Use panic=abort for fuzz crate and remove extern "C" FFI wrappers

Remove crate-type = ["rlib", "dylib", "staticlib"] from the fuzz
library, keeping only the default rlib. The dylib and staticlib types
were added in e28fd78 (2019) for a planned C-callable harness that
was never implemented. Nothing consumes the generated targets.h header
or links against the shared/static library.

Removing dylib is what enables panic=abort: Rust forces panic=unwind
on dylib crates for ABI compatibility, which prevented setting
panic=abort regardless of profile settings. With only rlib remaining,
panic=abort now works and is set on both dev and release profiles.

This eliminates unwind table generation and landing pad overhead,
producing smaller and faster fuzz binaries. The stdin_fuzz targets no
longer need catch_unwind + process::exit(1) since panics now abort
the process directly (exit code 134/SIGABRT). cargo test continues
to work because the test harness automatically overrides panic=abort
back to panic=unwind.

Also remove all #[no_mangle] pub extern "C" fn ..._run() wrappers
from every fuzz module. These existed to expose each target through
the C ABI via the now-removed staticlib/dylib, but all fuzzer
frontends (AFL, honggfuzz, libfuzzer, stdin_fuzz) are Rust binaries
that can call the _test() functions directly. The generated target
binaries are updated accordingly.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Author: joostjager

fuzz/Cargo.toml

@@ -39,19 +39,20 @@ cc = "1.0"
 members = ["."]
 
 [profile.release]
+panic = "abort"
 lto = true
 codegen-units = 1
 debug-assertions = true
 overflow-checks = true
 
 # When testing a large fuzz corpus, -O1 offers a nice speedup
 [profile.dev]
+panic = "abort"
 opt-level = 1
 
 [lib]
 name = "lightning_fuzz"
 path = "src/lib.rs"
-crate-type = ["rlib", "dylib", "staticlib"]
 
 [lints.rust.unexpected_cfgs]
 level = "forbid"

fuzz/README.md

@@ -155,8 +155,9 @@ creating test case files on disk:
 echo -ne '\x2d\x31\x36\x38\x37\x34\x09\x01...' | RUSTFLAGS="--cfg=fuzzing --cfg=secp256k1_fuzz --cfg=hashes_fuzz" cargo run --features stdin_fuzz --bin full_stack_target
 ```
 
-This is useful for reproducing crashes during `git bisect` or when working with AI agents that can
-construct and pipe byte sequences directly.
+Panics will abort the process directly (the crate uses `panic = "abort"`), resulting in a
+non-zero exit code. Piping via stdin is useful for reproducing crashes during `git bisect` or
+when working with AI agents that can construct and pipe byte sequences directly.
 
 ## How do I add a new fuzz test?
 
@@ -166,8 +167,8 @@ suitable. For the sake of example, let's call the new fuzz target we're creating
 `my_fuzzy_experiment`.
 
 2. In the newly created file `fuzz/src/my_fuzzy_experiment.rs`, run a string substitution
-of `process_network_graph` to `my_fuzzy_experiment`, such that the three methods in the
-file are `do_test`, `my_fuzzy_experiment_test`, and `my_fuzzy_experiment_run`.
+of `process_network_graph` to `my_fuzzy_experiment`, such that the two methods in the
+file are `do_test` and `my_fuzzy_experiment_test`.
 
 3. Adjust the body (not the signature!) of `do_test` as necessary for the new fuzz test.
 

fuzz/src/base32.rs

@@ -51,8 +51,3 @@ pub fn do_test(data: &[u8]) {
 pub fn base32_test<Out: test_logger::Output>(data: &[u8], _out: Out) {
 	do_test(data);
 }
-
-#[no_mangle]
-pub extern "C" fn base32_run(data: *const u8, datalen: usize) {
-	do_test(unsafe { std::slice::from_raw_parts(data, datalen) });
-}

fuzz/src/bech32_parse.rs

@@ -50,8 +50,3 @@ impl core::fmt::Display for Bytes {
 pub fn bech32_parse_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 	do_test(data, out);
 }
-
-#[no_mangle]
-pub extern "C" fn bech32_parse_run(data: *const u8, datalen: usize) {
-	do_test(unsafe { std::slice::from_raw_parts(data, datalen) }, test_logger::DevNull {});
-}

fuzz/src/bin/base32_target.rs

@@ -24,13 +24,14 @@ compile_error!("Fuzz targets need cfg=secp256k1_fuzz");
 
 extern crate lightning_fuzz;
 use lightning_fuzz::base32::*;
+use lightning_fuzz::utils::test_logger;
 
 #[cfg(feature = "afl")]
 #[macro_use] extern crate afl;
 #[cfg(feature = "afl")]
 fn main() {
 	fuzz!(|data| {
-		base32_run(data.as_ptr(), data.len());
+		base32_test(&data, test_logger::DevNull {});
 	});
 }
 
@@ -40,7 +41,7 @@ fn main() {
 fn main() {
 	loop {
 		fuzz!(|data| {
-			base32_run(data.as_ptr(), data.len());
+			base32_test(&data, test_logger::DevNull {});
 		});
 	}
 }
@@ -49,7 +50,7 @@ fn main() {
 #[macro_use] extern crate libfuzzer_sys;
 #[cfg(feature = "libfuzzer_fuzz")]
 fuzz_target!(|data: &[u8]| {
-	base32_run(data.as_ptr(), data.len());
+	base32_test(data, test_logger::DevNull {});
 });
 
 #[cfg(feature = "stdin_fuzz")]
@@ -58,12 +59,7 @@ fn main() {
 
 	let mut data = Vec::with_capacity(8192);
 	std::io::stdin().read_to_end(&mut data).unwrap();
-	let res = std::panic::catch_unwind(|| {
-		base32_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
-	});
-	if res.is_err() {
-		std::process::exit(1);
-	}
+	base32_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
 }
 
 #[test]
@@ -75,7 +71,7 @@ fn run_test_cases() {
 	use std::sync::{atomic, Arc};
 	{
 		let data: Vec<u8> = vec![0];
-		base32_run(data.as_ptr(), data.len());
+		base32_test(&data, test_logger::DevNull {});
 	}
 	let mut threads = Vec::new();
 	let threads_running = Arc::new(atomic::AtomicUsize::new(0));

fuzz/src/bin/bech32_parse_target.rs

@@ -24,13 +24,14 @@ compile_error!("Fuzz targets need cfg=secp256k1_fuzz");
 
 extern crate lightning_fuzz;
 use lightning_fuzz::bech32_parse::*;
+use lightning_fuzz::utils::test_logger;
 
 #[cfg(feature = "afl")]
 #[macro_use] extern crate afl;
 #[cfg(feature = "afl")]
 fn main() {
 	fuzz!(|data| {
-		bech32_parse_run(data.as_ptr(), data.len());
+		bech32_parse_test(&data, test_logger::DevNull {});
 	});
 }
 
@@ -40,7 +41,7 @@ fn main() {
 fn main() {
 	loop {
 		fuzz!(|data| {
-			bech32_parse_run(data.as_ptr(), data.len());
+			bech32_parse_test(&data, test_logger::DevNull {});
 		});
 	}
 }
@@ -49,7 +50,7 @@ fn main() {
 #[macro_use] extern crate libfuzzer_sys;
 #[cfg(feature = "libfuzzer_fuzz")]
 fuzz_target!(|data: &[u8]| {
-	bech32_parse_run(data.as_ptr(), data.len());
+	bech32_parse_test(data, test_logger::DevNull {});
 });
 
 #[cfg(feature = "stdin_fuzz")]
@@ -58,12 +59,7 @@ fn main() {
 
 	let mut data = Vec::with_capacity(8192);
 	std::io::stdin().read_to_end(&mut data).unwrap();
-	let res = std::panic::catch_unwind(|| {
-		bech32_parse_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
-	});
-	if res.is_err() {
-		std::process::exit(1);
-	}
+	bech32_parse_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
 }
 
 #[test]
@@ -75,7 +71,7 @@ fn run_test_cases() {
 	use std::sync::{atomic, Arc};
 	{
 		let data: Vec<u8> = vec![0];
-		bech32_parse_run(data.as_ptr(), data.len());
+		bech32_parse_test(&data, test_logger::DevNull {});
 	}
 	let mut threads = Vec::new();
 	let threads_running = Arc::new(atomic::AtomicUsize::new(0));

fuzz/src/bin/bolt11_deser_target.rs

@@ -24,13 +24,14 @@ compile_error!("Fuzz targets need cfg=secp256k1_fuzz");
 
 extern crate lightning_fuzz;
 use lightning_fuzz::bolt11_deser::*;
+use lightning_fuzz::utils::test_logger;
 
 #[cfg(feature = "afl")]
 #[macro_use] extern crate afl;
 #[cfg(feature = "afl")]
 fn main() {
 	fuzz!(|data| {
-		bolt11_deser_run(data.as_ptr(), data.len());
+		bolt11_deser_test(&data, test_logger::DevNull {});
 	});
 }
 
@@ -40,7 +41,7 @@ fn main() {
 fn main() {
 	loop {
 		fuzz!(|data| {
-			bolt11_deser_run(data.as_ptr(), data.len());
+			bolt11_deser_test(&data, test_logger::DevNull {});
 		});
 	}
 }
@@ -49,7 +50,7 @@ fn main() {
 #[macro_use] extern crate libfuzzer_sys;
 #[cfg(feature = "libfuzzer_fuzz")]
 fuzz_target!(|data: &[u8]| {
-	bolt11_deser_run(data.as_ptr(), data.len());
+	bolt11_deser_test(data, test_logger::DevNull {});
 });
 
 #[cfg(feature = "stdin_fuzz")]
@@ -58,12 +59,7 @@ fn main() {
 
 	let mut data = Vec::with_capacity(8192);
 	std::io::stdin().read_to_end(&mut data).unwrap();
-	let res = std::panic::catch_unwind(|| {
-		bolt11_deser_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
-	});
-	if res.is_err() {
-		std::process::exit(1);
-	}
+	bolt11_deser_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
 }
 
 #[test]
@@ -75,7 +71,7 @@ fn run_test_cases() {
 	use std::sync::{atomic, Arc};
 	{
 		let data: Vec<u8> = vec![0];
-		bolt11_deser_run(data.as_ptr(), data.len());
+		bolt11_deser_test(&data, test_logger::DevNull {});
 	}
 	let mut threads = Vec::new();
 	let threads_running = Arc::new(atomic::AtomicUsize::new(0));

fuzz/src/bin/chanmon_consistency_target.rs

@@ -24,13 +24,14 @@ compile_error!("Fuzz targets need cfg=secp256k1_fuzz");
 
 extern crate lightning_fuzz;
 use lightning_fuzz::chanmon_consistency::*;
+use lightning_fuzz::utils::test_logger;
 
 #[cfg(feature = "afl")]
 #[macro_use] extern crate afl;
 #[cfg(feature = "afl")]
 fn main() {
 	fuzz!(|data| {
-		chanmon_consistency_run(data.as_ptr(), data.len());
+		chanmon_consistency_test(&data, test_logger::DevNull {});
 	});
 }
 
@@ -40,7 +41,7 @@ fn main() {
 fn main() {
 	loop {
 		fuzz!(|data| {
-			chanmon_consistency_run(data.as_ptr(), data.len());
+			chanmon_consistency_test(&data, test_logger::DevNull {});
 		});
 	}
 }
@@ -49,7 +50,7 @@ fn main() {
 #[macro_use] extern crate libfuzzer_sys;
 #[cfg(feature = "libfuzzer_fuzz")]
 fuzz_target!(|data: &[u8]| {
-	chanmon_consistency_run(data.as_ptr(), data.len());
+	chanmon_consistency_test(data, test_logger::DevNull {});
 });
 
 #[cfg(feature = "stdin_fuzz")]
@@ -58,12 +59,7 @@ fn main() {
 
 	let mut data = Vec::with_capacity(8192);
 	std::io::stdin().read_to_end(&mut data).unwrap();
-	let res = std::panic::catch_unwind(|| {
-		chanmon_consistency_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
-	});
-	if res.is_err() {
-		std::process::exit(1);
-	}
+	chanmon_consistency_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
 }
 
 #[test]
@@ -75,7 +71,7 @@ fn run_test_cases() {
 	use std::sync::{atomic, Arc};
 	{
 		let data: Vec<u8> = vec![0];
-		chanmon_consistency_run(data.as_ptr(), data.len());
+		chanmon_consistency_test(&data, test_logger::DevNull {});
 	}
 	let mut threads = Vec::new();
 	let threads_running = Arc::new(atomic::AtomicUsize::new(0));

fuzz/src/bin/chanmon_deser_target.rs

@@ -24,13 +24,14 @@ compile_error!("Fuzz targets need cfg=secp256k1_fuzz");
 
 extern crate lightning_fuzz;
 use lightning_fuzz::chanmon_deser::*;
+use lightning_fuzz::utils::test_logger;
 
 #[cfg(feature = "afl")]
 #[macro_use] extern crate afl;
 #[cfg(feature = "afl")]
 fn main() {
 	fuzz!(|data| {
-		chanmon_deser_run(data.as_ptr(), data.len());
+		chanmon_deser_test(&data, test_logger::DevNull {});
 	});
 }
 
@@ -40,7 +41,7 @@ fn main() {
 fn main() {
 	loop {
 		fuzz!(|data| {
-			chanmon_deser_run(data.as_ptr(), data.len());
+			chanmon_deser_test(&data, test_logger::DevNull {});
 		});
 	}
 }
@@ -49,7 +50,7 @@ fn main() {
 #[macro_use] extern crate libfuzzer_sys;
 #[cfg(feature = "libfuzzer_fuzz")]
 fuzz_target!(|data: &[u8]| {
-	chanmon_deser_run(data.as_ptr(), data.len());
+	chanmon_deser_test(data, test_logger::DevNull {});
 });
 
 #[cfg(feature = "stdin_fuzz")]
@@ -58,12 +59,7 @@ fn main() {
 
 	let mut data = Vec::with_capacity(8192);
 	std::io::stdin().read_to_end(&mut data).unwrap();
-	let res = std::panic::catch_unwind(|| {
-		chanmon_deser_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
-	});
-	if res.is_err() {
-		std::process::exit(1);
-	}
+	chanmon_deser_test(&data, lightning_fuzz::utils::test_logger::Stdout {});
 }
 
 #[test]
@@ -75,7 +71,7 @@ fn run_test_cases() {
 	use std::sync::{atomic, Arc};
 	{
 		let data: Vec<u8> = vec![0];
-		chanmon_deser_run(data.as_ptr(), data.len());
+		chanmon_deser_test(&data, test_logger::DevNull {});
 	}
 	let mut threads = Vec::new();
 	let threads_running = Arc::new(atomic::AtomicUsize::new(0));