From 06ce899e71577083ff5f87134083916c9fbe019b Mon Sep 17 00:00:00 2001
From: Erin <erin@erindesu.cz>
Date: Wed, 9 Aug 2023 02:53:55 +0200
Subject: [PATCH] Now finally, leaving Hardvard!

---
 hbvm/src/main.rs           |  2 +-
 hbvm/src/softpaging/mod.rs | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/hbvm/src/main.rs b/hbvm/src/main.rs
index 11e08dde..74202713 100644
--- a/hbvm/src/main.rs
+++ b/hbvm/src/main.rs
@@ -22,7 +22,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                     program:    &prog,
                     root_pt:    Box::into_raw(Default::default()),
                 },
-                0,
+                4,
             );
             let data = {
                 let ptr = std::alloc::alloc_zeroed(std::alloc::Layout::from_size_align_unchecked(
diff --git a/hbvm/src/softpaging/mod.rs b/hbvm/src/softpaging/mod.rs
index ca2d3cd2..3db62486 100644
--- a/hbvm/src/softpaging/mod.rs
+++ b/hbvm/src/softpaging/mod.rs
@@ -97,6 +97,26 @@ impl<'p, PfH: HandlePageFault> SoftPagedMem<'p, PfH> {
         permission_check: fn(Permission) -> bool,
         action: fn(*mut u8, *mut u8, usize),
     ) -> Result<(), u64> {
+        let (src, len) = if src < self.program.len() as _ {
+            let to_copy = len.clamp(0, self.program.len().saturating_sub(src as _));
+            action(
+                unsafe { self.program.as_ptr().add(src as _).cast_mut() },
+                dst,
+                to_copy,
+            );
+
+            (
+                src.saturating_add(to_copy as _),
+                len.saturating_sub(to_copy),
+            )
+        } else {
+            (src, len)
+        };
+
+        if len == 0 {
+            return Ok(());
+        }
+
         // Create new splitter
         let mut pspl = AddrPageLookuper::new(src, len, self.root_pt);
         loop {