Consolidate lseek/lseek64/llseek implementations

This patch consolidates all Linux lseek/lseek64/llseek implementation
in on on sysdeps/unix/sysv/linux/lseek{64}.c.  It also removes the llseek
file and instead consolidate the LFS lseek implementation on lseek64.c
as for other LFS symbols implementations.

The general idea is:

  - lseek: ABIs that not define __OFF_T_MATCHES_OFF64_T will preferable
  use __NR__llseek if kernel supports it, otherwise they will use __NR_lseek.
  ABIs that defines __OFF_T_MATCHES_OFF64_T won't produce any symbol.

  - lseek64: ABIs with __OFF_T_MATCHES_OFF64_T will preferable use __NR_lseek
  (since it will use 64-bit arguments without low/high splitting) and
  __NR__llseek if __NR_lseek is not defined (for some ILP32 ports).

  - llseek: files will be removed and symbols will be aliased ot lseek64.

ABI without __OFF_T_MATCHES_OFF64_T and without __NR_llseek (basically MIPS64n32
so far) are covered by building lseek with off_t as expected and lseek64
using __NR_lseek (as expected for off64_t being passed using 64-bit registers).

For this consolidation I mantained the x32 assembly specific implementation
because to correctly fix this it would required both the x32 fix for
{INLINE,INTERNAL}_SYSCALL [1] and a wrapper to correctly subscribe it to
return 64 bits instead of default 32 bits (as for times).  It could a future
cleanup.

It is based on my previous {INTERNAL,INLINE}_SYSCALL_CALL macro [2],
although it is mainly for simplification.

Tested on x86_64, i686, aarch64, armhf, and powerpc64le.

	* nptl/Makefile (libpthread-routines): Remove ptw-llseek and add
	ptw-lseek64.
	* sysdeps/unix/sysv/linux/Makefile (sysdeps_routines): Remove llseek.
	* sysdeps/unix/sysv/linux/alpha/Makefile  (sysdeps_routines):
	Likewise.
	* sysdeps/unix/sysv/linux/generic/wordsize-32/llseek.c: Remove file.
	* sysdeps/unix/sysv/linux/generic/wordsize-32/lseek.c: Remove file.
	* sysdeps/unix/sysv/linux/mips/mips64/llseek.c: Likewise.
	* sysdeps/unix/sysv/linux/llseek.c: Remove file.
	* sysdeps/unix/sysv/linux/lseek.c: New file.
	* sysdeps/unix/sysv/linux/lseek64.c: Add default Linux implementation.
	* sysdeps/unix/sysv/linux/mips/mips64/syscalls.list: Remove lseek and
	__libc_lseek64 from auto-generation.
	* sysdeps/unix/sysv/linux/wordsize-64/syscalls.list: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/lseek64.S: New file.

[1] https://sourceware.org/ml/libc-alpha/2016-08/msg00443.html
[2] https://sourceware.org/ml/libc-alpha/2016-08/msg00646.html

1 files changed, 57 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/lseek.c b/sysdeps/unix/sysv/linux/lseek.c
new file mode 100644
index 0000000000..3b81bffe92
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/lseek.c
@@ -0,0 +1,57 @@
+/* Linux lseek implementation, 32 bits off_t.
+   Copyright (C) 2016 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <unistd.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <sysdep.h>
+#include <errno.h>
+
+#ifndef __OFF_T_MATCHES_OFF64_T
+
+/* Test for overflows of structures where we ask the kernel to fill them
+   in with standard 64-bit syscalls but return them through APIs that
+   only expose the low 32 bits of some fields.  */
+
+static inline off_t lseek_overflow (loff_t res)
+{
+  off_t retval = (off_t) res;
+  if (retval == res)
+    return retval;
+
+  __set_errno (EOVERFLOW);
+  return (off_t) -1;
+}
+
+off_t
+__lseek (int fd, off_t offset, int whence)
+{
+# ifdef __NR__llseek
+  loff_t res;
+  int rc = INLINE_SYSCALL_CALL (_llseek, fd,
+				(long) (((uint64_t) (offset)) >> 32),
+				(long) offset, &res, whence);
+  return rc ?: lseek_overflow (res);
+# else
+  return INLINE_SYSCALL_CALL (lseek, fd, offset, whence);
+# endif
+}
+libc_hidden_def (__lseek)
+weak_alias (__lseek, lseek)
+strong_alias (__lseek, __libc_lseek)
+#endif /* __OFF_T_MATCHES_OFF64_T  */