digest.py

   1 from xml.dom import minidom
   2 from zeroinstall.injector import namespaces
   3 from zeroinstall.zerostore import manifest, Stores, NotStored
   4 import xmltools
   5 from logging import info
   6
   7 stores = Stores()
   8
   9 def digests(impl):
  10         yield impl.getAttribute('id').split('=', 1)
  11         for x in xmltools.children(impl, 'manifest-digest'):
  12                 for name, value in x.attributes.itemsNS():
  13                         if name[0] is None:
  14                                 yield name[1], value
  15
  16 def get_version(impl):
  17         while impl:
  18                 v = impl.getAttribute('version')
  19                 if v: return v
  20                 impl = impl.parentNode
  21
  22 def add_digest(impl, alg_name):
  23         alg = manifest.get_algorithm(alg_name)
  24
  25         # Scan through the existing digests
  26         # - If we've already got the one we need, return
  27         # - Otherwise, find a cached implementation we can use
  28         existing_path = None
  29         for a, value in digests(impl):
  30                 digest = '%s=%s' % (a, value)
  31                 if a == alg_name:
  32                         return False                    # Already signed with this algorithm
  33                 if not existing_path:
  34                         try:
  35                                 existing_path = stores.lookup(digest)
  36                                 if existing_path:
  37                                         existing_digest = digest
  38                         except NotStored:
  39                                 pass            # OK
  40
  41         if existing_path is None:
  42                 print "No implementations of %s cached; can't calculate new digest" % get_version(impl)
  43                 return False
  44
  45         info("Verifying %s", existing_path)
  46         manifest.verify(existing_path, existing_digest)
  47
  48         print "Adding new digest to version %s" % get_version(impl)
  49
  50         new_digest = alg.new_digest()
  51         for line in alg.generate_manifest(existing_path):
  52                 new_digest.update(line + '\n')
  53
  54         for md in xmltools.children(impl, 'manifest-digest'):
  55                 break
  56         else:
  57                 md = xmltools.create_element(impl, 'manifest-digest')
  58         md.setAttribute(alg_name, new_digest.hexdigest())
  59
  60         return True
  61
  62 def add_digests(data, alg = None):
  63         doc = minidom.parseString(data)
  64
  65         if alg is None:
  66                 alg = 'sha1new'
  67
  68         changed = False
  69         for impl in doc.documentElement.getElementsByTagNameNS(namespaces.XMLNS_IFACE, 'implementation'):
  70                 if impl.getAttribute('id') in "./":
  71                         continue                # Local implementation
  72
  73                 if add_digest(impl, alg):
  74                         changed = True
  75
  76         if changed:
  77                 return doc.toxml()
  78         else:
  79                 return data