Add RootStorage.OpenWrite and tests

Author: jeremy-visionaid

OpenMcdf.Ole.Tests/OlePropertiesExtensionsTests.cs

@@ -101,7 +101,7 @@ public void ModifyDocumentSummaryInformation()
     public void ReadSummaryInformationUtf8()
     {
         // Regression test for #33
-        using var cf = RootStorage.Open("wstr_presets.doc", FileMode.Open);
+        using var cf = RootStorage.OpenRead("wstr_presets.doc");
         using CfbStream stream = cf.OpenStream(PropertySetNames.SummaryInformation);
         OlePropertiesContainer co = new(stream);
 

OpenMcdf.Tests/RootStorageTests.cs

@@ -3,6 +3,18 @@
 [TestClass]
 public sealed class RootStorageTests
 {
+    [TestMethod]
+    [DoNotParallelize] // Test sharing
+    [DataRow("MultipleStorage.cfs")]
+    public void Open(string fileName)
+    {
+        using var rootStorage = RootStorage.OpenRead(fileName);
+        using var rootStorage2 = RootStorage.OpenRead(fileName);
+
+        Assert.ThrowsException<IOException>(() => RootStorage.Open(fileName, FileMode.Open));
+        Assert.ThrowsException<IOException>(() => RootStorage.OpenWrite(fileName));
+    }
+
     [TestMethod]
     [DataRow(Version.V3, 0)]
     [DataRow(Version.V3, 1)]

OpenMcdf/RootStorage.cs

@@ -70,6 +70,17 @@ public static RootStorage Open(string fileName, FileMode mode, StorageModeFlags
         return Open(stream, flags);
     }
 
+    public static RootStorage Open(Stream stream, StorageModeFlags flags = StorageModeFlags.None)
+    {
+        stream.ThrowIfNotSeekable();
+        stream.Position = 0;
+
+        IOContextFlags contextFlags = ToIOContextFlags(flags);
+        RootContextSite rootContextSite = new();
+        _ = new RootContext(rootContextSite, stream, Version.Unknown, contextFlags);
+        return new RootStorage(rootContextSite, flags);
+    }
+
     public static RootStorage OpenRead(string fileName, StorageModeFlags flags = StorageModeFlags.None)
     {
         ThrowIfLeaveOpen(flags);
@@ -78,15 +89,12 @@ public static RootStorage OpenRead(string fileName, StorageModeFlags flags = Sto
         return Open(stream, flags);
     }
 
-    public static RootStorage Open(Stream stream, StorageModeFlags flags = StorageModeFlags.None)
+    public static RootStorage OpenWrite(string fileName, StorageModeFlags flags = StorageModeFlags.None)
     {
-        stream.ThrowIfNotSeekable();
-        stream.Position = 0;
+        ThrowIfLeaveOpen(flags);
 
-        IOContextFlags contextFlags = ToIOContextFlags(flags);
-        RootContextSite rootContextSite = new();
-        _ = new RootContext(rootContextSite, stream, Version.Unknown, contextFlags);
-        return new RootStorage(rootContextSite, flags);
+        FileStream stream = File.OpenWrite(fileName);
+        return Open(stream, flags);
     }
 
     RootStorage(RootContextSite rootContextSite, StorageModeFlags storageModeFlags)

StructuredStorageExplorer/MainForm.cs

@@ -142,7 +142,7 @@ private void LoadFile(string fileName)
             cf = null;
 
             // Load file
-            cf = RootStorage.Open(fileName, FileMode.Open);
+            cf = RootStorage.OpenWrite(fileName);
 
             fileNameLabel.Text = fileName;
             saveAsToolStripMenuItem.Enabled = true;