diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/library/subprocess.rst | 42 | ||||
| -rw-r--r-- | Doc/whatsnew/3.7.rst | 19 |
2 files changed, 55 insertions, 6 deletions
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst index a2c184a..af96f41 100644 --- a/Doc/library/subprocess.rst +++ b/Doc/library/subprocess.rst @@ -452,17 +452,20 @@ functions. common use of *preexec_fn* to call os.setsid() in the child. If *close_fds* is true, all file descriptors except :const:`0`, :const:`1` and - :const:`2` will be closed before the child process is executed. (POSIX only). - The default varies by platform: Always true on POSIX. On Windows it is - true when *stdin*/*stdout*/*stderr* are :const:`None`, false otherwise. + :const:`2` will be closed before the child process is executed. On Windows, if *close_fds* is true then no handles will be inherited by the - child process. Note that on Windows, you cannot set *close_fds* to true and - also redirect the standard handles by setting *stdin*, *stdout* or *stderr*. + child process unless explicitly passed in the ``handle_list`` element of + :attr:`STARTUPINFO.lpAttributeList`, or by standard handle redirection. .. versionchanged:: 3.2 The default for *close_fds* was changed from :const:`False` to what is described above. + .. versionchanged:: 3.7 + On Windows the default for *close_fds* was changed from :const:`False` to + :const:`True` when redirecting the standard handles. It's now possible to + set *close_fds* to :const:`True` when redirecting the standard handles. + *pass_fds* is an optional sequence of file descriptors to keep open between the parent and child. Providing any *pass_fds* forces *close_fds* to be :const:`True`. (POSIX only) @@ -764,7 +767,7 @@ The :class:`STARTUPINFO` class and following constants are only available on Windows. .. class:: STARTUPINFO(*, dwFlags=0, hStdInput=None, hStdOutput=None, \ - hStdError=None, wShowWindow=0) + hStdError=None, wShowWindow=0, lpAttributeList=None) Partial support of the Windows `STARTUPINFO <https://msdn.microsoft.com/en-us/library/ms686331(v=vs.85).aspx>`__ @@ -814,6 +817,33 @@ on Windows. :data:`SW_HIDE` is provided for this attribute. It is used when :class:`Popen` is called with ``shell=True``. + .. attribute:: lpAttributeList + + A dictionary of additional attributes for process creation as given in + ``STARTUPINFOEX``, see + `UpdateProcThreadAttribute <https://msdn.microsoft.com/en-us/library/windows/desktop/ms686880(v=vs.85).aspx>`__. + + Supported attributes: + + **handle_list** + Sequence of handles that will be inherited. *close_fds* must be true if + non-empty. + + The handles must be temporarily made inheritable by + :func:`os.set_handle_inheritable` when passed to the :class:`Popen` + constructor, else :class:`OSError` will be raised with Windows error + ``ERROR_INVALID_PARAMETER`` (87). + + .. warning:: + + In a multithreaded process, use caution to avoid leaking handles + that are marked inheritable when combining this feature with + concurrent calls to other process creation functions that inherit + all handles such as :func:`os.system`. This also applies to + standard handle redirection, which temporarily creates inheritable + handles. + + .. versionadded:: 3.7 Windows Constants ^^^^^^^^^^^^^^^^^ diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst index 3574b53..82f7cc0 100644 --- a/Doc/whatsnew/3.7.rst +++ b/Doc/whatsnew/3.7.rst @@ -437,6 +437,17 @@ string expression pattern for braced placeholders and non-braced placeholders separately. (Contributed by Barry Warsaw in :issue:`1198569`.) +subprocess +---------- + +On Windows the default for *close_fds* was changed from :const:`False` to +:const:`True` when redirecting the standard handles. It's now possible to set +*close_fds* to :const:`True` when redirecting the standard handles. See +:class:`subprocess.Popen`. + +This means that *close_fds* now defaults to :const:`True` on all supported +platforms. + sys --- @@ -883,6 +894,14 @@ Changes in the Python API .. _Unicode Technical Standard #18: https://unicode.org/reports/tr18/ +* On Windows the default for the *close_fds* argument of + :class:`subprocess.Popen` was changed from :const:`False` to :const:`True` + when redirecting the standard handles. If you previously depended on handles + being inherited when using :class:`subprocess.Popen` with standard io + redirection, you will have to pass ``close_fds=False`` to preserve the + previous behaviour, or use + :attr:`STARTUPINFO.lpAttributeList <subprocess.STARTUPINFO.lpAttributeList>`. + Changes in the C API -------------------- |