patchgit-submodule: New subcommand 'summary'

diff --git a/git-submodule.sh b/git-submodule.sh
index ad9fe62..0e81484 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -4,7 +4,7 @@
 #
 # Copyright (c) 2007 Lars Hjemli
 
-USAGE='[--quiet] [--cached] [add <repo> [-b branch]|status|init|update] [--] [<path>...]'
+USAGE='[--quiet] [--cached] [add <repo> [-b branch]|status|init|update|summary <commit>] [--] [<path>...]'
 OPTIONS_SPEC=
 . git-sh-setup
 require_work_tree
@@ -255,7 +255,46 @@ set_name_rev () {
 	) )
 	test -z "$revname" || revname=" ($revname)"
 }
+#
+# Show commit summary for submodules in index or working tree relative to the given commit
+#
+# If '--cached' is given, show summary between index and given commit,
+# or between working tree and given commit
+#
+# @ = [head counting commits from (default 'HEAD'),] requested paths (default to all)
+#
+modules_summary()
+{
+	cache_option=${cached:+--cached}
+
+	if rev=$(git rev-parse --verify "$1^0" 2>/dev/null)
+	then
+		head=$rev
+		shift
+	else
+		head=HEAD
+	fi
 
+	cwd=$(pwd)
+	cd_to_toplevel
+
+	# get modified modules which have been checked out (i.e. cared by user)
+	modules=$(git diff $cache_option --raw $head -- "$@" |
+		grep '^:160000\|:000000 160000' |
+		while read mod_src mod_dst sha1_src sha1_dst status name
+		do
+			test $status=D && echo "$name" && continue
+			GIT_DIR="$name/.git" git-rev-parse --git-dir >/dev/null 2>&1 &&
+			echo "$name"
+		done
+	)
+
+	# TODO: quote module names containing space or tab
+	test -n "$modules" &&
+	echo "# Submodules modified: "$modules &&
+	echo "#"
+	cd "$cwd"
+}
 #
 # List all submodules, prefixed with:
 #  - submodule not initialized
@@ -305,6 +344,9 @@ do
 	update)
 		update=1
 		;;
+	summary)
+		summary=1
+		;;
 	status)
 		status=1
 		;;
@@ -345,17 +387,20 @@ case "$add,$branch" in
 	;;
 esac
 
-case "$add,$init,$update,$status,$cached" in
-1,,,,)
+case "$add,$init,$update,$summary,$status,$cached" in
+1,,,,,)
 	module_add "$@"
 	;;
-,1,,,)
+,1,,,,)
 	modules_init "$@"
 	;;
-,,1,,)
+,,1,,,)
 	modules_update "$@"
 	;;
-,,,*,*)
+,,,1,,*)
+	modules_summary "$@"
+	;;
+,,,,*,*)
 	modules_list "$@"
 	;;
 *)

diff --git a/git-submodule.sh b/git-submodule.sh
index 0e81484..cccb539 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -292,7 +292,73 @@ modules_summary()
 	# TODO: quote module names containing space or tab
 	test -n "$modules" &&
 	echo "# Submodules modified: "$modules &&
-	echo "#"
+	echo "#" &&
+	git diff $cache_option --raw $head -- $modules |
+	grep '^:160000\|:000000 160000' |
+	cut -c2- |
+	while read mod_src mod_dst sha1_src sha1_dst status name
+	do
+		sha1_dst=$(echo $sha1_dst | cut -c1-7)
+		sha1_src=$(echo $sha1_src | cut -c1-7)
+		check_dst=t
+		check_src=t
+		case $status in
+		D)
+			check_dst=
+			;;
+		A)
+			check_src=
+			;;
+		esac
+
+		(
+			errmsg=
+			unfound_src=
+			unfound_dst=
+
+			test -z "$check_src" ||
+			GIT_DIR="$name/.git" git-rev-parse $sha1_src >&/dev/null ||
+			unfound_src=t
+
+			test -z "$check_dst" ||
+			GIT_DIR="$name/.git" git-rev-parse $sha1_dst >&/dev/null ||
+			unfound_dst=t
+
+			case "$unfound_src,$unfound_dst" in
+			t,)
+				errmsg="  Warn: $name doesn't contain commit $sha1_src"
+				;;
+			,t)
+				errmsg="  Warn: $name doesn't contain commit $sha1_dst"
+				;;
+			t,t)
+				errmsg="  Warn: $name doesn't contain commits $sha1_src and $sha1_dst"
+				;;
+			*)
+				left=
+				right=
+				test -n "$check_src" &&
+				left=$(GIT_DIR="$name/.git" git log --pretty=format:"  <%s" \
+				${check_dst:+$sha1_dst..}$sha1_src 2>/dev/null)
+
+				test -n "$check_dst" &&
+				right=$(GIT_DIR="$name/.git" git log --reverse --pretty=format:"  >%s" \
+				${check_src:+$sha1_src..}$sha1_dst 2>/dev/null)
+				;;
+			esac
+
+			echo "* $name $sha1_src...$sha1_dst:"
+			if test -n "$errmsg"
+			then
+				echo "$errmsg"
+			else
+				test -n "$left" && echo "$left"
+				test -n "$right" && echo "$right"
+			fi
+			echo
+		) | sed 's/^/# /'
+	done
+
 	cd "$cwd"
 }
 #

diff --git a/git-submodule.sh b/git-submodule.sh
index cccb539..58d0243 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -4,7 +4,8 @@
 #
 # Copyright (c) 2007 Lars Hjemli
 
-USAGE='[--quiet] [--cached] [add <repo> [-b branch]|status|init|update|summary <commit>] [--] [<path>...]'
+USAGE="[--quiet] [--cached] [-n|--summary-limit <number>] \
+[add <repo> [-b branch]|status|init|update|summary <commit>] [--] [<path>...]"
 OPTIONS_SPEC=
 . git-sh-setup
 require_work_tree
@@ -16,6 +17,7 @@ update=
 status=
 quiet=
 cached=
+summary_limit=
 
 #
 # print stuff on stdout unless -q was specified
@@ -265,6 +267,10 @@ set_name_rev () {
 #
 modules_summary()
 {
+	summary_limit=${summary_limit:-1000000}
+	summary_limit=$((summary_limit<0?1000000:summary_limit))
+	test $summary_limit = 0 && return
+
 	cache_option=${cached:+--cached}
 
 	if rev=$(git rev-parse --verify "$1^0" 2>/dev/null)
@@ -352,8 +358,29 @@ modules_summary()
 			then
 				echo "$errmsg"
 			else
-				test -n "$left" && echo "$left"
-				test -n "$right" && echo "$right"
+				lc0=0
+				rc0=0
+				test -n "$left" && lc0=$(echo "$left" | wc -l)
+				test -n "$right" && rc0=$(echo "$right" | wc -l)
+				lc=$((lc0<summary_limit?lc0:summary_limit))
+				rc=$((summary_limit>lc?summary_limit-lc:1))
+				rc=$((rc<rc0?rc:rc0))
+
+				if test -n "$left"
+				then
+					skip=$((lc0-lc))
+					echo "$left" | head -$((lc-1))
+					test $skip != 0 && echo "  <... ($skip more)"
+					echo "$left" | tail -1
+				fi
+
+				if test -n "$right"
+				then
+					skip=$((rc0-rc))
+					echo "$right" | head -$((rc-1))
+					test $skip != 0 && echo "  >... ($skip more)"
+					echo "$right" | tail -1
+				fi
 			fi
 			echo
 		) | sed 's/^/# /'
@@ -430,6 +457,13 @@ do
 	--cached)
 		cached=1
 		;;
+	-n|--summary-limit)
+		if [ -z "$2" ]; then
+			usage
+		fi
+		summary_limit="$2"
+		shift
+		;;
 	--)
 		break
 		;;