Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/misc/ConfigPathUtility.cs

@@ -0,0 +1,137 @@
+//------------------------------------------------------------------------------
+// <copyright file="ConfigPathUtility.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Configuration {
+
+#if CONFIGPATHUTILITY_SYSTEMWEB
+    using Debug=System.Web.Util.Debug;
+#endif
+
+    internal static class ConfigPathUtility {
+        private const char SeparatorChar = '/';
+
+        //
+        // A configPath is valid if
+        //  * It does not start or end with a '/'
+        //  * It is not null or empty, except in the case of the root configuration record
+        //  * It does not contain '\'
+        //  * It does not contain a path component equal to "." or ".."
+        //
+        // The checks for '\', ".", and ".." are not strictly necessary, but their presence
+        // could lead to problems for configuration hosts.
+        // 
+        static internal bool IsValid(string configPath) {
+            if (String.IsNullOrEmpty(configPath)) {
+                return false;
+            }
+
+            int start = -1;
+            for (int examine = 0; examine <= configPath.Length; examine++) {
+                char ch;
+
+                if (examine < configPath.Length) {
+                    ch = configPath[examine];
+                }
+                else {
+                    ch = SeparatorChar;
+                }
+
+                // backslash disallowed
+                if (ch == '\\') {
+                    return false;
+                }
+
+                if (ch == SeparatorChar) {
+                    // double slash disallowed
+                    // note this check also purposefully catches starting and ending slash
+                    if (examine == start + 1) {
+                        return false;
+                    }
+
+                    // "." disallowed
+                    if (examine == start + 2 && configPath[start + 1] == '.') {
+                        return false;
+                    }
+
+                    // ".." disallowed
+                    if (examine == start + 3 && configPath[start + 1] == '.' && configPath[start + 2] == '.') {
+                        return false;
+                    }
+
+                    start = examine;
+                }
+            }
+
+            return true;
+        }
+
+#if !CONFIGPATHUTILITY_SYSTEMWEB
+        static internal string Combine(string parentConfigPath, string childConfigPath) {
+            Debug.Assert(String.IsNullOrEmpty(parentConfigPath) || IsValid(parentConfigPath), "String.IsNullOrEmpty(parentConfigPath) || IsValid(parentConfigPath)");
+            Debug.Assert(String.IsNullOrEmpty(childConfigPath) || IsValid(childConfigPath), "String.IsNullOrEmpty(childConfigPath) || IsValid(childConfigPath)");
+
+            if (String.IsNullOrEmpty(parentConfigPath)) {
+                return childConfigPath;
+            }
+
+            if (String.IsNullOrEmpty(childConfigPath)) {
+                return parentConfigPath;
+            }
+
+            return parentConfigPath + "/" + childConfigPath;
+        }
+
+        static internal string[] GetParts(string configPath) {
+            Debug.Assert(IsValid(configPath), "IsValid(configPath)");
+
+            string[] parts = configPath.Split(SeparatorChar);
+            return parts;
+        }
+
+        //
+        // Return the last part of a config path, e.g.
+        //   GetName("MACHINE/WEBROOT/Default Web Site/app") == "app"
+        //
+        static internal string GetName(string configPath) {
+            Debug.Assert(String.IsNullOrEmpty(configPath) || IsValid(configPath), "String.IsNullOrEmpty(configPath) || IsValid(configPath)");
+
+            if (String.IsNullOrEmpty(configPath)) {
+                return configPath;
+            }
+
+            int index = configPath.LastIndexOf('/');
+            if (index == -1) {
+                return configPath;
+            }
+
+            Debug.Assert(index != configPath.Length - 1);
+            return configPath.Substring(index + 1);
+        }
+#endif
+
+// Avoid unused code warning in System.Configuration by including functions in assembly-specific #defines
+#if CONFIGPATHUTILITY_SYSTEMWEB
+        static internal string GetParent(string configPath) {
+            Debug.Assert(String.IsNullOrEmpty(configPath) || IsValid(configPath), "String.IsNullOrEmpty(configPath) || IsValid(configPath)");
+
+            if (String.IsNullOrEmpty(configPath)) {
+                return null;
+            }
+
+            string parentConfigPath;
+            int lastSlash = configPath.LastIndexOf(SeparatorChar);
+            if (lastSlash == -1) {
+                parentConfigPath = null;
+            }
+            else {
+                parentConfigPath = configPath.Substring(0, lastSlash);
+            }
+
+            return parentConfigPath;
+        }
+#endif
+    }
+}