C#设置文件权限的方法

   在开发中，我们经常会使用io操作，例如创建，删除文件等操作。在项目中这样的需求也较多，我们也会经常对这些操作进行编码，但是对文件的权限进行设置，这样的操作可能会手动操作，现在介绍一种采用代码动态对文件设置权限的操作。

   在对文件进行权限设置在dotnet中，会采用filesystemaccessrule类进行文件的权限操作。

1.现在看一下filesystemaccessrule的实现代码：

 public filesystemaccessrule(
      identityreference identity,
      filesystemrights filesystemrights,
      accesscontroltype type )
      : this(
        identity,
        accessmaskfromrights( filesystemrights, type ),
        false,
        inheritanceflags.none,
        propagationflags.none,
        type )
    {
    }

    public filesystemaccessrule(
      string identity,
      filesystemrights filesystemrights,
      accesscontroltype type )
      : this(
        new ntaccount(identity),
        accessmaskfromrights( filesystemrights, type ),
        false,
        inheritanceflags.none,
        propagationflags.none,
        type )
    {
    }

    //
    // constructor for creating access rules for folder objects
    //

    public filesystemaccessrule(
      identityreference identity,
      filesystemrights filesystemrights,
      inheritanceflags inheritanceflags,
      propagationflags propagationflags,
      accesscontroltype type )
      : this(
        identity,
        accessmaskfromrights( filesystemrights, type ),
        false,
        inheritanceflags,
        propagationflags,
        type )
    {
    }

    public filesystemaccessrule(
      string identity,
      filesystemrights filesystemrights,
      inheritanceflags inheritanceflags,
      propagationflags propagationflags,
      accesscontroltype type )
      : this(
        new ntaccount(identity),
        accessmaskfromrights( filesystemrights, type ),
        false,
        inheritanceflags,
        propagationflags,
        type )
    {
    }
    internal filesystemaccessrule(
      identityreference identity,
      int accessmask,
      bool isinherited,
      inheritanceflags inheritanceflags,
      propagationflags propagationflags,
      accesscontroltype type )
      : base(
        identity,
        accessmask,
        isinherited,
        inheritanceflags,
        propagationflags,
        type )
    {
    }

    #endregion

    #region public properties

    public filesystemrights filesystemrights
    {
      get { return rightsfromaccessmask( base.accessmask ); }
    }

 
    internal static int accessmaskfromrights( filesystemrights filesystemrights, accesscontroltype controltype )
    {
      if (filesystemrights < (filesystemrights) 0 || filesystemrights > filesystemrights.fullcontrol)
        throw new argumentoutofrangeexception("filesystemrights", environment.getresourcestring("argument_invalidenumvalue", filesystemrights, "filesystemrights"));
      contract.endcontractblock();

      if (controltype == accesscontroltype.allow) {
        filesystemrights |= filesystemrights.synchronize;
      }
      else if (controltype == accesscontroltype.deny) {
        if (filesystemrights != filesystemrights.fullcontrol &&
          filesystemrights != (filesystemrights.fullcontrol & ~filesystemrights.deletesubdirectoriesandfiles))
          filesystemrights &= ~filesystemrights.synchronize;
      }

      return ( int )filesystemrights;
    }

    internal static filesystemrights rightsfromaccessmask( int accessmask )
    {
      return ( filesystemrights )accessmask;
    }

  }

2.由于filesystemaccessrule继承自accessrule，现在看一下accessrule的源码：

/// <summary>
 /// 表示用户的标识、访问掩码和访问控制类型（允许或拒绝）的组合。<see cref="t:system.security.accesscontrol.accessrule"/> 对象还包含有关子对象如何继承规则以及如何传播继承的信息。
 /// </summary>
 public abstract class accessrule : authorizationrule
 {
  /// <summary>
  /// 使用指定的值初始化 <see cref="t:system.security.accesscontrol.accessrule"/> 类的一个新实例。
  /// </summary>
  /// <param name="identity">应用访问规则的标识。此参数必须是可以强制转换为 <see cref="t:system.security.principal.securityidentifier"/> 的对象。</param><param name="accessmask">此规则的访问掩码。访问掩码是一个 32 位的匿名位集合，其含义是由每个集成器定义的。</param><param name="isinherited">如果此规则继承自父容器，则为 true。</param><param name="inheritanceflags">访问规则的继承属性。</param><param name="propagationflags">继承的访问规则是否自动传播。如果 <paramref name="inheritanceflags"/> 设置为 <see cref="f:system.security.accesscontrol.inheritanceflags.none"/>，则将忽略传播标志。</param><param name="type">有效的访问控制类型。</param><exception cref="t:system.argumentexception"><paramref name="identity"/> 参数的值不能强制转换为 <see cref="t:system.security.principal.securityidentifier"/>，或者 <paramref name="type"/> 参数包含无效值。</exception><exception cref="t:system.argumentoutofrangeexception"><paramref name="accessmask"/> 参数的值为零，或者 <paramref name="inheritanceflags"/> 或 <paramref name="propagationflags"/> 参数包含无法识别的标志值。</exception>
  protected accessrule(identityreference identity, int accessmask, bool isinherited, inheritanceflags inheritanceflags, propagationflags propagationflags, accesscontroltype type);
  /// <summary>
  /// 获取与此 <see cref="t:system.security.accesscontrol.accessrule"/> 对象关联的 <see cref="t:system.security.accesscontrol.accesscontroltype"/> 对象。
  /// </summary>
  /// 
  /// <returns>
  /// 与此 <see cref="t:system.security.accesscontrol.accessrule"/> 对象关联的 <see cref="t:system.security.accesscontrol.accesscontroltype"/> 对象。
  /// </returns>
  public accesscontroltype accesscontroltype { get; }
 }

      看来dotnet中实现文件权限设置的操作的类，现在提供几个具体的文件设置操作代码：

3.获取目录权限列表：

    /// <summary>
    /// 获取目录权限列表
    /// </summary>
    /// <param name="path">目录的路径。</param>
    /// <returns>指示目录的权限列表</returns>
    public ilist<filesystemrights> getdirectorypermission(string path)
    {
      try
      {
        if (!directoryexists(path))
          return null;

        ilist<filesystemrights> result = new list<filesystemrights>();
        var dsecurity = directory.getaccesscontrol(new directoryinfo(path).fullname);
        foreach (filesystemaccessrule rule in dsecurity.getaccessrules(true, true, typeof(ntaccount)))
          result.add(rule.filesystemrights);

        return result;
      }
      catch (exception e)
      {
        throw new exception(e.message, e);
      }
    }

4.设置目录权限

    /// <summary>
    ///设置目录权限
    /// </summary>
    /// <param name="path">目录的路径。</param>
    /// <param name="permission">在目录上设置的权限。</param>
    /// <returns>指示是否在目录上应用权限的值。</returns>
    public bool setdirectorypermission(string path, filesystemrights permission)
    {
      try
      {
        if (!directoryexists(path))
          return false;

        var accessrule = new filesystemaccessrule("users", permission,
                      inheritanceflags.none,
                      propagationflags.nopropagateinherit,
                      accesscontroltype.allow);

        var info = new directoryinfo(path);
        var security = info.getaccesscontrol(accesscontrolsections.access);

        bool result;
        security.modifyaccessrule(accesscontrolmodification.set, accessrule, out result);

        if (!result)
          return false;

        const inheritanceflags iflags = inheritanceflags.containerinherit | inheritanceflags.objectinherit;

        accessrule = new filesystemaccessrule("users", permission,
                      iflags,
                      propagationflags.inheritonly,
                      accesscontroltype.allow);

        security.modifyaccessrule(accesscontrolmodification.add, accessrule, out result);

        if (!result)
          return false;

        info.setaccesscontrol(security);

        return true;
      }
      catch (exception e)
      {
        throw new exception(e.message, e);
      }
    }

5.设置目录权限列表

  /// <summary>
  /// 设置目录权限列表
  /// </summary>
  /// <param name="path">目录的路径。</param>
  /// <param name="permissions">在目录上设置的权限。</param>
  /// <returns>指示是否在目录上应用权限的值。</returns>
  public bool setdirectorypermissions(string path, filesystemrights[] permissions)
  {
   try
   {
    if (!directoryexists(path) || permissions == null || !permissions.any())
     return false;

    foreach (var permission in permissions)
     if (!setdirectorypermission(path, permission))
      return false;

    return true;
   }
   catch (exception e)
   {
    throw new exception(e.message, e);
   }
  }

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