We have a bad habit of duplicating contents of files that are sourced from
/dev/null and applied more than once... take the more sane (in most ways)
GNU route and complain if the file exists and offer reversal options.
This still falls short a little bit as selecting "don't reverse, apply
anyway" will still give you duplicated file contents. There's probably other
issues as well, but awareness is the first step to happiness.
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D21535
To remain compatible with GNU patch, we should ensure that once we're
removing empty files after a reversed /dev/null patch we don't remove files
that have been modified. GNU patch leaves these intact and just reverses the
hunk that created the file, effectively implying --remove-empty-files for
reversed /dev/null patches.
Summary:
- basic: test application of patches created by diff -u at the
beginning/middle/end of file, which have differing amounts of context
before and after chunks being added
- limited_ctx: stems from PR 74127 in which a rogue line was getting added
when the patch should have been rejected. Similar behavior was
reproducible with larger contexts near the beginning/end of a file. See
r326084 for details
- file_creation: patch sourced from /dev/null should create the file
- file_nodupe: said patch sourced from /dev/null shouldn't dupe the contents
when re-applied (personal vendetta, WIP, see comment)
- file_removal: this follows from nodupe; the reverse of a patch sourced
from /dev/null is most naturally deleting the file, as is expected based
on GNU patch behavior (WIP)
