291 lines
10 KiB
C#
291 lines
10 KiB
C#
// This code is derived from jcifs smb client library <jcifs at samba dot org>
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// Ported by J. Arturo <webmaster at komodosoft dot net>
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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using System.Text;
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using SharpCifs.Util;
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namespace SharpCifs.Smb
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{
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/// <summary>
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/// An Access Control Entry (ACE) is an element in a security descriptor
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/// such as those associated with files and directories.
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/// </summary>
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/// <remarks>
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/// An Access Control Entry (ACE) is an element in a security descriptor
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/// such as those associated with files and directories. The Windows OS
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/// determines which users have the necessary permissions to access objects
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/// based on these entries.
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/// <p>
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/// To fully understand the information exposed by this class a description
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/// of the access check algorithm used by Windows is required. The following
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/// is a basic description of the algorithm. For a more complete description
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/// we recommend reading the section on Access Control in Keith Brown's
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/// "The .NET Developer's Guide to Windows Security" (which is also
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/// available online).
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/// <p>
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/// Direct ACEs are evaluated first in order. The SID of the user performing
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/// the operation and the desired access bits are compared to the SID
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/// and access mask of each ACE. If the SID matches, the allow/deny flags
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/// and access mask are considered. If the ACE is a "deny"
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/// ACE and <i>any</i> of the desired access bits match bits in the access
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/// mask of the ACE, the whole access check fails. If the ACE is an "allow"
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/// ACE and <i>all</i> of the bits in the desired access bits match bits in
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/// the access mask of the ACE, the access check is successful. Otherwise,
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/// more ACEs are evaluated until all desired access bits (combined)
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/// are "allowed". If all of the desired access bits are not "allowed"
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/// the then same process is repeated for inherited ACEs.
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/// <p>
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/// For example, if user <tt>WNET\alice</tt> tries to open a file
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/// with desired access bits <tt>0x00000003</tt> (<tt>FILE_READ_DATA |
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/// FILE_WRITE_DATA</tt>) and the target file has the following security
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/// descriptor ACEs:
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/// <pre>
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/// Allow WNET\alice 0x001200A9 Direct
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/// Allow Administrators 0x001F01FF Inherited
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/// Allow SYSTEM 0x001F01FF Inherited
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/// </pre>
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/// the access check would fail because the direct ACE has an access mask
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/// of <tt>0x001200A9</tt> which doesn't have the
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/// <tt>FILE_WRITE_DATA</tt> bit on (bit <tt>0x00000002</tt>). Actually, this isn't quite correct. If
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/// <tt>WNET\alice</tt> is in the local <tt>Administrators</tt> group the access check
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/// will succeed because the inherited ACE allows local <tt>Administrators</tt>
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/// both <tt>FILE_READ_DATA</tt> and <tt>FILE_WRITE_DATA</tt> access.
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/// </remarks>
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public class Ace
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{
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public const int FileReadData = unchecked(0x00000001);
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public const int FileWriteData = unchecked(0x00000002);
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public const int FileAppendData = unchecked(0x00000004);
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public const int FileReadEa = unchecked(0x00000008);
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public const int FileWriteEa = unchecked(0x00000010);
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public const int FileExecute = unchecked(0x00000020);
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public const int FileDelete = unchecked(0x00000040);
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public const int FileReadAttributes = unchecked(0x00000080);
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public const int FileWriteAttributes = unchecked(0x00000100);
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public const int Delete = unchecked(0x00010000);
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public const int ReadControl = unchecked(0x00020000);
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public const int WriteDac = unchecked(0x00040000);
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public const int WriteOwner = unchecked(0x00080000);
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public const int Synchronize = unchecked(0x00100000);
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public const int GenericAll = unchecked(0x10000000);
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public const int GenericExecute = unchecked(0x20000000);
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public const int GenericWrite = unchecked(0x40000000);
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public const int GenericRead = unchecked((int)(0x80000000));
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public const int FlagsObjectInherit = unchecked(0x01);
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public const int FlagsContainerInherit = unchecked(0x02);
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public const int FlagsNoPropagate = unchecked(0x04);
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public const int FlagsInheritOnly = unchecked(0x08);
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public const int FlagsInherited = unchecked(0x10);
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internal bool Allow;
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internal int Flags;
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internal int Access;
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internal Sid Sid;
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// 1
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// 2
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// 3
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// 4
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// 5
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// 6
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// 7
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// 8
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// 9
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// 16
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// 17
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// 18
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// 19
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// 20
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// 28
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// 29
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// 30
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// 31
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/// <summary>Returns true if this ACE is an allow ACE and false if it is a deny ACE.</summary>
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/// <remarks>Returns true if this ACE is an allow ACE and false if it is a deny ACE.</remarks>
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public virtual bool IsAllow()
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{
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return Allow;
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}
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/// <summary>Returns true if this ACE is an inherited ACE and false if it is a direct ACE.
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/// </summary>
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/// <remarks>
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/// Returns true if this ACE is an inherited ACE and false if it is a direct ACE.
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/// <p>
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/// Note: For reasons not fully understood, <tt>FLAGS_INHERITED</tt> may
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/// not be set within all security descriptors even though the ACE was in
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/// face inherited. If an inherited ACE is added to a parent the Windows
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/// ACL editor will rebuild all children ACEs and set this flag accordingly.
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/// </remarks>
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public virtual bool IsInherited()
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{
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return (Flags & FlagsInherited) != 0;
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}
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/// <summary>Returns the flags for this ACE.</summary>
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/// <remarks>
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/// Returns the flags for this ACE. The <tt>isInherited()</tt>
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/// method checks the <tt>FLAGS_INHERITED</tt> bit in these flags.
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/// </remarks>
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public virtual int GetFlags()
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{
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return Flags;
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}
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/// <summary>
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/// Returns the 'Apply To' text for inheritance of ACEs on
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/// directories such as 'This folder, subfolder and files'.
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/// </summary>
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/// <remarks>
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/// Returns the 'Apply To' text for inheritance of ACEs on
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/// directories such as 'This folder, subfolder and files'. For
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/// files the text is always 'This object only'.
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/// </remarks>
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public virtual string GetApplyToText()
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{
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switch (Flags & (FlagsObjectInherit | FlagsContainerInherit | FlagsInheritOnly))
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{
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case unchecked(0x00):
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{
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return "This folder only";
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}
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case unchecked(0x03):
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{
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return "This folder, subfolders and files";
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}
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case unchecked(0x0B):
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{
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return "Subfolders and files only";
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}
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case unchecked(0x02):
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{
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return "This folder and subfolders";
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}
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case unchecked(0x0A):
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{
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return "Subfolders only";
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}
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case unchecked(0x01):
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{
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return "This folder and files";
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}
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case unchecked(0x09):
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{
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return "Files only";
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}
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}
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return "Invalid";
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}
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/// <summary>Returns the access mask accociated with this ACE.</summary>
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/// <remarks>
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/// Returns the access mask accociated with this ACE. Use the
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/// constants for <tt>FILE_READ_DATA</tt>, <tt>FILE_WRITE_DATA</tt>,
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/// <tt>READ_CONTROL</tt>, <tt>GENERIC_ALL</tt>, etc with bitwise
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/// operators to determine which bits of the mask are on or off.
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/// </remarks>
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public virtual int GetAccessMask()
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{
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return Access;
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}
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/// <summary>Return the SID associated with this ACE.</summary>
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/// <remarks>Return the SID associated with this ACE.</remarks>
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public virtual Sid GetSid()
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{
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return Sid;
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}
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internal virtual int Decode(byte[] buf, int bi)
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{
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Allow = buf[bi++] == unchecked(unchecked(0x00));
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Flags = buf[bi++] & unchecked(0xFF);
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int size = ServerMessageBlock.ReadInt2(buf, bi);
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bi += 2;
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Access = ServerMessageBlock.ReadInt4(buf, bi);
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bi += 4;
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Sid = new Sid(buf, bi);
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return size;
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}
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internal virtual void AppendCol(StringBuilder sb, string str, int width)
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{
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sb.Append(str);
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int count = width - str.Length;
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for (int i = 0; i < count; i++)
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{
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sb.Append(' ');
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}
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}
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/// <summary>Return a string represeting this ACE.</summary>
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/// <remarks>
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/// Return a string represeting this ACE.
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/// <p>
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/// Note: This function should probably be changed to return SDDL
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/// fragments but currently it does not.
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/// </remarks>
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public override string ToString()
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{
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int count;
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int i;
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string str;
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StringBuilder sb = new StringBuilder();
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sb.Append(IsAllow()
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? "Allow "
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: "Deny ");
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AppendCol(sb, Sid.ToDisplayString(), 25);
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sb.Append(" 0x").Append(Hexdump.ToHexString(Access, 8)).Append(' ');
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sb.Append(IsInherited()
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? "Inherited "
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: "Direct ");
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AppendCol(sb, GetApplyToText(), 34);
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return sb.ToString();
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}
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}
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}
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