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