SemaphoreSecurity.RemoveAccessRule(SemaphoreAccessRule) Method
Definition
Important
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Searches for an access control rule with the same user and AccessControlType (allow or deny) as the specified rule, and with compatible inheritance and propagation flags; if such a rule is found, the rights contained in the specified access rule are removed from it.
public:
bool RemoveAccessRule(System::Security::AccessControl::SemaphoreAccessRule ^ rule);public bool RemoveAccessRule (System.Security.AccessControl.SemaphoreAccessRule rule);override this.RemoveAccessRule : System.Security.AccessControl.SemaphoreAccessRule -> boolPublic Function RemoveAccessRule (rule As SemaphoreAccessRule) As BooleanParameters
- rule
- SemaphoreAccessRule
A SemaphoreAccessRule that specifies the user and AccessControlType to search for, and a set of inheritance and propagation flags that a matching rule, if found, must be compatible with. Specifies the rights to remove from the compatible rule, if found.
Returns
true if a compatible rule is found; otherwise false.
Exceptions
rule is null.
Examples
The following code example demonstrates the use of the RemoveAccessRule method to remove rights from an Allow rule in a SemaphoreSecurity object. It also shows that other rights in rule are ignored.
The example creates a SemaphoreSecurity object and adds rules that allow and deny various rights for the current user. The rights allowed include Modify, ReadPermissions, and Synchronize. The example then creates a new rule for the current user, including ReadPermissions and TakeOwnership rights, and uses that rule with the RemoveAccessRule method to remove ReadPermissions from the Allow rule in the SemaphoreSecurity object. The extraneous TakeOwnership right in rule is ignored.
Note
This example does not attach the security object to a Semaphore object. Examples that attach security objects can be found in Semaphore.GetAccessControl and Semaphore.SetAccessControl.
using System;
using System.Threading;
using System.Security.AccessControl;
using System.Security.Principal;
public class Example
{
public static void Main()
{
// Create a string representing the current user.
string user = Environment.UserDomainName + "\\" +
Environment.UserName;
// Create a security object that grants no access.
SemaphoreSecurity mSec = new SemaphoreSecurity();
// Add a rule that grants the current user the
// right to enter or release the semaphore and read the
// permissions on the semaphore.
SemaphoreAccessRule rule = new SemaphoreAccessRule(user,
SemaphoreRights.Synchronize | SemaphoreRights.Modify
| SemaphoreRights.ReadPermissions,
AccessControlType.Allow);
mSec.AddAccessRule(rule);
// Add a rule that denies the current user the
// right to change permissions on the semaphore.
rule = new SemaphoreAccessRule(user,
SemaphoreRights.ChangePermissions,
AccessControlType.Deny);
mSec.AddAccessRule(rule);
// Display the rules in the security object.
ShowSecurity(mSec);
// Create a rule that grants the current user
// the right to read permissions on the semaphore, and
// take ownership of the semaphore. Use this rule to
// remove the right to read permissions from the
// Allow rule for the current user. The inclusion
// of the right to take ownership has no effect.
rule = new SemaphoreAccessRule(user,
SemaphoreRights.TakeOwnership |
SemaphoreRights.ReadPermissions,
AccessControlType.Allow);
mSec.RemoveAccessRule(rule);
ShowSecurity(mSec);
}
private static void ShowSecurity(SemaphoreSecurity security)
{
Console.WriteLine("\r\nCurrent access rules:\r\n");
foreach(SemaphoreAccessRule ar in
security.GetAccessRules(true, true, typeof(NTAccount)))
{
Console.WriteLine(" User: {0}", ar.IdentityReference);
Console.WriteLine(" Type: {0}", ar.AccessControlType);
Console.WriteLine(" Rights: {0}", ar.SemaphoreRights);
Console.WriteLine();
}
}
}
/*This code example produces output similar to following:
Current access rules:
User: TestDomain\TestUser
Type: Deny
Rights: ChangePermissions
User: TestDomain\TestUser
Type: Allow
Rights: Modify, ReadPermissions, Synchronize
Current access rules:
User: TestDomain\TestUser
Type: Deny
Rights: ChangePermissions
User: TestDomain\TestUser
Type: Allow
Rights: Modify, Synchronize
*/
Imports System.Threading
Imports System.Security.AccessControl
Imports System.Security.Principal
Public Class Example
Public Shared Sub Main()
' Create a string representing the current user.
Dim user As String = Environment.UserDomainName _
& "\" & Environment.UserName
' Create a security object that grants no access.
Dim mSec As New SemaphoreSecurity()
' Add a rule that grants the current user the
' right to enter or release the semaphore, and to
' read its permissions.
Dim rule As New SemaphoreAccessRule(user, _
SemaphoreRights.Synchronize _
Or SemaphoreRights.Modify _
Or SemaphoreRights.ReadPermissions, _
AccessControlType.Allow)
mSec.AddAccessRule(rule)
' Add a rule that denies the current user the
' right to change permissions on the semaphore.
rule = New SemaphoreAccessRule(user, _
SemaphoreRights.ChangePermissions, _
AccessControlType.Deny)
mSec.AddAccessRule(rule)
' Display the rules in the security object.
ShowSecurity(mSec)
' Create a rule that grants the current user
' the right to read permissions on the semaphore, and
' take ownership of the semaphore. Use this rule to
' remove the right to read permissions from the
' Allow rule for the current user. The inclusion
' of the right to take ownership has no effect.
rule = New SemaphoreAccessRule(user, _
SemaphoreRights.TakeOwnership _
Or SemaphoreRights.ReadPermissions, _
AccessControlType.Allow)
mSec.RemoveAccessRule(rule)
ShowSecurity(mSec)
End Sub
Private Shared Sub ShowSecurity(ByVal security As SemaphoreSecurity)
Console.WriteLine(vbCrLf & "Current access rules:" & vbCrLf)
For Each ar As SemaphoreAccessRule In _
security.GetAccessRules(True, True, GetType(NTAccount))
Console.WriteLine(" User: {0}", ar.IdentityReference)
Console.WriteLine(" Type: {0}", ar.AccessControlType)
Console.WriteLine(" Rights: {0}", ar.SemaphoreRights)
Console.WriteLine()
Next
End Sub
End Class
'This code example produces output similar to following:
'
'Current access rules:
'
' User: TestDomain\TestUser
' Type: Deny
' Rights: ChangePermissions
'
' User: TestDomain\TestUser
' Type: Allow
' Rights: Modify, ReadPermissions, Synchronize
'
'
'Current access rules:
'
' User: TestDomain\TestUser
' Type: Deny
' Rights: ChangePermissions
'
' User: TestDomain\TestUser
' Type: Allow
' Rights: Modify, Synchronize
Remarks
The current SemaphoreSecurity is searched for a rule that has the same user and the same AccessControlType value as rule. If no such rule is found, no action is taken, and the method returns false. If matching rules are found, their inheritance and compatibility flags are checked for compatibility with the flags specified in rule. If no compatible rule is found, no action is taken, and the method returns false. If a rule with compatible flags is found, the rights specified in rule are removed from the compatible rule, and the method returns true. If rule specifies rights not contained in the compatible rule, no action is taken with respect to those rights. If all rights are removed from the compatible rule, the entire rule is removed from the current SemaphoreSecurity object.
Important
Although you can specify inheritance and propagation flags for semaphore access rules, by creating them with the AccessRuleFactory method, this is not recommended. Inheritance and propagation have no meaning for named semaphores, and they make the maintenance of access rules more complicated.
