[gentoo-portage-dev] [GLEP59v2 4/5] Manifest2 hash backend provider: mhash

[Robin H. Johnson]

From: "Robin H. Johnson" <robbat2@g.o>

Offer mhash as a provider for Manifest2 hash generation and validation.
This is important as either of pycrypto or fchksum offer an accelerated
Whirlpool implementation, and hashlib might not offer it. Additionally,
the mhash implementation is accelerated and ships with a rigorious
testsuite.

Signed-off-by: Robin H. Johnson <robbat2@g.o>
---
 pym/portage/checksum.py |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/pym/portage/checksum.py b/pym/portage/checksum.py
index 40ae836..c0c7c04 100644
--- a/pym/portage/checksum.py
+++ b/pym/portage/checksum.py
@@ -75,6 +75,25 @@ sha1hash = _generate_hash_function("SHA1", _new_sha1, origin="internal")
 from portage.util.whirlpool import new as _new_whirlpool
 whirlpoolhash = _generate_hash_function("WHIRLPOOL", _new_whirlpool, origin="bundled")
 
+# Try to use mhash if available
+# mhash causes GIL presently, so it gets less priority than hashlib and
+# pycrypto. However, it might be the only accelerated implementation of
+# WHIRLPOOL available.
+try:
+	import mhash, functools
+	md5hash = _generate_hash_function("MD5", functools.partial(mhash.MHASH, mhash.MHASH_MD5), origin="mhash")
+	sha1hash = _generate_hash_function("SHA1", functools.partial(mhash.MHASH, mhash.MHASH_SHA1), origin="mhash")
+	sha256hash = _generate_hash_function("SHA256", functools.partial(mhash.MHASH, mhash.MHASH_SHA256), origin="mhash")
+	sha512hash = _generate_hash_function("SHA512", functools.partial(mhash.MHASH, mhash.MHASH_SHA512), origin="mhash")
+	for local_name, hash_name in (("rmd160", "ripemd160"), ("whirlpool", "whirlpool")):
+		if hasattr(mhash, 'MHASH_%s' % local_name.upper()):
+			globals()['%shash' % local_name] = \
+				_generate_hash_function(local_name.upper(), \
+				functools.partial(mhash.MHASH, getattr(mhash, 'MHASH_%s' % s.upper())), \
+				origin='mhash')
+except ImportError as e:
+	pass
+
 # Use pycrypto when available, prefer it over the internal fallbacks
 try:
 	from Crypto.Hash import SHA256, RIPEMD
-- 
1.7.7