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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Text;
using System.Xml;
namespace Microsoft.Extensions.Configuration.Xml
{
/// <summary>
/// An XML file based <see cref="IConfigurationProvider"/>.
/// </summary>
[RequiresDynamicCode(XmlDocumentDecryptor.RequiresDynamicCodeMessage)]
[RequiresUnreferencedCode(XmlDocumentDecryptor.RequiresUnreferencedCodeMessage)]
public class XmlStreamConfigurationProvider : StreamConfigurationProvider
{
// work around https://github.com/dotnet/runtime/issues/81864 by splitting this into a separate class.
internal static class Consts
{
internal const string NameAttributeKey = "Name";
}
/// <summary>
/// Constructor.
/// </summary>
/// <param name="source">The <see cref="XmlStreamConfigurationSource"/>.</param>
public XmlStreamConfigurationProvider(XmlStreamConfigurationSource source) : base(source) { }
/// <summary>
/// Read a stream of XML values into a key/value dictionary.
/// </summary>
/// <param name="stream">The stream of XML data.</param>
/// <param name="decryptor">The <see cref="XmlDocumentDecryptor"/> to use to decrypt.</param>
/// <returns>The <see cref="IDictionary{String, String}"/> which was read from the stream.</returns>
public static IDictionary<string, string?> Read(Stream stream, XmlDocumentDecryptor decryptor)
{
var readerSettings = new XmlReaderSettings()
{
CloseInput = false, // caller will close the stream
DtdProcessing = DtdProcessing.Prohibit,
IgnoreComments = true,
IgnoreWhitespace = true
};
XmlConfigurationElement? root = null;
using (XmlReader reader = decryptor.CreateDecryptingXmlReader(stream, readerSettings))
{
// keep track of the tree we followed to get where we are (breadcrumb style)
var currentPath = new Stack<XmlConfigurationElement>();
XmlNodeType preNodeType = reader.NodeType;
while (reader.Read())
{
switch (reader.NodeType)
{
case XmlNodeType.Element:
var element = new XmlConfigurationElement(reader.LocalName, GetName(reader));
if (currentPath.Count == 0)
{
root = element;
}
else
{
var parent = currentPath.Peek();
// If parent already has a dictionary of children, update the collection accordingly
if (parent.ChildrenBySiblingName != null)
{
// check if this element has appeared before, elements are considered siblings if their SiblingName properties match
if (!parent.ChildrenBySiblingName.TryGetValue(element.SiblingName, out var siblings))
{
siblings = new List<XmlConfigurationElement>();
parent.ChildrenBySiblingName.Add(element.SiblingName, siblings);
}
siblings.Add(element);
}
else
{
// Performance optimization: parents with a single child don't even initialize a dictionary
if (parent.SingleChild == null)
{
parent.SingleChild = element;
}
else
{
// If we encounter a second child after assigning "SingleChild", we clear SingleChild and initialize the dictionary
var children = new Dictionary<string, List<XmlConfigurationElement>>(StringComparer.OrdinalIgnoreCase);
// Special case: the first and second child have the same sibling name
if (string.Equals(parent.SingleChild.SiblingName, element.SiblingName, StringComparison.OrdinalIgnoreCase))
{
children.Add(element.SiblingName, new List<XmlConfigurationElement>
{
parent.SingleChild,
element
});
}
else
{
children.Add(parent.SingleChild.SiblingName, new List<XmlConfigurationElement> { parent.SingleChild });
children.Add(element.SiblingName, new List<XmlConfigurationElement> { element });
}
parent.ChildrenBySiblingName = children;
parent.SingleChild = null;
}
}
}
currentPath.Push(element);
ReadAttributes(reader, element);
// If current element is self-closing
if (reader.IsEmptyElement)
{
currentPath.Pop();
}
break;
case XmlNodeType.EndElement:
if (currentPath.Count != 0)
{
XmlConfigurationElement parent = currentPath.Pop();
// If this EndElement node comes right after an Element node,
// it means there is no text/CDATA node in current element
if (preNodeType == XmlNodeType.Element)
{
var lineInfo = reader as IXmlLineInfo;
var lineNumber = lineInfo?.LineNumber;
var linePosition = lineInfo?.LinePosition;
parent.TextContent = new XmlConfigurationElementTextContent(string.Empty, linePosition, lineNumber);
}
}
break;
case XmlNodeType.CDATA:
case XmlNodeType.Text:
if (currentPath.Count != 0)
{
var lineInfo = reader as IXmlLineInfo;
var lineNumber = lineInfo?.LineNumber;
var linePosition = lineInfo?.LinePosition;
XmlConfigurationElement parent = currentPath.Peek();
parent.TextContent = new XmlConfigurationElementTextContent(reader.Value, linePosition, lineNumber);
}
break;
case XmlNodeType.XmlDeclaration:
case XmlNodeType.ProcessingInstruction:
case XmlNodeType.Comment:
case XmlNodeType.Whitespace:
// Ignore certain types of nodes
break;
default:
throw new FormatException(SR.Format(SR.Error_UnsupportedNodeType, reader.NodeType, GetLineInfo(reader)));
}
preNodeType = reader.NodeType;
// If this element is a self-closing element,
// we pretend that we just processed an EndElement node
// because a self-closing element contains an end within itself
if (preNodeType == XmlNodeType.Element && reader.IsEmptyElement)
{
preNodeType = XmlNodeType.EndElement;
}
}
}
return ProvideConfiguration(root);
}
/// <summary>
/// Loads XML configuration key/values from a stream into a provider.
/// </summary>
/// <param name="stream">The <see cref="Stream"/> to load ini configuration data from.</param>
public override void Load(Stream stream)
{
Data = Read(stream, XmlDocumentDecryptor.Instance);
}
private static string GetLineInfo(XmlReader reader)
{
var lineInfo = reader as IXmlLineInfo;
return lineInfo == null ? string.Empty :
SR.Format(SR.Msg_LineInfo, lineInfo.LineNumber, lineInfo.LinePosition);
}
private static void ReadAttributes(XmlReader reader, XmlConfigurationElement element)
{
if (reader.AttributeCount > 0)
{
element.Attributes = new List<XmlConfigurationElementAttributeValue>();
}
var lineInfo = reader as IXmlLineInfo;
for (int i = 0; i < reader.AttributeCount; i++)
{
reader.MoveToAttribute(i);
var lineNumber = lineInfo?.LineNumber;
var linePosition = lineInfo?.LinePosition;
// If there is a namespace attached to current attribute
if (!string.IsNullOrEmpty(reader.NamespaceURI))
{
throw new FormatException(SR.Format(SR.Error_NamespaceIsNotSupported, GetLineInfo(reader)));
}
element.Attributes!.Add(new XmlConfigurationElementAttributeValue(reader.LocalName, reader.Value, lineNumber, linePosition));
}
// Go back to the element containing the attributes we just processed
reader.MoveToElement();
}
// The special attribute "Name" only contributes to prefix
// This method retrieves the Name of the element, if the attribute is present
// Unfortunately XmlReader.GetAttribute cannot be used, as it does not support looking for attributes in a case insensitive manner
private static string? GetName(XmlReader reader)
{
string? name = null;
while (reader.MoveToNextAttribute())
{
if (string.Equals(reader.LocalName, Consts.NameAttributeKey, StringComparison.OrdinalIgnoreCase))
{
// If there is a namespace attached to current attribute
if (!string.IsNullOrEmpty(reader.NamespaceURI))
{
throw new FormatException(SR.Format(SR.Error_NamespaceIsNotSupported, GetLineInfo(reader)));
}
name = reader.Value;
break;
}
}
// Go back to the element containing the name we just processed
reader.MoveToElement();
return name;
}
private static Dictionary<string, string?> ProvideConfiguration(XmlConfigurationElement? root)
{
Dictionary<string, string?> configuration = new(StringComparer.OrdinalIgnoreCase);
if (root == null)
{
return configuration;
}
var rootPrefix = new Prefix();
// The root element only contributes to the prefix via its Name attribute
if (!string.IsNullOrEmpty(root.Name))
{
rootPrefix.Push(root.Name);
}
ProcessElementAttributes(rootPrefix, root);
ProcessElementContent(rootPrefix, root);
ProcessElementChildren(rootPrefix, root);
return configuration;
void ProcessElement(Prefix prefix, XmlConfigurationElement element)
{
ProcessElementAttributes(prefix, element);
ProcessElementContent(prefix, element);
ProcessElementChildren(prefix, element);
}
void ProcessElementAttributes(Prefix prefix, XmlConfigurationElement element)
{
// Add attributes to configuration values
if (element.Attributes != null)
{
for (var i = 0; i < element.Attributes.Count; i++)
{
var attribute = element.Attributes[i];
prefix.Push(attribute.Attribute);
AddToConfiguration(prefix.AsString, attribute.Value, attribute.LineNumber, attribute.LinePosition);
prefix.Pop();
}
}
}
void ProcessElementContent(Prefix prefix, XmlConfigurationElement element)
{
// Add text content to configuration values
if (element.TextContent != null)
{
var textContent = element.TextContent;
AddToConfiguration(prefix.AsString, textContent.TextContent, textContent.LineNumber, textContent.LinePosition);
}
}
void ProcessElementChildren(Prefix prefix, XmlConfigurationElement element)
{
if (element.SingleChild != null)
{
var child = element.SingleChild;
ProcessElementChild(prefix, child, null);
return;
}
if (element.ChildrenBySiblingName == null)
{
return;
}
// Recursively walk through the children of this element
foreach (var childrenWithSameSiblingName in element.ChildrenBySiblingName.Values)
{
if (childrenWithSameSiblingName.Count == 1)
{
var child = childrenWithSameSiblingName[0];
ProcessElementChild(prefix, child, null);
}
else
{
// Multiple children with the same sibling name. Add the current index to the prefix
for (int i = 0; i < childrenWithSameSiblingName.Count; i++)
{
var child = childrenWithSameSiblingName[i];
ProcessElementChild(prefix, child, i);
}
}
}
}
void ProcessElementChild(Prefix prefix, XmlConfigurationElement child, int? index)
{
// Add element name to prefix
prefix.Push(child.ElementName);
// Add value of name attribute to prefix
var hasName = !string.IsNullOrEmpty(child.Name);
if (hasName)
{
prefix.Push(child.Name!);
}
// Add index to the prefix
if (index != null)
{
prefix.Push(index.Value.ToString(CultureInfo.InvariantCulture));
}
ProcessElement(prefix, child);
// Remove index
if (index != null)
{
prefix.Pop();
}
// Remove 'Name' attribute
if (hasName)
{
prefix.Pop();
}
// Remove element name
prefix.Pop();
}
void AddToConfiguration(string key, string value, int? lineNumber, int? linePosition)
{
#if NETSTANDARD2_1
if (!configuration.TryAdd(key, value))
{
var lineInfo = lineNumber == null || linePosition == null
? string.Empty
: SR.Format(SR.Msg_LineInfo, lineNumber.Value, linePosition.Value);
throw new FormatException(SR.Format(SR.Error_KeyIsDuplicated, key, lineInfo));
}
#else
if (configuration.ContainsKey(key))
{
var lineInfo = lineNumber == null || linePosition == null
? string.Empty
: SR.Format(SR.Msg_LineInfo, lineNumber.Value, linePosition.Value);
throw new FormatException(SR.Format(SR.Error_KeyIsDuplicated, key, lineInfo));
}
configuration.Add(key, value);
#endif
}
}
}
/// <summary>
/// Helper class to build the configuration keys in a way that does not require string.Join
/// </summary>
internal sealed class Prefix
{
private readonly StringBuilder _sb;
private readonly Stack<int> _lengths;
public Prefix()
{
_sb = new StringBuilder();
_lengths = new Stack<int>();
}
public string AsString => _sb.ToString();
public void Push(string value)
{
if (_sb.Length != 0)
{
_sb.Append(ConfigurationPath.KeyDelimiter);
_sb.Append(value);
_lengths.Push(value.Length + ConfigurationPath.KeyDelimiter.Length);
}
else
{
_sb.Append(value);
_lengths.Push(value.Length);
}
}
public void Pop()
{
var length = _lengths.Pop();
_sb.Remove(_sb.Length - length, length);
}
}
}
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