[Distutils] setuptools: mishandles install of non-python scripts
Phillip J. Eby
pje at telecommunity.com
Thu Jun 15 21:05:48 CEST 2006
At 12:52 PM 6/12/2006 -0400, Phillip J. Eby wrote:
>At 05:22 PM 6/9/2006 -0700, Ned Deily wrote:
> >In build_scripts.py in distutils.command, distuitils uses the results of
> >first_line_re to decide whether to adjust the python value in the shbang
> >line of the script: if no "python" is found, distutils installs the
> >script without modification. easy_install.py uses the first_line_re
> >test from distutils but seems to unconditionally add a wrapper to the
> >script during installation regardless of the script's type.
>Who needs shell scripts when you have Python? ;)
>I can (sort of) fix this, but there are some potentially-significant
There's another wrinkle, as it turns out. It's not sufficient to inspect
the first line for a #!python presence - it's perfectly valid and possible
to have .py or .pyw scripts that don't have a #! line, especially on
Windows. So, the actual condition to test if the program is a Python
script should be to compile it. If it's valid Python syntax, easy_install
will assume it's a Python script, rather than a shell, batch, or other kind
of script file.
But, it's *also* necessary to check whether there is a *non*-Python #!
line, if the first line begins with #!. It's quite possible for a shell
script to be syntactically valid Python, especially if you have a shell
prolog hidden in what looks like a Python docstring. This is a trick that
I believe is listed in the Python FAQ, although I don't know if it's used
in any currently-distributed scripts. But it should be supported.
So the full rules for analyzing scripts should be:
* If there's a #! line, use first_line_re to tell if it's Python
* If there's a '.py' or '.pyw' extension, assume it's Python
* Otherwise, try to compile the script. If it compiles, assume it's Python
* Otherwise, assume it's not.
There is one possiblity I'm leaving out here, which is that you have some
other script interpreter (e.g. .bat or .cmd files on Windows) that just
magically happen to be syntactically-valid Python. In the .bat/.cmd case,
anything more complex than a series of one-word commands with no arguments
would fail to be valid Python, so it seems incredibly unlikely that this
would ever happen.
Actually, there's one other possibility I'm also leaving out, which is that
you have a .bat or .cmd or some other script whose first line uses -x to
skip that line. In such a case, lines 2-N of the file are valid Python,
but line 1 doesn't start with #!. In theory, what this should do is keep
the first line and wrap the rest. However, such scripts aren't supported
by the distutils, so I'm not going to add them to setuptools for 0.6.
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