Make deexit work on macOS again

.github/workflows/build_and_test.yml

@@ -15,6 +15,7 @@ env:
   CARGO_TERM_COLOR: always
   CARGO_NET_GIT_FETCH_WITH_CLI: true
   MAIN_LLVM_VERSION: 21
+  RUST_BACKTRACE: full
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}

Justfile

@@ -68,6 +68,11 @@ clippy-thumbv6m-none-eabi:
 test-miri:
     RUST_BACKTRACE=1 MIRIFLAGS="-Zmiri-disable-isolation" cargo +nightly miri test
 
+# Tests deexit utility
+[unix]
+test-deexit:
+    cd utils/deexit && just test
+
 # Tests all code in docs (macos version)
 [macos]
 [private]
@@ -274,11 +279,11 @@ test-repro-qemu-tmin:
 
 # Tests everything (crates, fuzzers, docs, repro)
 [linux]
-test-all: test test-fuzzers test-docs test-repro-qemu-tmin doc
+test-all: test test-deexit test-fuzzers test-docs test-repro-qemu-tmin doc
 
 # Tests everything (crates, fuzzers, docs, repro)
 [macos]
-test-all: test test-fuzzers test-docs test-repro-qemu-tmin doc
+test-all: test test-deexit test-fuzzers test-docs test-repro-qemu-tmin doc
 
 # Tests everything (crates, fuzzers, docs)
 [windows]

utils/deexit/.gitignore

@@ -0,0 +1 @@
+bin

utils/deexit/Cargo.toml

@@ -24,6 +24,9 @@ categories = [
 
 [dependencies]
 
+[target.'cfg(target_os = "macos")'.dependencies]
+fishhook = "0.3"
+
 [lib]
 name = "deexit"
 crate-type = ["cdylib"]

utils/deexit/Justfile

@@ -1,2 +1,34 @@
+build:
+    cargo build --lib
+
 doc:
     cargo doc --no-deps --all-features
+
+build-test-bin: build
+    cargo build --bin exit_test
+
+[private]
+test-helper env_var lib:
+    #!/usr/bin/env bash
+    echo "Running test..."
+    {{ env_var }}="{{ lib }}" ../../target/debug/exit_test
+    CODE=$?
+
+    if [ $CODE -eq 134 ]; then
+        echo "SUCCESS: Process aborted as expected (Exit code 134)"
+        exit 0
+    elif [ $CODE -eq 42 ]; then
+        echo "FAILURE: Process exited normally with code 42 (Hook failed)"
+        exit 1
+    else
+        echo "FAILURE: Process exited with unexpected code $CODE"
+        exit 1
+    fi
+
+[macos]
+test: build-test-bin
+    just test-helper DYLD_INSERT_LIBRARIES ../../target/debug/libdeexit.dylib
+
+[linux]
+test: build-test-bin
+    just test-helper LD_PRELOAD ../../target/debug/libdeexit.so

utils/deexit/README.md

@@ -2,5 +2,5 @@
 
 This util helps you, if your target calls `exit` during a fuzz run.
 A simple wrapper that can be inserted into a program to turn `exit` calls to `abort`, which LibAFL will be able to catch.
-If you are on MacOS, use the env variables `DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES="path/to/target/release/libdeexit.dylib" tool`
+If you are on MacOS, use the env variables `DYLD_INSERT_LIBRARIES="path/to/target/release/libdeexit.dylib" tool`
 On Linux, use `LD_PRELOAD="path/to/target/release/libdeexit.so" tool`.

utils/deexit/src/lib.rs

@@ -1,5 +1,5 @@
 //! A simple wrapper that can be inserted into a program to turn `exit` calls to `abort`, which `LibAFL` will be able to catch.
-//! If you are on `MacOS`, use the env variables `DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES="path/to/target/release/libdeexit.dylib" tool`
+//! If you are on `MacOS`, use the env variables `DYLD_INSERT_LIBRARIES="path/to/target/release/libdeexit.dylib" tool`
 //! On Linux, use `LD_PRELOAD="path/to/target/release/libdeexit.so" tool`.
 
 unsafe extern "C" {
@@ -14,3 +14,17 @@ pub extern "C" fn exit(status: i32) {
         abort();
     }
 }
+
+#[cfg(target_os = "macos")]
+use ctor::ctor;
+
+#[cfg(target_os = "macos")]
+#[ctor]
+fn init() {
+    unsafe {
+        fishhook::register(vec![fishhook::Rebinding {
+            name: "exit".to_string(),
+            function: exit as *const () as usize,
+        }]);
+    }
+}