Check for rename loops

diff --git a/src/update_image.c b/src/update_image.c
index 70038d42d0e605bbea400ef9a9406bf2779a88b2..3e7613fcfa5dbc12e37a7bdd3985a1cc24b764cb 100644 (file)
--- a/src/update_image.c
+++ b/src/update_image.c
@@ -949,6 +949,19 @@ free_dentry_full_path(struct wim_dentry *dentry, void *_ignore)
        return 0;
 }
 
+/* Is @d1 a (possibly nonproper) ancestor of @d2?  */
+static bool
+is_ancestor(struct wim_dentry *d1, struct wim_dentry *d2)
+{
+       for (;;) {
+               if (d2 == d1)
+                       return true;
+               if (dentry_is_root(d2))
+                       return false;
+               d2 = d2->parent;
+       }
+}
+
 /* Rename a file or directory in the WIM.
  *
  * This returns a -errno value.
@@ -1003,6 +1016,11 @@ rename_wim_path(WIMStruct *wim, const tchar *from, const tchar *to,
                        return -ENOTDIR;
        }
 
+       /* @src can't be an ancestor of @dst.  Otherwise we're unlinking @src
+        * from the tree and creating a loop...  */
+       if (is_ancestor(src, parent_of_dst))
+               return -EBUSY;
+
        if (j) {
                if (journaled_change_name(j, src, path_basename(to)))
                        return -ENOMEM;
@@ -1059,6 +1077,9 @@ execute_rename_command(struct update_command_journal *j,
                        ret = WIMLIB_ERR_NOTDIR;
                        break;
                case ENOTEMPTY:
+               case EBUSY:
+                       /* XXX: EBUSY is returned when the rename would create a
+                        * loop.  It maybe should have its own error code.  */
                        ret = WIMLIB_ERR_NOTEMPTY;
                        break;
                case EISDIR: