From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: "SZEDER Gábor" <szeder.dev@gmail.com>
Cc: git@vger.kernel.org, "Jeff King" <peff@peff.net>,
"Derrick Stolee" <stolee@gmail.com>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: Re: [PATCH v2 10/13] Add a base implementation of SHA-256 support
Date: Wed, 17 Oct 2018 23:04:09 +0000 [thread overview]
Message-ID: <20181017230409.GK432229@genre.crustytoothpaste.net> (raw)
In-Reply-To: <20181017161241.GS19800@szeder.dev>
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On Wed, Oct 17, 2018 at 06:12:41PM +0200, SZEDER Gábor wrote:
> On macOS there is a MIN macro already defined in the system headers,
> resulting in the following error:
>
> CC sha256/block/sha256.o
> sha256/block/sha256.c:133:9: error: 'MIN' macro redefined [-Werror,-Wmacro-redefined]
> #define MIN(x, y) ((x) < (y) ? (x) : (y))
> ^
> /usr/include/sys/param.h:215:9: note: previous definition is here
> #define MIN(a,b) (((a)<(b))?(a):(b))
> ^
> 1 error generated.
> make: *** [sha256/block/sha256.o] Error 1
>
> A simple "#undef MIN" solves this issue. However, I wonder whether we
> should #undef the other #define directives as well, just to be sure
> (and perhaps overly cautious).
I'll undefine the macros at the top.
For MIN, I'm going to go with the simple approach and pull pieces from
the block-sha1 implementation, which doesn't require this code path...
> Some GCC versions (e.g. gcc-4.8 with -O2 -Wall -Werror) complain about
> the above line:
>
> CC sha256/block/sha256.o
> sha256/block/sha256.c: In function ‘blk_SHA256_Final’:
> sha256/block/sha256.c:174:2: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
> put_be64(ctx->buf + trip, ctx->length);
> ^
> cc1: all warnings being treated as errors
> make: *** [sha256/block/sha256.o] Error 1
>
> Something like this makes it compile:
>
> void *ptr = ctx->buf + trip;
> put_be64(ptr, ctx->length);
>
> However, it's not immediately obvious to me why the compiler
> complains, or why that intermediate void* variable makes any
> difference, but now it's not the time to put on my language lawyer
> hat.
>
> Perhaps an old compiler bug? Clang in general, newer GCC versions, or
> gcc-4.8 with -Wall -Werror but without -O2 don't seem to be affected.
...or this code path. Presumably GCC 4.8 and macOS are happy with the
code that we already have in block-sha1.
--
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204
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next prev parent reply other threads:[~2018-10-17 23:04 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-15 2:18 [PATCH v2 00/13] Base SHA-256 implementation brian m. carlson
2018-10-15 2:18 ` [PATCH v2 01/13] sha1-file: rename algorithm to "sha1" brian m. carlson
2018-10-16 15:17 ` Duy Nguyen
2018-10-17 22:53 ` brian m. carlson
2018-10-15 2:18 ` [PATCH v2 02/13] sha1-file: provide functions to look up hash algorithms brian m. carlson
2018-10-17 13:32 ` SZEDER Gábor
2018-10-15 2:18 ` [PATCH v2 03/13] hex: introduce functions to print arbitrary hashes brian m. carlson
2018-10-16 1:54 ` Junio C Hamano
2018-10-17 23:49 ` brian m. carlson
2018-10-15 2:18 ` [PATCH v2 04/13] cache: make hashcmp and hasheq work with larger hashes brian m. carlson
2018-10-16 15:44 ` Duy Nguyen
2018-10-15 2:18 ` [PATCH v2 05/13] t: add basic tests for our SHA-1 implementation brian m. carlson
2018-10-15 2:18 ` [PATCH v2 06/13] t: make the sha1 test-tool helper generic brian m. carlson
2018-10-15 2:18 ` [PATCH v2 07/13] sha1-file: add a constant for hash block size brian m. carlson
2018-10-15 2:18 ` [PATCH v2 08/13] t/helper: add a test helper to compute hash speed brian m. carlson
2018-10-15 2:18 ` [PATCH v2 09/13] commit-graph: convert to using the_hash_algo brian m. carlson
2018-10-15 15:10 ` Derrick Stolee
2018-10-15 2:18 ` [PATCH v2 10/13] Add a base implementation of SHA-256 support brian m. carlson
2018-10-15 14:59 ` Duy Nguyen
2018-10-15 23:30 ` brian m. carlson
2018-10-16 14:59 ` Duy Nguyen
2018-10-17 16:12 ` SZEDER Gábor
2018-10-17 23:04 ` brian m. carlson [this message]
2018-10-15 2:18 ` [PATCH v2 11/13] sha256: add an SHA-256 implementation using libgcrypt brian m. carlson
2018-10-15 2:18 ` [PATCH v2 12/13] hash: add an SHA-256 implementation using OpenSSL brian m. carlson
2018-10-16 15:36 ` Duy Nguyen
2018-10-15 2:19 ` [PATCH v2 13/13] commit-graph: specify OID version for SHA-256 brian m. carlson
2018-10-15 15:11 ` Derrick Stolee
2018-10-16 2:00 ` Junio C Hamano
2018-10-16 22:39 ` brian m. carlson
2018-10-16 15:35 ` Duy Nguyen
2018-10-16 16:01 ` Derrick Stolee
2018-10-16 16:09 ` Duy Nguyen
2018-10-16 22:44 ` brian m. carlson
2018-10-17 14:31 ` Duy Nguyen
2018-10-18 0:06 ` brian m. carlson
2018-10-18 13:03 ` Derrick Stolee
2018-10-19 22:21 ` brian m. carlson
2018-10-17 12:21 ` Derrick Stolee
2018-10-17 22:38 ` brian m. carlson
2018-10-16 2:00 ` [PATCH v2 00/13] Base SHA-256 implementation Junio C Hamano
2018-10-16 4:01 ` Junio C Hamano
2018-10-16 22:45 ` brian m. carlson
2018-10-16 15:39 ` Duy Nguyen
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