git/contrib/rerere-train.sh
Elijah Newren 94b7f1563a Comment important codepaths regarding nuking untracked files/dirs
In the last few commits we focused on code in unpack-trees.c that
mistakenly removed untracked files or directories.  There may be more of
those, but in this commit we change our focus: callers of toplevel
commands that are expected to remove untracked files or directories.

As noted previously, we have toplevel commands that are expected to
delete untracked files such as 'read-tree --reset', 'reset --hard', and
'checkout --force'.  However, that does not mean that other highlevel
commands that happen to call these other commands thought about or
conveyed to users the possibility that untracked files could be removed.
Audit the code for such callsites, and add comments near existing
callsites to mention whether these are safe or not.

My auditing is somewhat incomplete, though; it skipped several cases:
  * git-rebase--preserve-merges.sh: is in the process of being
    deprecated/removed, so I won't leave a note that there are
    likely more bugs in that script.
  * contrib/git-new-workdir: why is the -f flag being used in a new
    empty directory??  It shouldn't hurt, but it seems useless.
  * git-p4.py: Don't see why -f is needed for a new dir (maybe it's
    not and is just superfluous), but I'm not at all familiar with
    the p4 stuff
  * git-archimport.perl: Don't care; arch is long since dead
  * git-cvs*.perl: Don't care; cvs is long since dead

Also, the reset --hard in builtin/worktree.c looks safe, due to only
running in an empty directory.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-27 13:38:37 -07:00

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#!/bin/sh
# Copyright (c) 2008, Nanako Shiraishi
# Prime rerere database from existing merge commits
me=rerere-train
USAGE=$(cat <<-EOF
usage: $me [--overwrite] <rev-list-args>
-h, --help show the help
-o, --overwrite overwrite any existing rerere cache
EOF
)
SUBDIRECTORY_OK=Yes
overwrite=0
while test $# -gt 0
do
opt="$1"
case "$opt" in
-h|--help)
echo "$USAGE"
exit 0
;;
-o|--overwrite)
overwrite=1
shift
break
;;
--)
shift
break
;;
*)
break
;;
esac
done
# Overwrite or help options are not valid except as first arg
for opt in "$@"
do
case "$opt" in
-h|--help)
echo "$USAGE"
exit 0
;;
-o|--overwrite)
echo "$USAGE"
exit 0
;;
esac
done
. "$(git --exec-path)/git-sh-setup"
require_work_tree
cd_to_toplevel
# Remember original branch
branch=$(git symbolic-ref -q HEAD) ||
original_HEAD=$(git rev-parse --verify HEAD) || {
echo >&2 "Not on any branch and no commit yet?"
exit 1
}
mkdir -p "$GIT_DIR/rr-cache" || exit
git rev-list --parents "$@" |
while read commit parent1 other_parents
do
if test -z "$other_parents"
then
# Skip non-merges
continue
fi
git checkout -q "$parent1^0"
if git merge $other_parents >/dev/null 2>&1
then
# Cleanly merges
continue
fi
if test $overwrite = 1
then
git rerere forget .
fi
if test -s "$GIT_DIR/MERGE_RR"
then
git show -s --pretty=format:"Learning from %h %s" "$commit"
git rerere
git checkout -q $commit -- .
git rerere
fi
git reset -q --hard # Might nuke untracked files...
done
if test -z "$branch"
then
git checkout "$original_HEAD"
else
git checkout "${branch#refs/heads/}"
fi