Add a -p flag that just runs the assign prepass, on an empty testbed.

You can look at the error code to figure out if it will ever be
possible to map this experiment onto the testbed.

tbsetup/assign_wrapper.in

@@ -44,14 +44,17 @@ sub usage ()
     print STDERR " -f   - Fix current resources during update mode\n";
     print STDERR " -t   - Create the TOP file and then exit\n";
     print STDERR " -n   - Run assign, but do not reserve/modify resources.\n";
+    print STDERR " -p   - Do a precheck for mapability on an empty testbed - ".
+		 "implies -n\n";
     exit($WRAPPER_FAILED);
 }
-my $optlist  = "vutnf";
+my $optlist  = "vutnfp";
 my $verbose  = 0;
 my $fixmode  = 0;
 my $updating = 0;
 my $toponly  = 0;
 my $impotent = 0;
+my $precheck = 0;
 my $warnings = 0;
 
 #
@@ -124,6 +127,10 @@ if (defined($options{"t"})) {
 if (defined($options{"n"})) {
     $impotent = 1;
 }
+if (defined($options{"p"})) {
+    $impotent = 1;
+    $precheck = 1;
+}
 if (defined($options{"f"})) {
     $fixmode = 1;
 }
@@ -581,6 +588,8 @@ sub RunAssign ()
 	if ($remotecount);
     $ptopargs   .= "-S "
 	if ($simcount);
+    $ptopargs	.= "-a "
+    	if ($precheck);
     system("ptopgen $ptopargs > $ptopfile");
     TBDebugTimeStamp("ptopgen finished");
 
@@ -589,6 +598,8 @@ sub RunAssign ()
     my $cmdargs = "$ptopfile $topfile";
     $cmdargs = "-uPod -c .75 $cmdargs"
 	if ($virtcount);
+    $cmdargs = "-n $cmdargs"
+    	if ($precheck);
 
     my $cmd;
 
@@ -658,6 +669,7 @@ sub RunAssign ()
 	print("Could not open assign logfile!\n");
 	return -1;
     }
+
     printdb "Reading assign results.\n";
 
     #
@@ -668,7 +680,7 @@ sub RunAssign ()
     #
     if ($assignexitcode) {
 	my $violations = 0;
-	
+
 	print "ASSIGN FAILED:\n";
 	while (<ASSIGNFP> !~ /^[\w\s]*precheck:$/) {}
 	while (<ASSIGNFP>) {
@@ -695,6 +707,15 @@ sub RunAssign ()
 	return (($assignexitcode == 1) ? 1 : -1);
     }
     
+    #
+    # If we were doing the precheck, go ahead and exit now - there won't be
+    # any useful information to parse out
+    #
+    if ($precheck) {
+	print "Precheck succeeded.\n";
+	return 0;
+    }
+
     #
     # Assign success; parse results.
     #