Add test for using Git at root of file system

This kind of test requires a throw-away root filesystem so that it can
play on. If you have such a system, go ahead, "chmod 777 /" and run
this test manually. Because this is a dangerous test, you are required
to set an env variable, and not to use root to run it.

Script prepare-root.sh may help you set up a chroot environment with
Git test suite inside. You will need Linux, static linked busybox,
rsync and root permission to use it.

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

2 files changed, 52 insertions, 0 deletions

diff --git a/t/t1509/excludes b/t/t1509/excludes
new file mode 100644
index 0000000..d4d21d3
--- /dev/null
+++ b/t/t1509/excludes
@@ -0,0 +1,14 @@
+*.o
+*~
+*.bak
+*.c
+*.h
+.git
+contrib
+Documentation
+git-gui
+gitk-git
+gitweb
+t/t4013
+t/t5100
+t/t5515
diff --git a/t/t1509/prepare-chroot.sh b/t/t1509/prepare-chroot.sh
new file mode 100755
index 0000000..c5334a8
--- /dev/null
+++ b/t/t1509/prepare-chroot.sh
@@ -0,0 +1,38 @@
+#!/bin/sh
+
+die() {
+	echo >&2 "$@"
+	exit 1
+}
+
+xmkdir() {
+	while [ -n "$1" ]; do
+		[ -d "$1" ] || mkdir "$1" || die "Unable to mkdir $1"
+		shift
+	done
+}
+
+R="$1"
+
+[ -n "$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"
+
+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 $R/dev/null"
+echo "root:x:0:0:root:/:/bin/sh" > "$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"
+
+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"
+done
+echo "Execute this in root: 'chroot $R /bin/su - $(id -nu)'"