timespec: fill in other members

This problem was found when compiling GNU Emacs with
--enable-gcc-warnings on a platform where tv_sec is 64 bits and
tv_nsec is 32 bits, and struct timespec has padding.  GCC
-Wuse-of-uninitialized-value complained when a struct timespec
initialized only via assigning to tv_sec and tv_nsec was copied
via assignment (this was in lib/timespec.h’s make_timespec).
Although behavior is well-defined on this platform, the warning is
annoying and the behavior might not be well-defined on theoretical
platforms where struct timespec has other members.  To work around
this, initialize all the struct’s members.
* lib/getsockopt.c (rpl_getsockopt):
* lib/gettime.c (gettime):
* lib/gettimeofday.c (gettimeofday):
* lib/glthread/thread.c (gl_thread_self):
* lib/nanosleep.c (nanosleep):
* lib/parse-datetime.y (digits_to_date_time, set_hhmmss)
(signed_seconds, unsigned_seconds, yylex, parse_datetime_body):
* lib/poll.c (poll):
* lib/pselect.c (pselect):
* lib/pthread-cond.c (endlessly, pthread_cond_timedwait):
* lib/pthread-rwlock.c (pthread_rwlock_timedrdlock)
(pthread_rwlock_timedwrlock):
* lib/pthread_mutex_timedlock.c (pthread_mutex_timedlock):
* lib/select.c (rpl_select):
* lib/settime.c (settime):
* lib/stat-time.h (get_stat_atime, get_stat_ctime)
(get_stat_mtime, get_stat_birthtime):
* lib/thrd.c (rpl_thrd_current):
* lib/timespec.h (make_timespec):
* lib/timespec_getres.c (timespec_getres):
* lib/utimecmp.c (utimecmpat):
* lib/utimens.c (fdutimens):
When filling in a struct timespec or similar time-related structure
that might be copied elsewhere, also assign to any storage other
than tv_sec and tv_nsec, to avoid undefined behavior on (likely
theoretical) platforms where struct timespec has other members,
and also to avoid warnings from GCC and/or valgrind.

1 files changed, 6 insertions, 5 deletions

diff --git a/lib/utimecmp.c b/lib/utimecmp.c
index b1e5e2ba32..639f99d132 100644
--- a/lib/utimecmp.c
+++ b/lib/utimecmp.c
@@ -319,7 +319,6 @@ utimecmpat (int dfd, char const *dst_name,
 
           if (SYSCALL_RESOLUTION < res)
             {
-              struct timespec timespec[2];
               struct stat dst_status;
 
               /* Ignore source timestamp information that must necessarily
@@ -344,10 +343,12 @@ utimecmpat (int dfd, char const *dst_name,
                  destination to the existing access time, except with
                  trailing nonzero digits.  */
 
-              timespec[0].tv_sec = dst_a_s;
-              timespec[0].tv_nsec = dst_a_ns;
-              timespec[1].tv_sec = dst_m_s | (res == 2 * BILLION);
-              timespec[1].tv_nsec = dst_m_ns + res / 9;
+              struct timespec timespec[2] = {
+                [0].tv_sec = dst_a_s,
+                [0].tv_nsec = dst_a_ns,
+                [1].tv_sec = dst_m_s | (res == 2 * BILLION),
+                [1].tv_nsec = dst_m_ns + res / 9
+              };
 
               if (utimensat (dfd, dst_name, timespec, AT_SYMLINK_NOFOLLOW))
                 return -2;