Question

我想在visual studio 2013中使用curl库（c ++）下载一些zip文件。使用我的代码进行的下载似乎运行良好，至少这是详细说明的输出。该文件总是比实际文件大一点，文件总是“损坏”，所以我用一些文本文件尝试它，它似乎随机添加一些行在文档的开头/结尾，并使随机空格/破坏形成。这是我的代码的卷曲部分：

//NOTE "CURL *curl" has already been used for previous requests and holds some cookies, so I won't paste the whole code here
//
//write to file function
size_t write_file(void *ptr, size_t size, size_t nmemb, FILE *stream) {
    size_t written = fwrite(ptr, size, nmemb, stream);
return written;
}

void download_file(string file_id){
    cout << "attempting to download file_id: " << file_id<< "\n";

    errno_t err; //error placeholder
    FILE * dl_file;

    string url = "http://foo.com/"; //base url

    string path_to_beatmap_file = "C:\\Users\\foo\\Desktop\\";
    string file_extension = ".txt";
    string full_filepath = path_to_beatmap_file + beatmap_id + file_extension;


    if (curl){
        cout << "attempting to download file to: " << full_filepath.c_str() << "\n";

        err = fopen_s(&dl_file, full_filepath.c_str(), "w+");
        if (err != 0){
            cout << "error: could not create file\n";
            return;
        }

        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1); //need this since 1 redirect
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_file);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, dl_file);
        curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); //shows some debug output
        CURLcode res = curl_easy_perform(curl); //execute download request
    }
    else{
        cout << "error: could not download file, no connection avaible\n";
        return;
    }




    cout << "\n\ndownloaded\n";


    if (fclose(dl_file) == 0){ cout << "closed the stream to file"; }
    else{ cout << "failed closing file"; }
}

如果我在notepad ++中打开txt文件，它会在文件的结尾处显示一堆空值或子值，但我似乎无法在此处粘贴它们。

非常感谢帮助。

更新似乎添加的随机文本是一些随机的ASCII字符（我使用调试功能在控制台中打印输出，并且有一些右箭头字符，但我不认为我可以通过删除所有右箭头字符来解决这个问题只要）。有什么想法吗？

Answer 1

显然在fopen上使用“wb”参数（写二进制）（在fopen_s上也一样）解决了所有格式化问题，现在一切正常。

libcurl在下载文件时损坏数据

1 个答案: