sha1dc: optionally use sha1collisiondetection as a submodule

Add an option to use the sha1collisiondetection library from the
submodule in sha1collisiondetection/ instead of in the copy in the
sha1dc/ directory.

This allows us to try out the submodule in sha1collisiondetection
without breaking the build for anyone who's not expecting them as we
work out any kinks.

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

diff --git a/.gitmodules b/.gitmodules
new file mode 100644 (file)
index 0000000..cbeebda
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "sha1collisiondetection"]
+       path = sha1collisiondetection
+       url = https://github.com/cr-marcstevens/sha1collisiondetection.git
+       branch = master

diff --git a/Makefile b/Makefile
index ffa6da71b7ccaecd6a1fb449b03d3002d5e15ea8..6baad1669e0e7610dcda2b2291bfb9cd56dc0202 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -144,6 +144,12 @@ all::
 # algorithm. This is slower, but may detect attempted collision attacks.
 # Takes priority over other *_SHA1 knobs.
 #
+# Define DC_SHA1_SUBMODULE in addition to DC_SHA1 to use the
+# sha1collisiondetection shipped as a submodule instead of the
+# non-submodule copy in sha1dc/. This is an experimental option used
+# by the git project to migrate to using sha1collisiondetection as a
+# submodule.
+#
 # Define OPENSSL_SHA1 environment variable when running make to link
 # with the SHA1 routine from openssl library.
 #
@@ -1412,8 +1418,14 @@ ifdef APPLE_COMMON_CRYPTO
        BASIC_CFLAGS += -DSHA1_APPLE
 else
        DC_SHA1 := YesPlease
+ifdef DC_SHA1_SUBMODULE
+       LIB_OBJS += sha1collisiondetection/lib/sha1.o
+       LIB_OBJS += sha1collisiondetection/lib/ubc_check.o
+       BASIC_CFLAGS += -DDC_SHA1_SUBMODULE
+else
        LIB_OBJS += sha1dc/sha1.o
        LIB_OBJS += sha1dc/ubc_check.o
+endif
        BASIC_CFLAGS += \
                -DSHA1_DC \
                -DSHA1DC_NO_STANDARD_INCLUDES \

diff --git a/hash.h b/hash.h
index a11fc9233fc9bb7d876e2e97a1a149260d7a633c..bef3e630a093b508e78419c5f4e228e836ecb88c 100644 (file)
--- a/hash.h
+++ b/hash.h
@@ -8,7 +8,11 @@
 #elif defined(SHA1_OPENSSL)
 #include <openssl/sha.h>
 #elif defined(SHA1_DC)
+#ifdef DC_SHA1_SUBMODULE
+#include "sha1collisiondetection/lib/sha1.h"
+#else
 #include "sha1dc/sha1.h"
+#endif
 #else /* SHA1_BLK */
 #include "block-sha1/sha1.h"
 #endif

diff --git a/sha1collisiondetection b/sha1collisiondetection
new file mode 160000 (submodule)
index 0000000..19d97bf
--- /dev/null
+++ b/sha1collisiondetection
@@ -0,0 +1 @@
+Subproject commit 19d97bf5af05312267c2e874ee6bcf584d9e9681