sha1dc: optionally use sha1collisiondetection as a submodule

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 \