y2038: linux: Provide __ntp_gettime64 implementation

This patch provides new __ntp_gettime64 explicit 64 bit function for getting
time parameters via NTP interface.

Internally, the __clock_adjtime64 syscall is used instead of __adjtimex. This
patch is necessary for having architectures with __WORDSIZE == 32 Y2038 safe.

Moreover, a 32 bit version - __ntp_gettime has been refactored to internally
use __ntp_gettime64.

The __ntp_gettime is now supposed to be used on systems still supporting 32
bit time (__TIMESIZE != 64) - hence the necessary conversions between struct
ntptimeval and 64 bit struct __ntptimeval64.

Build tests:
./src/scripts/build-many-glibcs.py glibcs

Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
  https://github.com/lmajewski/meta-y2038 and run tests:
  https://github.com/lmajewski/y2038-tests/commits/master

Above tests were performed with Y2038 redirection applied as well as without to
test the proper usage of both __ntp_gettime64 and __ntp_gettime.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

2 files changed, 27 insertions, 3 deletions

diff --git a/sysdeps/unix/sysv/linux/include/sys/timex.h b/sysdeps/unix/sysv/linux/include/sys/timex.h
index e762e03230..ef53515803 100644
--- a/sysdeps/unix/sysv/linux/include/sys/timex.h
+++ b/sysdeps/unix/sysv/linux/include/sys/timex.h
@@ -33,6 +33,7 @@ libc_hidden_proto (__adjtimex)
 #   define __clock_adjtime64 __clock_adjtime
 #   define ___adjtimex64 ___adjtimex
 #   define __ntptimeval64 ntptimeval
+#   define __ntp_gettime64 __ntp_gettime
 #  else
 
 struct __timex64
@@ -91,6 +92,9 @@ struct __ntptimeval64
   long int __glibc_reserved3;
   long int __glibc_reserved4;
 };
+extern int __ntp_gettime64 (struct __ntptimeval64 *ntv);
+libc_hidden_proto (__ntp_gettime64)
+
 #  endif
 
 /* Convert a known valid struct timex into a struct __timex64.  */
diff --git a/sysdeps/unix/sysv/linux/ntp_gettime.c b/sysdeps/unix/sysv/linux/ntp_gettime.c
index c8d6a197dc..8ce5d13e00 100644
--- a/sysdeps/unix/sysv/linux/ntp_gettime.c
+++ b/sysdeps/unix/sysv/linux/ntp_gettime.c
@@ -17,6 +17,7 @@
 
 #define ntp_gettime ntp_gettime_redirect
 
+#include <time.h>
 #include <sys/timex.h>
 
 #undef ntp_gettime
@@ -25,17 +26,36 @@
 # define modes mode
 #endif
 
+/* clock_adjtime64 with CLOCK_REALTIME does not trigger EINVAL,
+   ENODEV, or EOPNOTSUPP.  It might still trigger EPERM.  */
 
 int
-ntp_gettime (struct ntptimeval *ntv)
+__ntp_gettime64 (struct __ntptimeval64 *ntv)
 {
-  struct timex tntx;
+  struct __timex64 tntx;
   int result;
 
   tntx.modes = 0;
-  result = __adjtimex (&tntx);
+  result = __clock_adjtime64 (CLOCK_REALTIME, &tntx);
   ntv->time = tntx.time;
   ntv->maxerror = tntx.maxerror;
   ntv->esterror = tntx.esterror;
   return result;
 }
+
+#if __TIMESIZE != 64
+libc_hidden_def (__ntp_gettime64)
+
+int
+__ntp_gettime (struct ntptimeval *ntv)
+{
+  struct __ntptimeval64 ntv64;
+  int result;
+
+  result = __ntp_gettime64 (&ntv64);
+  *ntv = valid_ntptimeval64_to_ntptimeval (ntv64);
+
+  return result;
+}
+#endif
+strong_alias (__ntp_gettime, ntp_gettime)