{sharepoint} SetPermission

     using System;
     using System.Collections.Generic;
     using System.Linq;
     using System.Text;
     using Microsoft.SharePoint;  

     namespace CR.SharePoint.HR.Common
     {
         public static class PermissionManager
         {  

             //SPGroup group = web.Groups[0];
             //SPUser user = web.Users[0];
             //SPUser user2 = web.EnsureUser("mangaldas.mano");
             //SPUser user3 = web.EnsureUser("Domain Users");
             //SPPrincipal[] principals = { group, user, user2, user3 };   

             #region Adding Permissions to an item  

             /// <summary>
             /// Set Permissions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principals">IEnumerable</param>
             /// <param name="roleType">SPRoleType</param>
             public static void SetPermissions(SPListItem item, IEnumerable<SPPrincipal> principals, SPRoleType roleType)
             {
                 if (item != null)
                 {
                     foreach (SPPrincipal principal in principals)
                     {
                         SPRoleDefinition roleDefinition = item.Web.RoleDefinitions.GetByType(roleType);
                         SetPermissions(item, principal, roleDefinition);
                     }
                 }
             }       

             /// <summary>
             /// Set Permissions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="user">SPUser</param>
             /// <param name="roleType">SPRoleType</param>
             public static void SetPermissions(SPListItem item, SPUser user, SPRoleType roleType)
             {
                 if (item != null)
                 {
                     SPRoleDefinition roleDefinition = item.Web.RoleDefinitions.GetByType(roleType);
                     SetPermissions(item, (SPPrincipal)user, roleDefinition);
                 }
             }     

             /// <summary>
             /// Set Permissions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principal">SPPrincipal</param>
             /// <param name="roleType">SPRoleType</param>
             public static void SetPermissions(SPListItem item, SPPrincipal principal, SPRoleType roleType)
             {
                 if (item != null)
                 {
                     SPRoleDefinition roleDefinition = item.Web.RoleDefinitions.GetByType(roleType);
                     SetPermissions(item, principal, roleDefinition);
                 }
             }     

             /// <summary>
             /// Set Permissions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="user">SPUser</param>
             /// <param name="roleDefinition">SPRoleDefinition</param>
             public static void SetPermissions(SPListItem item, SPUser user, SPRoleDefinition roleDefinition)
             {
                 if (item != null)
                 {
                     SetPermissions(item, (SPPrincipal)user, roleDefinition);
                 }
             }     

             /// <summary>
             /// Set Permissions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principal">SPPrincipal</param>
             /// <param name="roleDefinition">SPRoleDefinition</param>
             public static void SetPermissions(SPListItem item, SPPrincipal principal, SPRoleDefinition roleDefinition)
             {
                 if (item != null)
                 {
                     SPRoleAssignment roleAssignment = new SPRoleAssignment(principal);
                     roleAssignment.RoleDefinitionBindings.Add(roleDefinition);
                     item.RoleAssignments.Add(roleAssignment);
                 }
             }  

             #endregion  

             #region Deleting all user Permissions from an item  

             /// <summary>
             /// remove permisions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="user">SPUser</param>
             public static void RemovePermissions(SPListItem item, SPUser user)
             {
                 if (item != null)
                 {
                     RemovePermissions(item, user as SPPrincipal);
                 }
             }     

             /// <summary>
             /// remove permisions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principal">SPPrincipal</param>
             public static void RemovePermissions(SPListItem item, SPPrincipal principal)
             {
                 if (item != null)
                 {
                     item.RoleAssignments.Remove(principal);
                     item.SystemUpdate();
                 }
             }  

             #endregion  

             #region Removing specific roles from an item  

             /// <summary>
             /// remove permission
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principal">SPPrincipal</param>
             /// <param name="roleDefinition">SPRoleDefinition</param>
             public static void RemovePermissionsSpecificRole(SPListItem item, SPPrincipal principal, SPRoleDefinition roleDefinition)
             {
                 if (item != null)
                 {
                     SPRoleAssignment roleAssignment = item.RoleAssignments.GetAssignmentByPrincipal(principal);
                     if (roleAssignment != null)
                     {
                         if (roleAssignment.RoleDefinitionBindings.Contains(roleDefinition))
                         {
                             roleAssignment.RoleDefinitionBindings.Remove(roleDefinition);
                             roleAssignment.Update();
                         }
                     }
                 }
             }  

             /// <summary>
             /// remove permission
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principal">SPPrincipal</param>
             /// <param name="roleType">SPRoleType</param>
             public static void RemovePermissionsSpecificRole(SPListItem item, SPPrincipal principal, SPRoleType roleType)
             {
                 if (item != null)
                 {
                     SPRoleDefinition roleDefinition = item.Web.RoleDefinitions.GetByType(roleType);
                     RemovePermissionsSpecificRole(item, principal, roleDefinition);
                 }
             }  

             #endregion  

             #region Updating or Modifying Permissions on an item  

             /// <summary>
             /// modify Permissions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principal">SPPrincipal</param>
             /// <param name="roleType">SPRoleType</param>
             public static void ChangePermissions(SPListItem item, SPPrincipal principal, SPRoleType roleType)
             {
                 if (item != null)
                 {
                     SPRoleDefinition roleDefinition = item.Web.RoleDefinitions.GetByType(roleType);
                     ChangePermissions(item, principal, roleDefinition);
                 }
             }  

             /// <summary>
             /// modify Permissions
             /// </summary>
             /// <param name="item">SPListItem</param>
             /// <param name="principal">SPPrincipal</param>
             /// <param name="roleDefinition">SPRoleDefinition</param>
             public static void ChangePermissions(SPListItem item, SPPrincipal principal, SPRoleDefinition roleDefinition)
             {
                 SPRoleAssignment roleAssignment = item.RoleAssignments.GetAssignmentByPrincipal(principal);   

                 if (roleAssignment != null)
                 {
                     roleAssignment.RoleDefinitionBindings.RemoveAll();
                     roleAssignment.RoleDefinitionBindings.Add(roleDefinition); roleAssignment.Update();
                 }
             }  

             #endregion  

         }
     }