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, 110 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/mips/mips64/getdents64.c b/sysdeps/unix/sysv/linux/mips/mips64/getdents64.c
new file mode 100644
index 0000000000..63afb2667e
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/mips/mips64/getdents64.c
@@ -0,0 +1,110 @@
+/* Get directory entries.  Linux/MIPSn64 LFS version.
+   Copyright (C) 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>
+#include <assert.h>
+#include <sys/param.h>
+#include <unistd.h>
+#include <scratch_buffer.h>
+
+ssize_t
+__getdents64 (int fd, char *buf, size_t nbytes)
+{
+#ifdef __NR_getdents64
+  ssize_t ret = INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
+  if (ret != -1)
+    return ret;
+#endif
+
+  /* Unfortunately getdents64 was only wire-up for MIPS n64 on Linux 3.10.
+     If syscall is not available it need to fallback to non-LFS one.  */
+
+  struct kernel_dirent
+    {
+      unsigned long d_ino;
+      unsigned long d_off;
+      unsigned short int d_reclen;
+      char d_name[256];
+    };
+
+  const size_t size_diff = (offsetof (struct dirent64, d_name)
+			   - offsetof (struct kernel_dirent, d_name));
+
+  size_t red_nbytes = MIN (nbytes
+			   - ((nbytes / (offsetof (struct dirent64, d_name)
+					 + 14)) * size_diff),
+			   nbytes - size_diff);
+
+  struct scratch_buffer tmpbuf;
+  scratch_buffer_init (&tmpbuf);
+  if (!scratch_buffer_set_array_size (&tmpbuf, red_nbytes, sizeof (uint8_t)))
+    INLINE_SYSCALL_ERROR_RETURN_VALUE (ENOMEM);
+
+  struct kernel_dirent *skdp, *kdp;
+  skdp = kdp = tmpbuf.data;
+
+  ssize_t retval = INLINE_SYSCALL_CALL (getdents, fd, kdp, red_nbytes);
+  if (retval == -1)
+    {
+      scratch_buffer_free (&tmpbuf);
+      return -1;
+    }
+
+  off64_t last_offset = -1;
+  struct dirent64 *dp = (struct dirent64 *) buf;
+  while ((char *) kdp < (char *) skdp + retval)
+    {
+      const size_t alignment = _Alignof (struct dirent64);
+      /* Since kdp->d_reclen is already aligned for the kernel structure
+	 this may compute a value that is bigger than necessary.  */
+      size_t new_reclen = ((kdp->d_reclen + size_diff + alignment - 1)
+			   & ~(alignment - 1));
+      if ((char *) dp + new_reclen > buf + nbytes)
+        {
+	  /* Our heuristic failed.  We read too many entries.  Reset
+	     the stream.  */
+	  assert (last_offset != -1);
+	  __lseek64 (fd, last_offset, SEEK_SET);
+
+	  if ((char *) dp == buf)
+	    {
+	      scratch_buffer_free (&tmpbuf);
+	      return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
+	    }
+
+	  break;
+	}
+
+      last_offset = kdp->d_off;
+      dp->d_ino = kdp->d_ino;
+      dp->d_off = kdp->d_off;
+      dp->d_reclen = new_reclen;
+      dp->d_type = *((char *) kdp + kdp->d_reclen - 1);
+      memcpy (dp->d_name, kdp->d_name,
+	      kdp->d_reclen - offsetof (struct kernel_dirent, d_name));
+
+      dp = (struct dirent64 *) ((char *) dp + new_reclen);
+      kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen);
+    }
+
+  scratch_buffer_free (&tmpbuf);
+  return (char *) dp - buf;
+}
+strong_alias (__getdents64, __getdents)