Offer the SDK by simply cloning it (closes #1357)

git-extra/git-sdk.sh

@@ -20,3 +20,120 @@ case "$rootdir" in
 	fi
 	;;
 esac
+
+sdk () {
+	case "$1" in
+	help|--help|-h)
+		cat >&2 <<-EOF
+		The 'sdk' shell function helps you to get up and running
+		with the Git for Windows SDK. The available subcommands are:
+
+		create-desktop-icon: install a desktop icon that starts the GfW SDK shell.
+
+		init <repo>: initialize and/or update a development repo. Known repos
+		    are: build-extra, git, MINGW-packages, MSYS2-packages.
+
+		build: builds one of the following: git, git-and-installer.
+		EOF
+		;;
+	welcome)
+		cat >&2 <<-EOF
+		Welcome to the Git for Windows SDK!
+
+		The common tasks are automated via the \`sdk\` function;
+		See \`sdk help\` for details.
+		EOF
+		;;
+	create-desktop-icon)
+		force=t &&
+		while case "$1" in
+		--gentle) force=;;
+		'') break;;
+		-*) sdk die "Unknown option: %s\n" "$1"; return 1;;
+		esac; do shift; done &&
+
+		case "$(uname -m)" in
+		i686) bitness=" 32-bit";;
+		x86_64) bitness=" 64-bit";;
+		*) bitness=;;
+		esac &&
+		desktop_icon_path="$HOME/Desktop/Git SDK$bitness.lnk" &&
+		if test -n "$force" || test ! -f "$desktop_icon_path"
+		then
+			create-shortcut.exe --icon-file /msys2.ico --work-dir \
+				/ /git-bash.exe "$desktop_icon_path"
+		fi
+		;;
+	die)
+		shift
+		echo "$*" >&2
+		return 1
+		;;
+	init-lazy)
+		case "$2" in
+		build-extra|git|MINGW-packages|MSYS2-packages)
+			mkdir -p /usr/src/"$2" &&
+			git -C /usr/src/"$2" init &&
+			git -C /usr/src/"$2" config core.autocrlf false &&
+			git -C /usr/src/"$2" remote add origin \
+				https://github.com/git-for-windows/"$2" ||
+			sdk die "Could not initialize /usr/src/$2"
+			;;
+		*)
+			sdk die "Unhandled repository: $2" >&2
+			;;
+		esac
+		;;
+	init)
+		sdk init-lazy "$2" &&
+		git -C "/usr/src/$2" pull origin master
+		;;
+	build)
+		case "$2" in
+		git)
+			sdk init git &&
+			make -C /usr/src/git -j$(nproc) DEVELOPER=1
+			;;
+		installer)
+			sdk init build-extra &&
+			/usr/src/build-extra/installer/release.sh "${3:-0-test}"
+			;;
+		git-and-installer)
+			sdk build git &&
+			make -C /usr/src/git strip install &&
+			pacman -Syyu git-extra &&
+			sdk init build-extra &&
+			/usr/src/build-extra/installer/release.sh "${3:-0-test}"
+			;;
+		*)
+			cat >&2 <<EOF
+sdk build <project>
+
+Supported projects:
+	git
+	installer [<version>]
+	git-and-installer [<version>]
+EOF
+			return 1
+			;;
+		esac
+		;;
+	*)
+		sdk die "Usage: sdk ( build-git | init <repo> | create-desktop-icon | help )"
+		;;
+	esac
+}
+
+# initialize (but do not fetch) worktrees in /usr/src, and also create the
+# Git SDK shortcut on the Desktop (unless it already exists).
+test -n "$JENKINS_URL" || {
+	for project in git build-extra MINGW-packages MSYS2-packages
+	do
+		test -d /usr/src/$project/.git ||
+		sdk init-lazy $project
+	done
+
+	sdk create-desktop-icon --gentle
+}
+
+sdk welcome