sha1dc: update from upstream

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

This version includes a commit of mine which allows for replacing the
local modifications done to the upstream files in git.git with macro
definitions to monkeypatch it in place.

It also brings in a change[2] upstream made for the breakage 2.13.0
introduced on SPARC and other platforms that forbid unaligned
access[3].

This means that the code customizations done since the initial import
in commit 28dc98e343 ("sha1dc: add collision-detecting sha1
implementation", 2017-03-16) can be done purely via Makefile
definitions and by including the content of our own sha1dc_git.[ch] in
sha1dc/sha1.c via a macro.

1. https://github.com/cr-marcstevens/sha1collisiondetection/commit/cc465543b310e5f59a1d534381690052e8509b22
2. https://github.com/cr-marcstevens/sha1collisiondetection/commit/33a694a9ee1b79c24be45f9eab5ac0e1aeeaf271
3. "Git 2.13.0 segfaults on Solaris SPARC due to DC_SHA1=YesPlease
   being on by default"
   (https://public-inbox.org/git/CACBZZX6nmKK8af0-UpjCKWV4R+hV-uk2xWXVA5U+_UQ3VXU03g@mail.gmail.com/)

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

1 files changed, 24 insertions, 0 deletions

diff --git a/sha1dc_git.c b/sha1dc_git.c
new file mode 100644
index 0000000..4d32b4f
--- /dev/null
+++ b/sha1dc_git.c
@@ -0,0 +1,24 @@
+/*
+ * This code is included at the end of sha1dc/sha1.c with the
+ * SHA1DC_CUSTOM_TRAILING_INCLUDE_SHA1_C macro.
+ */
+
+void git_SHA1DCFinal(unsigned char hash[20], SHA1_CTX *ctx)
+{
+	if (!SHA1DCFinal(hash, ctx))
+		return;
+	die("SHA-1 appears to be part of a collision attack: %s",
+	    sha1_to_hex(hash));
+}
+
+void git_SHA1DCUpdate(SHA1_CTX *ctx, const void *vdata, unsigned long len)
+{
+	const char *data = vdata;
+	/* We expect an unsigned long, but sha1dc only takes an int */
+	while (len > INT_MAX) {
+		SHA1DCUpdate(ctx, data, INT_MAX);
+		data += INT_MAX;
+		len -= INT_MAX;
+	}
+	SHA1DCUpdate(ctx, data, len);
+}