Question

我正在编写一个将在嵌入式平台上执行的python工具，每当我导入＆＃34;随机＆＃34;我将收到以下错误输出：

ERROR:root:code for hash sha1 was not found.
Traceback (most recent call last):
  File "/usr/lib/python2.7/hashlib.py", line 147, in <module>
    globals()[__func_name] = __get_hash(__func_name)
  File "/usr/lib/python2.7/hashlib.py", line 97, in __get_builtin_constructor
    raise ValueError('unsupported hash type ' + name)
ValueError: unsupported hash type sha1
ERROR:root:code for hash sha224 was not found.
Traceback (most recent call last):
  File "/usr/lib/python2.7/hashlib.py", line 147, in <module>
    globals()[__func_name] = __get_hash(__func_name)
  File "/usr/lib/python2.7/hashlib.py", line 97, in __get_builtin_constructor
    raise ValueError('unsupported hash type ' + name)
ValueError: unsupported hash type sha224
ERROR:root:code for hash sha256 was not found.
Traceback (most recent call last):
  File "/usr/lib/python2.7/hashlib.py", line 147, in <module>
    globals()[__func_name] = __get_hash(__func_name)
  File "/usr/lib/python2.7/hashlib.py", line 97, in __get_builtin_constructor
    raise ValueError('unsupported hash type ' + name)
ValueError: unsupported hash type sha256
ERROR:root:code for hash sha384 was not found.
Traceback (most recent call last):
  File "/usr/lib/python2.7/hashlib.py", line 147, in <module>
    globals()[__func_name] = __get_hash(__func_name)
  File "/usr/lib/python2.7/hashlib.py", line 97, in __get_builtin_constructor
    raise ValueError('unsupported hash type ' + name)
ValueError: unsupported hash type sha384
ERROR:root:code for hash sha512 was not found.
Traceback (most recent call last):
  File "/usr/lib/python2.7/hashlib.py", line 147, in <module>
    globals()[__func_name] = __get_hash(__func_name)
  File "/usr/lib/python2.7/hashlib.py", line 97, in __get_builtin_constructor
    raise ValueError('unsupported hash type ' + name)
ValueError: unsupported hash type sha512

除了此错误消息之外，该工具还会执行并执行此操作。尽职尽责。看了一下之后，似乎是因为嵌入式操作系统缺少特定的库。在目标上安装它并不是一个真正的选择，而且由于我没有使用这些哈希类型，所以我更加不受支持。但是，我宁愿没有这个错误信息，也无法弄清楚如何抑制它。我可以猜测只是在导入模块时将stderr重定向到/ dev / null，但我可能还会隐藏其他错误。我怎样才能最好地压制这个错误？

Answer 1

正如你所说，似乎是因为那些算法（sha1等）在所有平台上都是支持的，但是你所使用的那些算法不支持它们。

hashlib.py会发生什么：

__always_supported = ('md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512',
                  'blake2b', 'blake2s',
                  'sha3_224', 'sha3_256', 'sha3_384', 'sha3_512',
                  'shake_128', 'shake_256')

...

for __func_name in __always_supported:
    # try them all, some may not work due to the OpenSSL
    # version not supporting that algorithm.
    try:
        globals()[__func_name] = __get_hash(__func_name)
    except ValueError:
        import logging
        logging.exception('code for hash %s was not found.', __func_name)

所以你看到的是logging.exception()将这些异常和错误消息写入stderr的结果。

现在，logging模块已filtering capabilities。因此，您实际上可以过滤掉stderr上的特定异常。

以下代码导入random，同时精确过滤掉与“不支持的散列类型”相关的特定ValueError异常。并且它只在导入random时执行，因此如果代码中稍后出现类似错误，则会在此时报告它们。

import logging class RemoveUnsupportedHashTypeErrorsFilter(logging.Filter): def filter(self, record): # record is of type logging.LogRecord. if record.exc_info: exctype, value = record.exc_info[:2] if (exctype==ValueError) and ("unsupported hash type" in str(value)): return False # Do not log the record. return True # Log the record. filter = RemoveUnsupportedHashTypeErrorsFilter() logging.getLogger().addFilter(filter) try: import random finally: logging.getLogger().removeFilter(filter)

Python，压缩ERROR：root：导入随机时的代码

1 个答案: