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FileIOPermissionAttribute Class

Allows security actions for FileIOPermission to be applied to code using declarative security. This class cannot be inherited.

Namespace: System.Security.Permissions
Assembly: mscorlib (in mscorlib.dll)

[SerializableAttribute] 
[AttributeUsageAttribute(AttributeTargets.Assembly|AttributeTargets.Class|AttributeTargets.Struct|AttributeTargets.Constructor|AttributeTargets.Method, AllowMultiple=true, Inherited=false)] 
[ComVisibleAttribute(true)] 
public sealed class FileIOPermissionAttribute : CodeAccessSecurityAttribute
/** @attribute SerializableAttribute() */ 
/** @attribute AttributeUsageAttribute(AttributeTargets.Assembly|AttributeTargets.Class|AttributeTargets.Struct|AttributeTargets.Constructor|AttributeTargets.Method, AllowMultiple=true, Inherited=false) */ 
/** @attribute ComVisibleAttribute(true) */ 
public final class FileIOPermissionAttribute extends CodeAccessSecurityAttribute
SerializableAttribute 
AttributeUsageAttribute(AttributeTargets.Assembly|AttributeTargets.Class|AttributeTargets.Struct|AttributeTargets.Constructor|AttributeTargets.Method, AllowMultiple=true, Inherited=false) 
ComVisibleAttribute(true) 
public final class FileIOPermissionAttribute extends CodeAccessSecurityAttribute
Not applicable.

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 noteCaution:

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.

The following code example demonstrates how to request FileIOPermission by using the FileIOPermissionAttribute class, indicating that this permission, at a minimum, is required to run the code.

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

/** @assembly FileIOPermissionAttribute(SecurityAction.RequestMinimum,
    All = "C:\\example\\sample.txt")
 */
// In VJ#, 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.

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

/** @attribute FileIOPermissionAttribute(SecurityAction.Demand,
    Unrestricted = true)
 */

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

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

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

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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