Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/Crypto/Random/OSRNG/posix.py: 74%

1# 

2# Random/OSRNG/posix.py : OS entropy source for POSIX systems 

3# 

4# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net> 

5# 

6# =================================================================== 

7# The contents of this file are dedicated to the public domain. To 

8# the extent that dedication to the public domain is not available, 

9# everyone is granted a worldwide, perpetual, royalty-free, 

10# non-exclusive license to exercise all rights associated with the 

11# contents of this file for any purpose whatsoever. 

12# No rights are reserved. 

13# 

14# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 

15# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 

16# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 

17# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 

18# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 

19# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 

20# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 

21# SOFTWARE. 

22# =================================================================== 

23 

24 

25__revision__ = "$Id$" 

26__all__ = ['DevURandomRNG'] 

27 

28import errno 

29import os 

30import stat 

31 

32from .rng_base import BaseRNG 

33from Crypto.Util.py3compat import b 

34 

35class DevURandomRNG(BaseRNG): 

36 

37 def __init__(self, devname=None): 

38 if devname is None: 

39 self.name = "/dev/urandom" 

40 else: 

41 self.name = devname 

42 

43 # Test that /dev/urandom is a character special device 

44 f = open(self.name, "rb", 0) 

45 fmode = os.fstat(f.fileno())[stat.ST_MODE] 

46 if not stat.S_ISCHR(fmode): 

47 f.close() 

48 raise TypeError("%r is not a character special device" % (self.name,)) 

49 

50 self.__file = f 

51 

52 BaseRNG.__init__(self) 

53 

54 def _close(self): 

55 self.__file.close() 

56 

57 def _read(self, N): 

58 # Starting with Python 3 open with buffering=0 returns a FileIO object. 

59 # FileIO.read behaves like read(2) and not like fread(3) and thus we 

60 # have to handle the case that read returns less data as requested here 

61 # more carefully. 

62 data = b("") 

63 while len(data) < N: 

64 try: 

65 d = self.__file.read(N - len(data)) 

66 except IOError as e: 

67 # read(2) has been interrupted by a signal; redo the read 

68 if e.errno == errno.EINTR: 

69 continue 

70 raise 

71 

72 if d is None: 

73 # __file is in non-blocking mode and no data is available 

74 return data 

75 if len(d) == 0: 

76 # __file is in blocking mode and arrived at EOF 

77 return data 

78 

79 data += d 

80 return data 

81 

82def new(*args, **kwargs): 

83 return DevURandomRNG(*args, **kwargs) 

84 

85 

86# vim:set ts=4 sw=4 sts=4 expandtab: