From d8c08d9359f58bcc1513e1abc92a5ce48f0c2b4f Mon Sep 17 00:00:00 2001
From: Noratrieb <48135649+Noratrieb@users.noreply.github.com>
Date: Wed, 29 Jan 2025 21:50:11 +0100
Subject: [PATCH] stuff

---
 README.md   |  9 +++++++++
 src/lib.rs  | 11 ++++++++++-
 src/mmap.rs |  2 +-
 3 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 README.md

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..18fd8a7
--- /dev/null
+++ b/README.md
@@ -0,0 +1,9 @@
+# portability
+
+a PE loader for educational purposes.
+
+## references
+
+- https://learn.microsoft.com/en-us/windows/win32/debug/pe-format
+- https://learn.microsoft.com/en-us/archive/msdn-magazine/2002/february/inside-windows-win32-portable-executable-file-format-in-detail
+- https://learn.microsoft.com/en-us/archive/msdn-magazine/2002/march/inside-windows-an-in-depth-look-into-the-win32-portable-executable-file-format-part-2
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
index 34b6ac8..dd17707 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -253,6 +253,8 @@ pub fn execute(file: File, pe: &[u8]) {
     // just some arbitrary offset that probably won't collide with anything
     let base = optional_header.image_base as usize + 0xFFFFFF0000;
 
+    assert_eq!(base & (4096 - 1), 0);
+
     let map = unsafe { crate::mmap::map(file).unwrap() };
 
     // allocate the sections.
@@ -274,7 +276,14 @@ pub fn execute(file: File, pe: &[u8]) {
         } else {
             crate::mmap::Mode::Read
         };
-        let address = std::ptr::with_exposed_provenance(base + section.virtual_address as usize);
+        let address =
+            std::ptr::with_exposed_provenance::<()>(base + section.virtual_address as usize);
+        dbg!(section);
+
+        // assert stuff is aligned (yes 4096 as a hardcoded page is bad)
+        //assert_eq!(section.pointer_to_raw_data & (4096 - 1), 0);
+        assert_eq!(address.addr() & (4096 - 1), 0);
+
         unsafe {
             map.view(
                 mode,
diff --git a/src/mmap.rs b/src/mmap.rs
index 268f106..c6e8987 100644
--- a/src/mmap.rs
+++ b/src/mmap.rs
@@ -48,7 +48,7 @@ mod imp {
                     self.0,
                     match mode {
                         Mode::Read => FILE_MAP_READ,
-                        Mode::Write => FILE_MAP_READ | FILE_MAP_COPY,
+                        Mode::Write => FILE_MAP_COPY,
                         Mode::Execute => FILE_MAP_READ | FILE_MAP_EXECUTE,
                     },
                     (file_offset << 32) as u32,