Adds checks for user defined crontab entries

src/main/java/hudson/plugins/disk_usage/DiskUsageProjectActionFactory.java

@@ -8,6 +8,7 @@
 import hudson.model.Describable;
 import hudson.model.Descriptor;
 import hudson.model.TransientProjectActionFactory;
+import hudson.scheduler.CronTab;
 import hudson.security.Permission;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -17,8 +18,11 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.servlet.ServletException;
+
+import hudson.util.FormValidation;
 import jenkins.model.Jenkins;
 import net.sf.json.JSONObject;
+import org.kohsuke.stapler.QueryParameter;
 import org.kohsuke.stapler.StaplerRequest;
 
 /**
@@ -378,6 +382,30 @@ private void configureBuildsCalculation(JSONObject form) {
             }
         }
 
+
+        private FormValidation checkCrons(String cron){
+            try {
+                final CronTab cronTab = new CronTab(cron);
+                final String sanity = cronTab.checkSanity();
+                if (sanity == null){
+                    return FormValidation.ok();
+                } else {
+                    return FormValidation.warning(sanity);
+                }
+            } catch (IllegalArgumentException e){
+                return FormValidation.error(Messages.InvalidCrontab(cron));
+            }
+        }
+        public FormValidation doCheckCountIntervalBuilds(@QueryParameter String value){
+            return checkCrons(value);
+        }
+        public FormValidation doCheckCountIntervalJobs(@QueryParameter String value){
+            return checkCrons(value);
+        }
+        public FormValidation doCheckCountIntervalWorkspace(@QueryParameter String value){
+            return checkCrons(value);
+        }
+
         private void configureJobsCalculation(JSONObject form) {
             boolean oldCalculationJobs = calculationJobs;
             String oldcountIntervalJobs = countIntervalJobs;

src/main/resources/hudson/plugins/disk_usage/DiskUsageProjectActionFactory/global.jelly

@@ -10,21 +10,21 @@
 
     <f:optionalBlock name="calculationBuilds" title="${%Enable calculation of builds}"
                      checked="${descriptor.isCalculationBuildsEnabled()}">
-      <f:entry title="${%Time interval for calculation}">
+      <f:entry title="${%Time interval for calculation}" field="countIntervalBuilds">
         <f:textbox name="countIntervalBuilds" value="${descriptor.getCountIntervalForBuilds()}"/>
       </f:entry>
     </f:optionalBlock>
 
     <f:optionalBlock name="calculationJobs" title="${%Enable calculation of jobs}"
                      checked="${descriptor.isCalculationJobsEnabled()}">
-      <f:entry title="${%Time interval for calculation}">
+      <f:entry title="${%Time interval for calculation}" field="countIntervalJobs">
         <f:textbox name="countIntervalJobs" value="${descriptor.getCountIntervalForJobs()}"/>
       </f:entry>
     </f:optionalBlock>
 
     <f:optionalBlock name="calculationWorkspace" title="${%Enable calculation of workspace}"
                      checked="${descriptor.isCalculationWorkspaceEnabled()}">
-      <f:entry title="${%Time interval for calculation}">
+      <f:entry title="${%Time interval for calculation}" field="countIntervalWorkspace">
         <f:textbox name="countIntervalWorkspace" value="${descriptor.getCountIntervalForWorkspaces()}"/>
       </f:entry>
     </f:optionalBlock>

src/main/resources/hudson/plugins/disk_usage/Messages.properties

@@ -8,3 +8,4 @@ DiskUsage.Graph.JobDirectory=job
 DiskUsage.Graph.BuildDirectory=builds
 DiskUsage.Graph.AgentWorkspaces=agent workspaces
 DiskUsage.Graph.NonAgentWorkspaces=non-agent workspaces
+InvalidCrontab=Invalid cron {0}