in window7 (using python 3.4.3,3.5.2) following script crashes import os os.spawnl( os.P_NOWAIT, 'C:/Tcl/bin/tclsh.exe' )" Note: similar issue is already exist https://bugs.python.org/issue8036

small correction (removed " ) import os os.spawnl( os.P_NOWAIT, 'C:/Tcl/bin/tclsh.exe' )

Just to make sure: a crash means that the Python process is killed and you get a popup or something like that? Can you please try to run the script on Python 3.6 using: python.exe -X faulthandler script.py It should display the Windows error code at least.

spawnl is implemented by calling _spawnv [1], which is documented to invoke the invalid parameter handler if argv points to a NULL pointer. It wants the program name, or whatever, as long as argv[0] isn't NULL or an empty string, e.g. `os.spawnl(os.P_NOWAIT, 'C:/Tcl/bin/tclsh.exe', 'tclsh')`. The invalid parameter handler should be disabled (_Py_BEGIN_SUPPRESS_IPH) when calling _spawnv[e], which in this case would lead to an EINVAL OSError instead of crashing the process. For example: import os, sys from ctypes import * ucrt = CDLL('ucrtbase') @CFUNCTYPE(None, c_wchar_p, c_wchar_p, c_wchar_p, c_int, c_void_p) def iph(*args): pass ucrt._set_thread_local_invalid_parameter_handler(iph) >>> os.spawnl(os.P_NOWAIT, sys.executable) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Program Files\Python35\lib\os.py", line 977, in spawnl return spawnv(mode, file, args) OSError: [Errno 22] Invalid argument Also, in this case a descriptive ValueError would be friendlier, given an empty argv or argv[0] that's an empty string -- at least on Windows. [1]: https://msdn.microsoft.com/en-us/library/7zt1y878.aspx

I like the idea of using _Py_BEGIN_SUPPRESS_IPH, but also the idea of implementing most obvious checks on arguments. Sadly, I don't have access to Windows yet to write such patch. Eryk, if you write such patch, I would be happy to review it ;-) Especially if it includes unit tests :-D

Looks like a few functions in os module need this. os_execve_impl also doesn't release the GIL at any point, but I don't see why it shouldn't. I'll try and get to this over the weekend if nobody else comes up with a patch first.

New changeset 02f416441def by Steve Dower in branch '3.5': Issue #28732: Fix crash in os.spawnv() with no elements in args https://hg.python.org/cpython/rev/02f416441def

A ValueError should also be raised when argv[0] is an empty string.

New changeset 1a9e4b465497 by Steve Dower in branch '3.6': Issue #28732: Raise ValueError when os.spawn*() is passed an empty tuple of arguments https://hg.python.org/cpython/rev/1a9e4b465497 New changeset 75824899f0dd by Steve Dower in branch 'default': Issue #28732: Raise ValueError when os.spawn*() is passed an empty tuple of arguments https://hg.python.org/cpython/rev/75824899f0dd

New changeset e076ace7b0ff by Steve Dower in branch '3.5': Issue #28732: Raise ValueError when argv[0] is empty. https://hg.python.org/cpython/rev/e076ace7b0ff New changeset af78b33704af by Steve Dower in branch '3.6': Issue #28732: Raise ValueError when argv[0] is empty https://hg.python.org/cpython/rev/af78b33704af New changeset fc6f757e53de by Steve Dower in branch 'default': Issue #28732: Raise ValueError when argv[0] is empty https://hg.python.org/cpython/rev/fc6f757e53de

> ValueError should also be raised when argv[0] is an empty string. Added that too. Python 3.5 is missing the tests for these functions completely, so I only added those to 3.6 and later. Also the original issue was already resolved in 3.6, but I tidied up a few other functions that were missing proper handling.

New changeset 2e1fb851dfb4 by Steve Dower in branch '3.6': Issue #28732: Adds new errors to spawnv emulation for platforms that only have fork and execv https://hg.python.org/cpython/rev/2e1fb851dfb4 New changeset ac6de11fbd50 by Steve Dower in branch 'default': Issue #28732: Adds new errors to spawnv emulation for platforms that only have fork and execv https://hg.python.org/cpython/rev/ac6de11fbd50

Buildbots seem to be happy now so I'm closing the issue. Feel free to reopen if anyone spots anything in commit review.