[PATCH v5 0/5] Fix opendir regression on some FS

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

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,
readdir updates 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.

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

Changes from v4:
  * Allocate the telldir map an readdir, thus avoid telldir failure.
  * The translation buffer now uses a fixed size struct.
  * Fixed the condition to use the long to off64_t map.

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                            |   3 +-
 sysdeps/unix/sysv/linux/Makefile            |   1 +
 sysdeps/unix/sysv/linux/alpha/bits/dirent.h |   3 +
 sysdeps/unix/sysv/linux/bits/dirent.h       |   4 +
 sysdeps/unix/sysv/linux/closedir.c          |   4 +
 sysdeps/unix/sysv/linux/dirstream.h         |  22 ++-
 sysdeps/unix/sysv/linux/getdents64.c        |  93 ------------
 sysdeps/unix/sysv/linux/olddirent.h         |   4 +-
 sysdeps/unix/sysv/linux/opendir.c           |   3 +
 sysdeps/unix/sysv/linux/readdir.c           |  88 ++++++++---
 sysdeps/unix/sysv/linux/readdir64.c         |  92 ++++++++---
 sysdeps/unix/sysv/linux/readdir64_r.c       | 159 +++++---------------
 sysdeps/unix/sysv/linux/rewinddir.c         |   5 +
 sysdeps/unix/sysv/linux/seekdir.c           |  35 ++++-
 sysdeps/unix/sysv/linux/telldir.c           |  35 +++++
 sysdeps/unix/sysv/linux/telldir.h           |  65 ++++++++
 sysdeps/unix/sysv/linux/tst-opendir-nolfs.c | 146 ++++++++++++++++++
 19 files changed, 499 insertions(+), 277 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/telldir.h
 create mode 100644 sysdeps/unix/sysv/linux/tst-opendir-nolfs.c

-- 
2.34.1