From: Loup Vaillant <loup@loup-vaillant.fr>
Date: Fri, 25 Jan 2019 14:43:02 +0000 (+0100)
Subject: Link SHA-512 code when using -DED25519_SHA512
X-Git-Url: https://git.codecow.com/?a=commitdiff_plain;h=1094802ef4ed0c1a9429be5a3e8ef487aa62bee4;p=Monocypher.git

Link SHA-512 code when using -DED25519_SHA512

When the $CFLAGS variable contains the -DED25519_SHA512 option (by
default it doesn't), the code from src/optional/sha512.c is
automatically linked to the final libraries (libmonocypher.a and
libmonocypher.so).

That way, users who need to install a ED25519 compliant version of
Monocypher can do so simply by altering the compilation options with the
$CFLAGS variable.
---

diff --git a/README.md b/README.md
index 63604e5..3cdda5c 100644
--- a/README.md
+++ b/README.md
@@ -136,7 +136,11 @@ signatures.  The default is EdDSA with Curve25519 and Blake2b.
 Activating the option replaces it by Ed25519 (EdDSA with Curve25519 and
 SHA-512).  When this option is activated, you will need to link the
 final program with a suitable SHA-512 implementation.  You can use the
-`sha512.c` and `sha512.h` files provided in `src/optional`.
+`sha512.c` and `sha512.h` files provided in `src/optional`.  The
+makefile does this linking automatically whenever the `$CFLAGS` variable
+contains the `-DED25519_SHA512` option. For instance:
+
+    $ make CFLAGS="-O2 -DED25519_SHA512"
 
 The `-DBLAKE2_NO_UNROLLING` option is a performance tweak.  By default,
 Monocypher unrolls the Blake2b inner loop, because it is over 25% faster
diff --git a/makefile b/makefile
index 9d165e4..83a4bfa 100644
--- a/makefile
+++ b/makefile
@@ -8,6 +8,12 @@ MAN_DIR=$(DESTDIR)/$(PREFIX)/share/man/man3
 TARBALL_VERSION=$$(cat VERSION.md)
 TARBALL_DIR=.
 
+ifeq ($(findstring -DED25519_SHA512, $(CFLAGS)),)
+LINK_SHA512=
+else
+LINK_SHA512=lib/sha512.o
+endif
+
 .PHONY: all library static-library dynamic-library \
         install install-doc                        \
         check test speed                           \
@@ -63,12 +69,12 @@ test speed speed-sodium speed-tweetnacl:
 	./$<
 
 # Monocypher libraries
-lib/libmonocypher.a: lib/monocypher.o
+lib/libmonocypher.a: lib/monocypher.o $(LINK_SHA512)
 	ar cr $@ $^
 lib/libmonocypher.so: lib/libmonocypher.so.2
 	@mkdir -p $(@D)
 	ln -s $$(basename $<) $@
-lib/libmonocypher.so.2: lib/monocypher.o
+lib/libmonocypher.so.2: lib/monocypher.o $(LINK_SHA512)
 	@mkdir -p $(@D)
 	$(CC) $(CFLAGS) -shared -o $@ $^
 lib/sha512.o    : src/optional/sha512.c src/optional/sha512.h