SqlDataSourceEnumerator.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Data / System / Data / Sql / SqlDataSourceEnumerator.cs / 1305376 / SqlDataSourceEnumerator.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
//----------------------------------------------------------------------------- 
 
namespace System.Data.Sql {
 
    using System;
    using System.Data;
    using System.Data.Common;
    using System.Data.SqlClient; 
    using System.Diagnostics;
    using System.Globalization; 
    using System.Runtime.CompilerServices; 
    using System.Runtime.InteropServices;
    using System.Security; 
    using System.Text;

    public sealed class SqlDataSourceEnumerator : DbDataSourceEnumerator {
 
        private static readonly SqlDataSourceEnumerator SingletonInstance = new SqlDataSourceEnumerator();
        internal const string ServerName     = "ServerName"; 
        internal const string InstanceName   = "InstanceName"; 
        internal const string IsClustered    = "IsClustered";
        internal const string Version        = "Version"; 
        private  const int    timeoutSeconds = ADP.DefaultCommandTimeout;
        private long timeoutTime;                                // variable used for timeout computations, holds the value of the hi-res performance counter at which this request should expire

        private SqlDataSourceEnumerator() : base() { 
        }
 
        public static SqlDataSourceEnumerator Instance { 
            get {
                return SqlDataSourceEnumerator.SingletonInstance; 
            }
        }

        override public DataTable GetDataSources() { 
            (new NamedPermissionSet("FullTrust")).Demand(); // SQLBUDT 244304
            char[] buffer = null; 
            StringBuilder strbldr = new StringBuilder(); 

            Int32  bufferSize = 1024; 
            Int32  readLength = 0;
            buffer            = new char[bufferSize];
 			bool   more       = true;
            bool   failure    = false; 
            IntPtr handle     = ADP.PtrZero;
 
			RuntimeHelpers.PrepareConstrainedRegions(); 
            try {
                timeoutTime = TdsParserStaticMethods.GetTimeoutSeconds(timeoutSeconds); 
                RuntimeHelpers.PrepareConstrainedRegions();
                try {} finally {
                    handle = SNINativeMethodWrapper.SNIServerEnumOpen();
                } 

                if (ADP.PtrZero != handle) { 
                    while (more && !TdsParserStaticMethods.TimeoutHasExpired(timeoutTime)) { 
			            readLength = SNINativeMethodWrapper.SNIServerEnumRead(handle, buffer, bufferSize, ref more);
                        if (readLength > bufferSize) { 
                            failure = true;
                            more = false;
                        }
                        else if (0 < readLength) { 
							strbldr.Append(buffer, 0, readLength);
 						} 
                    } 
                }
            } 
            finally {
                if (ADP.PtrZero != handle) {
                    SNINativeMethodWrapper.SNIServerEnumClose(handle);
                } 
            }
 
            if (failure) { 
                Debug.Assert(false, "GetDataSources:SNIServerEnumRead returned bad length");
                Bid.Trace(" GetDataSources:SNIServerEnumRead returned bad length, requested %d, received %d", bufferSize, readLength); 
                throw ADP.ArgumentOutOfRange("readLength");
            }

            return ParseServerEnumString(strbldr.ToString()); 
        }
 
        private static string _Version = "Version:"; 
        private static string _Cluster = "Clustered:";
        private static int _clusterLength = _Cluster.Length; 
        private static int _versionLength =_Version.Length;

        static private DataTable ParseServerEnumString(string serverInstances) {
            DataTable dataTable = new DataTable("SqlDataSources"); 
            dataTable.Locale = CultureInfo.InvariantCulture;
            dataTable.Columns.Add(ServerName, typeof(string)); 
            dataTable.Columns.Add(InstanceName, typeof(string)); 
            dataTable.Columns.Add(IsClustered, typeof(string));
            dataTable.Columns.Add(Version, typeof(string)); 
            DataRow dataRow = null;
            string serverName = null;
            string instanceName = null;
            string isClustered = null; 
            string version = null;
 
            // Every row comes in the format "serverName\instanceName;Clustered:[Yes|No];Version:.." 
            // Every row is terminated by a null character.
            // Process one row at a time 
            foreach (string instance in serverInstances.Split('\0')) {
                string value = instance.Trim('\0'); // MDAC 91934
                if (0 == value.Length) {
                    continue; 
                }
				foreach (string instance2 in value.Split(';')) {					 
 					if (serverName == null) { 
                        foreach(string instance3 in instance2.Split('\\')) {							
 							if (serverName == null) { 
                                serverName = instance3;
                                continue;
                            }
                            Debug.Assert(instanceName == null); 
                            instanceName = instance3;
                        } 
                        continue; 
                    }
                    if (isClustered == null) { 
                        Debug.Assert(String.Compare(_Cluster, 0, instance2, 0, _clusterLength, StringComparison.OrdinalIgnoreCase) == 0);
                        isClustered = instance2.Substring(_clusterLength);
                        continue;
                    } 
                    Debug.Assert(version == null);
                    Debug.Assert(String.Compare(_Version, 0, instance2, 0, _versionLength, StringComparison.OrdinalIgnoreCase) == 0); 
                    version =  instance2.Substring(_versionLength); 
                }
 
                string query = "ServerName='"+serverName+"'";

                if (!ADP.IsEmpty(instanceName)) { // SQL BU DT 20006584: only append instanceName if present.
                    query += " AND InstanceName='"+instanceName+"'"; 
                }
 
                // SNI returns dupes - do not add them.  SQL BU DT 290323 
                if (dataTable.Select(query).Length == 0) {
                    dataRow = dataTable.NewRow(); 
                    dataRow[0] = serverName;
                    dataRow[1] = instanceName;
                    dataRow[2] = isClustered;
                    dataRow[3] = version; 
                    dataTable.Rows.Add(dataRow);
                } 
                serverName = null; 
                instanceName = null;
                isClustered = null; 
                version = null;
            }
            foreach(DataColumn column in dataTable.Columns) {
                column.ReadOnly = true; 
            }
            return dataTable; 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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SqlDataSourceEnumerator.cs source code in C# .NET

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