rwlaunchpad/plugins/rwlaunchpadtasklet/rift/package/checksums.py

   1
   2 #
   3 #   Copyright 2016 RIFT.IO Inc
   4 #
   5 #   Licensed under the Apache License, Version 2.0 (the "License");
   6 #   you may not use this file except in compliance with the License.
   7 #   You may obtain a copy of the License at
   8 #
   9 #       http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 #   Unless required by applicable law or agreed to in writing, software
  12 #   distributed under the License is distributed on an "AS IS" BASIS,
  13 #   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 #   See the License for the specific language governing permissions and
  15 #   limitations under the License.
  16 #
  17
  18 import hashlib
  19 import re
  20
  21 def checksum_string(s):
  22     return hashlib.md5(s.encode('utf-8')).hexdigest()
  23
  24
  25 def checksum(fd):
  26     """ Calculate a md5 checksum of fd file handle
  27
  28     Arguments:
  29       fd: A file descriptor return from open() call
  30
  31     Returns:
  32       A md5 checksum of the file
  33
  34     """
  35     pos = fd.tell()
  36     try:
  37         current = hashlib.md5()
  38         while True:
  39             data = fd.read(2 ** 16)
  40             if len(data) == 0:
  41                 return current.hexdigest()
  42             current.update(data)
  43     finally:
  44         fd.seek(pos)
  45
  46
  47 class ArchiveChecksums(dict):
  48     @classmethod
  49     def from_file_desc(cls, fd):
  50         checksum_pattern = re.compile(r"(\S+)\s+(\S+)")
  51         checksums = dict()
  52
  53         pos = fd.tell()
  54         try:
  55             for line in (line.decode('utf-8').strip() for line in fd if line):
  56
  57                 # Skip comments
  58                 if line.startswith('#'):
  59                     continue
  60
  61                 # Skip lines that do not contain the pattern we are looking for
  62                 result = checksum_pattern.search(line)
  63                 if result is None:
  64                     continue
  65
  66                 chksum, filepath = result.groups()
  67                 checksums[filepath] = chksum
  68
  69         finally:
  70             fd.seek(pos)
  71
  72         return cls(checksums)
  73
  74     def to_string(self):
  75         string = ""
  76         for file_name, file_checksum in self.items():
  77             string += "{}  {}\n".format(file_checksum, file_name)
  78
  79         return string