cat_param_file.cc

// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <fstream>
#include <iostream>

// Read a bazel param file and concatentate the inputs.
// file is line delimited with each line a file to concat.
int main(int argc, char** argv) {
    if (argc != 3) {
        std::cerr << "usage: cat_param_file <param_file> <out>" << std::endl;
        std::cerr << "args " << argc << std::endl;
        return 2;
    }

    const char* param_file = argv[1];
    const char* out_file = argv[2];
    std::ifstream ifs(param_file, std::ios::binary);
    std::ofstream ofs(out_file, std::ios::binary);

    for (std::string line; std::getline(ifs, line);) {
        std::ifstream in(line, std::ios::binary);
        std::cerr << line << ":" << in.good() << std::endl;
        int read = 0;
        constexpr size_t kBufSize = 256;
        char buf[kBufSize];
        while (true) {
            read = 0;
            in.read(buf, kBufSize);
            read = in.gcount();
            if (read == 0) {
                break;
            }
            ofs.write(buf, read);
        }
    }

    ofs.flush();

    return 0;
}