PER_USEC;
/* bring remaining time into canonical form */ /* bring remaining time into canonical form */
while (rmtp->tv_nsec < 0) while (rmtp->tv_nsec < 0)