Function botGetFile

botlib.c:499–558

This function should be called from the bot implementation callback. * If the bot request has a file (the user can see that by inspecting * the br->file_type field), then this function will attempt to download * the file from Telegram and store it in the current working directory * with the name 'br->file_id'. * * On success 1 is returned, otherwise 0. * When the function returns successful

 * When the function returns successfully, the caller can access
 * a file named 'br->file_id'. */
int botGetFile(BotRequest *br, const char *target_filename) {
    /* 1. Get the file information and path. */
    char *options[2];
    options[0] = "file_id";
    options[1] = br->file_id;

    int res;
    sds body = makeGETBotRequest("getFile",&res,options,1);
    if (res == 0) {
        sdsfree(body);
        return 0; // Error.
    }

    cJSON *json = cJSON_Parse(body);
    cJSON *result = cJSON_Select(json,".result.file_path:s");
    char *file_path = result ? result->valuestring : NULL;
    sdsfree(body);
    if (!file_path) {
        cJSON_Delete(json);
        return 0;
    }

    /* 2. Get the file content. */
    CURL* curl = curl_easy_init();
    if (!curl) {
        cJSON_Delete(json);
        return 0;
    }

    /* We need to open a file for writing. We will be
     * using the curl callback in order to append to the
     * file. */
    const char *filename = target_filename ? target_filename : br->file_id;
    FILE *fp = fopen(filename, "w");
    if (fp == NULL) {
        cJSON_Delete(json);
        curl_easy_cleanup(curl);
        return 0;
    }

    char url[1024];
    snprintf(url, sizeof(url),
        "https://api.telegram.org/file/bot%s/%s", Bot.apikey, file_path);
    cJSON_Delete(json);
    curl_easy_setopt(curl, CURLOPT_URL, url);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, makeHTTPGETCallWriterFILE);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &fp);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 1L);
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, 15);
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 15);

    /* Perform the request and cleanup. */
    int retval = curl_easy_perform(curl) == CURLE_OK ? 1 : 0;
    curl_easy_cleanup(curl);
    fclose(fp);
    /* Best effort removal of incomplete file. */
    if (retval == 0) unlink(filename);