现在需要将一台设备实时生成视频流文件存储到云端，但是在七牛的c-sdk中，没有发现类似于阿里云的文件追加上传接口，只有一个分片上传接口但是被封装起来了，没有类似的Demo。

阿里云相关接口：

void append_object_from_buffer()
{
    aos_pool_t *p = NULL;
    aos_string_t bucket;
    aos_string_t object;
    char *str = "test oss c sdk";
    aos_status_t *s = NULL;
    int64_t position = 0;
    aos_table_t *headers1 = NULL;
    aos_table_t *headers2 = NULL;
    aos_table_t *resp_headers = NULL;
    oss_request_options_t *options = NULL;
    aos_list_t buffer;
    aos_buf_t *content = NULL;
    char *next_append_position = NULL;
    aos_pool_create(&p, NULL);
    /* 创建并初始化options */
    options = oss_request_options_create(p);
    init_options(options);
    /* 初始化参数 */
    headers1 = aos_table_make(p, 0);
    aos_str_set(&bucket, "<您的bucket名字>");
    aos_str_set(&object, "<您的object名字>");
    /* 获取起始追加位置 */
    s = oss_head_object(options, &bucket, &object, headers1, &resp_headers);
    if (aos_status_is_ok(s)) {
        next_append_position = (char*)(apr_table_get(resp_headers, 
                        "x-oss-next-append-position"));
        position = atoi(next_append_position);
    }
    /* 追加文件 */
    headers2 = aos_table_make(p, 0);
    aos_list_init(&buffer);
    content = aos_buf_pack(p, str, strlen(str));
    aos_list_add_tail(&content->node, &buffer);
    s = oss_append_object_from_buffer(options, &bucket, &object, 
            position, &buffer, headers2, &resp_headers);
    /* 判断是否追加成功 */
    if (aos_status_is_ok(s))
    {
        printf("append object from buffer succeeded\n");
    } else {
        printf("append object from buffer failed\n");
    }
    /* 释放资源*/
    aos_pool_destroy(p);
}

七牛上有个好像是我需求的接口，但是没Demo和帮助文档，所以不知道该如何使用：

Qiniu_Error Qiniu_Io_PutStream(
        Qiniu_Client *self, Qiniu_Io_PutRet *ret,
        const char *uptoken, const char *key,
        void *ctx, size_t fsize, rdFunc rdr,
        Qiniu_Io_PutExtra *extra) {
    Qiniu_Io_form form;
    Qiniu_Io_form_init(&form, uptoken, key, &extra);

    if (key == NULL) {
        // Use an empty string instead of the NULL pointer to prevent the curl lib from crashing
        // when read it.
        // **NOTICE**: The magic variable $(filename) will be set as empty string.
        key = "";
    }

    // Add 'filename' property to make it like a file upload one
    // Otherwise it may report: CURL_ERROR(18) or "multipart/message too large"
    // See https://curl.haxx.se/libcurl/c/curl_formadd.html#CURLFORMSTREAM
    // FIXED by fengyh 2017-03-22 10:30
    curl_formadd(
            &form.formpost, &form.lastptr,
            CURLFORM_COPYNAME, "file",
            CURLFORM_FILENAME, "filename",
            CURLFORM_STREAM, ctx,
            CURLFORM_CONTENTSLENGTH, fsize,
            CURLFORM_END);

    return Qiniu_Io_call_with_callback(self, ret, form.formpost, rdr, extra);
}