it works!

1 files changed, 61 insertions, 1 deletions

diff --git a/kernel/vm/shadow.c b/kernel/vm/shadow.c
index bf04bc9..4166597 100644
--- a/kernel/vm/shadow.c
+++ b/kernel/vm/shadow.c
@@ -116,7 +116,67 @@ mobj_t *shadow_create(mobj_t *shadowed)
  */
 void shadow_collapse(mobj_t *o)
 {
-    NOT_YET_IMPLEMENTED("VM: shadow_collapse");
+    // NOT_YET_IMPLEMENTED("VM: shadow_collapse");
+
+    mobj_shadow_t *so = MOBJ_TO_SO(o);
+    mobj_t *shadowed = so->shadowed;
+
+    if (shadowed->mo_type != MOBJ_SHADOW)
+    {
+        return;
+    }
+
+    dbg(DBG_PRINT, "shadow_collapse: refcount bottom: %d\n", so->bottom_mobj->mo_refcount);
+
+    while (shadowed->mo_type == MOBJ_SHADOW)
+    {
+        mobj_shadow_t *so_shadowed = MOBJ_TO_SO(shadowed);
+        mobj_t *shadowed_shadowed = so_shadowed->shadowed;
+
+        // if the refcount is not 1, then we can't collapse
+        if (shadowed_shadowed->mo_refcount != 1)
+        {
+            // continue down the shadow chain
+            shadowed = shadowed_shadowed;
+            continue;
+        }
+
+        mobj_lock(shadowed_shadowed);
+        list_iterate(&shadowed_shadowed->mo_pframes, pf, pframe_t, pf_link)
+        {
+            pframe_t *pf_shadow = NULL;
+            mobj_find_pframe(shadowed_shadowed, pf->pf_pagenum, &pf_shadow);
+            if (!pf_shadow)
+            {
+                list_remove(&pf->pf_link);
+                // append to the list of pframes
+                list_insert_tail(&shadowed_shadowed->mo_pframes, &pf->pf_link);
+            }
+            else
+            {
+                pframe_release(&pf_shadow);
+            }
+        }
+        mobj_unlock(shadowed_shadowed);
+
+        if (shadowed_shadowed->mo_type != MOBJ_SHADOW)
+        {
+            // put the shadowed object
+            mobj_put(&shadowed);
+            break;
+        }
+
+        // get the pointer to the shadowed object
+        mobj_shadow_t *so_shadowed_shadowed = MOBJ_TO_SO(shadowed_shadowed);
+        so->shadowed = shadowed_shadowed;
+        mobj_ref(so->shadowed);
+
+        // put the shadowed object
+        mobj_put(&shadowed);
+
+        // continue down the shadow chain
+        shadowed = shadowed_shadowed;
+    }
 }