ConfigurationErrorsException.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Configuration / System / Configuration / ConfigurationErrorsException.cs / 1305376 / ConfigurationErrorsException.cs

                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Configuration { 
    using System.Configuration.Internal; 
    using System;
    using System.Collections; 
    using System.Collections.Generic;
    using System.Globalization;
    using System.IO;
    using System.Runtime.Serialization; 
    using System.Security;
    using System.Security.Permissions; 
    using System.Xml; 
    using System.Runtime.Versioning;
 
    [Serializable]
    public class ConfigurationErrorsException : ConfigurationException {

        // Constants 
        private const string HTTP_PREFIX                     = "http:";
        private const string SERIALIZATION_PARAM_FILENAME    = "firstFilename"; 
        private const string SERIALIZATION_PARAM_LINE        = "firstLine"; 
        private const string SERIALIZATION_PARAM_ERROR_COUNT = "count";
        private const string SERIALIZATION_PARAM_ERROR_DATA  = "_errors"; 
        private const string SERIALIZATION_PARAM_ERROR_TYPE  = "_errors_type";

        private string                      _firstFilename;
        private int                         _firstLine; 
        private ConfigurationException[]    _errors;
 
        void Init(string filename, int line) { 
            HResult = HResults.Configuration;
 
            // BaseConfigurationRecord.cs uses -1 as uninitialized line number.
            if (line == -1) {
                line = 0;
            } 

            _firstFilename = filename; 
            _firstLine = line; 
        }
 
        // The ConfigurationException class is obsolete, but we still need to derive from it and call the base ctor, so we
        // just disable the obsoletion warning.
#pragma warning disable 0618
        public ConfigurationErrorsException(string message, Exception inner, string filename, int line) : base(message, inner) { 
#pragma warning restore 0618
            Init(filename, line); 
        } 

        public ConfigurationErrorsException() : 
                this(null, null, null, 0) {}

        public ConfigurationErrorsException(string message) :
                this(message, null, null, 0) {} 

        public ConfigurationErrorsException(string message, Exception inner) : 
                this(message, inner, null, 0) {} 

        public ConfigurationErrorsException(string message, string filename, int line) : 
                this(message, null, filename, line) {}

        public ConfigurationErrorsException(string message, XmlNode node) :
                this(message, null, GetUnsafeFilename(node), GetLineNumber(node)) {} 

        public ConfigurationErrorsException(string message, Exception inner, XmlNode node) : 
                this(message, inner, GetUnsafeFilename(node), GetLineNumber(node)) {} 

        public ConfigurationErrorsException(string message, XmlReader reader) : 
                this(message, null, GetUnsafeFilename(reader), GetLineNumber(reader)) {}

        public ConfigurationErrorsException(string message, Exception inner, XmlReader reader) :
                this(message, inner, GetUnsafeFilename(reader), GetLineNumber(reader)) {} 

        internal ConfigurationErrorsException(string message, IConfigErrorInfo errorInfo) : 
                this(message, null, GetUnsafeConfigErrorInfoFilename(errorInfo), GetConfigErrorInfoLineNumber(errorInfo)) {} 

        internal ConfigurationErrorsException(string message, Exception inner, IConfigErrorInfo errorInfo) : 
                this(message, inner, GetUnsafeConfigErrorInfoFilename(errorInfo), GetConfigErrorInfoLineNumber(errorInfo)) {}

        internal ConfigurationErrorsException(ConfigurationException e) :
                this(GetBareMessage(e), GetInnerException(e), GetUnsafeFilename(e), GetLineNumber(e)) {} 

 
        [ResourceExposure(ResourceScope.None)] 
        internal ConfigurationErrorsException(ICollection coll) :
                this(GetFirstException(coll)) { 

            if (coll.Count > 1) {
                _errors = new ConfigurationException[coll.Count];
                coll.CopyTo(_errors, 0); 
            }
        } 
 
        internal ConfigurationErrorsException(ArrayList coll) :
                this((ConfigurationException) (coll.Count > 0 ? coll[0] : null)) { 

            if (coll.Count > 1) {
                _errors = new ConfigurationException[coll.Count];
                coll.CopyTo(_errors, 0); 

                foreach (object error in _errors) { 
                    // force an illegal typecast exception if the object is not 
                    // of the right type
                    ConfigurationException exception = (ConfigurationException) error; 
                }
            }
        }
 
        static private ConfigurationException GetFirstException(ICollection coll) {
            foreach (ConfigurationException e in coll) { 
                return e; 
            }
 
            return null;
        }

        static private string GetBareMessage(ConfigurationException e) { 
            if (e != null) {
                return e.BareMessage; 
            } 

            return null; 
        }

        static private Exception GetInnerException(ConfigurationException e) {
            if (e != null) { 
                return e.InnerException;
            } 
 
            return null;
        } 

        //
        // We assert PathDiscovery so that we get the full filename when calling ConfigurationException.Filename
        // 
        [FileIOPermission(SecurityAction.Assert, AllFiles=FileIOPermissionAccess.PathDiscovery)]
        static private string GetUnsafeFilename(ConfigurationException e) { 
            if (e != null) { 
                return e.Filename;
            } 

            return null;
        }
 
        static private int GetLineNumber(ConfigurationException e) {
            if (e != null) { 
                return e.Line; 
            }
 
            return 0;
        }

 
        // Serialization methods
        protected ConfigurationErrorsException(SerializationInfo info, StreamingContext context) : 
                base(info, context) { 

            string  firstFilename; 
            int     firstLine;
            int     count;
            string  numPrefix;
            string  currentType; 
            Type    currentExceptionType;
 
            // Retrieve out members 
            firstFilename = info.GetString(SERIALIZATION_PARAM_FILENAME);
            firstLine     = info.GetInt32(SERIALIZATION_PARAM_LINE); 

            Init(firstFilename, firstLine);

            // Retrieve errors for _errors object 
            count = info.GetInt32(SERIALIZATION_PARAM_ERROR_COUNT);
 
            if (count != 0) { 
                _errors = new ConfigurationException[count];
 
                for (int i = 0; i < count; i++) {
                    numPrefix = i.ToString(CultureInfo.InvariantCulture);

                    currentType = info.GetString(numPrefix + SERIALIZATION_PARAM_ERROR_TYPE); 
                    currentExceptionType = Type.GetType(currentType, true);
 
                    // Only allow our exception types 
                    if ( ( currentExceptionType != typeof( ConfigurationException ) ) &&
                         ( currentExceptionType != typeof( ConfigurationErrorsException ) ) ) { 
                        throw ExceptionUtil.UnexpectedError( "ConfigurationErrorsException" );
                    }

                    _errors[i] = (ConfigurationException) 
                                    info.GetValue(numPrefix + SERIALIZATION_PARAM_ERROR_DATA,
                                                  currentExceptionType); 
                } 
            }
        } 

        [SecurityPermissionAttribute(SecurityAction.Demand,SerializationFormatter=true)]
        public override void GetObjectData(SerializationInfo info, StreamingContext context) {
            int    subErrors = 0; 
            string numPrefix;
 
            // call base implementation 
            base.GetObjectData(info, context);
 
            // Serialize our members
            info.AddValue(SERIALIZATION_PARAM_FILENAME, Filename);
            info.AddValue(SERIALIZATION_PARAM_LINE,     Line);
 
            // Serialize rest of errors, along with count
            // (since first error duplicates this error, only worry if 
            //  there is more than one) 
            if ((_errors        != null) &&
                (_errors.Length >  1   )){ 
                subErrors = _errors.Length;

                for (int i = 0; i < _errors.Length; i++) {
                    numPrefix = i.ToString(CultureInfo.InvariantCulture); 

                    info.AddValue(numPrefix + SERIALIZATION_PARAM_ERROR_DATA, 
                                  _errors[i]); 
                    info.AddValue(numPrefix + SERIALIZATION_PARAM_ERROR_TYPE,
                                  _errors[i].GetType()); 
                }
            }

            info.AddValue(SERIALIZATION_PARAM_ERROR_COUNT, subErrors); 
        }
 
        // The message includes the file/line number information. 
        // To get the message without the extra information, use BareMessage.
        public override string Message { 
            get {
                string file = Filename;
                if (!string.IsNullOrEmpty(file)) {
                    if (Line != 0) { 
                        return BareMessage + " (" + file + " line " + Line.ToString(CultureInfo.CurrentCulture) + ")";
                    } 
                    else { 
                        return BareMessage + " (" + file + ")";
                    } 
                }
                else if (Line != 0) {
                    return BareMessage + " (line " + Line.ToString("G", CultureInfo.CurrentCulture) + ")";
                } 
                else {
                    return BareMessage; 
                } 
            }
        } 

        public override string BareMessage {
            get {
                return base.BareMessage; 
            }
        } 
 
        public override string Filename {
            get { 
                return SafeFilename(_firstFilename);
            }
        }
 
        public override int Line {
            get { 
                return _firstLine; 
            }
        } 

        public ICollection Errors {
            get {
                if (_errors != null) { 
                    return _errors;
                } 
                else { 
                    ConfigurationErrorsException e = new ConfigurationErrorsException(BareMessage, base.InnerException, _firstFilename, _firstLine);
                    ConfigurationException[] a = new ConfigurationException[] {e}; 
                    return a;
                }
            }
        } 

        internal ICollection ErrorsGeneric { 
            get { 
                return (ICollection) this.Errors;
            } 
        }

        //
        // Get file and linenumber from an XML Node in a DOM 
        //
        public static int GetLineNumber(XmlNode node) { 
            return GetConfigErrorInfoLineNumber(node as IConfigErrorInfo); 
        }
 
        public static string GetFilename(XmlNode node) {
            return SafeFilename(GetUnsafeFilename(node));
        }
 
        private static string GetUnsafeFilename(XmlNode node) {
            return GetUnsafeConfigErrorInfoFilename(node as IConfigErrorInfo); 
        } 

        // 
        // Get file and linenumber from an XML Reader
        //
        public static int GetLineNumber(XmlReader reader) {
            return GetConfigErrorInfoLineNumber(reader as IConfigErrorInfo); 
        }
 
        public static string GetFilename(XmlReader reader) { 
            return SafeFilename(GetUnsafeFilename(reader));
        } 

        private static string GetUnsafeFilename(XmlReader reader) {
            return GetUnsafeConfigErrorInfoFilename(reader as IConfigErrorInfo);
        } 

        // 
        // Get file and linenumber from an IConfigErrorInfo 
        //
        private static int GetConfigErrorInfoLineNumber(IConfigErrorInfo errorInfo) { 
            if (errorInfo != null) {
                return errorInfo.LineNumber;
            }
            else { 
                return 0;
            } 
        } 

        private static string GetUnsafeConfigErrorInfoFilename(IConfigErrorInfo errorInfo) { 
            if (errorInfo != null) {
                return errorInfo.Filename;
            }
            else { 
                return null;
            } 
        } 

        [FileIOPermission(SecurityAction.Assert, AllFiles=FileIOPermissionAccess.PathDiscovery)] 
        private static string FullPathWithAssert(string filename) {
            string fullPath = null;

            try { 
                fullPath = Path.GetFullPath(filename);
            } 
            catch { 
            }
 
            return fullPath;
        }

        // 
        // Internal Helper to strip a full path to just filename.ext when caller
        // does not have path discovery to the path (used for sane error handling). 
        // 
        internal static string SafeFilename(string filename) {
            if (string.IsNullOrEmpty(filename)) { 
                return filename;
            }

            // configuration file can be an http URL in IE 
            if (StringUtil.StartsWithIgnoreCase(filename, HTTP_PREFIX)) {
                return filename; 
            } 

            // 
            // If it is a relative path, return it as is.
            // This could happen if the exception was constructed from the serialization constructor,
            // and the caller did not have PathDiscoveryPermission for the file.
            // 
            try {
                if (!Path.IsPathRooted(filename)) { 
                    return filename; 
                }
            } 
            catch {
                return null;
            }
 
            try {
                // Confirm that it is a full path. 
                // GetFullPath will also Demand PathDiscovery for the resulting path 
                string fullPath = Path.GetFullPath(filename);
            } 
            catch (SecurityException) {
                // Get just the name of the file without the directory part.
                try {
                    string fullPath = FullPathWithAssert(filename); 
                    filename = Path.GetFileName(fullPath);
                } 
                catch { 
                    filename = null;
                } 
            }
            catch {
                filename = null;
            } 

            return filename; 
        } 

        // 
        // Internal Helper to always strip a full path to just filename.ext.
        //
        internal static string AlwaysSafeFilename(string filename) {
            if (string.IsNullOrEmpty(filename)) { 
                return filename;
            } 
 
            // configuration file can be an http URL in IE
            if (StringUtil.StartsWithIgnoreCase(filename, HTTP_PREFIX)) { 
                return filename;
            }

            // 
            // If it is a relative path, return it as is.
            // This could happen if the exception was constructed from the serialization constructor, 
            // and the caller did not have PathDiscoveryPermission for the file. 
            //
            try { 
                if (!Path.IsPathRooted(filename)) {
                    return filename;
                }
            } 
            catch {
                return null; 
            } 

            // Get just the name of the file without the directory part. 
            try {
                string fullPath = FullPathWithAssert(filename);
                filename = Path.GetFileName(fullPath);
            } 
            catch {
                filename = null; 
            } 

            return filename; 
        }

    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Configuration { 
    using System.Configuration.Internal; 
    using System;
    using System.Collections; 
    using System.Collections.Generic;
    using System.Globalization;
    using System.IO;
    using System.Runtime.Serialization; 
    using System.Security;
    using System.Security.Permissions; 
    using System.Xml; 
    using System.Runtime.Versioning;
 
    [Serializable]
    public class ConfigurationErrorsException : ConfigurationException {

        // Constants 
        private const string HTTP_PREFIX                     = "http:";
        private const string SERIALIZATION_PARAM_FILENAME    = "firstFilename"; 
        private const string SERIALIZATION_PARAM_LINE        = "firstLine"; 
        private const string SERIALIZATION_PARAM_ERROR_COUNT = "count";
        private const string SERIALIZATION_PARAM_ERROR_DATA  = "_errors"; 
        private const string SERIALIZATION_PARAM_ERROR_TYPE  = "_errors_type";

        private string                      _firstFilename;
        private int                         _firstLine; 
        private ConfigurationException[]    _errors;
 
        void Init(string filename, int line) { 
            HResult = HResults.Configuration;
 
            // BaseConfigurationRecord.cs uses -1 as uninitialized line number.
            if (line == -1) {
                line = 0;
            } 

            _firstFilename = filename; 
            _firstLine = line; 
        }
 
        // The ConfigurationException class is obsolete, but we still need to derive from it and call the base ctor, so we
        // just disable the obsoletion warning.
#pragma warning disable 0618
        public ConfigurationErrorsException(string message, Exception inner, string filename, int line) : base(message, inner) { 
#pragma warning restore 0618
            Init(filename, line); 
        } 

        public ConfigurationErrorsException() : 
                this(null, null, null, 0) {}

        public ConfigurationErrorsException(string message) :
                this(message, null, null, 0) {} 

        public ConfigurationErrorsException(string message, Exception inner) : 
                this(message, inner, null, 0) {} 

        public ConfigurationErrorsException(string message, string filename, int line) : 
                this(message, null, filename, line) {}

        public ConfigurationErrorsException(string message, XmlNode node) :
                this(message, null, GetUnsafeFilename(node), GetLineNumber(node)) {} 

        public ConfigurationErrorsException(string message, Exception inner, XmlNode node) : 
                this(message, inner, GetUnsafeFilename(node), GetLineNumber(node)) {} 

        public ConfigurationErrorsException(string message, XmlReader reader) : 
                this(message, null, GetUnsafeFilename(reader), GetLineNumber(reader)) {}

        public ConfigurationErrorsException(string message, Exception inner, XmlReader reader) :
                this(message, inner, GetUnsafeFilename(reader), GetLineNumber(reader)) {} 

        internal ConfigurationErrorsException(string message, IConfigErrorInfo errorInfo) : 
                this(message, null, GetUnsafeConfigErrorInfoFilename(errorInfo), GetConfigErrorInfoLineNumber(errorInfo)) {} 

        internal ConfigurationErrorsException(string message, Exception inner, IConfigErrorInfo errorInfo) : 
                this(message, inner, GetUnsafeConfigErrorInfoFilename(errorInfo), GetConfigErrorInfoLineNumber(errorInfo)) {}

        internal ConfigurationErrorsException(ConfigurationException e) :
                this(GetBareMessage(e), GetInnerException(e), GetUnsafeFilename(e), GetLineNumber(e)) {} 

 
        [ResourceExposure(ResourceScope.None)] 
        internal ConfigurationErrorsException(ICollection coll) :
                this(GetFirstException(coll)) { 

            if (coll.Count > 1) {
                _errors = new ConfigurationException[coll.Count];
                coll.CopyTo(_errors, 0); 
            }
        } 
 
        internal ConfigurationErrorsException(ArrayList coll) :
                this((ConfigurationException) (coll.Count > 0 ? coll[0] : null)) { 

            if (coll.Count > 1) {
                _errors = new ConfigurationException[coll.Count];
                coll.CopyTo(_errors, 0); 

                foreach (object error in _errors) { 
                    // force an illegal typecast exception if the object is not 
                    // of the right type
                    ConfigurationException exception = (ConfigurationException) error; 
                }
            }
        }
 
        static private ConfigurationException GetFirstException(ICollection coll) {
            foreach (ConfigurationException e in coll) { 
                return e; 
            }
 
            return null;
        }

        static private string GetBareMessage(ConfigurationException e) { 
            if (e != null) {
                return e.BareMessage; 
            } 

            return null; 
        }

        static private Exception GetInnerException(ConfigurationException e) {
            if (e != null) { 
                return e.InnerException;
            } 
 
            return null;
        } 

        //
        // We assert PathDiscovery so that we get the full filename when calling ConfigurationException.Filename
        // 
        [FileIOPermission(SecurityAction.Assert, AllFiles=FileIOPermissionAccess.PathDiscovery)]
        static private string GetUnsafeFilename(ConfigurationException e) { 
            if (e != null) { 
                return e.Filename;
            } 

            return null;
        }
 
        static private int GetLineNumber(ConfigurationException e) {
            if (e != null) { 
                return e.Line; 
            }
 
            return 0;
        }

 
        // Serialization methods
        protected ConfigurationErrorsException(SerializationInfo info, StreamingContext context) : 
                base(info, context) { 

            string  firstFilename; 
            int     firstLine;
            int     count;
            string  numPrefix;
            string  currentType; 
            Type    currentExceptionType;
 
            // Retrieve out members 
            firstFilename = info.GetString(SERIALIZATION_PARAM_FILENAME);
            firstLine     = info.GetInt32(SERIALIZATION_PARAM_LINE); 

            Init(firstFilename, firstLine);

            // Retrieve errors for _errors object 
            count = info.GetInt32(SERIALIZATION_PARAM_ERROR_COUNT);
 
            if (count != 0) { 
                _errors = new ConfigurationException[count];
 
                for (int i = 0; i < count; i++) {
                    numPrefix = i.ToString(CultureInfo.InvariantCulture);

                    currentType = info.GetString(numPrefix + SERIALIZATION_PARAM_ERROR_TYPE); 
                    currentExceptionType = Type.GetType(currentType, true);
 
                    // Only allow our exception types 
                    if ( ( currentExceptionType != typeof( ConfigurationException ) ) &&
                         ( currentExceptionType != typeof( ConfigurationErrorsException ) ) ) { 
                        throw ExceptionUtil.UnexpectedError( "ConfigurationErrorsException" );
                    }

                    _errors[i] = (ConfigurationException) 
                                    info.GetValue(numPrefix + SERIALIZATION_PARAM_ERROR_DATA,
                                                  currentExceptionType); 
                } 
            }
        } 

        [SecurityPermissionAttribute(SecurityAction.Demand,SerializationFormatter=true)]
        public override void GetObjectData(SerializationInfo info, StreamingContext context) {
            int    subErrors = 0; 
            string numPrefix;
 
            // call base implementation 
            base.GetObjectData(info, context);
 
            // Serialize our members
            info.AddValue(SERIALIZATION_PARAM_FILENAME, Filename);
            info.AddValue(SERIALIZATION_PARAM_LINE,     Line);
 
            // Serialize rest of errors, along with count
            // (since first error duplicates this error, only worry if 
            //  there is more than one) 
            if ((_errors        != null) &&
                (_errors.Length >  1   )){ 
                subErrors = _errors.Length;

                for (int i = 0; i < _errors.Length; i++) {
                    numPrefix = i.ToString(CultureInfo.InvariantCulture); 

                    info.AddValue(numPrefix + SERIALIZATION_PARAM_ERROR_DATA, 
                                  _errors[i]); 
                    info.AddValue(numPrefix + SERIALIZATION_PARAM_ERROR_TYPE,
                                  _errors[i].GetType()); 
                }
            }

            info.AddValue(SERIALIZATION_PARAM_ERROR_COUNT, subErrors); 
        }
 
        // The message includes the file/line number information. 
        // To get the message without the extra information, use BareMessage.
        public override string Message { 
            get {
                string file = Filename;
                if (!string.IsNullOrEmpty(file)) {
                    if (Line != 0) { 
                        return BareMessage + " (" + file + " line " + Line.ToString(CultureInfo.CurrentCulture) + ")";
                    } 
                    else { 
                        return BareMessage + " (" + file + ")";
                    } 
                }
                else if (Line != 0) {
                    return BareMessage + " (line " + Line.ToString("G", CultureInfo.CurrentCulture) + ")";
                } 
                else {
                    return BareMessage; 
                } 
            }
        } 

        public override string BareMessage {
            get {
                return base.BareMessage; 
            }
        } 
 
        public override string Filename {
            get { 
                return SafeFilename(_firstFilename);
            }
        }
 
        public override int Line {
            get { 
                return _firstLine; 
            }
        } 

        public ICollection Errors {
            get {
                if (_errors != null) { 
                    return _errors;
                } 
                else { 
                    ConfigurationErrorsException e = new ConfigurationErrorsException(BareMessage, base.InnerException, _firstFilename, _firstLine);
                    ConfigurationException[] a = new ConfigurationException[] {e}; 
                    return a;
                }
            }
        } 

        internal ICollection ErrorsGeneric { 
            get { 
                return (ICollection) this.Errors;
            } 
        }

        //
        // Get file and linenumber from an XML Node in a DOM 
        //
        public static int GetLineNumber(XmlNode node) { 
            return GetConfigErrorInfoLineNumber(node as IConfigErrorInfo); 
        }
 
        public static string GetFilename(XmlNode node) {
            return SafeFilename(GetUnsafeFilename(node));
        }
 
        private static string GetUnsafeFilename(XmlNode node) {
            return GetUnsafeConfigErrorInfoFilename(node as IConfigErrorInfo); 
        } 

        // 
        // Get file and linenumber from an XML Reader
        //
        public static int GetLineNumber(XmlReader reader) {
            return GetConfigErrorInfoLineNumber(reader as IConfigErrorInfo); 
        }
 
        public static string GetFilename(XmlReader reader) { 
            return SafeFilename(GetUnsafeFilename(reader));
        } 

        private static string GetUnsafeFilename(XmlReader reader) {
            return GetUnsafeConfigErrorInfoFilename(reader as IConfigErrorInfo);
        } 

        // 
        // Get file and linenumber from an IConfigErrorInfo 
        //
        private static int GetConfigErrorInfoLineNumber(IConfigErrorInfo errorInfo) { 
            if (errorInfo != null) {
                return errorInfo.LineNumber;
            }
            else { 
                return 0;
            } 
        } 

        private static string GetUnsafeConfigErrorInfoFilename(IConfigErrorInfo errorInfo) { 
            if (errorInfo != null) {
                return errorInfo.Filename;
            }
            else { 
                return null;
            } 
        } 

        [FileIOPermission(SecurityAction.Assert, AllFiles=FileIOPermissionAccess.PathDiscovery)] 
        private static string FullPathWithAssert(string filename) {
            string fullPath = null;

            try { 
                fullPath = Path.GetFullPath(filename);
            } 
            catch { 
            }
 
            return fullPath;
        }

        // 
        // Internal Helper to strip a full path to just filename.ext when caller
        // does not have path discovery to the path (used for sane error handling). 
        // 
        internal static string SafeFilename(string filename) {
            if (string.IsNullOrEmpty(filename)) { 
                return filename;
            }

            // configuration file can be an http URL in IE 
            if (StringUtil.StartsWithIgnoreCase(filename, HTTP_PREFIX)) {
                return filename; 
            } 

            // 
            // If it is a relative path, return it as is.
            // This could happen if the exception was constructed from the serialization constructor,
            // and the caller did not have PathDiscoveryPermission for the file.
            // 
            try {
                if (!Path.IsPathRooted(filename)) { 
                    return filename; 
                }
            } 
            catch {
                return null;
            }
 
            try {
                // Confirm that it is a full path. 
                // GetFullPath will also Demand PathDiscovery for the resulting path 
                string fullPath = Path.GetFullPath(filename);
            } 
            catch (SecurityException) {
                // Get just the name of the file without the directory part.
                try {
                    string fullPath = FullPathWithAssert(filename); 
                    filename = Path.GetFileName(fullPath);
                } 
                catch { 
                    filename = null;
                } 
            }
            catch {
                filename = null;
            } 

            return filename; 
        } 

        // 
        // Internal Helper to always strip a full path to just filename.ext.
        //
        internal static string AlwaysSafeFilename(string filename) {
            if (string.IsNullOrEmpty(filename)) { 
                return filename;
            } 
 
            // configuration file can be an http URL in IE
            if (StringUtil.StartsWithIgnoreCase(filename, HTTP_PREFIX)) { 
                return filename;
            }

            // 
            // If it is a relative path, return it as is.
            // This could happen if the exception was constructed from the serialization constructor, 
            // and the caller did not have PathDiscoveryPermission for the file. 
            //
            try { 
                if (!Path.IsPathRooted(filename)) {
                    return filename;
                }
            } 
            catch {
                return null; 
            } 

            // Get just the name of the file without the directory part. 
            try {
                string fullPath = FullPathWithAssert(filename);
                filename = Path.GetFileName(fullPath);
            } 
            catch {
                filename = null; 
            } 

            return filename; 
        }

    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

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