// libFuzzer harness for the .dinodata loader: arbitrary bytes -> temp file ->
// trellis2_load_dinodata -> (on success) fingerprints over the payload.
//
// .dinodata files typically come from this codebase itself, but the demo and
// CLI accept arbitrary paths, so the parser must be robust: reject bad magic /
// truncated headers / shape overflow cleanly, never over-read.
//
// Invariants checked with abort() (not just "no crash"):
//   * on success, data.size() == product(shape) and shape is non-empty
//   * fingerprints run over the whole payload without UB
//
// Run: ./build-fuzz/fuzz/fuzz_dinodata corpus_dinodata/ -max_len=1048576

#include "../trellis2.h"

#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <unistd.h>

extern "C" int LLVMFuzzerTestOneInput(const uint8_t * data, size_t size) {
    if (size > (16u << 20)) {
        return 0;
    }

    char path[] = "/tmp/fuzz_dinodata_XXXXXX";
    const int fd = mkstemp(path);
    if (fd < 0) {
        return 0;
    }
    const ssize_t written = write(fd, data, size);
    close(fd);
    if (written != (ssize_t) size) {
        unlink(path);
        return 0;
    }

    trellis2_dino_cond cond;
    std::string err;
    if (trellis2_load_dinodata(path, cond, &err)) {
        int64_t total = 1;
        for (int64_t d : cond.shape) total *= d;
        if (cond.shape.empty() || (size_t) total != cond.data.size()) {
            abort();   // loader produced an inconsistent cond
        }
        const trellis2_dino_fingerprint fp = trellis2_dino_fingerprints(cond);
        if (fp.count != cond.data.size()) {
            abort();
        }
    } else if (err.empty()) {
        abort();       // failure must come with a reason
    }

    unlink(path);
    return 0;
}