FFI Debug

Debug issues with the C FFI interface in kexedit-ffi.

When to Use

• •FFI calls returning unexpected error codes
• •Memory layout mismatches between Rust and C
• •Null pointer or buffer sizing issues
• •Integration problems with external consumers

Error Codes

The FFI functions return status codes:

• •0 - Success
• •-1 - Null pointer passed (check all pointer arguments)
• •-2 - Invalid enum/type value (e.g., invalid duration_type)
• •-3 - Output buffer overflow (pre-allocate larger buffers)
• •-4 - Graph cycle detected (check graph connectivity)

kexedit_track_build

Main entry point. Signature:

int kexedit_track_build(
    const DocumentData* doc,
    float resolution,
    int default_style_index,
    TrackOutput* out
);

Caller must pre-allocate all output buffers in TrackOutput. On -3, increase buffer sizes and retry.

Debugging Commands

# Build debug FFI for better stack traces
cargo build -p kexedit-ffi

# Run FFI tests with output
cargo test -p kexedit-ffi -- --nocapture

Memory Layout

All FFI structs use #[repr(C)]. Verify struct definitions match between Rust and consumer. Check kexedit-ffi/src/lib.rs for canonical definitions.