Fixed json bom handling when serializing/deserializing json

Dokumentation.md

@@ -82,6 +82,8 @@ Das BizTalk Platform Management Tool unterstützt kontrollierte Wartungsfenster
 
 Bei echten Shutdown- und Restore-Aktionen wird jeder Schritt vor der Ausführung mit Artefakttyp, WMI-Klasse, Schlüsselproperty, Schlüsselwert und Methodenname protokolliert. Die Objektauflösung verwendet eine breite `SELECT * FROM <class>`-Abfrage und filtert danach im Prozess auf den Schlüsselwert. Dadurch können Host-Instance-Namen und andere BizTalk-Namen mit Sonderzeichen keine ungültige WMI-WQL-`WHERE`-Query mehr erzeugen.
 
+Snapshot- und Plan-JSON-Dateien werden als UTF-8 ohne BOM geschrieben. Beim Laden werden vorhandene Dateien mit UTF-8-BOM oder durch Encoding-Konvertierung sichtbar gewordenem BOM-Marker toleriert.
+
 ## Status Mapping
 
 - `MSBTS_SendPort.Status`: `1=Bound`, `2=Stopped`, `3=Started`

README.md

@@ -65,6 +65,8 @@ Log files are retained for the current day plus the previous four days. Older `B
 
 The Operation Log shows the WMI class, key property, key value and method for real shutdown and restore steps. WMI objects are resolved with a broad `SELECT * FROM <class>` query and a client-side key filter so names containing special characters do not break the WMI query parser.
 
+Snapshot and plan JSON files are written as UTF-8 without BOM. Loading is tolerant of existing files that contain a UTF-8 BOM or a visible BOM marker from previous encoding conversions.
+
 ## Build
 
 Open `BizTalkPlatformManagementTool.sln` in Visual Studio on Windows with the .NET Framework 4.6.1 Developer Pack installed, then build the `Release|Any CPU` configuration.

src/BizTalkPlatformManagementTool/Services/JsonFileStore.cs

@@ -1,4 +1,5 @@
 using System.IO;
+using System.Runtime.Serialization;
 using System.Runtime.Serialization.Json;
 using System.Text;
 
@@ -6,6 +7,8 @@ namespace BizTalkPlatformManagementTool.Services
 {
     public static class JsonFileStore
     {
+        private static readonly Encoding Utf8NoBom = new UTF8Encoding(false);
+
         public static void Save<T>(string path, T value)
         {
             Directory.CreateDirectory(Path.GetDirectoryName(Path.GetFullPath(path)));
@@ -17,8 +20,8 @@ namespace BizTalkPlatformManagementTool.Services
             using (var stream = new MemoryStream())
             {
                 serializer.WriteObject(stream, value);
-                var json = Encoding.UTF8.GetString(stream.ToArray());
-                File.WriteAllText(path, json, Encoding.UTF8);
+                var json = Utf8NoBom.GetString(stream.ToArray());
+                File.WriteAllText(path, json, Utf8NoBom);
             }
         }
 
@@ -29,10 +32,55 @@ namespace BizTalkPlatformManagementTool.Services
                 UseSimpleDictionaryFormat = true
             });
 
-            using (var stream = File.OpenRead(path))
+            var json = NormalizeJson(File.ReadAllText(path, Encoding.UTF8));
+            using (var stream = new MemoryStream(Utf8NoBom.GetBytes(json)))
             {
-                return (T)serializer.ReadObject(stream);
+                try
+                {
+                    return (T)serializer.ReadObject(stream);
+                }
+                catch (SerializationException ex)
+                {
+                    throw new InvalidDataException("Failed to load JSON file '" + path + "'. " + DescribeJsonStart(json), ex);
+                }
             }
         }
+
+        private static string NormalizeJson(string json)
+        {
+            if (string.IsNullOrEmpty(json))
+            {
+                return json;
+            }
+
+            if (json[0] == '\uFEFF')
+            {
+                json = json.Substring(1);
+            }
+
+            if (json.StartsWith("\u00EF\u00BB\u00BF"))
+            {
+                json = json.Substring(3);
+            }
+
+            return json;
+        }
+
+        private static string DescribeJsonStart(string json)
+        {
+            if (string.IsNullOrWhiteSpace(json))
+            {
+                return "The file is empty or contains only whitespace.";
+            }
+
+            var trimmed = json.TrimStart();
+            var first = trimmed.Length == 0 ? '\0' : trimmed[0];
+            if (first != '{' && first != '[')
+            {
+                return "The first JSON character is '" + first + "' instead of '{' or '['.";
+            }
+
+            return "The file starts with valid JSON syntax but could not be deserialized into the expected model.";
+        }
     }
 }