1 files changed, 89 insertions, 0 deletions
diff --git a/chromium/mojo/tools/pylib/transitive_hash.py b/chromium/mojo/tools/pylib/transitive_hash.py
new file mode 100644
index 00000000000..93e8dc4e75e
--- /dev/null
+++ b/chromium/mojo/tools/pylib/transitive_hash.py
@@ -0,0 +1,89 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import logging
+import subprocess
+import sys
+
+from hashlib import sha256
+from os.path import basename, realpath
+
+_logging = logging.getLogger()
+
+# Based on/taken from
+#   http://code.activestate.com/recipes/578231-probably-the-fastest-memoization-decorator-in-the-/
+# (with cosmetic changes).
+def _memoize(f):
+  """Memoization decorator for a function taking a single argument."""
+  class Memoize(dict):
+    def __missing__(self, key):
+      rv = self[key] = f(key)
+      return rv
+  return Memoize().__getitem__
+
+@_memoize
+def _file_hash(filename):
+  """Returns a string representing the hash of the given file."""
+  _logging.debug("Hashing %s ...", filename)
+  rv = subprocess.check_output(['sha256sum', '-b', filename]).split(None, 1)[0]
+  _logging.debug("  => %s", rv)
+  return rv
+
+@_memoize
+def _get_dependencies(filename):
+  """Returns a list of filenames for files that the given file depends on."""
+  _logging.debug("Getting dependencies for %s ...", filename)
+  lines = subprocess.check_output(['ldd', filename]).splitlines()
+  rv = []
+  for line in lines:
+    i = line.find('/')
+    if i < 0:
+      _logging.debug("  => no file found in line: %s", line)
+      continue
+    rv.append(line[i:].split(None, 1)[0])
+  _logging.debug("  => %s", rv)
+  return rv
+
+def transitive_hash(filename):
+  """Returns a string that represents the "transitive" hash of the given
+  file. The transitive hash is a hash of the file and all the shared libraries
+  on which it depends (done in an order-independent way)."""
+  hashes = set()
+  to_hash = [filename]
+  while to_hash:
+    current_filename = realpath(to_hash.pop())
+    current_hash = _file_hash(current_filename)
+    if current_hash in hashes:
+      _logging.debug("Already seen %s (%s) ...", current_filename, current_hash)
+      continue
+    _logging.debug("Haven't seen %s (%s) ...", current_filename, current_hash)
+    hashes.add(current_hash)
+    to_hash.extend(_get_dependencies(current_filename))
+  return sha256('|'.join(sorted(hashes))).hexdigest()
+
+def main(argv):
+  logging.basicConfig()
+  # Uncomment to debug:
+  # _logging.setLevel(logging.DEBUG)
+
+  if len(argv) < 2:
+    print """\
+Usage: %s [file] ...
+
+Prints the \"transitive\" hash of each (executable) file. The transitive
+hash is a hash of the file and all the shared libraries on which it
+depends (done in an order-independent way).""" % basename(argv[0])
+    return 0
+
+  rv = 0
+  for filename in argv[1:]:
+    try:
+      print transitive_hash(filename), filename
+    except:
+      print "ERROR", filename
+      rv = 1
+  return rv
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))