y2038: linux: Provide __timerfd_gettime64 implementation

This patch replaces auto generated wrapper (as described in
sysdeps/unix/sysv/linux/syscalls.list) for timerfd_gettime with one which
adds extra support for reading 64 bit time values on machines with
__TIMESIZE != 64.
There is no functional change for architectures already supporting 64 bit
time ABI.

This patch is conceptually identical to timer_gettime conversion already
done in sysdeps/unix/sysv/linux/timer_gettime.c.
Please refer to corresponding commit message for detailed description of
introduced functions and the testing procedure.

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

---
Changes for v4:
- Update date from 2019 to 2020

Changes for v3:
- Add missing libc_hidden_def()

Changes for v2:
- Remove "Contributed by" from the file header
- Remove early check for (fd < 0) in __timerfd_gettime64 as the fd
  correctness check is already done in Linux kernel
- Add single descriptive comment line to provide concise explanation
  of the code

include/time.h

@@ -181,9 +181,12 @@ libc_hidden_proto (__futimens64);
 
 #if __TIMESIZE == 64
 # define __timer_gettime64 __timer_gettime
+# define __timerfd_gettime64 __timerfd_gettime
 #else
 extern int __timer_gettime64 (timer_t timerid, struct __itimerspec64 *value);
+extern int __timerfd_gettime64 (int fd, struct __itimerspec64 *value);
 libc_hidden_proto (__timer_gettime64);
+libc_hidden_proto (__timerfd_gettime64);
 #endif
 
 #if __TIMESIZE == 64

sysdeps/unix/sysv/linux/Makefile

@@ -60,7 +60,8 @@ sysdep_routines += adjtimex clone umount umount2 readahead \
 		   setfsuid setfsgid epoll_pwait signalfd \
 		   eventfd eventfd_read eventfd_write prlimit \
 		   personality epoll_wait tee vmsplice splice \
-		   open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get
+		   open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get \
+		   timerfd_gettime
 
 CFLAGS-gethostid.c = -fexceptions
 CFLAGS-tee.c = -fexceptions -fasynchronous-unwind-tables

sysdeps/unix/sysv/linux/syscalls.list

@@ -94,7 +94,6 @@ mq_setattr	-	mq_getsetattr	i:ipp	mq_setattr
 
 timerfd_create	EXTRA	timerfd_create	i:ii	timerfd_create
 timerfd_settime	EXTRA	timerfd_settime	i:iipp	timerfd_settime
-timerfd_gettime	EXTRA	timerfd_gettime	i:ip	timerfd_gettime
 
 fanotify_init	EXTRA	fanotify_init	i:ii	fanotify_init
 

sysdeps/unix/sysv/linux/timerfd_gettime.c

@@ -0,0 +1,68 @@
+/* timerfd_gettime -- get the timer setting referred to by file descriptor.
+   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, or (at your option) any later version.
+
+   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; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <time.h>
+#include <sysdep.h>
+#include <kernel-features.h>
+
+int
+__timerfd_gettime64 (int fd, struct __itimerspec64 *value)
+{
+#ifdef __ASSUME_TIME64_SYSCALLS
+# ifndef __NR_timerfd_gettime64
+#  define __NR_timerfd_gettime64 __NR_timerfd_gettime
+# endif
+  return INLINE_SYSCALL_CALL (timerfd_gettime64, fd, value);
+#else
+# ifdef __NR_timerfd_gettime64
+  int ret = INLINE_SYSCALL_CALL (timerfd_gettime64, fd, value);
+  if (ret == 0 || errno != ENOSYS)
+    return ret;
+# endif
+  struct itimerspec its32;
+  int retval = INLINE_SYSCALL_CALL (timerfd_gettime, fd, &its32);
+  if (retval == 0)
+    {
+      value->it_interval = valid_timespec_to_timespec64 (its32.it_interval);
+      value->it_value = valid_timespec_to_timespec64 (its32.it_value);
+    }
+
+  return retval;
+#endif
+}
+
+#if __TIMESIZE != 64
+libc_hidden_def (__timerfd_gettime64)
+
+int
+__timerfd_gettime (int fd, struct itimerspec *value)
+{
+  struct __itimerspec64 its64;
+  int retval = __timerfd_gettime64 (fd, &its64);
+  if (retval == 0)
+    {
+      value->it_interval = valid_timespec64_to_timespec (its64.it_interval);
+      value->it_value = valid_timespec64_to_timespec (its64.it_value);
+    }
+
+  return retval;
+}
+#endif
+strong_alias (__timerfd_gettime, timerfd_gettime)