Use real OS tmp dir on Linux for long path tests

[rsp]

Use os.tmpdir() on Linux if it is readable/writable
in test-fs-long-path.js and test-require-long-path.js
to avoid failing tests on ecryptfs filesystems - see issue #2255

[rvagg]

I think the best way to do this would be to first try the original way and then do the /tmp/ thing if it fails. One of the primary problems I see with relying on the OS tmpdir is that it's usually a completely different fs than the rest of the system, on Linux anyway, most distros now use tmpfs for it, so anything done in there may not be quite the same as working on other parts of the fs.

Need some more input on this, @bnoordhuis perhaps? Got any suggestions?

[rsp]

@rvagg Thanks for the advice. I prepared a second PR #3929 that works in a way that you describe. It retries the tests under os.tempdir() but only if the original tests fail (and only on Linux).

[rsp]

@rvagg Re: tmpfs not being the same as the rest of the file ststem - yes, that's why it works. The test fails on Ubuntu not because Node is broken but because ecryptfs is, well, limited. If it fails under one file system it retries under another one and if it's ok then it means that it's not Node's fault. This test was introduced to test Windows anyway, and my PR doesn't use os.tmpdir() on Windows, only on Linux. Please let me know if it needs any other changes. Thanks.

[jasnell]

Any updates on this one?

[rsp]

@jasnell I'm closing this one as well. See my comment in #3929.