Re: coreutils readlink buffer overflow on GNU/Hurd, plus speedup

[Jim Meyering]

Paul Eggert <address@hidden> wrote:
> While auditing coreutils I noticed a potential buffer overrun in
> copy.c on hosts like GNU/Hurd where symbolic links have potentially
> unlimited length.  Here's a patch.  As a nice side effect, this patch
> improves the performance of programs on 'ls' on more-ordinary hosts
> when they are given long symlinks, as it causes readlink to be invoked
> once, rather than twice, when the symlink is long.
>
> 2004-05-25  Paul Eggert  <address@hidden>
>
>       Improve the efficiency (and in one case, correctness) of code
>       that reads symlinks.
>
>       * lib/xreadlink.c: Include xreadlink.h first, to catch .h file
>       dependency problems.
>       (xreadlink): Accept new arg SIZE, for efficiency.
>       All decls and uses changed.
>       * lib/xreadlink.h: Include <stddef.h>, for size_t.
>       * src/copy.c (copy_internal): Don't use alloca, as it can mess up
>       royally if the link length is long (e.g., GNU/Hurd).  Use
>       xreadlink instead, it's safer.  Don't bother to read the link if
>       it's the wrong size.  Add a FIXME because this area is a bit murky
>       and undocumented.

Thanks!
Applied.