sha1dc: update from upstreamab/sha1dc-maint

Update sha1dc from the latest version by the upstream maintainer[1].

See commit 6b851e536b ("sha1dc: update from upstream", 2017-06-06) for
the last update.

This solves the Big Endian detection on Solaris reported against
v2.13.2[2], hopefully without any regressions. A version of this has
been tested on two Solaris SPARC installations, Cygwin (by jturney on
cygwin@Freenode), and on numerous more boring systems (mainly
linux/x86_64). See [3] for a discussion of the implementation and
platform-specific issues.

See commit a0103914c2 ("sha1dc: update from upstream", 2017-05-20) and
6b851e536b ("sha1dc: update from upstream", 2017-06-06) for previous
attempts in the 2.13 series to address various compile-time feature
detection in this library.

1. https://github.com/cr-marcstevens/sha1collisiondetection/commit/19d97bf5af05312267c2e874ee6bcf584d9e9681
2. <CAKKM46tHq13XiW5C8sux3=PZ1VHSu_npG8ExfWwcPD7rkZkyRQ@mail.gmail.com>
   (https://public-inbox.org/git/CAKKM46tHq13XiW5C8sux3=PZ1VHSu_npG8ExfWwcPD7rkZkyRQ@mail.gmail.com/)
3. https://github.com/cr-marcstevens/sha1collisiondetection/pull/34

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 66 insertions, 22 deletions

diff --git a/sha1dc/sha1.c b/sha1dc/sha1.c
index facea1bb56..d5948826c8 100644
--- a/sha1dc/sha1.c
+++ b/sha1dc/sha1.c
@@ -10,6 +10,9 @@
 #include <memory.h>
 #include <stdio.h>
 #include <stdlib.h>
+#ifdef __unix__
+#include <sys/types.h> /* make sure macros like _BIG_ENDIAN visible */
+#endif
 #endif
 
 #ifdef SHA1DC_CUSTOM_INCLUDE_SHA1_C
@@ -23,6 +26,13 @@
 #include "sha1.h"
 #include "ubc_check.h"
 
+#if (defined(__amd64__) || defined(__amd64) || defined(__x86_64__) || defined(__x86_64) || \
+     defined(i386) || defined(__i386) || defined(__i386__) || defined(__i486__)  || \
+     defined(__i586__) || defined(__i686__) || defined(_M_IX86) || defined(__X86__) || \
+     defined(_X86_) || defined(__THW_INTEL__) || defined(__I86__) || defined(__INTEL__) || \
+     defined(__386) || defined(_M_X64) || defined(_M_AMD64))
+#define SHA1DC_ON_INTEL_LIKE_PROCESSOR
+#endif
 
 /*
    Because Little-Endian architectures are most common,
@@ -32,29 +42,70 @@
    If you are compiling on a big endian platform and your compiler does not define one of these,
    you will have to add whatever macros your tool chain defines to indicate Big-Endianness.
  */
-#ifdef SHA1DC_BIGENDIAN
-#undef SHA1DC_BIGENDIAN
-#endif
 
-#if (defined(_BYTE_ORDER) || defined(__BYTE_ORDER) || defined(__BYTE_ORDER__))
-
-#if ((defined(_BYTE_ORDER) && (_BYTE_ORDER == _BIG_ENDIAN)) || \
-     (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || \
-     (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __BIG_ENDIAN__)) )
+#if defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__)
+/*
+ * Should detect Big Endian under GCC since at least 4.6.0 (gcc svn
+ * rev #165881). See
+ * https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html
+ *
+ * This also works under clang since 3.2, it copied the GCC-ism. See
+ * clang.git's 3b198a97d2 ("Preprocessor: add __BYTE_ORDER__
+ * predefined macro", 2012-07-27)
+ */
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 #define SHA1DC_BIGENDIAN
 #endif
 
-#else
-
-#if (defined(_BIG_ENDIAN) || defined(__BIG_ENDIAN) || defined(__BIG_ENDIAN__) || \
-     defined(__ARMEB__) || defined(__THUMBEB__) || defined(__AARCH64EB__) || \
-     defined(__MIPSEB__) || defined(__MIPSEB) || defined(_MIPSEB) || \
-     defined(__sparc))
+/* Not under GCC-alike */
+#elif defined(__BYTE_ORDER) && defined(__BIG_ENDIAN)
+/*
+ * Should detect Big Endian under glibc.git since 14245eb70e ("entered
+ * into RCS", 1992-11-25). Defined in <endian.h> which will have been
+ * brought in by standard headers. See glibc.git and
+ * https://sourceforge.net/p/predef/wiki/Endianness/
+ */
+#if __BYTE_ORDER == __BIG_ENDIAN
 #define SHA1DC_BIGENDIAN
 #endif
 
+/* Not under GCC-alike or glibc */
+#elif defined(_BYTE_ORDER) && defined(_BIG_ENDIAN) && defined(_LITTLE_ENDIAN)
+/*
+ * *BSD and newlib (embeded linux, cygwin, etc).
+ * the defined(_BIG_ENDIAN) && defined(_LITTLE_ENDIAN) part prevents
+ * this condition from matching with Solaris/sparc.
+ * (Solaris defines only one endian macro)
+ */
+#if _BYTE_ORDER == _BIG_ENDIAN
+#define SHA1DC_BIGENDIAN
 #endif
 
+/* 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))
+/*
+ * Should define Big Endian for a whitelist of known processors. See
+ * https://sourceforge.net/p/predef/wiki/Endianness/ and
+ * http://www.oracle.com/technetwork/server-storage/solaris/portingtosolaris-138514.html
+ */
+#define SHA1DC_BIGENDIAN
+
+/* Not under GCC-alike or glibc or *BSD or newlib or <processor whitelist> */
+#elif defined(SHA1DC_ON_INTEL_LIKE_PROCESSOR)
+/*
+ * As a last resort before we do anything else we're not 100% sure
+ * about below, we blacklist specific processors here. We could add
+ * more, see e.g. https://wiki.debian.org/ArchitectureSpecificsMemo
+ */
+#else /* Not under GCC-alike or glibc or *BSD or newlib or <processor whitelist>  or <processor blacklist> */
+
+/* We do nothing more here for now */
+/*#error "Uncomment this to see if you fall through all the detection"*/
+
+#endif /* Big Endian detection */
+
 #if (defined(SHA1DC_FORCE_LITTLEENDIAN) && defined(SHA1DC_BIGENDIAN))
 #undef SHA1DC_BIGENDIAN
 #endif
@@ -63,15 +114,8 @@
 #endif
 /*ENDIANNESS SELECTION*/
 
-#if (defined SHA1DC_FORCE_UNALIGNED_ACCESS || \
-     defined(__amd64__) || defined(__amd64) || defined(__x86_64__) || defined(__x86_64) || \
-     defined(i386) || defined(__i386) || defined(__i386__) || defined(__i486__)  || \
-     defined(__i586__) || defined(__i686__) || defined(_M_IX86) || defined(__X86__) || \
-     defined(_X86_) || defined(__THW_INTEL__) || defined(__I86__) || defined(__INTEL__) || \
-     defined(__386) || defined(_M_X64) || defined(_M_AMD64))
-
+#if defined(SHA1DC_FORCE_UNALIGNED_ACCESS) || defined(SHA1DC_ON_INTEL_LIKE_PROCESSOR)
 #define SHA1DC_ALLOW_UNALIGNED_ACCESS
-
 #endif /*UNALIGNMENT DETECTION*/