lora_models() produces dangling pointers after build() due to Clone on LoraStorage #84
Description
Firstly I do not claim to be a rust or pointer expert this was just a bug I faced when using this library and I investigated further with Opus 4.6.
1 — api.rs:595 — raw pointer created from c_path:
let c_path = CLibPath::from(path); // allocates heap buffer at address 0xABC
let lora = sd_lora_t {
path: c_path.as_ptr(), // stores raw pointer → 0xABC
};
2 — api.rs:656 — both stored together in builder (still fine):
self.lora_models = Some(LoraStorage {
data, // owns CLibPath (heap buffer at 0xABC)
loras_t, // sd_lora_t.path = 0xABC ✓
});
3 — build() auto-generated by derive_builder — the clone:
// derive_builder generates something like:
lora_models: self.lora_models.clone()
// ^^^^^^^^^^^^^^^^^^^^^^^^
// Clone produces:
// data → NEW CLibPath (heap buffer at 0xDEF)
// loras_t → sd_lora_t.path = 0xABC ← still points to ORIGINAL
Then the builder drops → heap at 0xABC is freed → sd_lora_t.path is dangling.
The integration code on my side
base model works:
let mut builder = ModelConfigBuilder::default();
builder.model(path);
lora doesn't work:
builder.lora_models(&dir_path, specs) — but the pointer was dangling after build()
pointer dangles after build, resulting in:
The LoRA path sd.cpp receives is the temp output directory, not the lora directory. It should be /Users/user/.../loras/pixel-art-xl-v1.1.safetensors but instead it's the temp dir /var/folders/.../T/.tmpUvEJGV.
platform: OSX metal
diffusion-rs version: 0.1.18