From d5c2e5559be96b396871a69fc4b7fd6c7b81f171 Mon Sep 17 00:00:00 2001
From: CUB3D <callumthom11@gmail.com>
Date: Fri, 2 Apr 2021 23:17:28 +0100
Subject: [PATCH] avm2: Don't mutably borrow for pos()

---
 core/src/avm2/activation.rs | 8 ++++----
 swf/src/avm1/read.rs        | 5 +++++
 swf/src/avm2/read.rs        | 5 +++++
 swf/src/extensions.rs       | 8 +++++++-
 swf/src/read.rs             | 5 +++++
 5 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/core/src/avm2/activation.rs b/core/src/avm2/activation.rs
index 6dc007301..97b53c40c 100644
--- a/core/src/avm2/activation.rs
+++ b/core/src/avm2/activation.rs
@@ -2393,14 +2393,14 @@ impl<'a, 'gc, 'gc_context> Activation<'a, 'gc, 'gc_context> {
     ) -> Result<FrameControl<'gc>, Error> {
         let index = self.context.avm2.pop().coerce_to_i32(self)?;
 
-        //TODO: can we just subtract the size of *this* op to save some of this maths
         let offset = case_offsets
             .get(index as usize)
             .copied()
             .unwrap_or(default_offset)
-            + current_pos as i32;
-        let current_pos = reader.pos(full_data) as i32;
-        reader.seek(full_data, offset - current_pos);
+            + current_pos as i32
+            - reader.pos(full_data) as i32;
+
+        reader.seek(full_data, offset);
 
         Ok(FrameControl::Continue)
     }
diff --git a/swf/src/avm1/read.rs b/swf/src/avm1/read.rs
index aebcef494..b4c159023 100644
--- a/swf/src/avm1/read.rs
+++ b/swf/src/avm1/read.rs
@@ -15,6 +15,11 @@ impl<'a> ReadSwfExt<'a> for Reader<'a> {
     fn as_mut_slice(&mut self) -> &mut &'a [u8] {
         &mut self.input
     }
+
+    #[inline(always)]
+    fn as_slice(&self) -> &'a [u8] {
+        &self.input
+    }
 }
 
 impl<'a> Reader<'a> {
diff --git a/swf/src/avm2/read.rs b/swf/src/avm2/read.rs
index e53f64cd9..45075a95c 100644
--- a/swf/src/avm2/read.rs
+++ b/swf/src/avm2/read.rs
@@ -12,6 +12,11 @@ impl<'a> ReadSwfExt<'a> for Reader<'a> {
     fn as_mut_slice(&mut self) -> &mut &'a [u8] {
         &mut self.input
     }
+
+    #[inline(always)]
+    fn as_slice(&self) -> &'a [u8] {
+        &self.input
+    }
 }
 
 impl<'a> Reader<'a> {
diff --git a/swf/src/extensions.rs b/swf/src/extensions.rs
index 112a12d99..b791cdc0f 100644
--- a/swf/src/extensions.rs
+++ b/swf/src/extensions.rs
@@ -6,9 +6,15 @@ use std::io::{self, Read};
 pub trait ReadSwfExt<'a> {
     fn as_mut_slice(&mut self) -> &mut &'a [u8];
 
+    fn as_slice(&self) -> &'a [u8];
+
+    fn pos(&self, data: &[u8]) -> usize {
+        self.as_slice().as_ptr() as usize - data.as_ptr() as usize
+    }
+
     // TODO: Make this fallible?
     fn seek(&mut self, data: &'a [u8], relative_offset: isize) {
-        let mut pos = self.as_mut_slice().as_ptr() as usize - data.as_ptr() as usize;
+        let mut pos = self.pos(data);
         pos = (pos as isize + relative_offset) as usize;
         pos = pos.min(data.len());
         *self.as_mut_slice() = &data[pos..];
diff --git a/swf/src/read.rs b/swf/src/read.rs
index 1d3c58e54..8c584e9e3 100644
--- a/swf/src/read.rs
+++ b/swf/src/read.rs
@@ -243,6 +243,11 @@ impl<'a> ReadSwfExt<'a> for Reader<'a> {
     fn as_mut_slice(&mut self) -> &mut &'a [u8] {
         &mut self.input
     }
+
+    #[inline(always)]
+    fn as_slice(&self) -> &'a [u8] {
+        &self.input
+    }
 }
 
 impl<'a> Reader<'a> {