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FileIOPermissionAttribute Class

Updated: August 2009

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

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 the only permission that is to be granted to the code.

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

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)]

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 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.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

Date

History

Reason

August 2009

Updated example.

Customer feedback.

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