Prevent nanosleep from potentially overwriting sleep time

suggested by Rene Zatvo

diff --git a/lib/posix/_nanosleep.c b/lib/posix/_nanosleep.c
index d926f50566612fdd35ee7da2581cef2d2d5935bb..18319e67da3f8ae5da987b171c2d70a80f62808c 100644 (file)
--- a/lib/posix/_nanosleep.c
+++ b/lib/posix/_nanosleep.c
@@ -22,6 +22,7 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
 {
        struct timeval timeout, timestart = { 0, 0 }, timeend;
        int errno_select, r;
+       struct timespec rqt;
 
        /* check parameters */
        if (!rqtp)
@@ -32,6 +33,9 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
                rqtp->tv_nsec >= NSEC_PER_SEC)
                return EINVAL;
 
+       /* store *rqtp to make sure it is not overwritten */
+       rqt = *rqtp;
+       
        /* keep track of start time if needed */
        if (rmtp)
        {
@@ -42,8 +46,8 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
        }
 
        /* use select to wait */
-       timeout.tv_sec = rqtp->tv_sec;
-       timeout.tv_usec = (rqtp->tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC;
+       timeout.tv_sec = rqt.tv_sec;
+       timeout.tv_usec = (rqt.tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC;
        r = select(0, NULL, NULL, NULL, &timeout);
 
        /* return remaining time only if requested */
@@ -59,8 +63,8 @@ int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
        errno = errno_select;
 
        /* compute remaining time */
-       rmtp->tv_sec = rqtp->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_sec = rqt.tv_sec - (timeend.tv_sec - timestart.tv_sec);
+       rmtp->tv_nsec = rqt.tv_nsec - (timeend.tv_usec - timestart.tv_usec) * NSEC_PER_USEC;
 
        /* bring remaining time into canonical form */
        while (rmtp->tv_nsec < 0)