Consolidate Linux getdents{64} implementation

This patch consolidates Linux getdents{64} implementation on just
the default sysdeps/unix/sysv/linux/getdents{64}{_r}.c ones.

Although this symbol is used only internally, the non-LFS version
still need to be build due the non-LFS getdirentries which requires
its semantic.

The non-LFS default implementation now uses the wordsize-32 as base
which uses getdents64 syscall plus adjustment for overflow (it allows
to use the same code for architectures that does not support non-LFS
getdents syscall).  It has two main differences to wordsize-32 one:

  - DIRENT_SET_DP_INO is added to handle alpha requirement to zero
    the padding.

  - alloca is removed by allocating a bounded temporary buffer (it
    increases stack usage by roughly 276 bytes).

The default implementation handle the Linux requirements:

  * getdents is only built for _DIRENT_MATCHES_DIRENT64 being 0.

  * getdents64 is always built and aliased to getdents for ABIs
    that define _DIRENT_MATCHES_DIRENT64 to 1.

  * A compat symbol is added for getdents64 for ABI that used to
    export the old non-LFS version.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu,
sparcv9-linux-gnu, sparc64-linux-gnu, powerpc-linux-gnu, and
powerpc64le-linux-gnu.

	* sysdeps/unix/sysv/linux/alpha/getdents.c: Add comments with alpha
	requirements.
	 (_DIRENT_MATCHES_DIRENT64): Undef
	* sysdeps/unix/sysv/linux/alpha/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/arm/getdents64.c: Remove file.
	* sysdeps/unix/sysv/linux/generic/getdents.c: Likewise.
	* sysdeps/unix/sysv/linux/generic/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/generic/wordsize-32/getdents.c: Likewise.
	* sysdeps/unix/sysv/linux/getdents.c: Simplify implementation by
	use getdents64 syscalls as base.
	* sysdeps/unix/sysv/linux/getdents64.c: Likewise and add compatibility
	symbol if required.
	* sysdeps/unix/sysv/linux/hppa/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/i386/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/m68k/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/wordsize-64/getdents.c: Likewise.
	* sysdeps/unix/sysv/linux/wordsize-64/getdents64.c: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/get_clockfreq.c
	(__get_clockfreq_via_proc_openprom): Use __getdents64.
	* sysdeps/unix/sysv/linux/mips/mips64/getdents64.c: New file.

1 files changed, 76 insertions, 3 deletions

diff --git a/sysdeps/unix/sysv/linux/getdents64.c b/sysdeps/unix/sysv/linux/getdents64.c
index 805917e274..3bde0cf4f0 100644
--- a/sysdeps/unix/sysv/linux/getdents64.c
+++ b/sysdeps/unix/sysv/linux/getdents64.c
@@ -1,3 +1,76 @@
-#define __GETDENTS __getdents64
-#define DIRENT_TYPE struct dirent64
-#include <sysdeps/unix/sysv/linux/getdents.c>
+/* Get directory entries.  Linux LFS version.
+   Copyright (C) 1997-2018 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 <string.h>
+#include <dirent.h>
+#include <errno.h>
+
+/* The kernel struct linux_dirent64 matches the 'struct getdents64' type.  */
+ssize_t
+__getdents64 (int fd, char *buf, size_t nbytes)
+{
+  return INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
+}
+
+#if _DIRENT_MATCHES_DIRENT64
+strong_alias (__getdents64, __getdents)
+#else
+# include <shlib-compat.h>
+
+# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
+# include <olddirent.h>
+
+/* kernel definition of as of 3.2.  */
+struct compat_linux_dirent
+{
+  /* Both d_ino and d_off are compat_ulong_t which are defined in all
+     architectures as 'u32'.  */
+  uint32_t        d_ino;
+  uint32_t        d_off;
+  unsigned short  d_reclen;
+  char            d_name[1];
+};
+
+ssize_t
+__old_getdents64 (int fd, char *buf, size_t nbytes)
+{
+  ssize_t retval = INLINE_SYSCALL_CALL (getdents, fd, buf, nbytes);
+
+  /* The kernel added the d_type value after the name.  Change this now.  */
+  if (retval != -1)
+    {
+      union
+      {
+	struct compat_linux_dirent k;
+	struct dirent u;
+      } *kbuf = (void *) buf;
+
+      while ((char *) kbuf < buf + retval)
+	{
+	  char d_type = *((char *) kbuf + kbuf->k.d_reclen - 1);
+	  memmove (kbuf->u.d_name, kbuf->k.d_name,
+		   strlen (kbuf->k.d_name) + 1);
+	  kbuf->u.d_type = d_type;
+
+	  kbuf = (void *) ((char *) kbuf + kbuf->k.d_reclen);
+	}
+     }
+  return retval;
+}
+# endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)  */
+#endif /* _DIRENT_MATCHES_DIRENT64  */