linux: Move posix dir implementations to Linux

This generic implementation already expects a getdents API which
is Linux specific.  It also allows simplify it by assuming
_DIRENT_HAVE_D_RECLEN and _DIRENT_HAVE_D_OFF support.

The readdir are also expanded on each required implementation,
futher fixes and improvements will make parametrize the
implementation more complex.

Checked on x86_64-linux-gnu, i686-linux-gnu, and with a build
for all affected ABIs.

12 files changed, 911 insertions, 23 deletions

diff --git a/sysdeps/unix/sysv/linux/closedir.c b/sysdeps/unix/sysv/linux/closedir.c
new file mode 100644
index 0000000..ccc19ee
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/closedir.c
@@ -0,0 +1,54 @@
+/* Copyright (C) 1991-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <dirstream.h>
+#include <not-cancel.h>
+
+
+/* Close the directory stream DIRP.
+   Return 0 if successful, -1 if not.  */
+int
+__closedir (DIR *dirp)
+{
+  int fd;
+
+  if (dirp == NULL)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  /* We do not try to synchronize access here.  If some other thread
+     still uses this handle it is a big mistake and that thread
+     deserves all the bad data it gets.  */
+
+  fd = dirp->fd;
+
+#if IS_IN (libc)
+  __libc_lock_fini (dirp->lock);
+#endif
+
+  free ((void *) dirp);
+
+  return __close_nocancel (fd);
+}
+weak_alias (__closedir, closedir)
diff --git a/sysdeps/unix/sysv/linux/dirfd.c b/sysdeps/unix/sysv/linux/dirfd.c
new file mode 100644
index 0000000..5d0928d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dirfd.c
@@ -0,0 +1,31 @@
+/* Return the file descriptor used by a DIR stream.  Unix version.
+   Copyright (C) 1995-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dirent.h>
+#include <dirstream.h>
+
+#undef dirfd
+
+int
+__dirfd (DIR *dirp)
+{
+  return dirp->fd;
+}
+
+weak_alias (__dirfd, dirfd)
+libc_hidden_def (dirfd)
diff --git a/sysdeps/unix/sysv/linux/dirstream.h b/sysdeps/unix/sysv/linux/dirstream.h
new file mode 100644
index 0000000..a3ea2b7
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dirstream.h
@@ -0,0 +1,55 @@
+/* Copyright (C) 1993-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef	_DIRSTREAM_H
+#define	_DIRSTREAM_H	1
+
+#include <sys/types.h>
+
+#include <libc-lock.h>
+
+/* Directory stream type.
+
+   The miscellaneous Unix `readdir' implementations read directory data
+   into a buffer and return `struct dirent *' pointers into it.  */
+
+struct __dirstream
+  {
+    int fd;			/* File descriptor.  */
+
+    __libc_lock_define (, lock) /* Mutex lock for this structure.  */
+
+    size_t allocation;		/* Space allocated for the block.  */
+    size_t size;		/* Total valid data in the block.  */
+    size_t offset;		/* Current offset into the block.  */
+
+    off_t filepos;		/* Position of next entry to read.  */
+
+    int errcode;		/* Delayed error code.  */
+
+    /* Directory block.  We must make sure that this block starts
+       at an address that is aligned adequately enough to store
+       dirent entries.  Using the alignment of "void *" is not
+       sufficient because dirents on 32-bit platforms can require
+       64-bit alignment.  We use "long double" here to be consistent
+       with what malloc uses.  */
+    char data[0] __attribute__ ((aligned (__alignof__ (long double))));
+  };
+
+#define _DIR_dirfd(dirp)	((dirp)->fd)
+
+#endif	/* dirstream.h */
diff --git a/sysdeps/unix/sysv/linux/fdopendir.c b/sysdeps/unix/sysv/linux/fdopendir.c
new file mode 100644
index 0000000..e424fbd
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/fdopendir.c
@@ -0,0 +1,52 @@
+/* Copyright (C) 2005-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <sys/stat.h>
+
+#include <not-cancel.h>
+
+
+DIR *
+__fdopendir (int fd)
+{
+  struct stat64 statbuf;
+
+  if (__builtin_expect (__fstat64 (fd, &statbuf), 0) < 0)
+    return NULL;
+  if (__glibc_unlikely (! S_ISDIR (statbuf.st_mode)))
+    {
+      __set_errno (ENOTDIR);
+      return NULL;
+    }
+
+  /* Make sure the descriptor allows for reading.  */
+  int flags = __fcntl64_nocancel (fd, F_GETFL);
+  if (__glibc_unlikely (flags == -1))
+    return NULL;
+  if (__glibc_unlikely ((flags & O_ACCMODE) == O_WRONLY))
+    {
+      __set_errno (EINVAL);
+      return NULL;
+    }
+
+  return __alloc_dir (fd, false, flags, &statbuf);
+}
+weak_alias (__fdopendir, fdopendir)
diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
new file mode 100644
index 0000000..e89e09b
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/opendir.c
@@ -0,0 +1,148 @@
+/* Copyright (C) 1991-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>	/* For BUFSIZ.  */
+#include <sys/param.h>	/* For MIN and MAX.  */
+
+#include <not-cancel.h>
+
+/* The st_blksize value of the directory is used as a hint for the
+   size of the buffer which receives struct dirent values from the
+   kernel.  st_blksize is limited to MAX_DIR_BUFFER_SIZE, in case the
+   file system provides a bogus value.  */
+#define MAX_DIR_BUFFER_SIZE 1048576U
+
+enum {
+  opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC
+};
+
+static bool
+invalid_name (const char *name)
+{
+  if (__glibc_unlikely (name[0] == '\0'))
+    {
+      /* POSIX.1-1990 says an empty name gets ENOENT;
+	 but `open' might like it fine.  */
+      __set_errno (ENOENT);
+      return true;
+    }
+  return false;
+}
+
+static DIR *
+opendir_tail (int fd)
+{
+  if (__glibc_unlikely (fd < 0))
+    return NULL;
+
+  /* Now make sure this really is a directory and nothing changed since the
+     `stat' call.  The S_ISDIR check is superfluous if O_DIRECTORY works,
+     but it's cheap and we need the stat call for st_blksize anyway.  */
+  struct stat64 statbuf;
+  if (__glibc_unlikely (__fstat64 (fd, &statbuf) < 0))
+    goto lose;
+  if (__glibc_unlikely (! S_ISDIR (statbuf.st_mode)))
+    {
+      __set_errno (ENOTDIR);
+    lose:
+      __close_nocancel_nostatus (fd);
+      return NULL;
+    }
+
+  return __alloc_dir (fd, true, 0, &statbuf);
+}
+
+
+#if IS_IN (libc)
+DIR *
+__opendirat (int dfd, const char *name)
+{
+  if (__glibc_unlikely (invalid_name (name)))
+    return NULL;
+
+  return opendir_tail (__openat_nocancel (dfd, name, opendir_oflags));
+}
+#endif
+
+
+/* Open a directory stream on NAME.  */
+DIR *
+__opendir (const char *name)
+{
+  if (__glibc_unlikely (invalid_name (name)))
+    return NULL;
+
+  return opendir_tail (__open_nocancel (name, opendir_oflags));
+}
+weak_alias (__opendir, opendir)
+
+DIR *
+__alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp)
+{
+  /* We have to set the close-on-exit flag if the user provided the
+     file descriptor.  */
+  if (!close_fd
+      && __glibc_unlikely (__fcntl64_nocancel (fd, F_SETFD, FD_CLOEXEC) < 0))
+	goto lose;
+
+  const size_t default_allocation = (4 * BUFSIZ < sizeof (struct dirent64)
+				     ? sizeof (struct dirent64) : 4 * BUFSIZ);
+  const size_t small_allocation = (BUFSIZ < sizeof (struct dirent64)
+				   ? sizeof (struct dirent64) : BUFSIZ);
+  size_t allocation = default_allocation;
+#ifdef _STATBUF_ST_BLKSIZE
+  /* Increase allocation if requested, but not if the value appears to
+     be bogus.  */
+  if (statp != NULL)
+    allocation = MIN (MAX ((size_t) statp->st_blksize, default_allocation),
+		      MAX_DIR_BUFFER_SIZE);
+#endif
+
+  DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation);
+  if (dirp == NULL)
+    {
+      allocation = small_allocation;
+      dirp = (DIR *) malloc (sizeof (DIR) + allocation);
+
+      if (dirp == NULL)
+      lose:
+	{
+	  if (close_fd)
+	    {
+	      int save_errno = errno;
+	      __close_nocancel_nostatus (fd);
+	      __set_errno (save_errno);
+	    }
+	  return NULL;
+	}
+    }
+
+  dirp->fd = fd;
+#if IS_IN (libc)
+  __libc_lock_init (dirp->lock);
+#endif
+  dirp->allocation = allocation;
+  dirp->size = 0;
+  dirp->offset = 0;
+  dirp->filepos = 0;
+  dirp->errcode = 0;
+
+  return dirp;
+}
diff --git a/sysdeps/unix/sysv/linux/readdir.c b/sysdeps/unix/sysv/linux/readdir.c
index df7a92a..2e03e66 100644
--- a/sysdeps/unix/sysv/linux/readdir.c
+++ b/sysdeps/unix/sysv/linux/readdir.c
@@ -19,5 +19,68 @@
 #include <dirent.h>
 
 #if !_DIRENT_MATCHES_DIRENT64
-# include <sysdeps/posix/readdir.c>
+#include <dirstream.h>
+
+/* Read a directory entry from DIRP.  */
+struct dirent *
+__readdir (DIR *dirp)
+{
+  struct dirent *dp;
+  int saved_errno = errno;
+
+#if IS_IN (libc)
+  __libc_lock_lock (dirp->lock);
+#endif
+
+  do
+    {
+      size_t reclen;
+
+      if (dirp->offset >= dirp->size)
+	{
+	  /* We've emptied out our buffer.  Refill it.  */
+
+	  size_t maxread = dirp->allocation;
+	  ssize_t bytes;
+
+	  bytes = __getdents (dirp->fd, dirp->data, maxread);
+	  if (bytes <= 0)
+	    {
+	      /* On some systems getdents fails with ENOENT when the
+		 open directory has been rmdir'd already.  POSIX.1
+		 requires that we treat this condition like normal EOF.  */
+	      if (bytes < 0 && errno == ENOENT)
+		bytes = 0;
+
+	      /* Don't modifiy errno when reaching EOF.  */
+	      if (bytes == 0)
+		__set_errno (saved_errno);
+	      dp = NULL;
+	      break;
+	    }
+	  dirp->size = (size_t) bytes;
+
+	  /* Reset the offset into the buffer.  */
+	  dirp->offset = 0;
+	}
+
+      dp = (struct dirent *) &dirp->data[dirp->offset];
+
+      reclen = dp->d_reclen;
+
+      dirp->offset += reclen;
+
+      dirp->filepos = dp->d_off;
+
+      /* Skip deleted files.  */
+    } while (dp->d_ino == 0);
+
+#if IS_IN (libc)
+  __libc_lock_unlock (dirp->lock);
+#endif
+
+  return dp;
+}
+weak_alias (__readdir, readdir)
+
 #endif
diff --git a/sysdeps/unix/sysv/linux/readdir64.c b/sysdeps/unix/sysv/linux/readdir64.c
index 170a889..1aa6e26 100644
--- a/sysdeps/unix/sysv/linux/readdir64.c
+++ b/sysdeps/unix/sysv/linux/readdir64.c
@@ -23,17 +23,71 @@
 #define readdir   __no_readdir_decl
 #define __readdir __no___readdir_decl
 #include <dirent.h>
+#undef __readdir
+#undef readdir
 
-#define __READDIR   __readdir64
-#define __GETDENTS  __getdents64
-#define DIRENT_TYPE struct dirent64
+/* Read a directory entry from DIRP.  */
+struct dirent64 *
+__readdir64 (DIR *dirp)
+{
+  struct dirent64 *dp;
+  int saved_errno = errno;
 
-#include <sysdeps/posix/readdir.c>
+#if IS_IN (libc)
+  __libc_lock_lock (dirp->lock);
+#endif
 
-#undef __readdir
-#undef readdir
+  do
+    {
+      size_t reclen;
+
+      if (dirp->offset >= dirp->size)
+	{
+	  /* We've emptied out our buffer.  Refill it.  */
+
+	  size_t maxread = dirp->allocation;
+	  ssize_t bytes;
+
+	  bytes = __getdents64 (dirp->fd, dirp->data, maxread);
+	  if (bytes <= 0)
+	    {
+	      /* On some systems getdents fails with ENOENT when the
+		 open directory has been rmdir'd already.  POSIX.1
+		 requires that we treat this condition like normal EOF.  */
+	      if (bytes < 0 && errno == ENOENT)
+		bytes = 0;
+
+	      /* Don't modifiy errno when reaching EOF.  */
+	      if (bytes == 0)
+		__set_errno (saved_errno);
+	      dp = NULL;
+	      break;
+	    }
+	  dirp->size = (size_t) bytes;
 
+	  /* Reset the offset into the buffer.  */
+	  dirp->offset = 0;
+	}
+
+      dp = (struct dirent64 *) &dirp->data[dirp->offset];
+
+      reclen = dp->d_reclen;
+
+      dirp->offset += reclen;
+
+      dirp->filepos = dp->d_off;
+
+      /* Skip deleted files.  */
+    } while (dp->d_ino == 0);
+
+#if IS_IN (libc)
+  __libc_lock_unlock (dirp->lock);
+#endif
+
+  return dp;
+}
 libc_hidden_def (__readdir64)
+
 #if _DIRENT_MATCHES_DIRENT64
 strong_alias (__readdir64, __readdir)
 weak_alias (__readdir64, readdir64)
@@ -49,10 +103,67 @@ versioned_symbol (libc, __readdir64, readdir64, GLIBC_2_2);
 # endif
 # if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
 #  include <olddirent.h>
-#  define __READDIR   attribute_compat_text_section __old_readdir64
-#  define __GETDENTS  __old_getdents64
-#  define DIRENT_TYPE struct __old_dirent64
-#  include <sysdeps/posix/readdir.c>
+
+attribute_compat_text_section
+struct __old_dirent64 *
+__old_readdir64 (DIR *dirp)
+{
+  struct __old_dirent64 *dp;
+  int saved_errno = errno;
+
+#if IS_IN (libc)
+  __libc_lock_lock (dirp->lock);
+#endif
+
+  do
+    {
+      size_t reclen;
+
+      if (dirp->offset >= dirp->size)
+	{
+	  /* We've emptied out our buffer.  Refill it.  */
+
+	  size_t maxread = dirp->allocation;
+	  ssize_t bytes;
+
+	  bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
+	  if (bytes <= 0)
+	    {
+	      /* On some systems getdents fails with ENOENT when the
+		 open directory has been rmdir'd already.  POSIX.1
+		 requires that we treat this condition like normal EOF.  */
+	      if (bytes < 0 && errno == ENOENT)
+		bytes = 0;
+
+	      /* Don't modifiy errno when reaching EOF.  */
+	      if (bytes == 0)
+		__set_errno (saved_errno);
+	      dp = NULL;
+	      break;
+	    }
+	  dirp->size = (size_t) bytes;
+
+	  /* Reset the offset into the buffer.  */
+	  dirp->offset = 0;
+	}
+
+      dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
+
+      reclen = dp->d_reclen;
+
+      dirp->offset += reclen;
+
+      dirp->filepos = dp->d_off;
+
+      /* Skip deleted files.  */
+    } while (dp->d_ino == 0);
+
+#if IS_IN (libc)
+  __libc_lock_unlock (dirp->lock);
+#endif
+
+  return dp;
+}
 libc_hidden_def (__old_readdir64)
 compat_symbol (libc, __old_readdir64, readdir64, GLIBC_2_1);
 # endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)  */
diff --git a/sysdeps/unix/sysv/linux/readdir64_r.c b/sysdeps/unix/sysv/linux/readdir64_r.c
index 6d589f3..c587787 100644
--- a/sysdeps/unix/sysv/linux/readdir64_r.c
+++ b/sysdeps/unix/sysv/linux/readdir64_r.c
@@ -23,15 +23,100 @@
 #define readdir_r   __no_readdir_r_decl
 #define __readdir_r __no___readdir_r_decl
 #include <dirent.h>
+#undef __readdir_r
+#undef readdir_r
 
-#define __READDIR_R __readdir64_r
-#define __GETDENTS  __getdents64
-#define DIRENT_TYPE struct dirent64
+/* Read a directory entry from DIRP.  */
+int
+__readdir64_r (DIR *dirp, struct dirent64 *entry, struct dirent64 **result)
+{
+  struct dirent64 *dp;
+  size_t reclen;
+  const int saved_errno = errno;
+  int ret;
 
-#include <sysdeps/posix/readdir_r.c>
+  __libc_lock_lock (dirp->lock);
+
+  do
+    {
+      if (dirp->offset >= dirp->size)
+	{
+	  /* We've emptied out our buffer.  Refill it.  */
+
+	  size_t maxread = dirp->allocation;
+	  ssize_t bytes;
+
+	  maxread = dirp->allocation;
+
+	  bytes = __getdents64 (dirp->fd, dirp->data, maxread);
+	  if (bytes <= 0)
+	    {
+	      /* On some systems getdents fails with ENOENT when the
+		 open directory has been rmdir'd already.  POSIX.1
+		 requires that we treat this condition like normal EOF.  */
+	      if (bytes < 0 && errno == ENOENT)
+		{
+		  bytes = 0;
+		  __set_errno (saved_errno);
+		}
+	      if (bytes < 0)
+		dirp->errcode = errno;
+
+	      dp = NULL;
+	      break;
+	    }
+	  dirp->size = (size_t) bytes;
+
+	  /* Reset the offset into the buffer.  */
+	  dirp->offset = 0;
+	}
+
+      dp = (struct dirent64 *) &dirp->data[dirp->offset];
+
+      reclen = dp->d_reclen;
+
+      dirp->offset += reclen;
+
+      dirp->filepos = dp->d_off;
+
+      if (reclen > offsetof (struct dirent64, d_name) + NAME_MAX + 1)
+	{
+	  /* The record is very long.  It could still fit into the
+	     caller-supplied buffer if we can skip padding at the
+	     end.  */
+	  size_t namelen = _D_EXACT_NAMLEN (dp);
+	  if (namelen <= NAME_MAX)
+	    reclen = offsetof (struct dirent64, d_name) + namelen + 1;
+	  else
+	    {
+	      /* The name is too long.  Ignore this file.  */
+	      dirp->errcode = ENAMETOOLONG;
+	      dp->d_ino = 0;
+	      continue;
+	    }
+	}
+
+      /* Skip deleted and ignored files.  */
+    }
+  while (dp->d_ino == 0);
+
+  if (dp != NULL)
+    {
+      *result = memcpy (entry, dp, reclen);
+      entry->d_reclen = reclen;
+      ret = 0;
+    }
+  else
+    {
+      *result = NULL;
+      ret = dirp->errcode;
+    }
+
+  __libc_lock_unlock (dirp->lock);
+
+  return ret;
+}
 
-#undef __readdir_r
-#undef readdir_r
 
 #if _DIRENT_MATCHES_DIRENT64
 strong_alias (__readdir64_r, __readdir_r)
@@ -44,10 +129,99 @@ weak_alias (__readdir64_r, readdir64_r)
 versioned_symbol (libc, __readdir64_r, readdir64_r, GLIBC_2_2);
 # if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
 #  include <olddirent.h>
-#  define __READDIR_R attribute_compat_text_section __old_readdir64_r
-#  define __GETDENTS  __old_getdents64
-#  define DIRENT_TYPE struct __old_dirent64
-#  include <sysdeps/posix/readdir_r.c>
+
+int
+attribute_compat_text_section
+__old_readdir64_r (DIR *dirp, struct __old_dirent64 *entry,
+		   struct __old_dirent64 **result)
+{
+  struct __old_dirent64 *dp;
+  size_t reclen;
+  const int saved_errno = errno;
+  int ret;
+
+  __libc_lock_lock (dirp->lock);
+
+  do
+    {
+      if (dirp->offset >= dirp->size)
+	{
+	  /* We've emptied out our buffer.  Refill it.  */
+
+	  size_t maxread = dirp->allocation;
+	  ssize_t bytes;
+
+	  maxread = dirp->allocation;
+
+	  bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
+	  if (bytes <= 0)
+	    {
+	      /* On some systems getdents fails with ENOENT when the
+		 open directory has been rmdir'd already.  POSIX.1
+		 requires that we treat this condition like normal EOF.  */
+	      if (bytes < 0 && errno == ENOENT)
+		{
+		  bytes = 0;
+		  __set_errno (saved_errno);
+		}
+	      if (bytes < 0)
+		dirp->errcode = errno;
+
+	      dp = NULL;
+	      break;
+	    }
+	  dirp->size = (size_t) bytes;
+
+	  /* Reset the offset into the buffer.  */
+	  dirp->offset = 0;
+	}
+
+      dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
+
+      reclen = dp->d_reclen;
+
+      dirp->offset += reclen;
+
+      dirp->filepos = dp->d_off;
+
+      if (reclen > offsetof (struct __old_dirent64, d_name) + NAME_MAX + 1)
+	{
+	  /* The record is very long.  It could still fit into the
+	     caller-supplied buffer if we can skip padding at the
+	     end.  */
+	  size_t namelen = _D_EXACT_NAMLEN (dp);
+	  if (namelen <= NAME_MAX)
+	    reclen = offsetof (struct __old_dirent64, d_name) + namelen + 1;
+	  else
+	    {
+	      /* The name is too long.  Ignore this file.  */
+	      dirp->errcode = ENAMETOOLONG;
+	      dp->d_ino = 0;
+	      continue;
+	    }
+	}
+
+      /* Skip deleted and ignored files.  */
+    }
+  while (dp->d_ino == 0);
+
+  if (dp != NULL)
+    {
+      *result = memcpy (entry, dp, reclen);
+      entry->d_reclen = reclen;
+      ret = 0;
+    }
+  else
+    {
+      *result = NULL;
+      ret = dirp->errcode;
+    }
+
+  __libc_lock_unlock (dirp->lock);
+
+  return ret;
+}
+
 compat_symbol (libc, __old_readdir64_r, readdir64_r, GLIBC_2_1);
 # endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)  */
 #endif /* _DIRENT_MATCHES_DIRENT64  */
diff --git a/sysdeps/unix/sysv/linux/readdir_r.c b/sysdeps/unix/sysv/linux/readdir_r.c
index 30f237d..0069041 100644
--- a/sysdeps/unix/sysv/linux/readdir_r.c
+++ b/sysdeps/unix/sysv/linux/readdir_r.c
@@ -19,5 +19,96 @@
 #include <dirent.h>
 
 #if !_DIRENT_MATCHES_DIRENT64
-# include <sysdeps/posix/readdir_r.c>
-#endif
+/* Read a directory entry from DIRP.  */
+int
+__readdir_r (DIR *dirp, struct dirent *entry, struct dirent **result)
+{
+  struct dirent *dp;
+  size_t reclen;
+  const int saved_errno = errno;
+  int ret;
+
+  __libc_lock_lock (dirp->lock);
+
+  do
+    {
+      if (dirp->offset >= dirp->size)
+	{
+	  /* We've emptied out our buffer.  Refill it.  */
+
+	  size_t maxread = dirp->allocation;
+	  ssize_t bytes;
+
+	  maxread = dirp->allocation;
+
+	  bytes = __getdents (dirp->fd, dirp->data, maxread);
+	  if (bytes <= 0)
+	    {
+	      /* On some systems getdents fails with ENOENT when the
+		 open directory has been rmdir'd already.  POSIX.1
+		 requires that we treat this condition like normal EOF.  */
+	      if (bytes < 0 && errno == ENOENT)
+		{
+		  bytes = 0;
+		  __set_errno (saved_errno);
+		}
+	      if (bytes < 0)
+		dirp->errcode = errno;
+
+	      dp = NULL;
+	      break;
+	    }
+	  dirp->size = (size_t) bytes;
+
+	  /* Reset the offset into the buffer.  */
+	  dirp->offset = 0;
+	}
+
+      dp = (struct dirent *) &dirp->data[dirp->offset];
+
+      reclen = dp->d_reclen;
+
+      dirp->offset += reclen;
+
+      dirp->filepos = dp->d_off;
+
+      if (reclen > offsetof (struct dirent, d_name) + NAME_MAX + 1)
+	{
+	  /* The record is very long.  It could still fit into the
+	     caller-supplied buffer if we can skip padding at the
+	     end.  */
+	  size_t namelen = _D_EXACT_NAMLEN (dp);
+	  if (namelen <= NAME_MAX)
+	    reclen = offsetof (struct dirent, d_name) + namelen + 1;
+	  else
+	    {
+	      /* The name is too long.  Ignore this file.  */
+	      dirp->errcode = ENAMETOOLONG;
+	      dp->d_ino = 0;
+	      continue;
+	    }
+	}
+
+      /* Skip deleted and ignored files.  */
+    }
+  while (dp->d_ino == 0);
+
+  if (dp != NULL)
+    {
+      *result = memcpy (entry, dp, reclen);
+      entry->d_reclen = reclen;
+      ret = 0;
+    }
+  else
+    {
+      *result = NULL;
+      ret = dirp->errcode;
+    }
+
+  __libc_lock_unlock (dirp->lock);
+
+  return ret;
+}
+
+weak_alias (__readdir_r, readdir_r)
+#endif /* _DIRENT_MATCHES_DIRENT64  */
diff --git a/sysdeps/unix/sysv/linux/rewinddir.c b/sysdeps/unix/sysv/linux/rewinddir.c
new file mode 100644
index 0000000..860bfda
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/rewinddir.c
@@ -0,0 +1,41 @@
+/* Copyright (C) 1991-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stddef.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <dirstream.h>
+
+/* Rewind DIRP to the beginning of the directory.  */
+void
+__rewinddir (DIR *dirp)
+{
+#if IS_IN (libc)
+  __libc_lock_lock (dirp->lock);
+#endif
+  (void) __lseek (dirp->fd, (off_t) 0, SEEK_SET);
+  dirp->filepos = 0;
+  dirp->offset = 0;
+  dirp->size = 0;
+  dirp->errcode = 0;
+#if IS_IN (libc)
+  __libc_lock_unlock (dirp->lock);
+#endif
+}
+libc_hidden_def (__rewinddir)
+weak_alias (__rewinddir, rewinddir)
diff --git a/sysdeps/unix/sysv/linux/seekdir.c b/sysdeps/unix/sysv/linux/seekdir.c
new file mode 100644
index 0000000..3c30520
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/seekdir.c
@@ -0,0 +1,35 @@
+/* Copyright (C) 1991-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stddef.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <dirstream.h>
+
+/* Seek to position POS in DIRP.  */
+/* XXX should be __seekdir ? */
+void
+seekdir (DIR *dirp, long int pos)
+{
+  __libc_lock_lock (dirp->lock);
+  (void) __lseek (dirp->fd, pos, SEEK_SET);
+  dirp->size = 0;
+  dirp->offset = 0;
+  dirp->filepos = pos;
+  __libc_lock_unlock (dirp->lock);
+}
diff --git a/sysdeps/unix/sysv/linux/telldir.c b/sysdeps/unix/sysv/linux/telldir.c
new file mode 100644
index 0000000..57d435e
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/telldir.c
@@ -0,0 +1,33 @@
+/* Copyright (C) 1991-2020 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; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dirent.h>
+
+#include <dirstream.h>
+
+/* Return the current position of DIRP.  */
+long int
+telldir (DIR *dirp)
+{
+  long int ret;
+
+  __libc_lock_lock (dirp->lock);
+  ret = dirp->filepos;
+  __libc_lock_unlock (dirp->lock);
+
+  return ret;
+}