On 2012-06-21 06:23, Armin Ronacher wrote:
Due to an user error on my part I was not using os.readlink correctly.
Since links can be relative to their location I think it would make sense
to provide an os.path.resolve helper that automatically returns the
absolute path:
def resolve(filename):
try:
target = os.readlink(filename)
except OSError as e:
if e.errno == errno.EINVAL:
return abspath(filename)
raise
return normpath(join(dirname(filename), target))
The above implementation also does not fail if an entity exists but is not
a link and just returns the absolute path of the given filename in that
case.
It's expensive (not to mention racy) to do this correctly, when any
component of the pathname (not just the component after the last slash)
might be a symlink. For example:
mkdir -p foo1/foo2
touch bar
ln -s ../../bar foo1/foo2/symlink
ln -s foo1/foo2 foo
Now try to resolve "foo/symlink" using your function. It produces
"../bar", which doesn't exist.
Why not just work with the pathname you're given and let the kernel
worry about resolving it?
-Phil
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