I am trying to decompress lz4 archive like this.

#include <iostream>
#include <lz4.h>
#include <gflags/gflags.h>

#include <fstream>

#include "pcapng.hpp"

DEFINE_int32(t, 1, "Number");

int main(int argc, char *argv[]){
    gflags::ParseCommandLineFlags(&argc, &argv, true);

    std::vector<std::string> files;
    for (int i = 1; i < argc; ++i) {
        files.emplace_back(argv[i]);
    }

    int threadsNumber = FLAGS_t;

    for (const auto& fileName : files) {
        if (fileName.size() > 4 && fileName.substr(fileName.size() - 4) == ".lz4") {
            std::ifstream input(fileName, std::ios::binary);
            if (!input.is_open()) {
                std::cerr << "Error: File not found: " << fileName << std::endl;
                return 1;
            }
            input.seekg(0, std::ios::end);
            size_t compressed_size = input.tellg();
            input.seekg(0, std::ios::beg);

            // Read compressed data into a buffer
            std::vector<char> compressed_data(compressed_size);
            input.read(compressed_data.data(), compressed_size);

            std::vector<char> decompressed_data(compressed_size * 5);

            int decompressed_size = LZ4_decompress_safe(compressed_data.data(), decompressed_data.data(), compressed_data.size(), decompressed_data.size());
            if (decompressed_size >= 0) {
                decompressed_data.resize(decompressed_size);
                std::cout << "File decompressed: " << std::endl;
            } else {
                std::cerr << "Decompression failed for file: " << fileName << std::endl;
            }
        }
        else{

        }
    }

    return 0;
}

And I always go to Decompression failed for file with error code -4. But I can easy decompress using lz4 utility.

lz4 -d temp.lz4

it works without errors, but need the code. Also I read about lz4_frame. Probably I should to use frame decompression.