ctypescrypto/exception.py

   1 """
   2 Exception which extracts libcrypto error information
   3 """
   4 from ctypes import *
   5 from ctypescrypto import libcrypto
   6 strings_loaded=False
   7
   8 __all__ = ['LibCryptoError','clear_err_stack']
   9
  10 def _check_null(s):
  11     """
  12     Handle transparently NULL returned from error reporting functions
  13     instead of strings
  14     """
  15     if s is None:
  16         return ""
  17     return s
  18
  19 class LibCryptoError(Exception):
  20     """
  21         Exception for libcrypto errors. Adds all the info, which can be
  22         extracted from internal (per-thread) libcrypto error stack to the message,
  23         passed to the constructor.
  24     """
  25     def __init__(self,msg):
  26         global strings_loaded
  27         if not strings_loaded:
  28             libcrypto.ERR_load_crypto_strings()
  29             strings_loaded = True
  30         e=libcrypto.ERR_get_error()
  31         m = msg
  32         while e != 0:
  33             m+="\n\t"+_check_null(libcrypto.ERR_lib_error_string(e))+":"+\
  34               _check_null(libcrypto.ERR_func_error_string(e))+":"+\
  35               _check_null(libcrypto.ERR_reason_error_string(e))
  36             e=libcrypto.ERR_get_error()
  37         self.args=(m,)
  38
  39 def clear_err_stack():
  40     """
  41       Clears internal libcrypto err stack. Call it if you've checked
  42       return code and processed exceptional situation, so subsequent
  43       raising of the LibCryptoError wouldn't list already handled errors
  44     """
  45     libcrypto.ERR_clear_error()
  46
  47
  48 libcrypto.ERR_lib_error_string.restype=c_char_p
  49 libcrypto.ERR_func_error_string.restype=c_char_p
  50 libcrypto.ERR_reason_error_string.restype=c_char_p