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| author | nsfisis <nsfisis@gmail.com> | 2023-03-15 02:20:00 +0900 |
|---|---|---|
| committer | nsfisis <nsfisis@gmail.com> | 2023-03-16 14:05:15 +0900 |
| commit | 7b6319986030fc8a2fb5f851a431b5113e774f60 (patch) | |
| tree | 522cb3837707660373ddaf43da26bc2bf1dbc683 /content/posts/2022-11-19/phperkaigi-2023-unused-token-quiz-2.xml | |
| parent | bfac7998b0f7abd8dbde016535037cf1d3174336 (diff) | |
| download | blog.nsfisis.dev-7b6319986030fc8a2fb5f851a431b5113e774f60.tar.gz blog.nsfisis.dev-7b6319986030fc8a2fb5f851a431b5113e774f60.tar.zst blog.nsfisis.dev-7b6319986030fc8a2fb5f851a431b5113e774f60.zip | |
fix(content): fix XML notations
Diffstat (limited to 'content/posts/2022-11-19/phperkaigi-2023-unused-token-quiz-2.xml')
| -rw-r--r-- | content/posts/2022-11-19/phperkaigi-2023-unused-token-quiz-2.xml | 52 |
1 files changed, 33 insertions, 19 deletions
diff --git a/content/posts/2022-11-19/phperkaigi-2023-unused-token-quiz-2.xml b/content/posts/2022-11-19/phperkaigi-2023-unused-token-quiz-2.xml index bc93868..f1df049 100644 --- a/content/posts/2022-11-19/phperkaigi-2023-unused-token-quiz-2.xml +++ b/content/posts/2022-11-19/phperkaigi-2023-unused-token-quiz-2.xml @@ -28,7 +28,8 @@ <section xml:id="_問題"> <title>問題</title> <simpara>注意: これはボツ問なので、得られたトークンを PHPerKaigi で入力してもポイントにはならない。</simpara> - <programlisting language="php" linenumbering="unnumbered"><?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> + <programlisting language="php" linenumbering="unnumbered"> + <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> @@ -37,13 +38,15 @@ <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> - <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?></programlisting> + <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> + </programlisting> <simpara>"And Then There Were None" (そして誰もいなくなった) と名付けた作品。変則 quine (自分自身と同じソースコードを出力するプログラム) になっている。</simpara> </section> <section xml:id="_トークン入手方法"> <title>トークン入手方法</title> <simpara>実行してみると、次のような出力が得られる。</simpara> - <programlisting language="php" linenumbering="unnumbered"># + <programlisting language="php" linenumbering="unnumbered"> + # <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> @@ -52,9 +55,11 @@ <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> - <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?></programlisting> + <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> + </programlisting> <simpara>1 行目を除き、先ほどのコードとほぼ同じものが出てきた。もう一度実行してみる。</simpara> -<programlisting language="php" linenumbering="unnumbered"># +<programlisting language="php" linenumbering="unnumbered"> + # W <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> @@ -63,34 +68,43 @@ W <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> -<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?></programlisting> + <?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s='<?php printf((isset($s)?fn($s)=>trim($s,""):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> +</programlisting> <simpara>今度は 2 行目が書き換えられた。すべての行が変化するまで繰り返すと次のようになる。</simpara> -<programlisting language="php" linenumbering="unnumbered"># -W -E -L -O -V -E -P -H -P</programlisting> +<programlisting language="php" linenumbering="unnumbered"> + # + W + E + L + O + V + E + P + H + P +</programlisting> <simpara>トークン「#WELOVEPHP」が手に入った。</simpara> </section> <section xml:id="_解説"> <title>解説</title> <simpara>一見すると同じ行が 10 行並んでいるだけなのにも関わらず、なぜそれぞれの行で出力が変わるのか。ソースコードをコピーして、適当なエディタに貼り付けるとわかりやすい。</simpara> <simpara>Vim で開くと次のようになる (1 行目を抜粋)。</simpara> - <programlisting language="php" linenumbering="unnumbered"><?php printf((isset($s)?fn($s)=>trim($s,"<200b>"):fn($s)=>chr(strlen($s)/3))($s='<200b><?php printf((isset($s)?fn($s)=>trim($s,"<200b>"):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?></programlisting> + <programlisting language="php" linenumbering="unnumbered"> + <?php printf((isset($s)?fn($s)=>trim($s,"<200b>"):fn($s)=>chr(strlen($s)/3))($s='<200b><?php printf((isset($s)?fn($s)=>trim($s,"<200b>"):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>')."\n","\x27$s\x27");?> + </programlisting> <simpara><literal><200b></literal> と表示されているのは、Unicode の U+200b で、ゼロ幅スペースである。</simpara> <note> <simpara>エディタによっては、ゼロ幅スペースが見えないことがある。VSCode ではブラウザと同様に不可視だった。</simpara> </note> <simpara>文字列リテラルの中にゼロ幅スペースを仕込むことで、見た目を変えずに情報をエンコードすることが可能となる。</simpara> <simpara>続いて、トークンへの変換ロジックを解析する。注目すべきはこの部分だ。以下、ゼロ幅スペースは Vim での表示に合わせて <literal><200b></literal> と記載する。</simpara> - <programlisting language="php" linenumbering="unnumbered">fn($s)=>chr(strlen($s)/3)</programlisting> + <programlisting language="php" linenumbering="unnumbered"> + fn($s)=>chr(strlen($s)/3) + </programlisting> <simpara>PHP の <literal>strlen()</literal> は文字列のバイト数を返す。1 行目の <literal>$s</literal> は以下の内容となっており、</simpara> - <programlisting language="php" linenumbering="unnumbered">$s='<200b><?php printf((isset($s)?fn($s)=>trim($s,"<200b>"):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>'</programlisting> + <programlisting language="php" linenumbering="unnumbered"> + $s='<200b><?php printf((isset($s)?fn($s)=>trim($s,"<200b>"):fn($s)=>chr(strlen($s)/3))($s=%s)."\n","\x27$s\x27");?>' + </programlisting> <simpara>このソースコードは UTF-8 で書かれているので、105 バイトになる。それを 3 で割ると 35 となり、これは <literal>#</literal> の ASCII コードと一致する。他の行も、同様にしてゼロ幅スペースを詰めることで文字列長を調整し、トークンをエンコードしている。</simpara> <simpara>デコード部以外の部分は、quine のための記述である。</simpara> </section> |