Subject: Re: [PATCH] sha1dc: fix for compiling on AIX using IBM XLC compiler

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Wed, 09 May 2018 14:11:43 +0200

On Wed, May 09 2018, jens persson wrote:

> Hello, first patch. I'm having trouble compiling on AIX using IBMs
> compiler, leading to
> unusable binaries. The following patch solved the problem for 2.17.0.
> The patch below is cut&pasted via gmail to allow for firewalls, but
> exists in an unmolested form on github:
> https://github.com/MrShark/git/commit/44bfcaca6637e24548ec06f46fb6035a846b14af
>
> Best regards
> /jp
>
> Building on AIX using XLC every checkout gives an error:
> fatal: pack is corrupted (SHA1 mismatch)
> fatal: index-pack failed
>
> Back tracking it was introduced in 2.13.2, most likely in [1]
>
> Add a #ifdef guard based on macros defined at [2] and [3].
>
> Should perhaps __xlc__ should should be changed to or combined with _AIX
> based on the behavour of GCC on AIX or XL C on Linux.
>
> 1. https://github.com/git/git/commit/6b851e536b05e0c8c61f77b9e4c3e7cedea39ff8
> 2. https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.3/com.ibm.xlc1313.aix.doc/compiler_ref/macros_platform.html
> 3. https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.3/com.ibm.xlc1313.aix.doc/compiler_ref/xlmacros.html
>
> Signed-off-by: jens persson <[email-masked]>
> ---
>  sha1dc/sha1.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sha1dc/sha1.c b/sha1dc/sha1.c
> index 25eded139..68a8a0180 100644
> --- a/sha1dc/sha1.c
> +++ b/sha1dc/sha1.c
> @@ -84,7 +84,7 @@
>  /* Not under GCC-alike or glibc or *BSD or newlib */
>  #elif (defined(__ARMEB__) || defined(__THUMBEB__) ||
> defined(__AARCH64EB__) || \
>         defined(__MIPSEB__) || defined(__MIPSEB) || defined(_MIPSEB) || \
> -       defined(__sparc))
> +       defined(__sparc) || (defined(__powerpc) && defined(__xlc__)))
>  /*
>   * Should define Big Endian for a whitelist of known processors. See
>   * https://sourceforge.net/p/predef/wiki/Endianness/ and

This patch looks sane to me, but we don't manage this software but
instead try to pull it as-is from upstream at
https://github.com/cr-marcstevens/sha1collisiondetection

Which we could apply this, it would be much better if you could submit a
pull request with this to upstream, and then we can update our copy as I
did in e.g. 9936c1b52a ("sha1dc: update from upstream", 2017-07-01).