feat: initial action implementation

scripts/checkout.sh

@@ -0,0 +1,121 @@
+#!/usr/bin/env bash
+shopt -s extglob
+
+ACTION_INPUT_TOKEN="${ACTION_INPUT_TOKEN:?}"
+ACTION_INPUT_REPOSITORY="${ACTION_INPUT_REPOSITORY:?}"
+ACTION_INPUT_PATH="${ACTION_INPUT_PATH:?}"
+ACTION_INPUT_REF="${ACTION_INPUT_REF:?}"
+
+error() {
+  echo "$*" 1>&2 ; exit 1;
+}
+
+# ensure we are in the right place
+[[ -z "${GITHUB_WORKSPACE:-}" ]] || { cd "${GITHUB_WORKSPACE}" || error ; }
+
+git config --global --add protocol.version 2
+
+git init -q "${ACTION_INPUT_PATH}" && { cd "${ACTION_INPUT_PATH}" || error ; }
+
+git config --local gc.auto 0
+
+# the server url and uri are important for determining the default checkout url
+GITHUB_SERVER_URL="${GITHUB_SERVER_URL:?}"
+GITHUB_SERVER_URI="${GITHUB_SERVER_URL//http?(s):\/\//}"
+
+# use https instead of everything else
+git config --add url."${GITHUB_SERVER_URL}/".insteadOf "git@${GITHUB_SERVER_URI}:"
+git config --add url."${GITHUB_SERVER_URL}/".insteadOf "ssh://git@${GITHUB_SERVER_URI}/"
+git config --add url."${GITHUB_SERVER_URL}/".insteadOf "git://${GITHUB_SERVER_URI}/"
+
+# prepare git config extra header for https auth
+BASE64="base64 --wrap 0"
+echo "" | ${BASE64} >/dev/null 2>&1 || BASE64="base64"
+echo "" | ${BASE64} >/dev/null 2>&1 || BASE64="openssl base64 -A"
+echo "" | ${BASE64} >/dev/null 2>&1
+
+GIT_HTTP_EXTRAHEADER="AUTHORIZATION: basic $(echo -n "x-access-token:${ACTION_INPUT_TOKEN}" | ${BASE64})"
+git config --local --add http."${GITHUB_SERVER_URL}".extraheader "${GIT_HTTP_EXTRAHEADER}"
+
+# add the repository as remote
+git remote add origin "${ACTION_INPUT_REPOSITORY}"
+
+git_default_refspec() {
+  git ls-remote --symref origin HEAD | { read -r _ ref name ; echo "${ref}" ; }
+}
+
+git_resolve_refspec() {
+  # shellcheck disable=SC2068
+  git ls-remote origin $@ | { read -r sha ref _ ; echo "${sha} ${ref}" ; }
+}
+
+fetch() {
+  # shellcheck disable=SC2068
+  git fetch --no-tags --prune --no-recurse-submodules --depth=1 origin $@
+}
+
+checkout() {
+  # shellcheck disable=SC2068
+  git checkout --force $@
+}
+
+# the checkout is based on a commit hash
+if [[ ${ACTION_INPUT_REF:-} =~ ^[0-9a-f]{5,40}$ ]]
+then
+  fetch "${ACTION_INPUT_REF}" && checkout "${ACTION_INPUT_REF}"
+  exit
+fi
+
+# update selected ref when no input is given to remote default branch
+: "${ACTION_INPUT_REF:=$( git_default_refspec )}"
+
+# TODO: check if repo is workflow repo, if so, use commit sha from env
+# like GITHUB_REF and GITHUB_SHA
+
+read -r GIT_SHA GIT_REF _ <<< "$( git_resolve_refspec "${ACTION_INPUT_REF}" )"
+: "${GIT_SHA:?}" "${GIT_REF:?}"
+
+# we always use the refspec with the commit sha as source to prevent
+# race conditions when running on a frequently used branch
+
+checkout_head() {
+  local name="${GIT_REF#refs\/heads\/}"
+  local remote="refs/remotes/origin/${name}"
+
+  fetch "+${GIT_SHA}:${remote}"
+
+  checkout -B "${name}" "${remote}"
+}
+
+checkout_pull() {
+  local name="${GIT_REF#refs\/pull\/}"
+  local remote="refs/remotes/pull/${name}"
+
+  fetch "+${GIT_SHA}:${remote}"
+  
+  # pull requests have a special treatment for the branch name. The name
+  # is determined by the branch the pull request is targeting.
+
+  local branch="${GITHUB_BASE_REF:-$( git_default_refspec )}"
+  checkout -B "${branch#refs\/heads\/}" "${remote}"
+}
+
+checkout_tag() {
+  local name="${GIT_REF#refs\/tags\/}"
+  local remote="refs/tags/${name}"
+
+  fetch "+${GIT_SHA}:${remote}"
+
+  checkout "${remote}"
+}
+
+case "${GIT_REF}" in
+  # heads and pull are a branch based checkout
+  refs/heads/*) checkout_head ;;
+  refs/pull/* ) checkout_pull ;;
+
+  # tags are a detached head checkout
+  refs/tags/* ) checkout_tag ;;
+
+  *) error "ref type '${GIT_REF}' is unknown" ;;
+esac