Add submodules.sh and use it during builds

This adds a shell script which can be be used to initialize, list and
update submodules in a git repository. It reads the file .gitmodules
to find a mapping between submodule path and repository url for the
initial clone of all submodules.

The script is used during cgit builds to enable automatic download and
checkout of the git git repository.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

1 files changed, 181 insertions, 0 deletions

diff --git a/submodules.sh b/submodules.sh
new file mode 100755
index 0000000..1d7b13f
--- /dev/null
+++ b/submodules.sh
@@ -0,0 +1,181 @@
+#!/bin/sh
+#
+# submodules.sh: init, update or list git submodules
+#
+# Copyright (C) 2006 Lars Hjemli
+#
+# Licensed under GNU General Public License v2
+#   (see COPYING for full license text)
+#
+
+
+usage="submodules.sh [-i | -u] [-q] [--cached] [path...]"
+init=
+update=
+quiet=
+cached=
+
+
+say()
+{
+	if test -z "$quiet"
+	then
+		echo -e "$@"
+	fi
+}
+
+
+die()
+{
+	echo >&2 -e "$@"
+	exit 1
+}
+
+
+
+#
+# Silently checkout specified submodule revision, return exit status of git-checkout
+#
+# $1 = local path
+# $2 = requested sha1
+#
+module_checkout()
+{
+	$(cd "$1" && git checkout "$2" 1>/dev/null 2>/dev/null)
+}
+
+
+#
+# Find all (requested) submodules, run clone + checkout on missing paths
+#
+# $@ = requested paths (default to all)
+#
+modules_init()
+{
+	git ls-files --stage -- $@ | grep -e '^160000 ' |
+	while read mode sha1 stage path
+	do
+		test -d "$path/.git" && continue
+
+		if test -d "$path"
+		then
+			rmdir "$path" 2>/dev/null ||
+			die "Directory '$path' exist, but not as a submodule"
+		fi
+
+		test -e "$path" && die "A file already exist at path '$path'"
+
+		url=$(sed -nre "s/^$path[ \t]+//p" .gitmodules)
+		test -z "$url" && die "No url found for $path in .gitmodules"
+
+		git clone "$url" "$path" || die "Clone of submodule '$path' failed"
+		module_checkout "$path" "$sha1" || die "Checkout of submodule '$path' failed"
+		say "Submodule '$path' initialized"
+	done
+}
+
+#
+# Checkout correct revision of each initialized submodule
+#
+# $@ = requested paths (default to all)
+#
+modules_update()
+{
+	git ls-files --stage -- $@ | grep -e '^160000 ' |
+	while read mode sha1 stage path
+	do
+		if ! test -d "$path/.git"
+		then
+			say "Submodule '$path' not initialized"
+			continue;
+		fi
+		subsha1=$(cd "$path" && git rev-parse --verify HEAD) ||
+		die "Unable to find current revision of submodule '$path'"
+		if test "$subsha1" != "$sha1"
+		then
+			module_checkout "$path" "$sha1" ||
+			die "Unable to checkout revision $sha1 of submodule '$path'"
+			say "Submodule '$path' reset to revision $sha1"
+		fi
+	done
+}
+
+#
+# List all registered submodules, prefixed with:
+#  - submodule not initialized
+#  + different version checked out
+#
+# If --cached was specified the revision in the index will be printed
+# instead of the currently checked out revision.
+#
+# $@ = requested paths (default to all)
+#
+modules_list()
+{
+	git ls-files --stage -- $@ | grep -e '^160000 ' |
+	while read mode sha1 stage path
+	do
+		if ! test -d "$path/.git"
+		then
+			say "-$sha1 $path"
+			continue;
+		fi
+		revname=$(cd "$path" && git describe $sha1)
+		if git diff-files --quiet -- "$path"
+		then
+			say " $sha1 $path\t($revname)"
+		else
+			if test -z "$cached"
+			then
+				sha1=$(cd "$path" && git rev-parse HEAD)
+				revname=$(cd "$path" && git describe HEAD)
+			fi
+			say "+$sha1 $path\t($revname)"
+		fi
+	done
+}
+
+
+while case "$#" in 0) break ;; esac
+do
+	case "$1" in
+	-i)
+		init=1
+		;;
+	-u)
+		update=1
+		;;
+	-q)
+		quiet=1
+		;;
+	--cached)
+		cached=1
+		;;
+	--)
+		break
+		;;
+	-*)
+		echo "Usage: $usage"
+		exit 1
+		;;
+	--*)
+		echo "Usage: $usage"
+		exit 1
+		;;
+	*)
+		break
+		;;
+	esac
+	shift
+done
+
+
+if test "$init" = "1"
+then
+	modules_init $@
+elif test "$update" = "1"
+then
+	modules_update $@
+else
+	modules_list $@
+fi