Added backups of all data, restorable on another computer (#1008)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Tools/ZipEntryNames.cs

@@ -0,0 +1,92 @@
+namespace AIStudio.Tools;
+
+/// <summary>
+/// Checks the names of entries in ZIP files before anything is written to the disk.
+/// </summary>
+/// <remarks>
+/// A ZIP file comes from somewhere else: a plugin archive, the configuration of an organization, or a
+/// backup. An entry name such as "../settings.json" or an absolute path would make extracting it
+/// write outside of the target directory (zip slip). Every name is therefore checked here before it
+/// becomes a path.<br/><br/>
+///
+/// Backslashes count as separators as well. Compatibility shim for ZIP files created on Windows
+/// with backslashes in their entry names (dotnet/runtime#27620); remove after dotnet/runtime#27620
+/// and #41914 are fixed. See documentation/compatibility-shims/2026-07-plugin-archive-zip-backslashes.md.
+/// </remarks>
+public static class ZipEntryNames
+{
+    /// <summary>
+    /// The separator of entry names, which the ZIP format prescribes.
+    /// </summary>
+    public const char SEPARATOR = '/';
+
+    /// <summary>
+    /// Normalizes the name of an entry, and rejects a name which could lead outside of the target
+    /// directory with an InvalidDataException: an empty, rooted, or drive-qualified name, or one which
+    /// contains "." or "..".
+    /// </summary>
+    /// <param name="entryName">The name as the ZIP file holds it.</param>
+    /// <returns>The name with forward slashes.</returns>
+    public static string Normalize(string entryName)
+    {
+        var normalizedEntryName = entryName.Replace('\\', SEPARATOR);
+        if (string.IsNullOrWhiteSpace(normalizedEntryName))
+            throw new InvalidDataException("The archive contains an empty entry name.");
+
+        if (normalizedEntryName.Contains('\0'))
+            throw new InvalidDataException($"The archive contains an invalid entry name: '{entryName}'.");
+
+        if (normalizedEntryName.StartsWith(SEPARATOR))
+            throw new InvalidDataException($"The archive contains a rooted entry name: '{entryName}'.");
+
+        if (normalizedEntryName is [_, ':', ..])
+            throw new InvalidDataException($"The archive contains a drive-qualified entry name: '{entryName}'.");
+
+        var pathSegments = normalizedEntryName.Split(SEPARATOR, StringSplitOptions.RemoveEmptyEntries);
+        if (pathSegments.Length == 0 || pathSegments.Any(segment => segment is "." or ".."))
+            throw new InvalidDataException($"The archive contains an unsafe entry name: '{entryName}'.");
+
+        return normalizedEntryName;
+    }
+
+    /// <summary>
+    /// Normalizes the name of an entry, cf. Normalize, without throwing.
+    /// </summary>
+    /// <param name="entryName">The name as the ZIP file holds it.</param>
+    /// <param name="normalizedEntryName">The name with forward slashes, or an empty string when it is unsafe.</param>
+    /// <returns>True when the name is safe.</returns>
+    public static bool TryNormalize(string entryName, out string normalizedEntryName)
+    {
+        try
+        {
+            normalizedEntryName = Normalize(entryName);
+            return true;
+        }
+        catch (InvalidDataException)
+        {
+            normalizedEntryName = string.Empty;
+            return false;
+        }
+    }
+
+    /// <summary>
+    /// The path at which an entry is written below the target directory. A path which would lie
+    /// outside of it is rejected with an InvalidDataException.
+    /// </summary>
+    /// <param name="destinationDirectory">The target directory.</param>
+    /// <param name="normalizedEntryName">The entry name, as Normalize returned it.</param>
+    /// <returns>The full path of the entry.</returns>
+    public static string GetDestinationPath(string destinationDirectory, string normalizedEntryName)
+    {
+        var fullDestinationDirectory = Path.GetFullPath(destinationDirectory);
+        if (!fullDestinationDirectory.EndsWith(Path.DirectorySeparatorChar))
+            fullDestinationDirectory += Path.DirectorySeparatorChar;
+
+        var pathSegments = normalizedEntryName.Split(SEPARATOR, StringSplitOptions.RemoveEmptyEntries);
+        var destinationPath = Path.GetFullPath(Path.Combine(fullDestinationDirectory, Path.Combine(pathSegments)));
+        if (!destinationPath.StartsWith(fullDestinationDirectory, StringComparison.Ordinal))
+            throw new InvalidDataException($"The archive contains an entry outside the destination directory: '{normalizedEntryName}'.");
+
+        return destinationPath;
+    }
+}