vfs/uwp: fix rename discarding new_path and inverted delete checks

retro_vfs_file_rename_impl passed old_path as both arguments of
uwp_move_path, and DeleteFileFromAppW's nonzero-on-success return was
checked inverted, so any rename whose source existed deleted it and
returned failure, while a missing source fell through to success.
Playlist writes on Xbox hit this through edb8fac's write-to-temporary
and reported success with nothing on disk.

Pass new_path through, fix both delete checks, fail on a missing
source, and treat a self-rename as a no-op success. Needs a UWP build
to verify; this TU is not compilable outside MSVC/WinRT.

Author: LibretroAdmin

libretro-common/vfs/vfs_implementation_uwp.cpp

@@ -23,6 +23,7 @@
 #include <ppl.h>
 #include <ppltasks.h>
 #include <stdio.h>
+#include <string.h>
 #include <wrl.h>
 #include <wrl/implements.h>
 #include <robuffer.h>
@@ -555,7 +556,10 @@ static int uwp_move_path(
                               && targetfileinfo.dwFileAttributes != 0
                               && (!(targetfileinfo.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)))
                         {
-                            if (DeleteFileFromAppW(new_path.wstring().c_str()))
+                            /* DeleteFileFromAppW returns nonzero on
+                             * success; MoveFileFromAppW cannot replace
+                             * an existing destination. */
+                            if (!DeleteFileFromAppW(new_path.wstring().c_str()))
                                 return -1;
                         }
                     }
@@ -567,7 +571,11 @@ static int uwp_move_path(
                     uwp_set_acl(new_path.wstring().c_str(), L"S-1-15-2-1");
                 }
             }
+            else
+                return -1; /* source attributes unusable */
         }
+        else
+            return -1; /* source does not exist */
 
     }
     else
@@ -617,7 +625,8 @@ static int uwp_move_path(
                             && (!(targetfileinfo.dwFileAttributes
                                   & FILE_ATTRIBUTE_DIRECTORY)))
                       {
-                         if (DeleteFileFromAppW(temp_new.wstring().c_str()))
+                         /* Nonzero is success. */
+                         if (!DeleteFileFromAppW(temp_new.wstring().c_str()))
                             fail = true;
                       }
                    }
@@ -647,8 +656,12 @@ static int uwp_move_path(
  * Default arguments mean that we can do better recursion */
 int retro_vfs_file_rename_impl(const char* old_path, const char* new_path)
 {
+    /* A self-rename is a no-op; it must not reach the replace logic,
+     * which would delete the destination - and the source with it. */
+    if (old_path && new_path && strcmp(old_path, new_path) == 0)
+        return 0;
     return uwp_move_path(std::filesystem::path(old_path),
-          std::filesystem::path(old_path), true);
+          std::filesystem::path(new_path), true);
 }
 
 const char *retro_vfs_file_get_path_impl(libretro_vfs_implementation_file *stream)