X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=topgit.git;a=blobdiff_plain;f=tg-depend.sh;h=474ccda4e098a2046a2e60a52d5addad4b007f81;hp=43d8321a20ac2df48bdc60d87b91358512831329;hb=refs%2Ftop-bases%2Ffixes%2Fexport--b-deps;hpb=1b5ad09b5bf411f83c0e20ed5cf6ac02f06b940f

diff --git a/tg-depend.sh b/tg-depend.sh
index 43d8321..474ccda 100644
--- a/tg-depend.sh
+++ b/tg-depend.sh
@@ -42,11 +42,30 @@ done
 branchrev="$(git rev-parse --verify "$name" 2>/dev/null)" ||
 	die "invalid branch name: $name"
 
+# Check that we are on a TopGit branch.
+current_name="$(git symbolic-ref HEAD | sed 's#^refs/\(heads\|top-bases\)/##')"
+current_base_rev="$(git rev-parse --short --verify "refs/top-bases/$current_name" 2>/dev/null)" ||
+	die "not a TopGit-controlled branch"
+
 ## Record new dependency
+depend_add()
+{
+	[ "$name" = "$current_name" ] &&
+		die "$name cannot depend on itself."
+
+	{ $tg summary --deps; echo "$current_name" "$name"; } |
+		tsort >/dev/null ||
+		die "tg: that dependency would introduce a dependency loop"
+
+	grep -F -x -e "$name" "$root_dir/.topdeps" >/dev/null &&
+		die "tg: $current_name already depends on $name"
+
+	echo "$name" >>"$root_dir/.topdeps"
+	git add -f "$root_dir/.topdeps"
+	git commit -m"New TopGit dependency: $name"
+	$tg update
+}
 
-echo "$name" >>"$root_dir/.topdeps"
-git add -f "$root_dir/.topdeps"
-git commit -m"New TopGit dependency: $name"
-$tg update
+depend_$subcmd
 
 # vim:noet