[PATCH v2 08/11] Use clock_gettime to implement timespec_get.

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

From: Zack Weinberg <zackw@panix.com>

Use clock_gettime to implement timespec_get.

Changes from previous version:

  - Change commit message remove the rationale to not promote it.

--

timespec_get is the same function as clock_gettime, with an obnoxious
coating of NIH painted on it by the ISO C committee.  In addition to
the rename, it takes its arguments in a different order, it returns 0
on *failure* or a positive number on *success*, and it requires that
all of its TIME_* constants be positive.  This last means we cannot
directly reuse the existing CLOCK_* constants for it, because
those have been allocated starting with CLOCK_REALTIME = 0 on all
existing platforms.

This patch simply promotes the sysdeps/posix implementation to
universal, and removes the Linux-specific implementation, whose
apparent reason for existing was to cut out one function call's worth
of overhead.

Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
powerpc64-linux-gnu, powerpc-linux-gnu, and aarch64-linux-gnu.
---
 sysdeps/posix/timespec_get.c           | 32 ------------------
 sysdeps/unix/sysv/linux/timespec_get.c | 46 --------------------------
 time/timespec_get.c                    | 14 +++-----
 3 files changed, 4 insertions(+), 88 deletions(-)
 delete mode 100644 sysdeps/posix/timespec_get.c
 delete mode 100644 sysdeps/unix/sysv/linux/timespec_get.c

diff --git a/sysdeps/posix/timespec_get.c b/sysdeps/posix/timespec_get.c
deleted file mode 100644
index e3146da2d3..0000000000
--- a/sysdeps/posix/timespec_get.c
+++ /dev/null
@@ -1,32 +0,0 @@
-/* timespec_get -- C11 interface to sample a clock.  Generic POSIX.1 version.
-   Copyright (C) 2013-2019 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; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <time.h>
-
-
-/* Set TS to calendar time based in time base BASE.  */
-int
-timespec_get (struct timespec *ts, int base)
-{
-  if (base == TIME_UTC)
-    {
-      __clock_gettime (CLOCK_REALTIME, ts);
-      return base;
-    }
-  return 0;
-}
diff --git a/sysdeps/unix/sysv/linux/timespec_get.c b/sysdeps/unix/sysv/linux/timespec_get.c
deleted file mode 100644
index 629827d0f9..0000000000
--- a/sysdeps/unix/sysv/linux/timespec_get.c
+++ /dev/null
@@ -1,46 +0,0 @@
-/* Copyright (C) 2011-2019 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 <sysdep.h>
-#include <errno.h>
-
-#ifdef HAVE_CLOCK_GETTIME_VSYSCALL
-# define HAVE_VSYSCALL
-#endif
-#include <sysdep-vdso.h>
-
-/* Set TS to calendar time based in time base BASE.  */
-int
-timespec_get (struct timespec *ts, int base)
-{
-  switch (base)
-    {
-      int res;
-      INTERNAL_SYSCALL_DECL (err);
-    case TIME_UTC:
-      res = INTERNAL_VSYSCALL (clock_gettime, err, 2, CLOCK_REALTIME, ts);
-      if (INTERNAL_SYSCALL_ERROR_P (res, err))
-	return 0;
-      break;
-
-    default:
-      return 0;
-    }
-
-  return base;
-}
diff --git a/time/timespec_get.c b/time/timespec_get.c
index cef9a4263c..5124c747c2 100644
--- a/time/timespec_get.c
+++ b/time/timespec_get.c
@@ -22,16 +22,10 @@
 int
 timespec_get (struct timespec *ts, int base)
 {
-  switch (base)
+  if (base == TIME_UTC)
     {
-    case TIME_UTC:
-      /* Not supported.  */
-      return 0;
-
-    default:
-      return 0;
+      __clock_gettime (CLOCK_REALTIME, ts);
+      return base;
     }
-
-  return base;
+  return 0;
 }
-stub_warning (timespec_get)
-- 
2.17.1