PySFTP / Paramiko异常泄漏到stderr中

Question

我正在尝试捕获paramiko异常，但它们仍被写入stderr。

有没有办法停止在那儿写作？

编辑：甚至在paramiko参与之前就发生了：

import pysftp

try:
    pysftp.Connection(host="localhost")
except Exception as e:
    print(e)

结果：

具有正确的SFTP参数的示例：

UPDATE：

$ pipenv graph
...
pysftp==0.2.9
  - paramiko [required: >=1.17, installed: 2.6.0]
...

$ pipenv run python
Python 3.7.3 (default, Jul 19 2019, 11:21:39)
[Clang 11.0.0 (clang-1100.0.28.3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pysftp
>>> try:
...     pysftp.Connection(host="localhost")
... except Exception as e:
...     print(e)
...
No hostkey for host localhost found.
Exception ignored in: <function Connection.__del__ at 0x10f7e8268>
Traceback (most recent call last):
  File "/Users/andrei/Work/try/.venv/lib/python3.7/site-packages/pysftp/__init__.py", line 1013, in __del__
    self.close()
  File "/Users/andrei/Work/try/.venv/lib/python3.7/site-packages/pysftp/__init__.py", line 784, in close
    if self._sftp_live:
AttributeError: 'Connection' object has no attribute '_sftp_live'
>>>

Answer 1

我想指出PySFTP（[PyPI]: PySFTP）已有[3 +年未维护（或已移至其他位置-到目前为止保密:)）。

我转载了问题。下面是您的代码的更详细的版本。

code00.py：

#!/usr/bin/env python3

import sys
import pysftp
import traceback


def main(argv):
    hostname = argv[0] if argv else "localhost"
    print("Attempting to connect to {0:s} ...".format(hostname))
    try:
        print("----------Before conn----------")
        conn = pysftp.Connection(host=hostname)
        print("----------After conn----------")
    except:
        print("----------Before exc print----------")
        traceback.print_exc()
        print("----------After exc print----------")
    finally:
        print("----------Finally----------")
    print("----------After try / except / finally----------")

if __name__ == "__main__":
    print("Python {0:s} {1:d}bit on {2:s}".format(" ".join(item.strip() for item in sys.version.split("\n")), 64 if sys.maxsize > 0x100000000 else 32, sys.platform))
    print("pysftp version: {0:s}\n".format(pysftp.__version__))
    main(sys.argv[1:])
    print("\nDone.")

输出：

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q058110732]> "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\Scripts\python.exe" code00.py
Python 3.7.3 (v3.7.3:ef4ec6ed12, Mar 25 2019, 22:22:05) [MSC v.1916 64 bit (AMD64)] 64bit on win32
pysftp version: 0.2.9

Attempting to connect to localhost ...
----------Before conn----------
e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py:61: UserWarning: Failed to load HostKeys from C:\Users\cfati\.ssh\known_hosts.  You will need to explicitly load HostKeys (cnopts.hostkeys.load(filename)) or disableHostKey checking (cnopts.hostkeys = None).
  warnings.warn(wmsg, UserWarning)
----------Before exc print----------
Traceback (most recent call last):
  File "code00.py", line 13, in main
    conn = pysftp.Connection(host=hostname)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py", line 132, in __init__
    self._tconnect['hostkey'] = self._cnopts.get_hostkey(host)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py", line 71, in get_hostkey
    raise SSHException("No hostkey for host %s found." % host)
paramiko.ssh_exception.SSHException: No hostkey for host localhost found.
----------After exc print----------
Exception ignored in: <function Connection.__del__ at 0x000001CC720C80D0>
Traceback (most recent call last):
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py", line 1013, in __del__
    self.close()
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py", line 784, in close
    if self._sftp_live:
AttributeError: 'Connection' object has no attribute '_sftp_live'
----------Finally----------
----------After try / except / finally----------

Done.

这是PySFTP错误：

1. Connection对象被构造（__ new __）
2. 初始化器（__ init __）被称为
   1. 在初始化程序中的某个地方发生异常
   2. 不执行异常后的行
3. 当对象（自动）被垃圾回收时（当对象超出范围时，在[[except块的末尾）），采用其close方法（由析构函数（__ del__]调用） >）），引用了某些属性
   但是由于这些属性初始化发生在
   1. ＃2.2。
   的行（引发异常）中，所以它们从未被初始化，因此它们的引用引发了[[AttributeError

解决方法很简单：在初始化程序的开头将属性初始化为一些默认值，因此，如果发生上述情况，则对它们的引用不会出现问题。我注意到您已经在BitBucket上提交了问题。

考虑：

我不是

BitBucket

专家

我没有[BitBucket]: dundeemt/pysftp - pysftp is an easy to use sftp module that utilizes paramiko and pycrypto.的权限（我既不能推送也不能提交请求请求）

我创建了自己的repo

（在上一个中），并将更改推送到：[[[BitBucket]: CristiFati0/pysftp - [Issue #144]: Exceptions leaking into stderr（到目前为止，一次提交）。

输出

（在将修补程序手动应用于pip安装的文件之后）：

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q058110732]> "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\Scripts\python.exe" code00.py
Python 3.7.3 (v3.7.3:ef4ec6ed12, Mar 25 2019, 22:22:05) [MSC v.1916 64 bit (AMD64)] 64bit on win32
pysftp version: 0.2.9

Attempting to connect to localhost ...
----------Before conn----------
e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py:61: UserWarning: Failed to load HostKeys from C:\Users\cfati\.ssh\known_hosts.  You will need to explicitly load HostKeys (cnopts.hostkeys.load(filename)) or disableHostKey checking (cnopts.hostkeys = None).
  warnings.warn(wmsg, UserWarning)
----------Before exc print----------
Traceback (most recent call last):
  File "code00.py", line 13, in main
    conn = pysftp.Connection(host=hostname)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py", line 135, in __init__
    self._tconnect['hostkey'] = self._cnopts.get_hostkey(host)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py", line 71, in get_hostkey
    raise SSHException("No hostkey for host %s found." % host)
paramiko.ssh_exception.SSHException: No hostkey for host localhost found.
----------After exc print----------
----------Finally----------
----------After try / except / finally----------

Done.

不用说，对于不同的情况，可能会引发其他未处理的异常。

@ EDIT0

显然，这不只是眼神。除了上述

PySFTP

错误外，还有2件事会污染stderr。1。警告

就我而言（因为我在Win

上并且没有安装任何本机SSH工具），它每次都会弹出（除非我在其中创建/复制了一些有效的

known_hosts

文件我的家

dir），但在Nix系统上很可能不会。无论如何，此修复程序（如果需要）很容易，例如，通过设置％PYTHONWARNINGS％

env

var，只需抑制UserWarning

到ignore :: UserWarning。2。 Paramiko例外我能够通过手动修改transport.py（并提高socket.timeout）来重现此内容。由paramiko.Transport初始化（由初始化程序调用）的

pysftp.Connection._start_transport执行其工作[[在线程中。如果该线程中引发了某些异常，则无法被调用线程捕获。这是

Python

的限制，请选中[Python.Bugs]: threading.Thread should have way to catch an exception thrown within。为此，有一个（lame）解决方法（

gainarie

），并且正在重定向stderr。当然，还有其他解决方法，但是它们暗示着修改Paramiko，因此我建议您不要使用它们。下面是将

stderr

重定向到stdout的示例（但是您可以选择任何其他文件-包括/ dev / null（或Win上的

nul

））。它是通过代码完成的（但也可以通过解释器命令行完成），因此它仅影响所需的（热）区域。code01.py：

#!/usr/bin/env python3

import sys
import pysftp
import paramiko
import traceback
import threading


_sys_stderr = sys.stderr  # For restoring purposes


def main(argv):
    hostname = argv[0] if argv else "localhost"
    print("Attempting to connect to {0:s} ...".format(hostname))
    try:
        cnopts = pysftp.CnOpts()
        cnopts.hostkeys = None
        print("---------- STATS: {0:s} {1:d} ----------".format(__file__, threading.get_ident()))
        print("---------- Before conn ----------")
        sys.stderr.write("DUMMY TEXT before sent to stderr\n")
        sys.stderr = sys.stdout  # @TODO - cfati: decomment so that everything from stderr is redirected to stdout
        conn = pysftp.Connection(host=hostname, port=22001, username="usr", password="pwd", cnopts=cnopts,)
        print("---------- After conn ----------")
    except:
        sys.stderr = _sys_stderr
        print("---------- Before exc tb ----------")
        traceback.print_exc(file=sys.stdout)
        print("---------- After exc tb ----------")
    finally:
        sys.stderr = _sys_stderr
        print("---------- Finally ----------")
        sys.stderr.write("DUMMY TEXT after sent to stderr\n")
    print("---------- After try / except / finally ----------")


if __name__ == "__main__":
    print("Python {0:s} {1:d}bit on {2:s}".format(" ".join(item.strip() for item in sys.version.split("\n")), 64 if sys.maxsize > 0x100000000 else 32, sys.platform))
    print("pysftp version: {0:s}\nparamiko version: {1:s}".format(pysftp.__version__, paramiko.__version__))
    main(sys.argv[1:])
    print("\nDone.")

输出：

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q058110732]> sopr.bat
*** Set shorter prompt to better fit when pasted in StackOverflow (or other) pages ***

[prompt]> dir /b
code00.py
code01.py

[prompt]> :: Suppress warning
[prompt]> set PYTHONWARNINGS=ignore::UserWarning

[prompt]> :: Redirect stdout and stderr to different files, so it is obvious which is which
[prompt]> "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\Scripts\python.exe" code01.py 1>1.out 2>1.err

[prompt]> type 1.err
DUMMY TEXT before sent to stderr
DUMMY TEXT after sent to stderr

[prompt]> type 1.out
Python 3.7.3 (v3.7.3:ef4ec6ed12, Mar 25 2019, 22:22:05) [MSC v.1916 64 bit (AMD64)] 64bit on win32
pysftp version: 0.2.9
paramiko version: 2.6.0
Attempting to connect to localhost ...
---------- STATS: code01.py 23016 ----------
---------- Before conn ----------
---------- STATS: e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py 45616 ----------
Exception: Error reading SSH protocol banner
Traceback (most recent call last):
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 2212, in _check_banner
    raise socket.timeout()
socket.timeout

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 2039, in run
    self._check_banner()
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 2218, in _check_banner
    "Error reading SSH protocol banner" + str(e)
paramiko.ssh_exception.SSHException: Error reading SSH protocol banner

---------- Before exc tb ----------
Traceback (most recent call last):
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 2212, in _check_banner
    raise socket.timeout()
socket.timeout

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "code01.py", line 23, in main
    conn = pysftp.Connection(host=hostname, port=22001, username="usr", password="pwd", cnopts=cnopts,)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\pysftp\__init__.py", line 144, in __init__
    self._transport.connect(**self._tconnect)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 1291, in connect
    self.start_client()
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 660, in start_client
    raise e
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 2039, in run
    self._check_banner()
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\paramiko\transport.py", line 2218, in _check_banner
    "Error reading SSH protocol banner" + str(e)
paramiko.ssh_exception.SSHException: Error reading SSH protocol banner
---------- After exc tb ----------
---------- Finally ----------
---------- After try / except / finally ----------

Done.

以及它在
PyCharm

中的外观（必须将其拉伸到最大以适合整个东西）：