[PATCH 0/5] disallow symlinks for .gitignore and .gitattributes

I noticed in a nearby discussion that we will follow in-filesystem symlinks for in-tree .gitignore and .gitattributes files, but not when those files are read out of the index (e.g., when switching branches).

This series teaches git to open those files with O_NOFOLLOW (when it is available) to get more consistent behavior. Note that this only applies to the in-tree versions; you can still symlink $GIT_DIR/info/attributes, etc.

I stopped short of warning about symlinked entries in git-fsck, but perhaps we would want to do that as well (doing it completely is tricky because of all of the case-folding issues around matching pathnames).

  [1/5]: add open_nofollow() helper
  [2/5]: attr: convert "macro_ok" into a flags field
  [3/5]: exclude: convert "check_index" into a flags field
  [4/5]: attr: do not respect symlinks for in-tree .gitattributes
  [5/5]: exclude: do not respect symlinks for in-tree .gitignore

 attr.c                | 58 ++++++++++++++++++++++++++++++++-------------------
 dir.c                 | 20 +++++++++++++-----
 dir.h                 |  2 +-
 git-compat-util.h     |  3 +++
 t/t0003-attributes.sh | 31 +++++++++++++++++++++++++++
 t/t0008-ignores.sh    | 29 ++++++++++++++++++++++++++
 wrapper.c             |  8 +++++++
 7 files changed, 123 insertions(+), 28 deletions(-)

-Peff