System.Security.Permissions.FileIOPermissionAttribute Class

Summary

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

C# Syntax:

[AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Constructor | AttributeTargets.Method)] [Serializable] public sealed class FileIOPermissionAttribute : 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.

Unrestricted FileIOPermission to a specified file effectively grants permission for all paths within a file system that can be used to access that file. To CodeAccessPermission.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 example of a declarative attribute shows the correct way to request FileIOPermission for full access to the specified file and states that you must have at least this permission to run your 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.

    

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

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

    

System.Security.Permissions Namespace See also:
MSDN: extendingmetadatausingattributes | FileIOPermission | FileIOPermissionAccess

System.Security.Permissions.FileIOPermissionAttribute Member List:

Public Constructors

ctor #1

Initializes a new instance of the FileIOPermissionAttribute class with the specified SecurityAction.

Public Properties

Action (inherited from System.Security.Permissions.SecurityAttribute)	Read-write See base class member description: System.Security.Permissions.SecurityAttribute.Action Gets or sets a security action.
All	Write-only Sets full access for the file or directory specified by the string value.
Append	Read-write Gets or sets append access for the file or directory specified by the string value.
PathDiscovery	Read-write Gets or sets the file or directory to which to grant path discovery.
Read	Read-write Gets or sets read access for the file or directory specified by the string value.
TypeId (inherited from System.Attribute)	Read-only See base class member description: System.Attribute.TypeId When implemented in a derived class, gets a unique identifier for this Attribute.
Unrestricted (inherited from System.Security.Permissions.SecurityAttribute)	Read-write See base class member description: System.Security.Permissions.SecurityAttribute.Unrestricted Gets or sets a value indicating whether full (unrestricted) permission to the resource protected by the attribute is declared.
Write	Read-write Gets or sets write access for the file or directory specified by the string value.

Public Methods

CreatePermission	Overridden: Creates and returns a new FileIOPermission.
Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetHashCode (inherited from System.Attribute)	See base class member description: System.Attribute.GetHashCode Returns the hash code for this instance.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
IsDefaultAttribute (inherited from System.Attribute)	See base class member description: System.Attribute.IsDefaultAttribute When overridden in a derived class, returns an indication whether the value of this instance is the default value for the derived class.
Match (inherited from System.Attribute)	See base class member description: System.Attribute.Match When overridden in a derived class, returns a value indicating whether this instance equals a specified object.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

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

System.Security.Permissions.FileIOPermissionAttribute Member Details

Summary

Initializes a new instance of the FileIOPermissionAttribute class with the specified SecurityAction.

C# Syntax:

public FileIOPermissionAttribute(    SecurityAction action );

action

One of the SecurityAction values.

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Inherited
See base class member description: System.Security.Permissions.SecurityAttribute.Action

Summary

Gets or sets a security action.

C# Syntax:

public SecurityAction Action {get; set;}

This property is inherited by all classes implementing custom attributes for declarative security.

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Summary

Sets full access for the file or directory specified by the string value.

C# Syntax:

string All {set;}

This property sets access for a single file or directory. Use additional attributes to specify additional files and directories.

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Summary

Gets or sets append access for the file or directory specified by the string value.

C# Syntax:

public string Append {get; set;}

This property sets access for a single file or directory. Use additional attributes to specify additional files and directories.

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Summary

Gets or sets the file or directory to which to grant path discovery.

C# Syntax:

public string PathDiscovery {get; set;}

Path discovery controls access to the information in the path itself. This protects sensitive information in the path, such as user names, as well as information about the directory structure revealed in the path. This value does not grant access to files or folders represented by the path.

Note For performance reasons, PathDiscovery should only be granted to directories, not to files. For example, PathDiscovery permission should be granted to paths such as C:\test and C:\test\, not C:\test\example.txt.

This property sets access for a single file or directory. Use additional attributes to specify additional files and directories.

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Summary

Gets or sets read access for the file or directory specified by the string value.

C# Syntax:

public string Read {get; set;}

This property sets access for a single file or directory. Use additional attributes to specify additional files and directories.

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Inherited
See base class member description: System.Attribute.TypeId

Summary

When implemented in a derived class, gets a unique identifier for this Attribute.

C# Syntax:

public virtual object TypeId {get;}

As implemented, this identifier is merely the Type of the attribute. However, it is intended that the unique identifier be used to identify two attributes of the same type.

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Inherited
See base class member description: System.Security.Permissions.SecurityAttribute.Unrestricted

Summary

Gets or sets a value indicating whether full (unrestricted) permission to the resource protected by the attribute is declared.

C# Syntax:

public bool Unrestricted {get; set;}

This property is inherited by all classes implementing custom attributes for declarative security.

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Summary

Gets or sets write access for the file or directory specified by the string value.

C# Syntax:

public string Write {get; set;}

This property sets access for a single file or directory. Use additional attributes to specify additional files and directories.

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Summary

Creates and returns a new FileIOPermission.

C# Syntax:

public override IPermission CreatePermission();

Return Value:

A FileIOPermission that corresponds to this attribute.

This method should only be called by the security system, never by application code.

At compile time, attributes convert security declarations to a serialized form in metadata. Declarative security data in metadata is created from the permission that this method returns that corresponds to this attribute.

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Inherited
See base class member description: System.Object.Equals

C# Syntax:

public virtual bool Equals(    object obj );

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.Finalize

C# Syntax:

~FileIOPermissionAttribute();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Attribute.GetHashCode

Summary

Returns the hash code for this instance.

C# Syntax:

public override int GetHashCode();

Return Value:

A 32-bit signed integer hash code.

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Inherited
See base class member description: System.Object.GetType

C# Syntax:

public Type GetType();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Attribute.IsDefaultAttribute

Summary

When overridden in a derived class, returns an indication whether the value of this instance is the default value for the derived class.

C# Syntax:

public virtual bool IsDefaultAttribute();

Return Value:

true if this instance is the default attribute for the class; otherwise, false.

The default implementation of this class returns false, and must be implemented in the derived class to be useful to that class.

The implementation of this method in a derived class compares the value of this instance to a standard, default value obtained by some means, then returns a Boolean value that indicates whether the value of this instance is equal to the standard. The standard value is typically coded as a constant in the implementation, or stored programmatically in a field used by the implementation.

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Inherited
See base class member description: System.Attribute.Match

Summary

When overridden in a derived class, returns a value indicating whether this instance equals a specified object.

C# Syntax:

public virtual bool Match(    object obj );

obj

An Object to compare with this instance of Attribute.

Return Value:

true if this instance equals obj; otherwise, false.

This method determines if one Attribute equals another. Its default implementation is the same as Attribute.Equals, which performs a value and reference comparison. Override this method to implement support for attribute values, such as flags or bitfields, that consist of components that are meaningful in themselves. For example, consider an attribute whose value is a binary field divided into a bitfield of flags. Two instances of this attribute have one flag in set in common while all the other flags differ. The Equal method cannot determine that the two instances have the same flag set, but the Match method can.

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Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:

protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.ToString

C# Syntax:

public virtual string ToString();

For more information on members inherited from System.Object click on the link above.

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