FileIOPermissionAttribute Class (System.Security.Permissions)

<SerializableAttribute> _
<ComVisibleAttribute(True)> _
<AttributeUsageAttribute(AttributeTargets.Assembly Or AttributeTargets.Class Or AttributeTargets.Struct Or AttributeTargets.Constructor Or AttributeTargets.Method, AllowMultiple := True,  _
    Inherited := False)> _
Public NotInheritable Class FileIOPermissionAttribute _
    Inherits CodeAccessSecurityAttribute

Visual Basic (Usage)

Dim instance As FileIOPermissionAttribute

[SerializableAttribute]
[ComVisibleAttribute(true)]
[AttributeUsageAttribute(AttributeTargets.Assembly|AttributeTargets.Class|AttributeTargets.Struct|AttributeTargets.Constructor|AttributeTargets.Method, AllowMultiple = true, 
    Inherited = false)]
public sealed class FileIOPermissionAttribute : CodeAccessSecurityAttribute

Visual C++

[SerializableAttribute]
[ComVisibleAttribute(true)]
[AttributeUsageAttribute(AttributeTargets::Assembly|AttributeTargets::Class|AttributeTargets::Struct|AttributeTargets::Constructor|AttributeTargets::Method, AllowMultiple = true, 
    Inherited = false)]
public ref class FileIOPermissionAttribute sealed : public CodeAccessSecurityAttribute

JScript

public final class FileIOPermissionAttribute extends CodeAccessSecurityAttribute

Remarks

Files and directories are specified using absolute paths. When accessing files, a security check is performed when the file is created or opened. The security check is not done again unless the file is closed and reopened. Checking permissions when the file is first accessed minimizes the impact of the security check on application performance because opening a file happens only once, while reading and writing can happen multiple times.

The scope of the declaration that is allowed depends on the SecurityAction that is used.

The security information declared by a security attribute is stored in the metadata of the attribute target and is accessed by the system at run time. Security attributes are used only for declarative security. For imperative security, use the corresponding permission class.

Caution:
Unrestricted FileIOPermission grants permission for all paths within a file system, including multiple pathnames that can be used to access a single given file. To Deny access to a file, you must Deny all possible paths to the file. For example, if \\server\share is mapped to the network drive X, to Deny access to \\server\share\file, you must Deny \\server\share\file, X:\file and any other path that you can use to access the file.

Caution:

Unrestricted FileIOPermission grants permission for all paths within a file system, including multiple pathnames that can be used to access a single given file. To Deny access to a file, you must Deny all possible paths to the file. For example, if \\server\share is mapped to the network drive X, to Deny access to \\server\share\file, you must Deny \\server\share\file, X:\file and any other path that you can use to access the file.

Examples

The following code example demonstrates how to request FileIOPermission by using the FileIOPermissionAttribute class, indicating the only permission that is to be granted to the code.

Visual Basic

<FileIOPermissionAttribute(SecurityAction.PermitOnly, _
ViewAndModify:="C:\example\sample.txt")> _
    Public Class SampleClass

[FileIOPermissionAttribute(SecurityAction.PermitOnly, ViewAndModify = "C:\\example\\sample.txt")]

Visual C++

[assembly:FileIOPermissionAttribute(SecurityAction::PermitOnly,ViewAndModify="C:\\example\\sample.txt")];
//In C++, you must specify that you are using the assembly scope when making a request.

The following example shows how to demand that the calling code has unrestricted FileIOPermission. You typically make demands in managed libraries (DLLs) to help protect methods or classes from potentially harmful code.

Visual Basic

<FileIOPermissionAttribute(SecurityAction.Demand, Unrestricted:=True)> _
Public Class SampleClass

[FileIOPermissionAttribute(SecurityAction.Demand, Unrestricted = true)]

Visual C++

[FileIOPermissionAttribute(SecurityAction::Demand,Unrestricted=true)]

Inheritance Hierarchy

System..::.Object
  System..::.Attribute
    System.Security.Permissions..::.SecurityAttribute
      System.Security.Permissions..::.CodeAccessSecurityAttribute
        System.Security.Permissions..::.FileIOPermissionAttribute

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information