From 16b0675fe6641e2a35e6db67afd53cbfee677ae4 Mon Sep 17 00:00:00 2001
From: Thomas Leonard <talex5@gmail.com>
Date: Thu, 3 Feb 2005 20:34:47 +0000
Subject: [PATCH] Never choose an unusable impl.

git-svn-id: file:///home/talex/Backups/sf.net/Subversion/zero-install/injector/head@36 9f8c893c-44ee-0310-b757-c8ca8341c71e
---
 model.py  | 25 +++++++++++++++++++++++--
 policy.py |  2 ++
 run.py    | 13 ++++++++++---
 3 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/model.py b/model.py
index 886fdeb..d62f0b9 100644
--- a/model.py
+++ b/model.py
@@ -68,7 +68,7 @@ class Dependency(object):
 class Implementation(object):
 	"""An Implementation is a package which implements an Interface."""
 	__slots__ = ['path', 'arch', 'upstream_stability', 'user_stability',
-		     'version', 'size', 'dependencies']
+		     'version', 'size', 'dependencies', '_cached']
 
 	def __init__(self, path):
 		assert path
@@ -78,13 +78,24 @@ class Implementation(object):
 		self.user_stability = None
 		self.upstream_stability = None
 		self.arch = None
+		self._cached = None
 		self.dependencies = {}	# URI -> Dependency
 	
 	def get_stability(self):
 		return self.user_stability or self.upstream_stability or testing
 	
 	def get_cached(self):
-		return os.path.exists(self.path)
+		if self._cached is None:
+			self._cached = False
+			if os.path.exists(self.path):
+				cache_dir = cache_for(self.path)
+				for x in os.listdir(cache_dir):
+					if x[0] == '.': continue
+					if x == 'AppInfo.xml': continue
+					if os.path.isfile(os.path.join(cache_dir, x)):
+						self._cached = True
+						break
+		return self._cached
 	
 	def get_version(self):
 		return '.'.join(map(str, self.version))
@@ -156,3 +167,13 @@ def escape(uri):
 
 class SafeException(Exception):
 	pass
+
+try:
+	_cache = os.readlink('/uri/0install/.lazyfs-cache')
+except:
+	_cache = None
+def cache_for(path):
+	prefix = '/uri/0install/'
+	if path.startswith(prefix) and _cache:
+		return os.path.join(_cache, path[len(prefix):])
+	return path
diff --git a/policy.py b/policy.py
index a741ded..ff9e43c 100644
--- a/policy.py
+++ b/policy.py
@@ -64,6 +64,8 @@ class Policy(object):
 		for x in impls[1:]:
 			if self.compare(iface, x, best) < 0:
 				best = x
+		if self.is_unusable(best):
+			return None
 		return best
 	
 	def compare(self, interface, b, a):
diff --git a/run.py b/run.py
index ea9574c..606f7a9 100644
--- a/run.py
+++ b/run.py
@@ -33,6 +33,13 @@ def get_impl(interface):
 	try:
 		return policy.implementation[interface]
 	except KeyError:
-		raise SafeException("We don't have enough information to "
-				    "run this program yet. "
-				    "Need to download:\n%s" % interface.uri)
+		if not interface.name:
+			raise SafeException("We don't have enough information to "
+					    "run this program yet. "
+					    "Need to download:\n%s" % interface.uri)
+		if interface.implementations:
+			offline = ""
+			if policy.network_use == network_offline:
+				offline = "\nThis may be because 'Network Use' is set to Off-line."
+			raise SafeException("No usable implementation found for '%s'.%s" %
+					(interface.name, offline))
-- 
2.11.4.GIT