t1509: update prepare script to be able to run t1509 in chroot again

Tested on Gentoo and OpenSUSE 13.1, both x86-64

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1509/prepare-chroot.sh

@@ -14,25 +14,45 @@ xmkdir() {
 
 R="$1"
 
+[ "$(id -u)" -eq 0 ] && die "This script should not be run as root, what if it does rm -rf /?"
 [ -n "$R" ] || die "usage: prepare-chroot.sh <root>"
 [ -x git ] || die "This script needs to be executed at git source code's top directory"
-[ -x /bin/busybox ] || die "You need busybox"
+if [ -x /bin/busybox ]; then
+	BB=/bin/busybox
+elif [ -x /usr/bin/busybox ]; then
+	BB=/usr/bin/busybox
+else
+	die "You need busybox"
+fi
 
 xmkdir "$R" "$R/bin" "$R/etc" "$R/lib" "$R/dev"
-[ -c "$R/dev/null" ] || die "/dev/null is missing. Do mknod $R/dev/null c 1 3 && chmod 666 $R/dev/null"
+touch "$R/dev/null"
 echo "root:x:0:0:root:/:/bin/sh" > "$R/etc/passwd"
 echo "$(id -nu):x:$(id -u):$(id -g)::$(pwd)/t:/bin/sh" >> "$R/etc/passwd"
 echo "root::0:root" > "$R/etc/group"
 echo "$(id -ng)::$(id -g):$(id -nu)" >> "$R/etc/group"
 
-[ -x "$R/bin/busybox" ] || cp /bin/busybox "$R/bin/busybox"
-[ -x "$R/bin/sh" ] || ln -s /bin/busybox "$R/bin/sh"
-[ -x "$R/bin/su" ] || ln -s /bin/busybox "$R/bin/su"
+[ -x "$R$BB" ] || cp $BB "$R/bin/busybox"
+for cmd in sh su ls expr tr basename rm mkdir mv id uname dirname cat true sed diff; do
+	ln -f -s /bin/busybox "$R/bin/$cmd"
+done
 
 mkdir -p "$R$(pwd)"
 rsync --exclude-from t/t1509/excludes -Ha . "$R$(pwd)"
-ldd git | grep '/' | sed 's,.*\s\(/[^ ]*\).*,\1,' | while read i; do
-	mkdir -p "$R$(dirname $i)"
-	cp "$i" "$R/$i"
+# Fake perl to reduce dependency, t1509 does not use perl, but some
+# env might slip through, see test-lib.sh, unset.*PERL_PATH
+sed 's|^PERL_PATH=.*|PERL_PATH=/bin/true|' GIT-BUILD-OPTIONS > "$R$(pwd)/GIT-BUILD-OPTIONS"
+for cmd in git $BB;do 
+	ldd $cmd | grep '/' | sed 's,.*\s\(/[^ ]*\).*,\1,' | while read i; do
+		mkdir -p "$R$(dirname $i)"
+		cp "$i" "$R/$i"
+	done
 done
-echo "Execute this in root: 'chroot $R /bin/su - $(id -nu)'"
+cat <<EOF
+All is set up in $R, execute t1509 with the following commands:
+
+sudo chroot $R /bin/su - $(id -nu)
+IKNOWWHATIAMDOING=YES ./t1509-root-worktree.sh -v -i
+
+When you are done, simply delete $R to clean up
+EOF