HTTPレスポンス内に含まれる日本語がUnicode文字になる。

前提と問題

curlを用いてMediaWikiのAPIを叩き、特定のページのwikitextを得るプログラムを、C++を用いて組んでいます。実行時、レスポンス自体は正しく返ってくる(ステータスコードが200)のですが、レスポンスに含まれる日本語がUnicode文字として返ってきてしまいます。

実現したいこと

レスポンスを、後述の期待する出力の項に示されるような形式で得たい。

該当のソースコード

以下Main()関数内。変数urlはUITF8でパーセントエンコーディングされたURL。

c++
1	CURL* curl = curl_easy_init();
2	Buffer* buf = new Buffer();
3
4	//ヘッダー
5	curl_slist* headers = nullptr;
6	headers = curl_slist_append(headers, "Content-Type : application/json; charset=utf-8");
7
8	curl_easy_setopt(curl, CURLOPT_URL, url);
9	curl_easy_setopt(curl, CURLOPT_WRITEDATA, buf);
10	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, callback);
11	curl_easy_setopt(curl, CURLOPT_HEADER, headers);
12	curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "UTF-8");
13
14
15	curl_easy_perform(curl);
16	long* response_code = (long*)malloc(sizeof(long));
17
18	//ステータスコード
19	curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, response_code);
20
21	char end = '\0';
22	buf->data = (char*)realloc(buf->data, buf->data_size + sizeof(char));
23
24	memcpy(buf->data + buf->data_size, &end, sizeof(char));
25
26	curl_easy_cleanup(curl);
27
28	delete(buf);

以下Main()内で使用した自作関数と自作クラス

c++
1struct Buffer {
2	char* data = nullptr;
3	int data_size = 0;
4};
5
6
7//curlのコールバック
8size_t callback(void* buffer, size_t size, size_t nmemb, void* userp) {
9	size_t realsize = size * nmemb;
10	Buffer* buf = (Buffer*)userp;
11	if (buf == nullptr) return realsize;
12
13	if (!buf->data) {
14		buf->data = (char*)malloc(realsize);
15	}
16	else {
17		buf->data = (char*)realloc(buf->data, buf->data_size + realsize);
18	}
19
20	if (buf->data) {
21		memcpy(buf->data + buf->data_size, buffer, realsize);
22		buf->data_size += realsize;
23	}
24
25	return realsize;
26}
27

コード実行時の、curl_easy_cleanup(curl);でブレークした際のbuf->dataの内容

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 2185
content-type: application/json; charset=utf-8
x-content-type-options: nosniff
x-frame-options: DENY
content-disposition: inline; filename=api-result.json
cache-control: private, must-revalidate, max-age=0
x-envoy-upstream-service-time: 70
X-Datacenter: SJC
Accept-Ranges: bytes
X-Cacheable: NO:Cache-Control=private
Date: Thu, 05 May 2022 15:09:07 GMT
X-Served-By: cache-wk-sjc11421-SJC, cache-tyo11922-TYO
X-Cache: MISS, MISS
X-Cache-Hits: 0, 0
X-Timer: S1651763347.149674,VS0,VE177
Vary: Accept-Encoding, Treat-as-Untrusted, Cookie
Set-Cookie: wikia_beacon_id=YH1Gq-ALwC; domain=.fandom.com; path=/; expires=Tue, 01 Nov 2022 15:09:07 GMT; SameSite=None; Secure;
Set-Cookie: wikia_session_id=zjwddvu88d; domain=.fandom.com; path=/; expires=Thu, 05 May 2022 15:39:07 GMT; SameSite=None; Secure;
Set-Cookie: _b2=ZYE7xfiRcH.1651763347150; domain=.fandom.com; path=/; expires=Sat, 04 May 2024 15:09:07 GMT; SameSite=None; Secure;
Set-Cookie: Geo={%22region%22:%2208%22%2C%22city%22:%22tsukuba%22%2C%22country_name%22:%22japan%22%2C%22country%22:%22JP%22%2C%22continent%22:%22AS%22}; path=/; domain=.fandom.com; SameSite=None; Secure;

{"parse":{"title":"SCP-165-JP \u30d8\u30a4\u30eb\u30b0\u30ed\u30fc\u30d6","pageid":6907,"wikitext":{"*":"{{Cardtable| card_type = \u30aa\u30d6\u30b8\u30a7\u30af\u30c8| sub_type = | type = Euclid| number = 165| name = SCP-165-JP \u30d8\u30a4\u30eb\u30b0\u30ed\u30fc\u30d6| image =420dfff8-eccc-4ee0-8092-50f2734d8d53.jpg| object_class =Euclid| attack =0| cost =2| effect_text =\u2460\u3053\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f\u8ca1\u56e3\u4e0a\u3092\u96e2\u308c\u306a\u3044\u3002<br> \u2461\u81ea\u5206\u306e\u30bf\u30fc\u30f3\u958b\u59cb\u6642\u306b\u767a\u52d5\u3059\u308b\u3002\u81ea\u5206\u307e\u305f\u306f\u76f8\u624b\u4eba\u4e8b\u3092\u3053\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4e0b\u306b\u91cd\u306d\u308b\u3002<br> \u2462\u2461\u306e\u52b9\u679c\u3092\u767a\u52d5\u3057\u3066\u304b\u30895\u30bf\u30fc\u30f3\u5f8c\u306e\u30bf\u30fc\u30f3\u7d42\u4e86\u6642\u306b\u767a\u52d5\u3059\u308b\u3002\u3053\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4e0b\u306b\u5b58\u5728\u3059\u308b\u4eba\u4e8b\u3092decommissioned\u306b\u9001\u308b\u3002<br>| flavor_text = \u5c0f\u585a\u7814\u7a76\u54e1: \u8336\u8272\u3058\u3083\u3054\u4e0d\u6e80\u304b\u3002<br><br>SCP-165-JP-A: \u52ff\u8ad6\uff01 \u3082\u3046\u5c11\u3057\u660e\u308b\u3044\u8272\u306e\u65b9\u304c\u3044\u3044\u306d\u3002<br> \u305d\u308c\u3068\u3053\u306e\u5b89\u3063\u307d\u3055\u304c\u6c17\u306b\u5165\u3089\u306a\u3044\u30022000\u5186\u3082\u3057\u306a\u3044\u306a\u3053\u308c\u306f\u3002<br>| tags =scp-jp \u4eba\u9593\u578b \u5bb9\u5668 \u77ac\u9593\u79fb\u52d5 \u7cbe\u795e\u5f71\u97ff| limited = | effect_tags = |source =<span class=\"ui_wikidb_title\">\u51fa\u5178</span>&nbsp;JP<br><span class=\"ui_bottom_detail\">\"kasyu-maki\"\u4f5c SCP-165-JP - \u30d8\u30a4\u30eb\u30b0\u30ed\u30fc\u30d6<br>\"https://scptcgjpjwiki.gamerch.com/gamerch/external_link/?url=http%3A%2F%2Fja.scp-wiki.net%2Fscp-165-jp\" http://ja.scp-wiki.net/scp-165-jp<br><br>\u30ab\u30fc\u30c9\u516c\u958b\u5148<br>\"https://scptcgjpjwiki.gamerch.com/gamerch/external_link/?url=https%3A%2F%2Ftwitter.com%2Fkeroyu_scp%2Fstatus%2F1283263861898932224\" https://twitter.com/keroyu_scp/status/1283263861898932224<br></span>}}"}}}

期待する出力

HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 2185
content-type: application/json; charset=utf-8
x-content-type-options: nosniff
x-frame-options: DENY
content-disposition: inline; filename=api-result.json
cache-control: private, must-revalidate, max-age=0
x-envoy-upstream-service-time: 70
X-Datacenter: SJC
Accept-Ranges: bytes
X-Cacheable: NO:Cache-Control=private
Date: Thu, 05 May 2022 15:09:07 GMT
X-Served-By: cache-wk-sjc11421-SJC, cache-tyo11922-TYO
X-Cache: MISS, MISS
X-Cache-Hits: 0, 0
X-Timer: S1651763347.149674,VS0,VE177
Vary: Accept-Encoding, Treat-as-Untrusted, Cookie
Set-Cookie: wikia_beacon_id=YH1Gq-ALwC; domain=.fandom.com; path=/; expires=Tue, 01 Nov 2022 15:09:07 GMT; SameSite=None; Secure;
Set-Cookie: wikia_session_id=zjwddvu88d; domain=.fandom.com; path=/; expires=Thu, 05 May 2022 15:39:07 GMT; SameSite=None; Secure;
Set-Cookie: _b2=ZYE7xfiRcH.1651763347150; domain=.fandom.com; path=/; expires=Sat, 04 May 2024 15:09:07 GMT; SameSite=None; Secure;
Set-Cookie: Geo={%22region%22:%2208%22%2C%22city%22:%22tsukuba%22%2C%22country_name%22:%22japan%22%2C%22country%22:%22JP%22%2C%22continent%22:%22AS%22}; path=/; domain=.fandom.com; SameSite=None; Secure;

{"parse":{"title":"SCP-165-JP ヘイルグローブ","pageid":6907,"wikitext":{"*":"{{Cardtable| card_type = オブジェクト| sub_type = | type = Euclid| number = 165| name = SCP-165-JP ヘイルグローブ| image =420dfff8-eccc-4ee0-8092-50f2734d8d53.jpg| object_class =Euclid| attack =0| cost =2| effect_text =①このオブジェクトは財団上を離れない。<br> ②自分のターン開始時に発動する。自分または相手人事をこのオブジェクトの下に重ねる。<br> ③②の効果を発動してから5ターン後のターン終了時に発動する。このオブジェクトの下に存在する人事をdecommissionedに送る。<br>| flavor_text = 小塚研究員: 茶色じゃご不満か。<br><br>SCP-165-JP-A: 勿論！ もう少し明るい色の方がいいね。<br> それとこの安っぽさが気に入らない。2000円もしないなこれは。<br>| tags =scp-jp 人間型 容器 瞬間移動 精神影響| limited = | effect_tags = |source =<span class="ui_wikidb_title">出典</span>&nbsp;JP<br><span class="ui_bottom_detail">"kasyu-maki"作 SCP-165-JP - ヘイルグローブ<br>"https://scptcgjpjwiki.gamerch.com/gamerch/external_link/?url=http%3A%2F%2Fja.scp-wiki.net%2Fscp-165-jp" http://ja.scp-wiki.net/scp-165-jp<br><br>カード公開先<br>"https://scptcgjpjwiki.gamerch.com/gamerch/external_link/?url=https%3A%2F%2Ftwitter.com%2Fkeroyu_scp%2Fstatus%2F1283263861898932224" https://twitter.com/keroyu_scp/status/1283263861898932224<br></span>}}"}}}