Preserve assertion code for the cdylib panic handler

libbz2-rs-sys-cdylib/Cargo.toml

@@ -6,14 +6,15 @@ 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
 
 [lib]
 name = "bz2_rs" # turns into e.g. `libbz2_rs.so`
 crate-type = ["cdylib"]
 test = false
+bench = false
 
 [features]
 default = ["stdio"]

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 {}
     }
 }

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;
@@ -135,13 +137,21 @@ 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")]
     std::eprint!("{}", AssertFail(errcode));
     #[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));
 }