Source Code for Module backend.common.checksum

 1  # 
 2  # Copyright (c) 2009--2016 Red Hat, Inc. 
 3  # 
 4  # This software is licensed to you under the GNU General Public License, 
 5  # version 2 (GPLv2). There is NO WARRANTY for this software, express or 
 6  # implied, including the implied warranties of MERCHANTABILITY or FITNESS 
 7  # FOR A PARTICULAR PURPOSE. You should have received a copy of GPLv2 
 8  # along with this software; if not, see 
 9  # http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt. 
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13  # in this software or its documentation. 
14  # 
15   
16  import os 
17   
18  try: 
19      import hashlib 
20      import inspect 
21   
22      hashlib_has_usedforsecurity = 'usedforsecurity' in inspect.getargspec(hashlib.new)[0] 
23  except ImportError: 
24      import md5 
25      import sha 
26      from Crypto.Hash import SHA256 as sha256 
27   
28      hashlib_has_usedforsecurity = False 
29   
30 -    class hashlib(object): 
31   
32          @staticmethod 
33 -        def new(checksum): 
34              if checksum == 'md5': 
35                  return md5.new() 
36              elif checksum == 'sha1': 
37                  return sha.new() 
38              elif checksum == 'sha256': 
39                  return sha256.new() 
40              else: 
41                  raise ValueError("Incompatible checksum type") 
42   
43 -def getHashlibInstance(hash_type, used_for_security): 
44      """Get an instance of a hashlib object. 
45      """ 
46      if hashlib_has_usedforsecurity: 
47          return hashlib.new(hash_type, usedforsecurity=used_for_security) 
48      else: 
49          return hashlib.new(hash_type) 
50   
51   
52 -def getFileChecksum(hashtype, filename=None, fd=None, file_obj=None, buffer_size=None, used_for_security=False): 
53      """ Compute a file's checksum 
54          Used by rotateFile() 
55      """ 
56   
57      # python's md5 lib sucks 
58      # there's no way to directly import a file. 
59      if buffer_size is None: 
60          buffer_size = 65536 
61   
62      if hashtype == 'sha': 
63          hashtype = 'sha1' 
64   
65      if filename is None and fd is None and file_obj is None: 
66          raise ValueError("no file specified") 
67      if file_obj: 
68          f = file_obj 
69      elif fd is not None: 
70          f = os.fdopen(os.dup(fd), "rb") 
71      else: 
72          f = open(filename, "rb") 
73      # Rewind it 
74      f.seek(0, 0) 
75      m = getHashlibInstance(hashtype, used_for_security) 
76      while 1: 
77          buf = f.read(buffer_size) 
78          if not buf: 
79              break 
80          m.update(buf) 
81   
82      # cleanup time 
83      if file_obj is not None: 
84          file_obj.seek(0, 0) 
85      else: 
86          f.close() 
87      return m.hexdigest() 
88   
89   
90 -def getStringChecksum(hashtype, s): 
91      """ compute checksum of an arbitrary string """ 
92      h = getHashlibInstance(hashtype, False) 
93      h.update(s) 
94      return h.hexdigest() 
95