From 8b08b0ee68ac2afa2e4252b49fe191a781019bc7 Mon Sep 17 00:00:00 2001
From: Jujstme <just.tribe@gmail.com>
Date: Sun, 15 Oct 2023 00:53:14 +0200
Subject: [PATCH] Porting DeepPointer over from classic LiveSplit (#64)

Despite the runtime already allows to resolve pointer paths with `process.read_pointer_path32()` and `process.read_pointer_path64()`, sometimes it's more convenient to define pointer paths, store them in a struct and dereference them when needed inside the autosplitter logic. This provides an essentially equal implementation of `DeepPointer` from OG LiveSplit, allowing for easier retrieval of memory addresses or values via the defined `deref_offset()` or `deeref::<T>()` functions.
---
 src/deep_pointer.rs | 81 +++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs          |  1 +
 2 files changed, 82 insertions(+)
 create mode 100644 src/deep_pointer.rs

diff --git a/src/deep_pointer.rs b/src/deep_pointer.rs
new file mode 100644
index 0000000..253d2b2
--- /dev/null
+++ b/src/deep_pointer.rs
@@ -0,0 +1,81 @@
+//! Support for storing pointer paths for easy dereferencing inside the autosplitter logic.
+
+use arrayvec::ArrayVec;
+use bytemuck::CheckedBitPattern;
+
+use crate::{Address, Address32, Address64, Error, Process};
+
+/// An abstraction of a pointer path, usable for easy dereferencing inside an autosplitter logic.
+///
+/// The maximum depth of the pointer path is given by the generic parameter `CAP`.
+/// Of note, `CAP` must be higher or equal to the number of offsets provided in `path`,
+/// otherwise calling `new()` on this struct will trigger a ***Panic***.
+#[derive(Clone)]
+pub struct DeepPointer<const CAP: usize> {
+    base_address: Address,
+    path: ArrayVec<u64, CAP>,
+    deref_type: DerefType,
+}
+
+impl<const CAP: usize> Default for DeepPointer<CAP> {
+    /// Creates a new empty DeepPointer.
+    #[inline]
+    fn default() -> Self {
+        Self {
+            base_address: Address::default(),
+            path: ArrayVec::default(),
+            deref_type: DerefType::default(),
+        }
+    }
+}
+
+impl<const CAP: usize> DeepPointer<CAP> {
+    /// Creates a new DeepPointer and specify the pointer size dereferencing
+    #[inline]
+    pub fn new(base_address: Address, deref_type: DerefType, path: &[u64]) -> Self {
+        assert!(CAP != 0 && CAP >= path.len());
+        Self {
+            base_address,
+            path: path.iter().cloned().collect(),
+            deref_type,
+        }
+    }
+
+    /// Creates a new DeepPointer with 32bit pointer size dereferencing
+    pub fn new_32bit(base_address: Address, path: &[u64]) -> Self {
+        Self::new(base_address, DerefType::Bit32, path)
+    }
+
+    /// Creates a new DeepPointer with 64bit pointer size dereferencing
+    pub fn new_64bit(base_address: Address, path: &[u64]) -> Self {
+        Self::new(base_address, DerefType::Bit64, path)
+    }
+
+    /// Dereferences the pointer path, returning the memory address of the value of interest
+    pub fn deref_offsets(&self, process: &Process) -> Result<Address, Error> {
+        let mut address = self.base_address;
+        let (&last, path) = self.path.split_last().ok_or(Error {})?;
+        for &offset in path {
+            address = match self.deref_type {
+                DerefType::Bit32 => process.read::<Address32>(address + offset)?.into(),
+                DerefType::Bit64 => process.read::<Address64>(address + offset)?.into(),
+            };
+        }
+        Ok(address + last)
+    }
+
+    /// Dereferences the pointer path, returning the value stored at the final memory address
+    pub fn deref<T: CheckedBitPattern>(&self, process: &Process) -> Result<T, Error> {
+        process.read(self.deref_offsets(process)?)
+    }
+}
+
+/// Describes the pointer size that should be used while deferecencing a pointer path
+#[derive(Copy, Clone, Default)]
+pub enum DerefType {
+    /// 4-byte pointer size, used in 32bit processes
+    Bit32,
+    /// 8-byte pointer size, used in 64bit processes
+    #[default]
+    Bit64,
+}
diff --git a/src/lib.rs b/src/lib.rs
index cd479a1..a53754b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -143,6 +143,7 @@ pub mod time_util;
 #[cfg(all(feature = "wasi-no-std", target_os = "wasi"))]
 mod wasi_no_std;
 pub mod watcher;
+pub mod deep_pointer;
 
 pub use self::{primitives::*, runtime::*};
 pub use arrayvec;