Abstract out CVS's involvement in the wrapper:

* In Wrapper.pm, add a new hook "wrapperargcheck" to examine argc/argv
  and return success or failure. In the failure case, the wrapper
  terminates.

* In cvs.pm, implement the new hook to return failure if a directory is
  being cvs added.

IkiWiki/Plugin/cvs.pm

@@ -6,6 +6,7 @@ use strict;
 use IkiWiki;
 
 sub import {
+	hook(type => "wrapperargcheck", id => "cvs", call => \&wrapperargcheck);
 	hook(type => "checkconfig", id => "cvs", call => \&checkconfig);
 	hook(type => "getsetup", id => "cvs", call => \&getsetup);
 	hook(type => "rcs", id => "rcs_update", call => \&rcs_update);
@@ -20,6 +21,17 @@ sub import {
 	hook(type => "rcs", id => "rcs_getctime", call => \&rcs_getctime);
 }
 
+sub wrapperargcheck () {
+	my $check_args=<<"EOF";
+	int j;
+	for (j = 1; j < argc; j++)
+		if (strstr(argv[j], "New directory") != NULL)
+			return 0;
+	return 1;
+EOF
+	return $check_args;
+}
+
 sub checkconfig () {
 	if (! defined $config{cvspath}) {
 		$config{cvspath}="ikiwiki";

IkiWiki/Wrapper.pm

@@ -44,17 +44,8 @@ EOF
 		$test_receive=IkiWiki::Receive::gen_wrapper();
 	}
 
-	my $check_cvs_add_dir="";
+	my $check_args="	return 0;";
-	if ($config{rcs} eq 'cvs') {
+	run_hooks(wrapperargcheck => sub { $check_args = shift->(); });
-		$check_cvs_add_dir=<<"EOF";
-	{
-		int j;
-		for (j = 1; j < argc; j++)
-			if (strstr(argv[j], "New directory") != NULL)
-				exit(0);
-	}
-EOF
-	}
 
 	my $check_commit_hook="";
 	my $pre_exec="";
@@ -128,10 +119,16 @@ addenv(char *var, char *val) {
 	newenviron[i++]=s;
 }
 
+int checkargs(int argc, char **argv) {
+$check_args
+}
+
 int main (int argc, char **argv) {
 	char *s;
 
-$check_cvs_add_dir
+	if (!checkargs(argc, argv))
+		exit(0);
+
 $check_commit_hook
 $test_receive
 $envsave