Fix repair of corrupt BlobSizes.sql and mount tolerance

GVFS/GVFS.Common/Database/SqliteDatabase.cs

@@ -21,7 +21,7 @@ public static bool HasIssue(string databasePath, PhysicalFileSystem filesystem,
 
                 try
                 {
-                    string sqliteConnectionString = CreateConnectionString(databasePath);
+                    string sqliteConnectionString = $"data source={databasePath};Pooling=False";
                     using (SqliteConnection integrityConnection = new SqliteConnection(sqliteConnectionString))
                     {
                         integrityConnection.Open();

GVFS/GVFS.Common/Database/SqliteErrorCodes.cs

@@ -0,0 +1,15 @@
+namespace GVFS.Common.Database
+{
+    /// <summary>
+    /// SQLite result codes used for error classification.
+    /// See https://www.sqlite.org/rescode.html
+    /// </summary>
+    public static class SqliteErrorCodes
+    {
+        /// <summary>SQLITE_CORRUPT (11) — database disk image is malformed</summary>
+        public const int Corrupt = 11;
+
+        /// <summary>SQLITE_NOTADB (26) — file is not a database</summary>
+        public const int NotADatabase = 26;
+    }
+}

GVFS/GVFS.FunctionalTests/Tests/MultiEnlistmentTests/SharedCacheTests.cs

@@ -60,7 +60,6 @@ public void SecondCloneDoesNotDownloadAdditionalObjects()
         }
 
         [TestCase]
-        [SkipInCI("Product bug: repair does not fully restore corrupt BlobSizes.sql — mount crashes after repair")]
         public void RepairFixesCorruptBlobSizesDatabase()
         {
             GVFSFunctionalTestEnlistment enlistment = this.CloneAndMountEnlistment();
@@ -74,9 +73,12 @@ public void RepairFixesCorruptBlobSizesDatabase()
             blobSizesDbPath.ShouldBeAFile(this.fileSystem);
             this.fileSystem.WriteAllText(blobSizesDbPath, "0000");
 
-            // GVFS now tolerates corrupt blob sizes DB on mount (recreates
-            // in-memory), but repair should still fix the underlying file.
+            // Repair should detect and fix the corrupt database
             enlistment.Repair(confirm: true);
+
+            // Verify repair actually cleaned up the corrupt file
+            blobSizesRoot.ShouldNotExistOnDisk(this.fileSystem);
+
             enlistment.MountGVFS();
         }
 

GVFS/GVFS.Virtualization/BlobSize/BlobSizes.cs

@@ -54,6 +54,54 @@ public virtual void Initialize()
             string folderPath = Path.GetDirectoryName(this.databasePath);
             this.fileSystem.CreateDirectory(folderPath);
 
+            try
+            {
+                this.InitializeDatabase();
+            }
+            catch (SqliteException ex) when (ex.SqliteErrorCode == SqliteErrorCodes.Corrupt || ex.SqliteErrorCode == SqliteErrorCodes.NotADatabase)
+            {
+                EventMetadata metadata = this.CreateEventMetadata(ex);
+                metadata.Add("SqliteErrorCode", ex.SqliteErrorCode);
+                this.tracer.RelatedWarning(metadata, $"{nameof(BlobSizes)}.{nameof(this.Initialize)}: database corrupt, deleting and recreating");
+
+                SqliteConnection.ClearAllPools();
+                this.DeleteDatabaseFiles();
+                this.InitializeDatabase();
+            }
+
+            this.flushDataThread = new Thread(this.FlushDbThreadMain);
+            this.flushDataThread.IsBackground = true;
+            this.flushDataThread.Start();
+        }
+
+        public virtual void Shutdown()
+        {
+            this.isStopping = true;
+            this.wakeUpFlushThread.Set();
+            this.flushDataThread.Join();
+        }
+
+        public virtual void AddSize(Sha1Id sha, long size)
+        {
+            this.queuedSizes.Enqueue(new BlobSize(sha, size));
+        }
+
+        public virtual void Flush()
+        {
+            this.wakeUpFlushThread.Set();
+        }
+
+        public void Dispose()
+        {
+            if (this.wakeUpFlushThread != null)
+            {
+                this.wakeUpFlushThread.Dispose();
+                this.wakeUpFlushThread = null;
+            }
+        }
+
+        private void InitializeDatabase()
+        {
             using (SqliteConnection connection = new SqliteConnection(this.sqliteConnectionString))
             {
                 connection.Open();
@@ -125,36 +173,13 @@ public virtual void Initialize()
                     createTableCommand.ExecuteNonQuery();
                 }
             }
-
-            this.flushDataThread = new Thread(this.FlushDbThreadMain);
-            this.flushDataThread.IsBackground = true;
-            this.flushDataThread.Start();
         }
 
-        public virtual void Shutdown()
+        private void DeleteDatabaseFiles()
         {
-            this.isStopping = true;
-            this.wakeUpFlushThread.Set();
-            this.flushDataThread.Join();
-        }
-
-        public virtual void AddSize(Sha1Id sha, long size)
-        {
-            this.queuedSizes.Enqueue(new BlobSize(sha, size));
-        }
-
-        public virtual void Flush()
-        {
-            this.wakeUpFlushThread.Set();
-        }
-
-        public void Dispose()
-        {
-            if (this.wakeUpFlushThread != null)
-            {
-                this.wakeUpFlushThread.Dispose();
-                this.wakeUpFlushThread = null;
-            }
+            this.fileSystem.TryDeleteFile(this.databasePath);
+            this.fileSystem.TryDeleteFile(this.databasePath + "-wal");
+            this.fileSystem.TryDeleteFile(this.databasePath + "-shm");
         }
 
         private void FlushDbThreadMain()