[PATCH v2] y2038: linux: Provide __timespec_get64 implementation

[Lukasz Majewski <lukma at denx dot de>]

This patch provides new instance of Linux specific timespec_get.c file placed
in ./sysdeps/unix/sysv/linux/.

When compared to this file version from ./time directory, it provides
__timespec_get64 explicit 64 bit function for getting 64 bit time in the
struct __timespec64 (for compilation using C11 standard).
Moreover, a 32 bit version - __timespec_get internally uses
__timespec_get64.

The __timespec_get is now supposed to be used on systems still supporting 32
bit time (__TIMESIZE != 64) - hence the necessary conversion to 32 bit struct
timespec.

Internally the timespec_get uses __clock_gettime64. This patch is necessary
for having architectures with __WORDSIZE == 32 Y2038 safe.

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 proper usage of both __timespec_get64 and __timespec_get.

---
Changes for v2:

- The conversion to support 64 bit time for timespec_get() has been moved
  from ./time/timespec_get.c to sysdeps/unix/sysv/linux/timespec_get.c
  (as suggested by Adhemerval) to avoid the need to create __clock_gettime64()
  method for HURD (as 64 bit time support for machines with __WORDSIZE=32
  and __TIMESIZE=32 is now developed solely for Linux).
---
 include/time.h                         |  3 ++
 sysdeps/unix/sysv/linux/timespec_get.c | 59 ++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/timespec_get.c

diff --git a/include/time.h b/include/time.h
index 558923274a..047f431a1a 100644
--- a/include/time.h
+++ b/include/time.h
@@ -254,6 +254,7 @@ extern double __difftime (time_t time1, time_t time0);
 #if __TIMESIZE == 64
 # define __clock_nanosleep_time64 __clock_nanosleep
 # define __clock_gettime64 __clock_gettime
+# define __timespec_get64 __timespec_get
 #else
 extern int __clock_nanosleep_time64 (clockid_t clock_id,
                                      int flags, const struct __timespec64 *req,
@@ -261,6 +262,8 @@ extern int __clock_nanosleep_time64 (clockid_t clock_id,
 libc_hidden_proto (__clock_nanosleep_time64)
 extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
 libc_hidden_proto (__clock_gettime64)
+extern int __timespec_get64 (struct __timespec64 *ts, int base);
+libc_hidden_proto (__timespec_get64)
 #endif
 
 /* Use in the clock_* functions.  Size of the field representing the
diff --git a/sysdeps/unix/sysv/linux/timespec_get.c b/sysdeps/unix/sysv/linux/timespec_get.c
new file mode 100644
index 0000000000..7e634f9dac
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/timespec_get.c
@@ -0,0 +1,59 @@
+/* timespec_get -- get system time - Linux version supporting 64 bit time.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <time.h>
+#include <errno.h>
+
+/* Set TS to calendar time based in time base BASE.  */
+int
+__timespec_get64 (struct __timespec64 *ts, int base)
+{
+  if (base == TIME_UTC)
+    {
+      __clock_gettime64 (CLOCK_REALTIME, ts);
+      return base;
+    }
+  return 0;
+}
+
+#if __TIMESIZE != 64
+libc_hidden_def (__timespec_get64)
+
+int
+__timespec_get (struct timespec *ts, int base)
+{
+  int ret;
+  struct __timespec64 tp64;
+
+  ret = __timespec_get64 (&tp64, base);
+
+  if (ret == TIME_UTC)
+    {
+      if (! in_time_t_range (tp64.tv_sec))
+        {
+          __set_errno (EOVERFLOW);
+          return 0;
+        }
+
+      *ts = valid_timespec64_to_timespec (tp64);
+    }
+
+  return ret;
+}
+#endif
+strong_alias (__timespec_get, timespec_get);
-- 
2.20.1