[PATCH] BROKEN_STRNDUP and BROKEN_STRNLEN and AIX

[Alexander Bokovoy]

Hi,


On Wed, May 22, 2013 at 10:39 AM, Andrew Bartlett <abartlet at samba.org>wrote:

> Simo and Christian,
>
> I'm wondering if either of you know more about the allegation that
> strndup and strnlen are broken on AIX?
>
> This is one of the very few outstanding config.h differences I'm tracking
> in https://bugzilla.samba.org/show_bug.cgi?id=8969
>
> It appears to be forced on for all AIX hosts:
>
> commit 804cfb20a067b4b687089dc72a8271b3abf20f31
> Author: Simo Sorce <idra at samba.org>
> Date:   Wed Aug 25 14:24:16 2004 +0000
>
>     r2070: Let's try to overload srnlen and strndup for AIX where they are
> natly broken.
>     (This used to be commit 98feb3318f54bb48ce56fc8f4721fec4967b9dd9)
>
> diff --git a/source3/configure.in b/source3/configure.in
> index d35e89c..4329665 100644
> --- a/source3/configure.in
> +++ b/source3/configure.in
> @@ -1206,6 +1206,8 @@ if test "$enable_shared" = "yes"; then
>                         fi
>
>                         AC_DEFINE(STAT_ST_BLOCKSIZE,DEV_BSIZE,[The size of
> a block])
> +                       AC_DEFINE(BROKEN_STRNLEN,1,[Does strnlen work
> correctly])
> +                       AC_DEFINE(BROKEN_STRNDUP,1,[Does strndup work
> correctly])
>                         ;;
>                 *hpux*) AC_DEFINE(HPUX,1,[Whether the host os is HPUX])
>                         SHLIBEXT="sl"
>
> Before I simply do the same in waf (probably in libreplace), do either
> of you know more of the background here, such as does this apply to all
> AIX versions, or is it possible to test for it less bluntly?
>
This discussion (which refers to our bug #1097) clarifies the issue:
http://stackoverflow.com/questions/2091460/strndup-call-is-currupting-stack-frames

strndup() is broken at least on AIX 6.1:
".. Tracing through the instructions in strndup, it appears that it mallocs
a buffer that is just large enough to handle the string in s plus a NULL
terminator. However, it will always copy n characters to the new buffer,
padding with zeros if necessary, causing a buffer overflow if strlen(s) <
n."

-- 
/ Alexander Bokovoy