From 03aad742d3f4d46e5e6245e9ff765b7e53e1b2f9 Mon Sep 17 00:00:00 2001
From: Michael Eischer <michael.eischer@fau.de>
Date: Thu, 31 Oct 2024 21:44:34 +0100
Subject: [PATCH] fs: add correct vss support to fixpath

Paths that only contain the volume shadow copy snapshot name require
special treatment. These paths must end with a slash for regular file
operations to work.
---
 internal/fs/file_windows.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/internal/fs/file_windows.go b/internal/fs/file_windows.go
index 7fb53e658..d7aabf360 100644
--- a/internal/fs/file_windows.go
+++ b/internal/fs/file_windows.go
@@ -21,6 +21,15 @@ func fixpath(name string) string {
 		if strings.HasPrefix(abspath, uncPathPrefix) {
 			return abspath
 		}
+		// Check if \\?\GLOBALROOT exists which marks volume shadow copy snapshots
+		if strings.HasPrefix(abspath, globalRootPrefix) {
+			if strings.Count(abspath, `\`) == 5 {
+				// Append slash if this just a volume name, e.g. `\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopyXX`
+				// Without the trailing slash any access to the volume itself will fail.
+				return abspath + string(filepath.Separator)
+			}
+			return abspath
+		}
 		// Check if \\?\ already exist
 		if strings.HasPrefix(abspath, extendedPathPrefix) {
 			return abspath