#!/bin/sh
# linux-bundle-clone
# ------------------
# Use this script to clone a Linux repository using a CDN-hosted bundle.
# This is the recommended way to clone Linux in a CI environment where
# the full repository needs to be cloned every time.
[ "${REMOTE:=$1}" ] || {
    echo "Please specify the remote to clone"
    echo "Example: ${0} https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux master"
    exit 1
}

[ "${TARGET:=$2}" ] || {
    echo "Please specify the target directory"
    echo "Example: ${0} https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux master"
    exit 1
}

CHECKOUT=${3:-master}

# You can also use "http" if you are behind a caching proxy and want to
# benefit from a locally stored copy. Initial time to first byte may be
# long if the CDN frontend doesn't have the copy of the bundle yet, but
# repeat requests will use the cached CDN copy.
#
# NOTICE: Pick the tree that's likely to have most of the objects you want
#         We have mainline, stable, and linux-next bundles for you to choose
#CDNBUNDLE="https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/clone.bundle"
#CDNBUNDLE="https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/clone.bundle"
CDNBUNDLE="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/clone.bundle"

# We'll put the bundle into a safe temp location, but WARNING -- it's a
# 1Gb+ file, so if you have limited space in /tmp, you should consider
# changing the path here. See "man mktemp".
BUNDLELOCAL=$(mktemp /tmp/linux-bundle.XXXXXXXXXX)

echo "Getting the bundle file"
curl -L "${CDNBUNDLE}" -o "${BUNDLELOCAL}" || {
    echo "Getting the clone bundle failed."
    # clean up to not litter huge files around
    rm -f "${BUNDLELOCAL}"
    exit 1
}

echo "Cloning from the bundle file"
git clone "${BUNDLELOCAL}" "${TARGET}" || {
    echo "Cloning from bundle failed."
    echo "The bundle is in ${BUNDLELOCAL}"
    exit 1
}

# We're done with the bundle now
rm -f "${BUNDLELOCAL}"

cd "${TARGET}"
echo "Fetching latest objects"
git remote set-url origin "${REMOTE}"
git remote update origin

git checkout "${CHECKOUT}"