Fix building slnf with @ in the path (#11421)

* fix building slnf with @ in the path

* use Path.GetFullPath(Path.Combine( )) instead of Path.GetFullPat(str1, str2) because it is not available for .net framework

* add more symbols to the test @, %, $

* normalize solution path in the slnf before combinening with directory path

* add escape param to FileUtilities.GetFulllPath

* be more specific in doc comment for FileUtilities.GetFullPath

* Clarify GetFullPath escape behavior

* Add comment to preserve special symbols in path

Author: surayya-MS

src/Build.UnitTests/Construction/SolutionFilter_Tests.cs

@@ -284,6 +284,56 @@ public void ParseSolutionFilter(bool convertToSlnx)
             }
         }
 
+        [Fact]
+        public void SolutionFilterWithSpecialSymbolInThePath()
+        {
+            using TestEnvironment testEnvironment = TestEnvironment.Create();
+            TransientTestFolder folder = testEnvironment.CreateFolder(createFolder: true);
+            // Create folder with special symbols in the name
+            folder = testEnvironment.CreateFolder(Path.Combine(folder.Path, $"test@folder%special$symbols"), createFolder: true);
+            // Create simple solution and simple solution filter
+            TransientTestFile sln = testEnvironment.CreateFile(folder, "SimpleSolution.sln",
+            """
+            Microsoft Visual Studio Solution File, Format Version 12.00
+            # Visual Studio Version 17
+            VisualStudioVersion = 17.0.31903.59
+            MinimumVisualStudioVersion = 10.0.40219.1
+            Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SolutionTest", "SolutionTest.csproj", "{767AA460-C33F-41C3-A8B6-4DA283263A51}"
+            EndProject
+            Global
+                GlobalSection(SolutionConfigurationPlatforms) = preSolution
+                    Debug|Any CPU = Debug|Any CPU
+                    Release|Any CPU = Release|Any CPU
+                EndGlobalSection
+                GlobalSection(SolutionProperties) = preSolution
+                    HideSolutionNode = FALSE
+                EndGlobalSection
+                GlobalSection(ProjectConfigurationPlatforms) = postSolution
+                    {767AA460-C33F-41C3-A8B6-4DA283263A51}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+                    {767AA460-C33F-41C3-A8B6-4DA283263A51}.Debug|Any CPU.Build.0 = Debug|Any CPU
+                    {767AA460-C33F-41C3-A8B6-4DA283263A51}.Release|Any CPU.ActiveCfg = Release|Any CPU
+                    {767AA460-C33F-41C3-A8B6-4DA283263A51}.Release|Any CPU.Build.0 = Release|Any CPU
+                EndGlobalSection
+            EndGlobal
+            """);
+            TransientTestFile slnf = testEnvironment.CreateFile(folder, "SimpleSolution.slnf",
+            """
+            {
+                "solution": {
+                    "path": "SimpleSolution.sln",
+                    "projects": [
+                        "SolutionTest.csproj"
+                    ]
+                }
+            }
+            """);
+
+            SolutionFile sp = SolutionFile.Parse(slnf.Path);
+
+            // just assert that no error is thrown
+            Assert.True(sp.ProjectShouldBuild("SolutionTest.csproj"));
+        }
+
         private static string ConvertToSlnx(string slnPath)
         {
             string slnxPath = slnPath + "x";

src/Build/Construction/Solution/SolutionFile.cs

@@ -658,7 +658,8 @@ internal static string ParseSolutionFromSolutionFilter(string solutionFilterFile
                 JsonDocumentOptions options = new JsonDocumentOptions() { AllowTrailingCommas = true, CommentHandling = JsonCommentHandling.Skip };
                 JsonDocument text = JsonDocument.Parse(File.ReadAllText(solutionFilterFile), options);
                 solution = text.RootElement.GetProperty("solution");
-                return FileUtilities.GetFullPath(solution.GetProperty("path").GetString(), Path.GetDirectoryName(solutionFilterFile));
+                // We do NOT want to escape in order to preserve symbols like @, %, $ etc.
+                return FileUtilities.GetFullPath(solution.GetProperty("path").GetString(), Path.GetDirectoryName(solutionFilterFile), escape: false);
             }
             catch (Exception e) when (e is JsonException || e is KeyNotFoundException || e is InvalidOperationException)
             {

src/Shared/FileUtilities.cs

@@ -752,14 +752,20 @@ internal static bool HasExtension(string fileName, string[] allowedExtensions)
         /// </summary>
         /// <param name="fileSpec">The file spec to get the full path of.</param>
         /// <param name="currentDirectory"></param>
-        /// <returns>full path</returns>
-        internal static string GetFullPath(string fileSpec, string currentDirectory)
+        /// <param name="escape">Whether to escape the path after getting the full path.</param>
+        /// <returns>Full path to the file, escaped if not specified otherwise.</returns>
+        internal static string GetFullPath(string fileSpec, string currentDirectory, bool escape = true)
         {
             // Sending data out of the engine into the filesystem, so time to unescape.
             fileSpec = FixFilePath(EscapingUtilities.UnescapeAll(fileSpec));
 
-            // Data coming back from the filesystem into the engine, so time to escape it back.
-            string fullPath = EscapingUtilities.Escape(NormalizePath(Path.Combine(currentDirectory, fileSpec)));
+            string fullPath = NormalizePath(Path.Combine(currentDirectory, fileSpec));
+            // In some cases we might want to NOT escape in order to preserve symbols like @, %, $ etc.
+            if (escape)
+            {
+                // Data coming back from the filesystem into the engine, so time to escape it back.
+                fullPath = EscapingUtilities.Escape(fullPath);
+            }
 
             if (NativeMethodsShared.IsWindows && !EndsWithSlash(fullPath))
             {