[New-bugs-announce] [issue7757] sys.path is incorrect when prefix is ""

[Michael Smith]

New submission from Michael Smith <msmith at cbnco.com>:

I've built Python 2.6.2 with a prefix of "" for an embedded system, so it's installed into /bin/python, /lib/python2.6/, etc.

If I run a script with "python /tmp/script.py" or by putting in a #!/bin/python and executing it directly, sys.path is missing the leading slashes:

['/tmp', 'lib/python26.zip', 'lib/python2.6/', 'lib/python2.6/plat-linux2', 'lib/python2.6/lib-tk', 'lib/python2.6/lib-old', 'lib/lib-dynload']

This causes all module imports to fail. I can work around this by making /usr a symlink to / and running the script as "/usr/bin/python /tmp/script.py", or by setting PYTHONHOME=/ before starting Python.

In Modules/getpath.c, search_for_prefix() calls reduce() on argv0_path at the end of a do-while loop, so "/bin" becomes "" and the loop terminates. Then there's a call to joinpath(PREFIX, "lib/python2.6"), where PREFIX is "", and this fails (no leading slash).

calculate_path() warns:

Could not find platform independent libraries <prefix>

and falls back to joinpath(PREFIX, "lib/python2.6") again, which still fails.

I was thinking I could work around it by building with prefix="/" instead of "", but the behaviour is the same - I don't know why, yet.

----------
components: Interpreter Core
messages: 98152
nosy: msmith at cbnco.com
severity: normal
status: open
title: sys.path is incorrect when prefix is ""
type: behavior
versions: Python 2.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue7757>
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