Support Mac SceneManager without std

Author: AlexKnauth

src/file_format/macho.rs

@@ -1,10 +1,15 @@
 //! Support for parsing MachO files
 
-use crate::Process;
+use crate::{Process, Address};
 
 use core::mem;
 
-use std::{fs::File, io::Read};
+// Magic mach-o header constants from:
+// https://opensource.apple.com/source/xnu/xnu-4570.71.2/EXTERNAL_HEADERS/mach-o/loader.h.auto.html
+const MH_MAGIC_32: u32 = 0xfeedface;
+const MH_CIGAM_32: u32 = 0xcefaedfe;
+const MH_MAGIC_64: u32 = 0xfeedfacf;
+const MH_CIGAM_64: u32 = 0xcffaedfe;
 
 struct MachOFormatOffsets {
     number_of_commands: usize,
@@ -35,20 +40,29 @@ impl MachOFormatOffsets {
     }
 }
 
-/// Determines whether a MachO process is 64-bit or 32-bit
-pub fn is_64_bit(process: &Process) -> Option<bool> {
-    // Magic mach-o header constants from:
-    // https://opensource.apple.com/source/xnu/xnu-4570.71.2/EXTERNAL_HEADERS/mach-o/loader.h.auto.html
-    const MH_MAGIC_32: u32 = 0xfeedface;
-    const MH_CIGAM_32: u32 = 0xcefaedfe;
-    const MH_MAGIC_64: u32 = 0xfeedfacf;
-    const MH_CIGAM_64: u32 = 0xcffaedfe;
+/// Scans the range for a page that begins with MachO Magic
+pub fn scan_macho_page(process: &Process, range: (Address, u64)) -> Option<Address> {
+    const PAGE_SIZE: u64 = 0x1000;
+    let (addr, len) = range;
+    // negation mod PAGE_SIZE
+    let distance_to_page = (PAGE_SIZE - (addr.value() % PAGE_SIZE)) % PAGE_SIZE;
+    // round up to the next multiple of PAGE_SIZE
+    let first_page = addr + distance_to_page;
+    for i in 0..((len - distance_to_page) / PAGE_SIZE) {
+        let a = first_page + (i * PAGE_SIZE);
+        match process.read::<u32>(a) {
+            Ok(MH_MAGIC_64 | MH_CIGAM_64 | MH_MAGIC_32 | MH_CIGAM_32) => {
+                return Some(a);
+            }
+            _ => ()
+        }
+    }
+    None
+}
 
-    let process_path = process.get_path().ok()?;
-    let mut process_file = File::open(process_path).ok()?;
-    let mut buffer: [u8; 4] = [0; 4];
-    process_file.read_exact(&mut buffer).ok();
-    let magic: u32 = bytemuck::checked::try_from_bytes(&buffer).ok().cloned()?;
+/// Determines whether a MachO header at the address is 64-bit or 32-bit
+pub fn is_64_bit(process: &Process, address: Address) -> Option<bool> {
+    let magic: u32 = process.read(address).ok()?;
     match magic {
         MH_MAGIC_64 | MH_CIGAM_64 => Some(true),
         MH_MAGIC_32 | MH_CIGAM_32 => Some(false),

src/file_format/mod.rs

@@ -2,5 +2,4 @@
 
 pub mod elf;
 pub mod pe;
-#[cfg(feature = "std")]
 pub mod macho;

src/game_engine/unity/mono.rs

@@ -139,7 +139,7 @@ impl Module {
 
     #[cfg(feature = "std")]
     fn attach_dylib(process: &Process, version: Version, module_range: (Address, u64)) -> Option<Self> {
-        let is_64_bit = macho::is_64_bit(process)?;
+        let is_64_bit = macho::is_64_bit(process, macho::scan_macho_page(process, module_range)?)?;
         let offsets = Offsets::new(version, is_64_bit, BinaryFormat::MachO);
 
         let process_path = process.get_path().ok()?;

src/game_engine/unity/scene.rs

@@ -9,11 +9,9 @@ use core::{array, mem::MaybeUninit};
 use crate::{
     file_format::pe, future::retry, signature::Signature, string::ArrayCString, Address, Address32,
     Address64, Error, Process,
+    file_format::macho,
 };
 
-#[cfg(feature = "std")]
-use crate::file_format::macho;
-
 /// The scene manager allows you to easily identify the current scene loaded in
 /// the attached Unity game.
 ///
@@ -32,7 +30,6 @@ impl SceneManager {
         if let Ok(unity_player) = process.get_module_range("UnityPlayer.dll") {
             return Self::attach_dll(process, unity_player);
         }
-        #[cfg(feature = "std")]
         if let Ok(unity_player) = process.get_module_range("UnityPlayer.dylib") {
             return Self::attach_dylib(process, unity_player);
         }
@@ -71,11 +68,10 @@ impl SceneManager {
         })
     }
 
-    #[cfg(feature = "std")]
     fn attach_dylib(process: &Process, unity_player: (Address, u64)) -> Option<Self> {
         const SIG_64_BIT_DYLIB: Signature<13> = Signature::new("41 54 53 50 4C 8B ?5 ???????? 41 83");
 
-        let is_64_bit = macho::is_64_bit(process)?;
+        let is_64_bit = macho::is_64_bit(process, macho::scan_macho_page(process, unity_player)?)?;
         let is_il2cpp = false;
 
         let address = if is_64_bit {