tree b7f2bb24121342b769fd4c604faeea9163eb6171
parent 5f1189894b87fd7e494fd04a835c22d77f1e0a1e
author Yiding Jia <yiding@fb.com> 1383787748 -0800
committer Michael Bolin <mbolin@fb.com> 1384307559 -0800

buck.py more permissive symlinking.

Summary:
f0dedaec09331f73b3970658344cf8f3cb37a83b introduced a symlink aware walk aimed
at preventing recursively symlink loops; however, it was too restrictive in
that it pruned all symlinks that it has visited before, not only those that
would result in recursive symlinks. This breaks legitimate uses of symlinking
to siblings and cousin directories.

This diff adds a second test before pruning the symlink: not only must the
target directory be one already visited, but it must also be a direct ancestor
of the current directory.

Test Plan:
Trigger the traversal code by using recursive `glob` and `buck test --all` on
directories with the following configurations:

Test that siblings are okay (`b` and `c` are both traversed):

  a/
    b/
    c -> b

Test that ancestors are still rejected (`c` is not traversed):

  a/
    b/
      c/ -> ../b