[Python-Dev] PEP 376

[Paul Moore]

2009/7/2 Tarek Ziadé <ziade.tarek at gmail.com>:
> On Thu, Jul 2, 2009 at 2:39 PM, Paul Moore<p.f.moore at gmail.com> wrote:
>> 2009/7/2 Tarek Ziadé <ziade.tarek at gmail.com>:
>>> For absolute paths now that gets installed, what would be the
>>> difference between the pre-generated
>>> RECORD file and the RECORD file installed on the win32 target system, if any ?
>>
>> When is an absolute path generated? If you can give me a small sample
>> of a distribution that installs a file in an absolute path, I'll do
>> some testing on Windows.
>
> Try this setup.py file:
>
> """
> from distutils.core import setup
>
> setup(name='foo', version='1.0', data_files=[('/tmp', ['data'])])
> """
>
> with this MANIFEST.in file:
> ""
> include data
> """
>
> and add a 'data' file alongside
>
> If you install it, data is copied in /tmp. If you create a bdist
> distribution it will be created in the root of the dumb directory
> which is used to generate the binary distro.
>
> Of course you'll have to change '/tmp' to 'c:\tmp'

>python setup.py bdist_wininst
running bdist_wininst
running build
installing to build\bdist.win32\wininst
running install_data
creating build
creating build\bdist.win32
creating build\bdist.win32\wininst
creating build\bdist.win32\wininst\DATA
Traceback (most recent call last):
  File "setup.py", line 3, in <module>
    setup(name='foo', version='1.0', data_files=[('/tmp', ['data'])])
  File "C:\Apps\Python26\lib\distutils\core.py", line 152, in setup
    dist.run_commands()
  File "C:\Apps\Python26\lib\distutils\dist.py", line 975, in run_commands
    self.run_command(cmd)
  File "C:\Apps\Python26\lib\distutils\dist.py", line 995, in run_command
    cmd_obj.run()
  File "C:\Apps\Python26\lib\distutils\command\bdist_wininst.py", line
171, in run
    install.run()
  File "C:\Apps\Python26\lib\distutils\command\install.py", line 589, in run
    self.run_command(cmd_name)
  File "C:\Apps\Python26\lib\distutils\cmd.py", line 333, in run_command
    self.distribution.run_command(command)
  File "C:\Apps\Python26\lib\distutils\dist.py", line 995, in run_command
    cmd_obj.run()
  File "C:\Apps\Python26\lib\distutils\command\install_data.py", line 62, in run
    dir = convert_path(f[0])
  File "C:\Apps\Python26\lib\distutils\util.py", line 164, in convert_path
    raise ValueError, "path '%s' cannot be absolute" % pathname
ValueError: path '/tmp' cannot be absolute

Looks like bdist_wininst doesn't support absolute paths. Which isn't
surprising, really.

Same with bdist_msi.

Actually, with setup.py install:

>python setup.py install
running install
running build
running install_data
Traceback (most recent call last):
  File "setup.py", line 3, in <module>
    setup(name='foo', version='1.0', data_files=[('/tmp', ['data'])])
  File "C:\Apps\Python26\lib\distutils\core.py", line 152, in setup
    dist.run_commands()
  File "C:\Apps\Python26\lib\distutils\dist.py", line 975, in run_commands
    self.run_command(cmd)
  File "C:\Apps\Python26\lib\distutils\dist.py", line 995, in run_command
    cmd_obj.run()
  File "C:\Apps\Python26\lib\distutils\command\install.py", line 589, in run
    self.run_command(cmd_name)
  File "C:\Apps\Python26\lib\distutils\cmd.py", line 333, in run_command
    self.distribution.run_command(command)
  File "C:\Apps\Python26\lib\distutils\dist.py", line 995, in run_command
    cmd_obj.run()
  File "C:\Apps\Python26\lib\distutils\command\install_data.py", line 62, in run
    dir = convert_path(f[0])
  File "C:\Apps\Python26\lib\distutils\util.py", line 164, in convert_path
    raise ValueError, "path '%s' cannot be absolute" % pathname
ValueError: path '/tmp' cannot be absolute

So how do absolute paths work??? It sure ain't like this!

Changing '/tmp' to c:/tmp' gives this:

>python setup.py bdist_wininst
running bdist_wininst
running build
installing to build\bdist.win32\wininst
running install_data
creating build\bdist.win32\wininst\DATA\c:tmp
error: could not create 'build\bdist.win32\wininst\DATA\c:tmp': The
directory name is invalid

Changing it to 'c:\\tmp' gives (sort of) success:

python setup.py bdist_wininst
running bdist_wininst
running build
installing to build\bdist.win32\wininst
running install_data
creating build\bdist.win32\wininst\tmp
copying data -> build\bdist.win32\wininst\tmp
running install_egg_info
Creating build\bdist.win32\wininst\PURELIB\
Writing build\bdist.win32\wininst\PURELIB\foo-1.0-py2.6.egg-info
creating 'c:\users\gustav\appdata\local\temp\tmpcs9rmi.zip' and adding '.' to it
adding 'PURELIB\foo-1.0-py2.6.egg-info'
adding 'tmp\data'
creating dist
removing 'build\bdist.win32\wininst' (and everything under it)

The installer packs a *relative* path tmp/data - which isn't right.

bdist_msi copies the data file to c:\tmp - when building the msi!.
This is very wrong. I can't introspect a msi file to see what ends up
in it, but if I install it, no c:\tmp\data is installed, so it does
look like it's screwed up.

Frankly, handling of absolute paths looks so broken, that I'd
explicitly state that it's not supported.

I'd raise bugs for some of these things, but to be honest, I'm not at
all sure what I'd expect to be correct behaviour (on Windows). In my
view absolute paths shouldn't be supported - I can see that might be
different on Linux, but I don't see how it's ever going to be
cross-platform.

Not sure where that leaves things. Absolute path handling seems broken
enough (on Windows) that whatever the PEP says isn't much of an issue,
as it's not usable anyway. One definite point, though - given the
behaviour of bdist_msi, it thought it had installed something that it
simply didn't - so there's a serious risk that the distutils uninstall
function could uninstall something that the installer never installed
- that's far worse than simply deleting the files and messing up the
installer metadata.

Maybe the answer is that distutils reject *all* uses of absolute paths
on Windows. The PEP can then say whatever you want as far as I'm
concerned, as it doesn't affect me. If the existing bugs don't get
fixed, though, I'd say that the RECORD file should be explicitly
disallowed from containing absolute paths on Windows (for safety
reasons if nothing else).

Paul.