[PATCH 0/2] fix read past end of array in alternates files

This series fixes a regression in v2.11.1 where we might read past the end of an mmap'd buffer. It was introduced in cf3c635210, but I didn't base the patch on there, for a few reasons:

  1. There's a trivial conflict when merging up (because of
     git_open_noatime() becoming just git_open() in the inerim).

  2. The reproduction advice relies on our SANITIZE Makefile knob, which
     didn't exist back then.

  3. The second patch does not apply there because we don't have
     warn_on_fopen_errors(). Though admittedly it could be applied
     separately after merging up; it's just a clean-up on top.

It does apply on the current "maint".

  [1/2]: read_info_alternates: read contents into strbuf
  [2/2]: read_info_alternates: warn on non-trivial errors

 sha1_file.c | 30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

-Peff