From d386cd38907beca639672a9bedd67607ccd37260 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Wed, 11 Dec 2024 14:42:49 +0100
Subject: [PATCH] Preserve assertion code for the cdylib panic handler

---
 libbz2-rs-sys-cdylib/Cargo.toml |  3 ++-
 libbz2-rs-sys-cdylib/src/lib.rs |  6 +++++-
 libbz2-rs-sys/src/lib.rs        | 10 ++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/libbz2-rs-sys-cdylib/Cargo.toml b/libbz2-rs-sys-cdylib/Cargo.toml
index fe75dd69b..47e359016 100644
--- a/libbz2-rs-sys-cdylib/Cargo.toml
+++ b/libbz2-rs-sys-cdylib/Cargo.toml
@@ -6,7 +6,7 @@ license = "bzip2-1.0.6"
 repository = "https://github.com/trifectatechfoundation/libbzip2-rs"
 homepage = "https://github.com/trifectatechfoundation/libbzip2-rs"
 readme = "./README.md"
-description = "a drop-in compatible libbz2 cdylib" 
+description = "a drop-in compatible libbz2 cdylib"
 publish = true
 rust-version = "1.82" # MSRV
 
@@ -14,6 +14,7 @@ rust-version = "1.82" # MSRV
 name = "bz2_rs" # turns into e.g. `libbz2_rs.so`
 crate-type = ["cdylib"]
 test = false
+bench = false
 
 [features]
 default = ["stdio"]
diff --git a/libbz2-rs-sys-cdylib/src/lib.rs b/libbz2-rs-sys-cdylib/src/lib.rs
index 0fdc94927..afcded9d4 100644
--- a/libbz2-rs-sys-cdylib/src/lib.rs
+++ b/libbz2-rs-sys-cdylib/src/lib.rs
@@ -37,11 +37,15 @@ fn panic_handler(_info: &PanicInfo) -> ! {
 
     #[cfg(not(feature = "stdio"))]
     {
+        use core::sync::atomic::Ordering;
+
         extern "C" {
             fn bz_internal_error(errcode: core::ffi::c_int);
         }
 
-        unsafe { bz_internal_error(-1) }
+        // If the panic was triggered by handle_assert_failure ASSERT_CODE will contain the
+        // assertion code. Otherwise it will contain -1.
+        unsafe { bz_internal_error(ASSERT_CODE.load(Ordering::Relaxed)) }
         loop {}
     }
 }
diff --git a/libbz2-rs-sys/src/lib.rs b/libbz2-rs-sys/src/lib.rs
index 88f950253..35c18ab3a 100644
--- a/libbz2-rs-sys/src/lib.rs
+++ b/libbz2-rs-sys/src/lib.rs
@@ -11,6 +11,8 @@
 extern crate std;
 
 use core::ffi::c_int;
+#[cfg(not(feature = "std"))]
+use core::sync::atomic::{AtomicI32, Ordering};
 
 mod allocator;
 mod blocksort;
@@ -135,6 +137,10 @@ macro_rules! assert_h {
     };
 }
 
+#[cfg(not(feature = "std"))]
+#[doc(hidden)]
+pub static ASSERT_CODE: AtomicI32 = AtomicI32::new(-1);
+
 #[cold]
 fn handle_assert_failure(errcode: c_int) -> ! {
     #[cfg(feature = "std")]
@@ -142,6 +148,10 @@ fn handle_assert_failure(errcode: c_int) -> ! {
     #[cfg(feature = "std")]
     std::process::exit(3);
 
+    // Stash the assertion code for the panic handler in the cdylib to pass to bz_internal_error.
+    // Using relaxed ordering as this will be accessed on the same thread.
+    #[cfg(not(feature = "std"))]
+    ASSERT_CODE.store(errcode as i32, Ordering::Relaxed);
     #[cfg(not(feature = "std"))]
     panic!("{}", AssertFail(errcode));
 }