[PATCH v4 0/5] Fix opendir regression on some FS

[PATCH v4 0/5] Fix opendir regression on some FS

[Adhemerval Zanella]

Some filesystem might return a non-representable d_off on getdents
call, even if there are few entries in the directories (for instance
ext4, which returns a hash).  This trigger issues with non-LFS readdir
when it finds the first non representable entry, and also for LFS
interface when used along with telldir (which return a 'long int',
while d_off is potentially off64_t).

This patch changes non-LFS readdir so it ignore non representable
entries.  The opendir now uses getdents64, even for non-LFS and uses
a translation buffer to return the getdents entry from the getdents64
buffer.

The second part fixes the broken telldir on non LP64 ABIs, where
returning d_off as stream position might overflow.  For these ABIs,
telldir mantains an internal list that maps the DIR object off64_t
offsets to the returned long int (the function return value).  The
seekdir will then set the correct offset from the internal list using
the telldir as the list key.

One drawback of such strategy is now telldir might silent fail if
seekdir fails to allocate the off64_t map entry, however non-LFS is a
compat interface and overflowed entries currently also does not fully
work even for LFS interface.

I have checked on x86_64-linux-gnu, i686-linux-gnu, and
arm-linux-gnueabihf.

Changes from v3:
  * Rebase against master.
  * Fixed a missing lock unlock on telldir.
  * Renamed tst-seekdir2 to tst-opendir-nolfs and check the opendir
    result against getdents64.

Adhemerval Zanella (5):
  linux: Use getdents64 on non-LFS readdir
  linux: Set internal DIR filepos as off64_t (BZ #23960, BZ #24050)
  linux: Add __readdir64_unlocked
  linux: Add __old_readdir64_unlocked
  linux: Use getdents64 on readdir64 compat implementation

 dirent/tst-scandir.c                        |   6 +-
 dirent/tst-seekdir.c                        |   8 +
 include/dirent.h                            |   1 +
 sysdeps/unix/sysv/linux/Makefile            |   1 +
 sysdeps/unix/sysv/linux/closedir.c          |   7 +
 sysdeps/unix/sysv/linux/dirstream.h         |  11 +-
 sysdeps/unix/sysv/linux/getdents64.c        |  93 ------------
 sysdeps/unix/sysv/linux/olddirent.h         |   4 +-
 sysdeps/unix/sysv/linux/opendir.c           |  37 +++++
 sysdeps/unix/sysv/linux/readdir.c           |  90 +++++++----
 sysdeps/unix/sysv/linux/readdir64.c         | 104 ++++++++++---
 sysdeps/unix/sysv/linux/readdir64_r.c       | 159 +++++---------------
 sysdeps/unix/sysv/linux/rewinddir.c         |   5 +
 sysdeps/unix/sysv/linux/seekdir.c           |  36 ++++-
 sysdeps/unix/sysv/linux/telldir.c           |  45 +++++-
 sysdeps/unix/sysv/linux/telldir.h           |  65 ++++++++
 sysdeps/unix/sysv/linux/tst-opendir-nolfs.c | 146 ++++++++++++++++++
 17 files changed, 539 insertions(+), 279 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/telldir.h
 create mode 100644 sysdeps/unix/sysv/linux/tst-opendir-nolfs.c

-- 
2.34.1

[PATCH v4 1/5] linux: Use getdents64 on non-LFS readdir

[Adhemerval Zanella]

The non-LFS opendir allocates a translation buffer to be used to
return the non-LFS readdir entry.  The obtained dirent64 struct
is translated to the temporary buffer on each readdir call.

Entries that overflow d_off/d_ino and the buffer reallocation failure
(in case of large d_name) are ignored.

Checked on x86_64-linux-gnu and i686-linux-gnu.
---
 dirent/tst-scandir.c                |  6 +-
 sysdeps/unix/sysv/linux/closedir.c  |  4 ++
 sysdeps/unix/sysv/linux/dirstream.h |  5 ++
 sysdeps/unix/sysv/linux/opendir.c   | 21 +++++++
 sysdeps/unix/sysv/linux/readdir.c   | 90 ++++++++++++++++++++---------
 5 files changed, 99 insertions(+), 27 deletions(-)

diff --git a/dirent/tst-scandir.c b/dirent/tst-scandir.c
index 8d87d4dd74..7bc666449e 100644
--- a/dirent/tst-scandir.c
+++ b/dirent/tst-scandir.c
@@ -155,8 +155,12 @@ do_test (void)
     }
   if (n != 6)
     {
+      /* Non-lfs opendir skips entries that can not be represented (for
+	 instance if d_off is not an offset but rather an internal filesystem
+	 representation.  For this case there is no point in continue the
+	 testcase.  */
       printf ("scandir returned %d entries instead of 6\n", n);
-      return 1;
+      return EXIT_UNSUPPORTED;
     }
 
   struct
diff --git a/sysdeps/unix/sysv/linux/closedir.c b/sysdeps/unix/sysv/linux/closedir.c
index f1c2608642..8adbc99892 100644
--- a/sysdeps/unix/sysv/linux/closedir.c
+++ b/sysdeps/unix/sysv/linux/closedir.c
@@ -47,6 +47,10 @@ __closedir (DIR *dirp)
   __libc_lock_fini (dirp->lock);
 #endif
 
+#if !_DIRENT_MATCHES_DIRENT64
+  free (dirp->tbuffer);
+#endif
+
   free ((void *) dirp);
 
   return __close_nocancel (fd);
diff --git a/sysdeps/unix/sysv/linux/dirstream.h b/sysdeps/unix/sysv/linux/dirstream.h
index 3cb313b410..cd8bc56276 100644
--- a/sysdeps/unix/sysv/linux/dirstream.h
+++ b/sysdeps/unix/sysv/linux/dirstream.h
@@ -41,6 +41,11 @@ struct __dirstream
 
     int errcode;		/* Delayed error code.  */
 
+#if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T
+    char *tbuffer;		/* Translation buffer for non-LFS calls.  */
+    size_t tbuffer_size;	/* Size of translation buffer.  */
+#endif
+
     /* 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
diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
index 4336196a4d..2badafd888 100644
--- a/sysdeps/unix/sysv/linux/opendir.c
+++ b/sysdeps/unix/sysv/linux/opendir.c
@@ -120,6 +120,27 @@ __alloc_dir (int fd, bool close_fd, int flags,
       return NULL;
     }
 
+#if !_DIRENT_MATCHES_DIRENT64
+  /* Allocate a translation buffer to use as the returned 'struct direct'
+     for non-LFS 'readdir' calls.
+
+     The initial NAME_MAX size should handle most cases, readdir might expand
+     it if required (i.e for names larger than NAME_MAX).  */
+  enum
+    {
+      tbuffer_size = sizeof (struct dirent) + NAME_MAX + 1
+    };
+  dirp->tbuffer = malloc (tbuffer_size);
+  if (dirp->tbuffer == NULL)
+    {
+      free (dirp);
+      if (close_fd)
+	__close_nocancel_nostatus (fd);
+      return NULL;
+    }
+  dirp->tbuffer_size = tbuffer_size;
+#endif
+
   dirp->fd = fd;
 #if IS_IN (libc)
   __libc_lock_init (dirp->lock);
diff --git a/sysdeps/unix/sysv/linux/readdir.c b/sysdeps/unix/sysv/linux/readdir.c
index 4a4c00ea07..ea4805c03d 100644
--- a/sysdeps/unix/sysv/linux/readdir.c
+++ b/sysdeps/unix/sysv/linux/readdir.c
@@ -21,42 +21,80 @@
 #if !_DIRENT_MATCHES_DIRENT64
 #include <dirstream.h>
 
+/* Translate the DP64 entry to the non-LFS one in the translation buffer
+   at dirstream DS.  Return true is the translation was possible or
+   false if either an internal field can not be represented in the non-LFS
+   entry or if the translation can not be resized.  */
+static bool
+dirstream_entry (struct __dirstream *ds, const struct dirent64 *dp64)
+{
+  if (!in_off_t_range (dp64->d_off) || !in_ino_t_range (dp64->d_ino))
+    return false;
+
+  /* Expand the translation buffer to hold the new name size.  */
+  size_t new_reclen = sizeof (struct dirent)
+		    + dp64->d_reclen - offsetof (struct dirent64, d_name);
+  if (new_reclen > ds->tbuffer_size)
+    {
+      char *newbuffer = realloc (ds->tbuffer, new_reclen);
+      if (newbuffer == NULL)
+	return false;
+      ds->tbuffer = newbuffer;
+      ds->tbuffer_size = new_reclen;
+    }
+
+  struct dirent *dp = (struct dirent *) ds->tbuffer;
+
+  dp->d_off = dp64->d_off;
+  dp->d_ino = dp64->d_ino;
+  dp->d_reclen = new_reclen;
+  dp->d_type = dp64->d_type;
+  memcpy (dp->d_name, dp64->d_name,
+	  dp64->d_reclen - offsetof (struct dirent64, d_name));
+
+  return true;
+}
+
 /* Read a directory entry from DIRP.  */
 struct dirent *
 __readdir_unlocked (DIR *dirp)
 {
-  struct dirent *dp;
   int saved_errno = errno;
 
-  if (dirp->offset >= dirp->size)
+  while (1)
     {
-      /* 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)
+      if (dirp->offset >= dirp->size)
+	{
+	  /* We've emptied out our buffer.  Refill it.  */
+	  ssize_t bytes = __getdents64 (dirp->fd, dirp->data,
+					dirp->allocation);
+	  if (bytes <= 0)
+	    {
+	      /* Linux may fail with ENOENT on some file systems if the
+		 directory inode is marked as dead (deleted).  POSIX
+		 treats this as a regular end-of-directory condition, so
+		 do not set errno in that case, to indicate success.  */
+	      if (bytes < 0 && errno == ENOENT)
+		__set_errno (saved_errno);
+	      return NULL;
+	    }
+	  dirp->size = bytes;
+
+ 	  /* Reset the offset into the buffer.  */
+	  dirp->offset = 0;
+ 	}
+
+      struct dirent64 *dp64 = (struct dirent64 *) &dirp->data[dirp->offset];
+      dirp->offset += dp64->d_reclen;
+
+      /* Skip entries which might overflow d_off/d_ino or if the translation
+	 buffer can not be resized.  */
+      if (dirstream_entry (dirp, dp64))
 	{
-	  /* Linux may fail with ENOENT on some file systems if the
-	     directory inode is marked as dead (deleted).  POSIX
-	     treats this as a regular end-of-directory condition, so
-	     do not set errno in that case, to indicate success.  */
-	  if (bytes == 0 || errno == ENOENT)
-	    __set_errno (saved_errno);
-	  return NULL;
+          dirp->filepos = dp64->d_off;
+	  return (struct dirent *) dirp->tbuffer;
 	}
-      dirp->size = (size_t) bytes;
-
-      /* Reset the offset into the buffer.  */
-      dirp->offset = 0;
     }
-
-  dp = (struct dirent *) &dirp->data[dirp->offset];
-  dirp->offset += dp->d_reclen;
-  dirp->filepos = dp->d_off;
-
-  return dp;
 }
 
 struct dirent *
-- 
2.34.1

[PATCH v4 2/5] linux: Set internal DIR filepos as off64_t (BZ #23960, BZ #24050)

[Adhemerval Zanella]

It allows to obtain the expected entry offset on telldir and set
it correctly on seekdir on platforms where long int is smaller
than off64_t.

On such cases telldir mantains an internal list that maps the DIR
object off64_t offsets to the returned long int (the function
return value).  The seekdir will then set the correct offset from
the internal list using the telldir as the list key.

It also removes the overflow check on readdir and the returned value
will be truncated by the non-LFS off_t size.  As Joseph has noted
in BZ #23960 comment #22, d_off is an opaque value and since
telldir/seekdir works regardless of the returned dirent d_off value.

Finally it removes the requirement to check for overflow values on
telldir (BZ #24050).

Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc-linux-gnu,
and arm-linux-gnueabihf.
---
 dirent/tst-seekdir.c                        |   8 ++
 sysdeps/unix/sysv/linux/Makefile            |   1 +
 sysdeps/unix/sysv/linux/closedir.c          |   3 +
 sysdeps/unix/sysv/linux/dirstream.h         |   6 +-
 sysdeps/unix/sysv/linux/opendir.c           |   3 +
 sysdeps/unix/sysv/linux/rewinddir.c         |   5 +
 sysdeps/unix/sysv/linux/seekdir.c           |  36 ++++-
 sysdeps/unix/sysv/linux/telldir.c           |  45 +++++-
 sysdeps/unix/sysv/linux/telldir.h           |  65 +++++++++
 sysdeps/unix/sysv/linux/tst-opendir-nolfs.c | 146 ++++++++++++++++++++
 10 files changed, 310 insertions(+), 8 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/telldir.h
 create mode 100644 sysdeps/unix/sysv/linux/tst-opendir-nolfs.c

diff --git a/dirent/tst-seekdir.c b/dirent/tst-seekdir.c
index dcdd699b09..222a83407a 100644
--- a/dirent/tst-seekdir.c
+++ b/dirent/tst-seekdir.c
@@ -41,6 +41,14 @@ do_test (void)
       if (i == 400)
 	break;
     }
+  if (i != 400)
+    {
+      /* Non-lfs opendir skips entries that can not be represented (for
+	 instance if d_off is not an offset but rather an internal filesystem
+	 representation.  For this case there is no point in continue the
+	 testcase.  */
+      return 77;
+    }
 
   printf ("going back past 4-th entry...\n");
 
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index f298878e8f..33708f910b 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -465,6 +465,7 @@ ifeq ($(subdir),dirent)
 sysdep_routines += getdirentries getdirentries64
 tests += \
   tst-getdents64 \
+  tst-opendir-nolfs \
   tst-readdir64-compat \
   # tests
 endif # $(subdir) == dirent
diff --git a/sysdeps/unix/sysv/linux/closedir.c b/sysdeps/unix/sysv/linux/closedir.c
index 8adbc99892..c637e022fe 100644
--- a/sysdeps/unix/sysv/linux/closedir.c
+++ b/sysdeps/unix/sysv/linux/closedir.c
@@ -50,6 +50,9 @@ __closedir (DIR *dirp)
 #if !_DIRENT_MATCHES_DIRENT64
   free (dirp->tbuffer);
 #endif
+#ifndef __LP64__
+  dirstream_loc_clear (&dirp->locs);
+#endif
 
   free ((void *) dirp);
 
diff --git a/sysdeps/unix/sysv/linux/dirstream.h b/sysdeps/unix/sysv/linux/dirstream.h
index cd8bc56276..5fa07d3d66 100644
--- a/sysdeps/unix/sysv/linux/dirstream.h
+++ b/sysdeps/unix/sysv/linux/dirstream.h
@@ -21,6 +21,7 @@
 #include <sys/types.h>
 
 #include <libc-lock.h>
+#include <telldir.h>
 
 /* Directory stream type.
 
@@ -37,7 +38,7 @@ struct __dirstream
     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.  */
+    off64_t filepos;		/* Position of next entry to read.  */
 
     int errcode;		/* Delayed error code.  */
 
@@ -45,6 +46,9 @@ struct __dirstream
     char *tbuffer;		/* Translation buffer for non-LFS calls.  */
     size_t tbuffer_size;	/* Size of translation buffer.  */
 #endif
+#ifndef __LP64__
+    struct dirstream_loc_t locs; /* off64_t to long int map for telldir.  */
+#endif
 
     /* Directory block.  We must make sure that this block starts
        at an address that is aligned adequately enough to store
diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
index 2badafd888..01c05f0c6c 100644
--- a/sysdeps/unix/sysv/linux/opendir.c
+++ b/sysdeps/unix/sysv/linux/opendir.c
@@ -150,6 +150,9 @@ __alloc_dir (int fd, bool close_fd, int flags,
   dirp->offset = 0;
   dirp->filepos = 0;
   dirp->errcode = 0;
+#ifndef __LP64__
+  dirstream_loc_init (&dirp->locs);
+#endif
 
   return dirp;
 }
diff --git a/sysdeps/unix/sysv/linux/rewinddir.c b/sysdeps/unix/sysv/linux/rewinddir.c
index c0fb7aa765..1b158a584f 100644
--- a/sysdeps/unix/sysv/linux/rewinddir.c
+++ b/sysdeps/unix/sysv/linux/rewinddir.c
@@ -33,6 +33,11 @@ __rewinddir (DIR *dirp)
   dirp->offset = 0;
   dirp->size = 0;
   dirp->errcode = 0;
+
+#ifndef __LP64__
+  dirstream_loc_clear (&dirp->locs);
+#endif
+
 #if IS_IN (libc)
   __libc_lock_unlock (dirp->lock);
 #endif
diff --git a/sysdeps/unix/sysv/linux/seekdir.c b/sysdeps/unix/sysv/linux/seekdir.c
index 939ccc4447..3494ea3d78 100644
--- a/sysdeps/unix/sysv/linux/seekdir.c
+++ b/sysdeps/unix/sysv/linux/seekdir.c
@@ -22,14 +22,40 @@
 #include <dirstream.h>
 
 /* Seek to position POS in DIRP.  */
-/* XXX should be __seekdir ? */
 void
 seekdir (DIR *dirp, long int pos)
 {
+  off64_t filepos;
+
   __libc_lock_lock (dirp->lock);
-  (void) __lseek (dirp->fd, pos, SEEK_SET);
-  dirp->size = 0;
-  dirp->offset = 0;
-  dirp->filepos = pos;
+
+#ifndef __LP64__
+  union dirstream_packed dsp = { .l = pos };
+  if (dsp.p.is_packed == 1)
+    filepos = dsp.p.info;
+  else
+    {
+      size_t index = dsp.p.info;
+
+      if (index >= dirstream_loc_size (&dirp->locs))
+	{
+	  __libc_lock_unlock (dirp->lock);
+	  return;
+	}
+      struct dirstream_loc *loc = dirstream_loc_at (&dirp->locs, index);
+      filepos = loc->filepos;
+    }
+#else
+  filepos = pos;
+#endif
+
+  if (dirp->filepos != filepos)
+    {
+      __lseek64 (dirp->fd, filepos, SEEK_SET);
+      dirp->filepos = filepos;
+      dirp->offset = 0;
+      dirp->size = 0;
+    }
+
   __libc_lock_unlock (dirp->lock);
 }
diff --git a/sysdeps/unix/sysv/linux/telldir.c b/sysdeps/unix/sysv/linux/telldir.c
index 1e5c129e9f..c5a0301a98 100644
--- a/sysdeps/unix/sysv/linux/telldir.c
+++ b/sysdeps/unix/sysv/linux/telldir.c
@@ -18,16 +18,57 @@
 #include <dirent.h>
 
 #include <dirstream.h>
+#include <telldir.h>
 
 /* Return the current position of DIRP.  */
 long int
 telldir (DIR *dirp)
 {
   long int ret;
-
   __libc_lock_lock (dirp->lock);
+
+#ifndef __LP64__
+  /* If the directory position fits in the packet structure, returns it.
+     Otherwise, check if the position is already been recorded in the
+     dynamic array.  If not, add the new record.  */
+
+  union dirstream_packed dsp;
+
+  if (dirp->filepos < (1U << 31))
+    {
+      dsp.p.is_packed = 1;
+      dsp.p.info = dirp->filepos;
+    }
+  else
+    {
+      dsp.l = -1;
+
+      size_t i;
+      for (i = 0; i < dirstream_loc_size (&dirp->locs); i++)
+	{
+	  struct dirstream_loc *loc = dirstream_loc_at (&dirp->locs, i);
+	  if (loc->filepos == dirp->filepos)
+	    break;
+	}
+      if (i == dirstream_loc_size (&dirp->locs))
+	{
+	  dirstream_loc_add (&dirp->locs,
+			     (struct dirstream_loc) { dirp->filepos });
+	  if (!dirstream_loc_has_failed (&dirp->locs))
+	    {
+	      dsp.p.is_packed = 0;
+	      /* This assignment might overflow, however most likely ENOMEM
+		 would happen long before.  */
+	      dsp.p.info = i;
+	    }
+	}
+    }
+
+  ret = dsp.l;
+
+#else
   ret = dirp->filepos;
+#endif
   __libc_lock_unlock (dirp->lock);
-
   return ret;
 }
diff --git a/sysdeps/unix/sysv/linux/telldir.h b/sysdeps/unix/sysv/linux/telldir.h
new file mode 100644
index 0000000000..1ae8410804
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/telldir.h
@@ -0,0 +1,65 @@
+/* Linux internal telldir definitions.
+   Copyright (C) 2023 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 _TELLDIR_H
+#define _TELLDIR_H 1
+
+#ifndef __LP64__
+
+/* On platforms where 'long int' is smaller than 'off64_t' this is how the
+   returned value is encoded and returned by 'telldir'.  If the directory
+   offset can be enconded in 31 bits it is returned in the 'info' member
+   with 'is_packed' set to 1.
+
+   Otherwise, the 'info' member describes an index in a dynamic array at
+   'DIR' structure.  */
+
+union dirstream_packed
+{
+  long int l;
+  struct
+  {
+    unsigned long is_packed:1;
+    unsigned long info:31;
+  } p;
+};
+
+_Static_assert (sizeof (long int) == sizeof (union dirstream_packed),
+		"sizeof (long int) != sizeof (union dirstream_packed)");
+
+/* telldir maintains a list of offsets that describe the obtained diretory
+   position if it can fit this information in the returned 'dirstream_packed'
+   struct.  */
+
+struct dirstream_loc
+{
+  off64_t filepos;
+};
+
+# define DYNARRAY_STRUCT  dirstream_loc_t
+# define DYNARRAY_ELEMENT struct dirstream_loc
+# define DYNARRAY_PREFIX  dirstream_loc_
+# include <malloc/dynarray-skeleton.c>
+#else
+
+_Static_assert (sizeof (long int) == sizeof (off64_t),
+		"sizeof (long int) != sizeof (off64_t)");
+
+#endif /* __LP64__  */
+
+#endif /* _TELLDIR_H  */
diff --git a/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c b/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c
new file mode 100644
index 0000000000..52e18171a7
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c
@@ -0,0 +1,146 @@
+/* Check multiple telldir and seekdir.
+   Copyright (C) 2023 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/xunistd.h>
+
+/* Some filesystems returns an arbitrary value for d_off direnty entry (ext4
+   for instance, where the value is an internal hash key).  The idea of create
+   a large number of file is to try trigger a overflow d_off value in a entry
+   to check if telldir/seekdir does work corretly in such case.  */
+static const char *dirname;
+/* The 2 extra files are '.' and '..'.  */
+static const size_t nfiles = (1<<14) + 2;
+
+static inline bool
+in_ino_t_range (ino64_t v)
+{
+  ino_t s = v;
+  return s == v;
+}
+
+static inline bool
+in_off_t_range (off64_t v)
+{
+  off_t s = v;
+  return s == v;
+}
+
+static void
+do_prepare (int argc, char *argv[])
+{
+  dirname = support_create_temp_directory ("tst-opendir-nolfs-");
+
+  for (size_t i = 0; i < nfiles - 2; i++)
+    {
+      int fd = create_temp_file_in_dir ("tempfile.", dirname, NULL);
+      TEST_VERIFY_EXIT (fd > 0);
+      close (fd);
+    }
+}
+#define PREPARE do_prepare
+
+static int
+do_test (void)
+{
+  DIR *dirp = opendir (dirname);
+  TEST_VERIFY_EXIT (dirp != NULL);
+
+  long int *tdirp = xmalloc (nfiles * sizeof (long int));
+  struct dirent **ddirp = xmalloc (nfiles * sizeof (struct dirent *));
+
+  /* For non-LFS, the entry is skipped if it can not be converted.  */
+  int count = 0;
+  for (; count < nfiles; count++)
+    {
+      tdirp[count] = telldir (dirp);
+      struct dirent *dp = readdir (dirp);
+      if (dp == NULL)
+	break;
+      ddirp[count] = xmalloc (dp->d_reclen);
+      memcpy (ddirp[count], dp, dp->d_reclen);
+    }
+
+  closedir (dirp);
+
+  /* Check against the getdents64 syscall.  */
+  int fd = xopen (dirname, O_RDONLY | O_DIRECTORY, 0);
+  int i = 0;
+  while (true)
+    {
+      struct
+      {
+	char buffer[1024];
+	struct dirent64 pad;
+      } data;
+
+      ssize_t ret = getdents64 (fd, &data.buffer, sizeof (data.buffer));
+      if (ret < 0)
+	FAIL_EXIT1 ("getdents64: %m");
+      if (ret == 0)
+	break;
+
+      char *current = data.buffer;
+      char *end = data.buffer + ret;
+      while (current != end)
+	{
+	  struct dirent64 entry;
+          memcpy (&entry, current, sizeof (entry));
+          /* Truncate overlong strings.  */
+          entry.d_name[sizeof (entry.d_name) - 1] = '\0';
+          TEST_VERIFY (strlen (entry.d_name) < sizeof (entry.d_name) - 1);
+
+	  if (in_ino_t_range (entry.d_ino) && in_off_t_range (entry.d_off))
+	    {
+	      TEST_COMPARE_STRING (entry.d_name, ddirp[i]->d_name);
+	      TEST_COMPARE (entry.d_ino, ddirp[i]->d_ino);
+	      TEST_COMPARE (entry.d_off, ddirp[i]->d_off);
+	      TEST_COMPARE (entry.d_type, ddirp[i]->d_type);
+
+	      /* Offset zero is reserved for the first entry.  */
+	      TEST_VERIFY (entry.d_off != 0);
+
+	      TEST_VERIFY_EXIT (entry.d_reclen <= end - current);
+	      i++;
+	    }
+
+	  current += entry.d_reclen;
+	}
+    }
+
+  /* direntries_read has been called more than once.  */
+  TEST_COMPARE (count, i);
+
+  free (tdirp);
+  for (int i = 0; i < count; i++)
+    free (ddirp[i]);
+  free (ddirp);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.34.1

[PATCH v4 3/5] linux: Add __readdir64_unlocked

[Adhemerval Zanella]

And use it on readdir_r implementation.

Checked on i686-linux-gnu.
---
 include/dirent.h                      |  1 +
 sysdeps/unix/sysv/linux/readdir64.c   | 20 +++++--
 sysdeps/unix/sysv/linux/readdir64_r.c | 80 ++++++---------------------
 3 files changed, 33 insertions(+), 68 deletions(-)

diff --git a/include/dirent.h b/include/dirent.h
index d7567f5e86..0c6715d0e4 100644
--- a/include/dirent.h
+++ b/include/dirent.h
@@ -21,6 +21,7 @@ extern DIR *__fdopendir (int __fd) attribute_hidden;
 extern int __closedir (DIR *__dirp) attribute_hidden;
 extern struct dirent *__readdir (DIR *__dirp) attribute_hidden;
 extern struct dirent *__readdir_unlocked (DIR *__dirp) attribute_hidden;
+extern struct dirent64 *__readdir64_unlocked (DIR *__dirp) attribute_hidden;
 extern struct dirent64 *__readdir64 (DIR *__dirp);
 libc_hidden_proto (__readdir64)
 extern int __readdir_r (DIR *__dirp, struct dirent *__entry,
diff --git a/sysdeps/unix/sysv/linux/readdir64.c b/sysdeps/unix/sysv/linux/readdir64.c
index db1c6214d8..2327511736 100644
--- a/sysdeps/unix/sysv/linux/readdir64.c
+++ b/sysdeps/unix/sysv/linux/readdir64.c
@@ -28,15 +28,11 @@
 
 /* Read a directory entry from DIRP.  */
 struct dirent64 *
-__readdir64 (DIR *dirp)
+__readdir64_unlocked (DIR *dirp)
 {
   struct dirent64 *dp;
   int saved_errno = errno;
 
-#if IS_IN (libc)
-  __libc_lock_lock (dirp->lock);
-#endif
-
   if (dirp->offset >= dirp->size)
     {
       /* We've emptied out our buffer.  Refill it.  */
@@ -68,6 +64,20 @@ __readdir64 (DIR *dirp)
   dirp->offset += dp->d_reclen;
   dirp->filepos = dp->d_off;
 
+  return dp;
+}
+
+struct dirent64 *
+__readdir64 (DIR *dirp)
+{
+  struct dirent64 *dp;
+
+#if IS_IN (libc)
+  __libc_lock_lock (dirp->lock);
+#endif
+
+  dp = __readdir64_unlocked (dirp);
+
 #if IS_IN (libc)
   __libc_lock_unlock (dirp->lock);
 #endif
diff --git a/sysdeps/unix/sysv/linux/readdir64_r.c b/sysdeps/unix/sysv/linux/readdir64_r.c
index 285dc99509..5ae099bde7 100644
--- a/sysdeps/unix/sysv/linux/readdir64_r.c
+++ b/sysdeps/unix/sysv/linux/readdir64_r.c
@@ -32,89 +32,43 @@ __readdir64_r (DIR *dirp, struct dirent64 *entry, struct dirent64 **result)
 {
   struct dirent64 *dp;
   size_t reclen;
-  const int saved_errno = errno;
-  int ret;
 
   __libc_lock_lock (dirp->lock);
-
-  do
+  while (1)
     {
-      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];
+      dp = __readdir64_unlocked (dirp);
+      if (dp == NULL)
+	break;
 
       reclen = dp->d_reclen;
+      if (reclen <= offsetof (struct dirent64, d_name) + NAME_MAX + 1)
+	break;
 
-      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)
 	{
-	  /* 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;
-	    }
+	  reclen = offsetof (struct dirent64, d_name) + namelen + 1;
+	  break;
 	}
 
-      /* Skip deleted and ignored files.  */
+      /* The name is too long.  Ignore this file.  */
+      dirp->errcode = ENAMETOOLONG;
+      dp->d_ino = 0;
     }
-  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;
-    }
+    *result = NULL;
 
   __libc_lock_unlock (dirp->lock);
 
-  return ret;
+  return dp != NULL ? 0 : dirp->errcode;
 }
 
 
-- 
2.34.1

[PATCH v4 4/5] linux: Add __old_readdir64_unlocked

[Adhemerval Zanella]

And use it __old_readdir64_r.

Checked on i686-linux-gnu.
---
 sysdeps/unix/sysv/linux/olddirent.h   |  2 +
 sysdeps/unix/sysv/linux/readdir64.c   | 24 +++++---
 sysdeps/unix/sysv/linux/readdir64_r.c | 79 ++++++---------------------
 3 files changed, 35 insertions(+), 70 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/olddirent.h b/sysdeps/unix/sysv/linux/olddirent.h
index 9789ffae07..cde95e192e 100644
--- a/sysdeps/unix/sysv/linux/olddirent.h
+++ b/sysdeps/unix/sysv/linux/olddirent.h
@@ -32,6 +32,8 @@ struct __old_dirent64
 /* Now define the internal interfaces.  */
 extern struct __old_dirent64 *__old_readdir64 (DIR *__dirp);
 libc_hidden_proto (__old_readdir64);
+extern struct __old_dirent64 *__old_readdir64_unlocked (DIR *__dirp)
+        attribute_hidden;
 extern int __old_readdir64_r (DIR *__dirp, struct __old_dirent64 *__entry,
 			  struct __old_dirent64 **__result);
 extern __ssize_t __old_getdents64 (int __fd, char *__buf, size_t __nbytes)
diff --git a/sysdeps/unix/sysv/linux/readdir64.c b/sysdeps/unix/sysv/linux/readdir64.c
index 2327511736..b901071aa7 100644
--- a/sysdeps/unix/sysv/linux/readdir64.c
+++ b/sysdeps/unix/sysv/linux/readdir64.c
@@ -104,15 +104,11 @@ versioned_symbol (libc, __readdir64, readdir64, GLIBC_2_2);
 
 attribute_compat_text_section
 struct __old_dirent64 *
-__old_readdir64 (DIR *dirp)
+__old_readdir64_unlocked (DIR *dirp)
 {
   struct __old_dirent64 *dp;
   int saved_errno = errno;
 
-#if IS_IN (libc)
-  __libc_lock_lock (dirp->lock);
-#endif
-
   if (dirp->offset >= dirp->size)
     {
       /* We've emptied out our buffer.  Refill it.  */
@@ -129,9 +125,6 @@ __old_readdir64 (DIR *dirp)
 	     do not set errno in that case, to indicate success.  */
 	  if (bytes == 0 || errno == ENOENT)
 	    __set_errno (saved_errno);
-#if IS_IN (libc)
-	  __libc_lock_unlock (dirp->lock);
-#endif
 	  return NULL;
 	}
       dirp->size = (size_t) bytes;
@@ -144,6 +137,21 @@ __old_readdir64 (DIR *dirp)
   dirp->offset += dp->d_reclen;
   dirp->filepos = dp->d_off;
 
+  return dp;
+}
+
+attribute_compat_text_section
+struct __old_dirent64 *
+__old_readdir64 (DIR *dirp)
+{
+  struct __old_dirent64 *dp;
+
+#if IS_IN (libc)
+  __libc_lock_lock (dirp->lock);
+#endif
+
+  dp = __old_readdir64_unlocked (dirp);
+
 #if IS_IN (libc)
   __libc_lock_unlock (dirp->lock);
 #endif
diff --git a/sysdeps/unix/sysv/linux/readdir64_r.c b/sysdeps/unix/sysv/linux/readdir64_r.c
index 5ae099bde7..b499388de7 100644
--- a/sysdeps/unix/sysv/linux/readdir64_r.c
+++ b/sysdeps/unix/sysv/linux/readdir64_r.c
@@ -91,89 +91,44 @@ __old_readdir64_r (DIR *dirp, struct __old_dirent64 *entry,
 {
   struct __old_dirent64 *dp;
   size_t reclen;
-  const int saved_errno = errno;
-  int ret;
 
   __libc_lock_lock (dirp->lock);
 
-  do
+  while (1)
     {
-      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];
+      dp = __old_readdir64_unlocked (dirp);
+      if (dp == NULL)
+	break;
 
       reclen = dp->d_reclen;
+      if (reclen <= offsetof (struct __old_dirent64, d_name) + NAME_MAX + 1)
+	break;
 
-      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)
 	{
-	  /* 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;
-	    }
+	  reclen = offsetof (struct dirent64, d_name) + namelen + 1;
+	  break;
 	}
 
-      /* Skip deleted and ignored files.  */
+      /* The name is too long.  Ignore this file.  */
+      dirp->errcode = ENAMETOOLONG;
+      dp->d_ino = 0;
     }
-  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;
-    }
+    *result = NULL;
 
   __libc_lock_unlock (dirp->lock);
 
-  return ret;
+  return dp != NULL ? 0 : dirp->errcode;
 }
 
 compat_symbol (libc, __old_readdir64_r, readdir64_r, GLIBC_2_1);
-- 
2.34.1

[PATCH v4 5/5] linux: Use getdents64 on readdir64 compat implementation

[Adhemerval Zanella]

It uses a similar strategy from the non-LFS readdir that also
uses getdents64 internally and uses a translation buffer to return
the compat readdir64 entry.

It allows to remove __old_getdents64.

Checked on i686-linux-gnu.
---
 sysdeps/unix/sysv/linux/getdents64.c | 93 ----------------------------
 sysdeps/unix/sysv/linux/olddirent.h  |  2 -
 sysdeps/unix/sysv/linux/opendir.c    | 15 ++++-
 sysdeps/unix/sysv/linux/readdir64.c  | 62 +++++++++++++++----
 4 files changed, 64 insertions(+), 108 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/getdents64.c b/sysdeps/unix/sysv/linux/getdents64.c
index 01c3517deb..db299864ed 100644
--- a/sysdeps/unix/sysv/linux/getdents64.c
+++ b/sysdeps/unix/sysv/linux/getdents64.c
@@ -36,97 +36,4 @@ weak_alias (__getdents64, getdents64)
 
 #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>
-#  include <unistd.h>
-
-static ssize_t
-handle_overflow (int fd, __off64_t offset, ssize_t count)
-{
-  /* If this is the first entry in the buffer, we can report the
-     error.  */
-  if (offset == 0)
-    {
-      __set_errno (EOVERFLOW);
-      return -1;
-    }
-
-  /* Otherwise, seek to the overflowing entry, so that the next call
-     will report the error, and return the data read so far.  */
-  if (__lseek64 (fd, offset, SEEK_SET) != 0)
-    return -1;
-  return count;
-}
-
-ssize_t
-__old_getdents64 (int fd, char *buf, size_t nbytes)
-{
-  /* We do not move the individual directory entries.  This is only
-     possible if the target type (struct __old_dirent64) is smaller
-     than the source type.  */
-  _Static_assert (offsetof (struct __old_dirent64, d_name)
-		  <= offsetof (struct dirent64, d_name),
-		  "__old_dirent64 is larger than dirent64");
-  _Static_assert (__alignof__ (struct __old_dirent64)
-		  <= __alignof__ (struct dirent64),
-		  "alignment of __old_dirent64 is larger than dirent64");
-
-  ssize_t retval = INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
-  if (retval > 0)
-    {
-      /* This is the marker for the first entry.  Offset 0 is reserved
-	 for the first entry (see rewinddir).  Here, we use it as a
-	 marker for the first entry in the buffer.  We never actually
-	 seek to offset 0 because handle_overflow reports the error
-	 directly, so it does not matter that the offset is incorrect
-	 if entries have been read from the descriptor before (so that
-	 the descriptor is not actually at offset 0).  */
-      __off64_t previous_offset = 0;
-
-      char *p = buf;
-      char *end = buf + retval;
-      while (p < end)
-	{
-	  struct dirent64 *source = (struct dirent64 *) p;
-
-	  /* Copy out the fixed-size data.  */
-	  __ino_t ino = source->d_ino;
-	  __off64_t offset = source->d_off;
-	  unsigned int reclen = source->d_reclen;
-	  unsigned char type = source->d_type;
-
-	  /* Check for ino_t overflow.  */
-	  if (__glibc_unlikely (ino != source->d_ino))
-	    return handle_overflow (fd, previous_offset, p - buf);
-
-	  /* Convert to the target layout.  Use a separate struct and
-	     memcpy to side-step aliasing issues.  */
-	  struct __old_dirent64 result;
-	  result.d_ino = ino;
-	  result.d_off = offset;
-	  result.d_reclen = reclen;
-	  result.d_type = type;
-
-	  /* Write the fixed-sized part of the result to the
-	     buffer.  */
-	  size_t result_name_offset = offsetof (struct __old_dirent64, d_name);
-	  memcpy (p, &result, result_name_offset);
-
-	  /* Adjust the position of the name if necessary.  Copy
-	     everything until the end of the record, including the
-	     terminating NUL byte.  */
-	  if (result_name_offset != offsetof (struct dirent64, d_name))
-	    memmove (p + result_name_offset, source->d_name,
-		     reclen - offsetof (struct dirent64, d_name));
-
-	  p += reclen;
-	  previous_offset = offset;
-	}
-     }
-  return retval;
-}
-# endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)  */
 #endif /* _DIRENT_MATCHES_DIRENT64  */
diff --git a/sysdeps/unix/sysv/linux/olddirent.h b/sysdeps/unix/sysv/linux/olddirent.h
index cde95e192e..2d682a6919 100644
--- a/sysdeps/unix/sysv/linux/olddirent.h
+++ b/sysdeps/unix/sysv/linux/olddirent.h
@@ -36,8 +36,6 @@ extern struct __old_dirent64 *__old_readdir64_unlocked (DIR *__dirp)
         attribute_hidden;
 extern int __old_readdir64_r (DIR *__dirp, struct __old_dirent64 *__entry,
 			  struct __old_dirent64 **__result);
-extern __ssize_t __old_getdents64 (int __fd, char *__buf, size_t __nbytes)
-	attribute_hidden;
 int __old_scandir64 (const char * __dir,
 		     struct __old_dirent64 *** __namelist,
 		     int (*__selector) (const struct __old_dirent64 *),
diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
index 01c05f0c6c..5bd45928e7 100644
--- a/sysdeps/unix/sysv/linux/opendir.c
+++ b/sysdeps/unix/sysv/linux/opendir.c
@@ -23,6 +23,11 @@
 
 #include <not-cancel.h>
 
+#include <shlib-compat.h>
+#if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
+# include <olddirent.h>
+#endif
+
 enum {
   opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC
 };
@@ -128,7 +133,15 @@ __alloc_dir (int fd, bool close_fd, int flags,
      it if required (i.e for names larger than NAME_MAX).  */
   enum
     {
-      tbuffer_size = sizeof (struct dirent) + NAME_MAX + 1
+      tbuffer_size =
+# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
+      /* This is used on compat readdir64.  */
+		     MAX (sizeof (struct dirent),
+			  sizeof (struct __old_dirent64))
+# else
+		     sizeof (struct dirent)
+# endif
+                     + NAME_MAX + 1
     };
   dirp->tbuffer = malloc (tbuffer_size);
   if (dirp->tbuffer == NULL)
diff --git a/sysdeps/unix/sysv/linux/readdir64.c b/sysdeps/unix/sysv/linux/readdir64.c
index b901071aa7..7651eeb08e 100644
--- a/sysdeps/unix/sysv/linux/readdir64.c
+++ b/sysdeps/unix/sysv/linux/readdir64.c
@@ -102,21 +102,52 @@ versioned_symbol (libc, __readdir64, readdir64, GLIBC_2_2);
 # if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
 #  include <olddirent.h>
 
+/* Translate the DP64 entry to the old LFS one in the translation buffer
+   at dirstream DS.  Return true is the translation was possible or
+   false if either an internal fields can be represented in the non-LFS
+   entry or if the translation can not be resized.  */
+static bool
+dirstream_old_entry (struct __dirstream *ds, const struct dirent64 *dp64)
+{
+  /* Check for overflow.  */
+  ino_t d_ino = dp64->d_ino;
+  if (d_ino != dp64->d_ino)
+    return false;
+
+  /* Expand the translation buffer to hold the new namesize.  */
+  size_t d_reclen = sizeof (struct __old_dirent64)
+		    + dp64->d_reclen - offsetof (struct dirent64, d_name);
+  if (d_reclen > ds->tbuffer_size)
+    {
+      char *newbuffer = realloc (ds->tbuffer, d_reclen);
+      if (newbuffer == NULL)
+	return false;
+      ds->tbuffer = newbuffer;
+      ds->tbuffer_size = d_reclen;
+    }
+
+  struct __old_dirent64 *olddp64 = (struct __old_dirent64 *) ds->tbuffer;
+
+  olddp64->d_off = dp64->d_off;
+  olddp64->d_ino = dp64->d_ino;
+  olddp64->d_reclen = dp64->d_reclen;
+  olddp64->d_type = dp64->d_type;
+  memcpy (olddp64->d_name, dp64->d_name,
+	  dp64->d_reclen - offsetof (struct dirent64, d_name));
+
+  return true;
+}
+
 attribute_compat_text_section
 struct __old_dirent64 *
 __old_readdir64_unlocked (DIR *dirp)
 {
-  struct __old_dirent64 *dp;
-  int saved_errno = errno;
+  const int saved_errno = errno;
 
   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);
+      ssize_t bytes = __getdents64 (dirp->fd, dirp->data, dirp->allocation);
       if (bytes <= 0)
 	{
 	  /* Linux may fail with ENOENT on some file systems if the
@@ -127,17 +158,24 @@ __old_readdir64_unlocked (DIR *dirp)
 	    __set_errno (saved_errno);
 	  return NULL;
 	}
-      dirp->size = (size_t) bytes;
+      dirp->size = bytes;
 
       /* Reset the offset into the buffer.  */
       dirp->offset = 0;
     }
 
-  dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
-  dirp->offset += dp->d_reclen;
-  dirp->filepos = dp->d_off;
+  struct dirent64 *dp64 = (struct dirent64 *) &dirp->data[dirp->offset];
+  dirp->offset += dp64->d_reclen;
 
-  return dp;
+  /* Skip entries which might overflow d_ino or for memory allocation failure
+     in case of large file names.  */
+  if (dirstream_old_entry (dirp, dp64))
+    {
+      dirp->filepos = dp64->d_off;
+      return (struct __old_dirent64 *) dirp->tbuffer;
+    }
+
+  return NULL;
 }
 
 attribute_compat_text_section
-- 
2.34.1

Re: [PATCH v4 0/5] Fix opendir regression on some FS

[Florian Weimer]

* Adhemerval Zanella via Libc-alpha:

> One drawback of such strategy is now telldir might silent fail if
> seekdir fails to allocate the off64_t map entry, however non-LFS is a
> compat interface and overflowed entries currently also does not fully
> work even for LFS interface.

Could we please fix this by allocating an entry ahead of time, in
readdir?

Thanks,
Florian

Re: [PATCH v4 2/5] linux: Set internal DIR filepos as off64_t (BZ #23960, BZ #24050)

[Florian Weimer]

* Adhemerval Zanella via Libc-alpha:

> index 8adbc99892..c637e022fe 100644
> --- a/sysdeps/unix/sysv/linux/closedir.c
> +++ b/sysdeps/unix/sysv/linux/closedir.c
> @@ -50,6 +50,9 @@ __closedir (DIR *dirp)
>  #if !_DIRENT_MATCHES_DIRENT64
>    free (dirp->tbuffer);
>  #endif
> +#ifndef __LP64__
> +  dirstream_loc_clear (&dirp->locs);
> +#endif

Maybe

/* The telldir function returns long int, which may not be
   large enough to store off64_t values.  In this case, translation is
   needed.  */
#define DIRENT_OFFSET_TRANSLATION (LONG_WIDTH < 64)

and then:

#if DIRENT_OFFSET_TRANSLATION

?  __LP64__ doesn't look right for Morello.

Thanks,
Florian

Re: [PATCH v4 1/5] linux: Use getdents64 on non-LFS readdir

[Paul Eggert]

On 1/26/23 11:29, Adhemerval Zanella via Libc-alpha wrote:
> +#if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T
> +    char *tbuffer;		/* Translation buffer for non-LFS calls.  */
> +    size_t tbuffer_size;	/* Size of translation buffer.  */
> +#endif

How about something like this instead?

#if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T
     struct dirent tdirent;
     char tbuffer[USHRT_MAX - offsetof (struct dirent64, d_name)];
#endif

In other words, simply allocate the maximum-sized buffer you might need. 
This should simplify memory allocation code. Sure, it uses more memory 
but that's not a big deal nowadays even on 32-bit platforms.

Similarly for dirstream_old_entry in patch 5/5.

Re: [PATCH v4 1/5] linux: Use getdents64 on non-LFS readdir

[Adhemerval Zanella Netto]

On 26/01/23 20:06, Paul Eggert wrote:
> On 1/26/23 11:29, Adhemerval Zanella via Libc-alpha wrote:
>> +#if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T
>> +    char *tbuffer;        /* Translation buffer for non-LFS calls.  */
>> +    size_t tbuffer_size;    /* Size of translation buffer.  */
>> +#endif
> 
> How about something like this instead?
> 
> #if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T
>     struct dirent tdirent;
>     char tbuffer[USHRT_MAX - offsetof (struct dirent64, d_name)];
> #endif
> 
> In other words, simply allocate the maximum-sized buffer you might need. This should simplify memory allocation code. Sure, it uses more memory but that's not a big deal nowadays even on 32-bit platforms.
> 
> Similarly for dirstream_old_entry in patch 5/5.

I fact I don't think we need a translation buffer at all, since
readdir_r (which also calls __readdir_unlocked) will not return
entries with d_name larger than NAME_MAX.  I think an extra
struct direct, along with the expected overflow and maximum name
checks should be suffice.

Re: [PATCH v4 0/5] Fix opendir regression on some FS

[Adhemerval Zanella Netto]

On 26/01/23 19:42, Florian Weimer wrote:
> * Adhemerval Zanella via Libc-alpha:
> 
>> One drawback of such strategy is now telldir might silent fail if
>> seekdir fails to allocate the off64_t map entry, however non-LFS is a
>> compat interface and overflowed entries currently also does not fully
>> work even for LFS interface.
> 
> Could we please fix this by allocating an entry ahead of time, in
> readdir?

Right, I forgot to add this change you require in last iteration. I will
send a new version.