vss: add useful warning for WOW64 processes

diff --git a/src/win32_vss.c b/src/win32_vss.c
index 6e5d3ebc5f2e21fa9f2882208c203b64be58fa91..914cd9127267a69b215ea0895b8f28e51b4ce82b 100644 (file)
--- a/src/win32_vss.c
+++ b/src/win32_vss.c
@@ -408,6 +408,15 @@ request_vss_snapshot(IVssBackupComponents *vss, wchar_t *volume,
        return true;
 }
 
+static bool
+is_wow64(void)
+{
+       BOOL wow64 = FALSE;
+       if (sizeof(size_t) == 4)
+               IsWow64Process(GetCurrentProcess(), &wow64);
+       return wow64;
+}
+
 /*
  * Create a VSS snapshot of the specified @volume.  Return the NT namespace path
  * to the snapshot root directory in @vss_path_ret and a handle to the snapshot
@@ -494,8 +503,16 @@ vss_create_snapshot(const wchar_t *source, UNICODE_STRING *vss_path_ret,
 
 vss_err:
        ret = WIMLIB_ERR_SNAPSHOT_FAILURE;
-       ERROR("A problem occurred while creating a VSS snapshot of \"%ls\".\n"
-             "        Aborting the operation.", volume);
+       if (is_wow64()) {
+               ERROR("64-bit Windows doesn't allow 32-bit applications to "
+                     "create VSS snapshots.\n"
+                     "        Run the 64-bit version of this application "
+                     "instead.");
+       } else {
+               ERROR("A problem occurred while creating a VSS snapshot of "
+                     "\"%ls\".\n"
+                     "        Aborting the operation.", volume);
+       }
 err:
        if (snapshot)
                vss_delete_snapshot(&snapshot->base);