Re: test-openat-safer failure on older kernel

[Jim Meyering]

Eric Blake wrote:
> On on older machine (2.6.16.29 kernel, glibc 3.4.6), when using /proc
> emulation, openat(fd,"",O_RDONLY) was accidentally succeeding in opening a
> copy of /proc/self/fd/n (ie. the directory pointed to by fd) instead of
> failing with ENOENT.  Fixed as follows.  Fortunately, in a quick audit, I
> didn't see any code path in fts or coreutils that seems like it would pass
> an empty argument to openat, which is why my test-openat-safer was the
> first thing to catch this in nearly 3 years of use.
>
> --
> Don't work too hard, make some time for fun as well!
>
> Eric Blake             address@hidden
>>From c46ae39631773a7fdae7d171cc4ef0bf2123efff Mon Sep 17 00:00:00 2001
> From: Eric Blake <address@hidden>
> Date: Fri, 4 Sep 2009 21:22:21 -0600
> Subject: [PATCH] openat: fail with ENOENT on empty name
>
> * lib/openat-proc.c (openat_proc_name): Special-case the empty
> buffer.
>
> Signed-off-by: Eric Blake <address@hidden>
> ---
>  ChangeLog         |    4 ++++
>  lib/openat-proc.c |    7 +++++++
>  2 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/ChangeLog b/ChangeLog
> index 193ec7f..ecbf16e 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,5 +1,9 @@
>  2009-09-04  Eric Blake  <address@hidden>
>
> +     openat: fail with ENOENT on empty name
> +     * lib/openat-proc.c (openat_proc_name): Special-case the empty
> +     buffer.

Good catch.  Thanks.