Re: [Bug-tar] [PATCH] tar: more reliable directory traversal when creating archives

[Jim Meyering]

Paul Eggert wrote:
> I installed this:
>
> * NEWS: Document this.
> * gnulib.modules: Add openat, readlinkat.
> * src/common.h (open_read_flags, fstatat_flags): New global variables.
> (cachedir_file_p, dump_file, check_exclusion_tags, scan_directory):
> Adjust to new signatures, described below.
> (name_fill_directory): Remove.
> * src/compare.c (diff_file, diff_multivol): Use open_read_flags.
> * src/create.c (struct exclusion_tag): Exclusion predicates now take
> a file descriptor, not a file name.
> (add_exclusion_tag): Likewise.  All uses changed.
...

Hi Paul,

This change makes it so tar can no longer archive a hierarchy with a depth
of OPEN_MAX or greater.  OPEN_MAX is a file descriptor limit, and should
not limit the depth of hierarchy that a program like tar can process.

On most systems I use, OPEN_MAX is 1024, which is high compared to some
other systems.  For example, on NetBSD 5.0.2 it's just 128.  While most
distribution tarballs fit easily within such a limitation, when you
use tar to perform backups, you might find such a low number to be a
serious limitation.  Even 1024 seems far too low for a tool like tar.