`require("@napi-ffi/ffi-napi")` segfaults on macOS

[hhas]

Thank you for restoring ffi-napi &co to working order!

I’m getting a crash on import on macOS:

~ % npm install '@napi-ffi/ffi-napi'

added 9 packages, and audited 13 packages in 13s

found 0 vulnerabilities
~ % node
Welcome to Node.js v24.13.0.
Type ".help" for more information.
> require("@napi-ffi/ffi-napi")
zsh: segmentation fault  node

M1 Mac, macOS 15.5 and 16.2, with Node 24.13.0 LTS release. Any ideas? Can you replicate this yourself/recommend next steps?

[urbanogilson]

A segmentation fault on require is definitely not expected

Could you run node through lldb so it can show exactly where it crashes:

lldb -- node -e 'require("@napi-ffi/ffi-napi")'
(lldb) run
# Wait for crash, then type:
(lldb) bt

I don't have a macOS machine handy right this second, but I'll try to replicate this. Any additional logs from the bt command above would be incredibly helpful!

[hhas]

Oh-ho, this is interesting. If I run this:

node -e 'require("@napi-ffi/ffi-napi"); console.log("ok");'

it prints "ok" and doesn’t crash. It only crashes in the REPL:

~ % lldb -- node
(lldb) target create "node"
Current executable set to '/usr/local/bin/node' (arm64).
(lldb) run
Process 42730 launched: '/usr/local/bin/node' (arm64)
Welcome to Node.js v24.13.0.
Type ".help" for more information.
> require("@napi-ffi/ffi-napi")
Process 42730 stopped
* thread #1, name = 'MainThread', queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0xffffffffffffffff)
    frame #0: 0x000000010189a134 node`nbytes::HexEncode(char const*, unsigned long, char*, unsigned long) + 36
node`nbytes::HexEncode:
->  0x10189a134 <+36>: ldrb   w12, [x8], #0x1
    0x10189a138 <+40>: lsr    x13, x12, #4
    0x10189a13c <+44>: ldrb   w13, [x11, x13]
    0x10189a140 <+48>: sturb  w13, [x9, #-0x1]
Target 0: (node) stopped.
(lldb) bt
* thread #1, name = 'MainThread', queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0xffffffffffffffff)
  * frame #0: 0x000000010189a134 node`nbytes::HexEncode(char const*, unsigned long, char*, unsigned long) + 36
    frame #1: 0x000000010023d260 node`node::StringBytes::Encode(v8::Isolate*, char const*, unsigned long, node::encoding) + 648
    frame #2: 0x00000001000d426c node`void node::Buffer::(anonymous namespace)::StringSlice<(node::encoding)5>(v8::FunctionCallbackInfo<v8::Value> const&) + 744
    frame #3: 0x0000000100f82818 node`Builtins_CallApiCallbackGeneric + 152
    frame #4: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #5: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #6: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #7: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #8: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #9: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #10: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #11: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #12: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #13: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #14: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #15: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #16: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #17: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #18: 0x000000011f387258
    frame #19: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #20: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #21: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #22: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #23: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #24: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #25: 0x000000011f387104
    frame #26: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #27: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #28: 0x0000000100fc1ce8 node`Builtins_GeneratorPrototypeNext + 136
    frame #29: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #30: 0x000000011f387104
    frame #31: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #32: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #33: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #34: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #35: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #36: 0x0000000100f80bec node`Builtins_InterpreterEntryTrampoline + 268
    frame #37: 0x0000000100f7e8cc node`Builtins_JSEntryTrampoline + 172
    frame #38: 0x0000000100f7e570 node`Builtins_JSEntry + 176
    frame #39: 0x00000001004a8adc node`v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) + 1652
    frame #40: 0x00000001004a8440 node`v8::internal::Execution::Call(v8::internal::Isolate*, v8::internal::DirectHandle<v8::internal::Object>, v8::internal::DirectHandle<v8::internal::Object>, v8::base::Vector<v8::internal::DirectHandle<v8::internal::Object> const>) + 120
    frame #41: 0x000000010031cbd8 node`v8::Function::Call(v8::Isolate*, v8::Local<v8::Context>, v8::Local<v8::Value>, int, v8::Local<v8::Value>*) + 492
    frame #42: 0x0000000100005320 node`node::InternalMakeCallback(node::Environment*, v8::Local<v8::Object>, v8::Local<v8::Object>, v8::Local<v8::Function>, int, v8::Local<v8::Value>*, node::async_context, v8::Local<v8::Value>) + 428
    frame #43: 0x0000000100018748 node`node::AsyncWrap::MakeCallback(v8::Local<v8::Function>, int, v8::Local<v8::Value>*) + 256
    frame #44: 0x0000000100235988 node`node::StreamBase::CallJSOnreadMethod(long, v8::Local<v8::ArrayBuffer>, unsigned long, node::StreamBase::StreamBaseJSChecks) + 232
    frame #45: 0x0000000100237124 node`node::EmitToJSStreamListener::OnStreamRead(long, uv_buf_t const&) + 380
    frame #46: 0x000000010023b590 node`node::LibuvStreamWrap::OnUvRead(long, uv_buf_t const*) + 692
    frame #47: 0x000000010023bcd8 node`node::LibuvStreamWrap::ReadStart()::$_1::__invoke(uv_stream_s*, long, uv_buf_t const*) + 88
    frame #48: 0x0000000100f691e4 node`uv__stream_io + 1332
    frame #49: 0x0000000100f7180c node`uv__io_poll + 1032
    frame #50: 0x0000000100f5dbbc node`uv_run + 408
    frame #51: 0x0000000100005b7c node`node::SpinEventLoopInternal(node::Environment*) + 256
    frame #52: 0x00000001001584b0 node`node::NodeMainInstance::Run() + 276
    frame #53: 0x00000001000be2d8 node`node::Start(int, char**) + 604
    frame #54: 0x000000018f1fab98 dyld`start + 6076

I hope this is helpful! Please let me know what else I can do to assist.

[hhas]

After additional experimentation:

• When @napi-ffi/ffi-napi is a dependency to another package, everything works as expected.

• It is only when I require("@napi-ffi/ffi-napi") directly in the REPL that it segfaults.

Further testing shows the segfault occurs when printing the imported ffi-napi module’s debug representation.

This works:

% node -e 'require("@napi-ffi/ffi-napi"); console.log("ok")'

This crashes:

% node -e 'const ffi = require("@napi-ffi/ffi-napi"); console.log(ffi)'
zsh: segmentation fault  node -e 'const ffi = require("@napi-ffi/ffi-napi"); console.log(ffi)'

This works:

% node -e 'const ffi = require("@napi-ffi/ffi-napi"); console.log(String(ffi))'
[object Object]

This crashes:

% node -e 'const util = require("util"); const ffi = require("@napi-ffi/ffi-napi"); util.inspect(ffi)'
zsh: segmentation fault  node -e 

I hope this is helpful.

[urbanogilson]

Thanks for the detailed report, it was very helpful in tracking this down.

I was able to reproduce the crash on Linux as well.

The fix is in @napi-ffi/ref-napi. A regression test covering the exact repro cases from this report is included.

The fix will ship in:

• @napi-ffi/ref-napi@3.0.6
• @napi-ffi/ffi-napi@4.0.4