From bad81ab61eb44a6c209345a0863f76626aaa6534 Mon Sep 17 00:00:00 2001
From: Thomas Leonard <talex5@gmail.com>
Date: Sun, 21 Feb 2010 17:17:37 +0000
Subject: [PATCH] Rank digest algorithms and download using the best available

---
 zeroinstall/injector/fetch.py     | 14 +++++++++-----
 zeroinstall/injector/model.py     |  1 -
 zeroinstall/zerostore/manifest.py | 12 +++++++++---
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/zeroinstall/injector/fetch.py b/zeroinstall/injector/fetch.py
index b6013b9..c43193e 100644
--- a/zeroinstall/injector/fetch.py
+++ b/zeroinstall/injector/fetch.py
@@ -300,11 +300,15 @@ class Fetcher(object):
 		assert retrieval_method
 
 		from zeroinstall.zerostore import manifest
-		for required_digest in impl.digests:
-			alg = required_digest.split('=', 1)[0]
-			if alg in manifest.algorithms:
-				break
-		else:
+		best = None
+		for digest in impl.digests:
+			alg_name = digest.split('=', 1)[0]
+			alg = manifest.algorithms.get(alg_name, None)
+			if alg and (best is None or best.rating < alg.rating):
+				best = alg
+				required_digest = digest
+
+		if best is None:
 			if not impl.digests:
 				raise SafeException(_("No <manifest-digest> given for '%(implementation)s' version %(version)s") %
 						{'implementation': impl.feed.get_name(), 'version': impl.get_version()})
diff --git a/zeroinstall/injector/model.py b/zeroinstall/injector/model.py
index 9d27b06..77b8fdc 100644
--- a/zeroinstall/injector/model.py
+++ b/zeroinstall/injector/model.py
@@ -759,7 +759,6 @@ class ZeroInstallFeed(object):
 					for aname, avalue in elem.attrs.iteritems():
 						if ' ' not in aname:
 							impl.digests.append('%s=%s' % (aname, avalue))
-					impl.digests.sort()
 				elif elem.name == 'recipe':
 					recipe = Recipe()
 					for recipe_step in elem.childNodes:
diff --git a/zeroinstall/zerostore/manifest.py b/zeroinstall/zerostore/manifest.py
index 09ec81b..36d94bc 100644
--- a/zeroinstall/zerostore/manifest.py
+++ b/zeroinstall/zerostore/manifest.py
@@ -40,6 +40,8 @@ except:
 class Algorithm:
 	"""Abstract base class for algorithms.
 	An algorithm knows how to generate a manifest from a directory tree.
+	@ivar rating: how much we like this algorithm (higher is better)
+	@type rating: int
 	"""
 	def generate_manifest(self, root):
 		"""Returns an iterator that yields each line of the manifest for the directory
@@ -57,6 +59,9 @@ class Algorithm:
 
 class OldSHA1(Algorithm):
 	"""@deprecated: Injector versions before 0.20 only supported this algorithm."""
+
+	rating = 10
+
 	def generate_manifest(self, root):
 		def recurse(sub):
 			# To ensure that a line-by-line comparison of the manifests
@@ -414,13 +419,14 @@ def _copy_files(alg, wanted, source, target):
 class HashLibAlgorithm(Algorithm):
 	new_digest = None		# Constructor for digest objects
 
-	def __init__(self, name):
+	def __init__(self, name, rating):
 		if name == 'sha1':
 			self.new_digest = sha1_new
 			self.name = 'sha1new'
 		else:
 			self.new_digest = getattr(hashlib, name)
 			self.name = name
+		self.rating = rating
 
 	def generate_manifest(self, root):
 		def recurse(sub):
@@ -477,11 +483,11 @@ class HashLibAlgorithm(Algorithm):
 
 algorithms = {
 	'sha1': OldSHA1(),
-	'sha1new': HashLibAlgorithm('sha1'),
+	'sha1new': HashLibAlgorithm('sha1', 50),
 }
 
 if hashlib is not None:
-	algorithms['sha256'] = HashLibAlgorithm('sha256')
+	algorithms['sha256'] = HashLibAlgorithm('sha256', 80)
 
 def fixup_permissions(root):
 	"""Set permissions recursively for children of root:
-- 
2.11.4.GIT