Re: [PATCH] block-sha1/sha1.c: silence compiler complaints by casting void* to uintptr_t

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 15, 2009, 03:16 UTC
Message-ID: <7v63cp22cc.fsf@alter.siamese.dyndns.org>
In-Reply-To: <MecVLMUB15cEJQiZpwSBg9ysnmFSB1QYZfIQuSOStnFx2KoeScNXGQ@cipher.nrlssc.navy.mil>

Brandon Casey <casey@nrlssc.navy.mil> writes:

Show 6 quoted lines

> I was just pointing out that the SUNWspro compiler does not produce an
> identical binary on x86 for each of the three versions like the GNU
> compiler does.
>
> Sorry for the confusion.  Linus's suggestion of casting to "const char*"
> should be adopted.

Ah, I see.  Thanks.

Let's queue this, then.

-- >8 --
From: Brandon Casey <drafnel@gmail.com>
Date: Fri, 14 Aug 2009 17:52:15 -0500
Subject: [PATCH] block-sha1/sha1.c: silence compiler complaints by casting void * to char *

Some compilers produce errors when arithmetic is attempted on pointers to void. We want computations done on byte addresses, so cast them to char * to work them around.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 block-sha1/sha1.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c
index e5a1007..464cb25 100644
--- a/block-sha1/sha1.c
+++ b/block-sha1/sha1.c
@@ -246,14 +246,14 @@ void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
 		memcpy(lenW + (char *)ctx->W, data, left);
 		lenW = (lenW + left) & 63;
 		len -= left;
-		data += left;
+		data = ((const char *)data + left);
 		if (lenW)
 			return;
 		blk_SHA1_Block(ctx, ctx->W);
 	}
 	while (len >= 64) {
 		blk_SHA1_Block(ctx, data);
-		data += 64;
+		data = ((const char *)data + 64);
 		len -= 64;
 	}
 	if (len)