git/contrib/workdir/git-new-workdir
Shawn O. Pearce ea09ea22d6 Don't allow contrib/workdir/git-new-workdir to trash existing dirs
Recently I found that doing a sequence like the following:

  git-new-workdir a b
  ...
  git-new-workdir a b

by accident will cause a (and now also b) to have an infinite cycle
in its refs directory.  This is caused by git-new-workdir trying
to create the "refs" symlink over again, only during the second
time it is being created within a's refs directory and is now also
pointing back at a's refs.

This causes confusion in git as suddenly branches are named things
like "refs/refs/refs/refs/refs/refs/refs/heads/foo" instead of the
more commonly accepted "refs/heads/foo".  Plenty of commands start
to see ambiguous ref names and others just take ages to compute.

git-clone has the same safety check, so git-new-workdir should
behave just like it.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-09-05 22:24:54 -07:00

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#!/bin/sh
usage () {
echo "usage:" $@
exit 127
}
die () {
echo $@
exit 128
}
if test $# -lt 2 || test $# -gt 3
then
usage "$0 <repository> <new_workdir> [<branch>]"
fi
orig_git=$1
new_workdir=$2
branch=$3
# want to make sure that what is pointed to has a .git directory ...
git_dir=$(cd "$orig_git" 2>/dev/null &&
git rev-parse --git-dir 2>/dev/null) ||
die "\"$orig_git\" is not a git repository!"
case "$git_dir" in
.git)
git_dir="$orig_git/.git"
;;
.)
git_dir=$orig_git
;;
esac
# don't link to a configured bare repository
isbare=$(git --git-dir="$git_dir" config --bool --get core.bare)
if test ztrue = z$isbare
then
die "\"$git_dir\" has core.bare set to true," \
" remove from \"$git_dir/config\" to use $0"
fi
# don't link to a workdir
if test -L "$git_dir/config"
then
die "\"$orig_git\" is a working directory only, please specify" \
"a complete repository."
fi
# don't recreate a workdir over an existing repository
if test -e "$new_workdir"
then
die "destination directory '$new_workdir' already exists."
fi
# make sure the the links use full paths
git_dir=$(cd "$git_dir"; pwd)
# create the workdir
mkdir -p "$new_workdir/.git" || die "unable to create \"$new_workdir\"!"
# create the links to the original repo. explictly exclude index, HEAD and
# logs/HEAD from the list since they are purely related to the current working
# directory, and should not be shared.
for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache
do
case $x in
*/*)
mkdir -p "$(dirname "$new_workdir/.git/$x")"
;;
esac
ln -s "$git_dir/$x" "$new_workdir/.git/$x"
done
# now setup the workdir
cd "$new_workdir"
# copy the HEAD from the original repository as a default branch
cp "$git_dir/HEAD" .git/HEAD
# checkout the branch (either the same as HEAD from the original repository, or
# the one that was asked for)
git checkout -f $branch