Re: [PATCH v4 3/3] cache.h: eliminate SHA-1 deprecation warnings on OS X 10.8

From: Eric Sunshine <sunshine@sunshineco.com>
Date: May 13, 2013, 13:32 UTC
Message-ID: <CAPig+cQwhhwyt+XHXz2_PLqmZ=goy7pz-GC3kFqOHm1R6=70YA@mail.gmail.com>
In-Reply-To: <1368433419-24065-2-git-send-email-davvid@gmail.com>

On Mon, May 13, 2013 at 4:23 AM, David Aguilar <davvid@gmail.com> wrote:

Show 10 quoted lines

> Mac OS X Mountain Lion prints warnings when building git:
>
>         warning: 'SHA1_Init' is deprecated
>         (declared at /usr/include/openssl/sha.h:121)
>
> Silence the warnings by using the CommonCrytpo SHA-1
> functions for SHA1_Init(), SHA1_Update(), and SHA1_Final().
>
> Add a COMMON_DIGEST_SHA1 option to the Makefile to allow
> choosing this implementation and define it by default on Darwin.

The approach of adding a Makefile option for each CommonCrypto facility does not really scale well. For instance, these days, I generally build git against OpenSSL from MacPorts, which gives me a warning-free git build since MacPorts/OpenSSL lacks those Apple-specific deprecation flags. With this patch series introducing several Makefile knobs, people wishing to use MacPorts/OpenSSL will have to tweak each knob. These patches already introduce two knobs (COMMON_DIGEST_SHA1, COMMON_DIGEST_HMAC). Adding more knobs to silence the remaining 29 deprecation warnings will make the build more cumbersome for those who prefer OpenSSL. Instead, introducing a single knob (such as APPLE_COMMON_CRYPTO) would avoid this problem.

More generally, is the approach of trying to figure out CommonCrypto replacements for DIGEST, HMAC, and the other 29 warnings worthwhile? After all, Apple introduced deprecation warnings due to the ABI-instability of OpenSSL, not due to any particular flaw in OpenSSL or its API. A more manageable approach might simply be to disable that particular warning on Darwin (via CFLAGS or perhaps '#pragma GCC diagnostic ignored' for more fine-grained control).

Show 43 quoted lines

> Define COMMON_DIGEST_FOR_OPENSSL to enable the OpenSSL
> compatibility macros in CommonDigest.h.
>
> Helped-by: Eric Sunshine <sunshine@sunshineco.com>
> Signed-off-by: David Aguilar <davvid@gmail.com>
> ---
> Changes since last round:
> COMMON_DIGEST_FOR_OPENSSL is used to enable the compatibility macros.
>
>  Makefile | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index a0f7afc..29c02ed 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1055,6 +1055,7 @@ ifeq ($(uname_S),Darwin)
>                 endif
>         endif
>         COMMON_DIGEST_HMAC = YesPlease
> +       COMMON_DIGEST_SHA1 = YesPlease
>         NO_REGEX = YesPlease
>         PTHREAD_LIBS =
>  endif
> @@ -1390,10 +1391,15 @@ ifdef PPC_SHA1
>         LIB_OBJS += ppc/sha1.o ppc/sha1ppc.o
>         LIB_H += ppc/sha1.h
>  else
> +ifdef COMMON_DIGEST_SHA1
> +       BASIC_CFLAGS += -DCOMMON_DIGEST_FOR_OPENSSL
> +       SHA1_HEADER = <CommonCrypto/CommonDigest.h>
> +else
>         SHA1_HEADER = <openssl/sha.h>
>         EXTLIBS += $(LIB_4_CRYPTO)
>  endif
>  endif
> +endif
>
>  ifdef COMMON_DIGEST_HMAC
>         BASIC_CFLAGS += -DCOMMON_DIGEST_FOR_HMAC
> --
> 1.8.3.rc1.52.g872cb7b
>