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Diffstat (limited to 'services/nuldoc/public/blog/posts/2025-01-08')
| -rw-r--r-- | services/nuldoc/public/blog/posts/2025-01-08/phperkaigi-2023-tokens-q1/index.html | 254 |
1 files changed, 131 insertions, 123 deletions
diff --git a/services/nuldoc/public/blog/posts/2025-01-08/phperkaigi-2023-tokens-q1/index.html b/services/nuldoc/public/blog/posts/2025-01-08/phperkaigi-2023-tokens-q1/index.html index 7231d693..3b35dd5b 100644 --- a/services/nuldoc/public/blog/posts/2025-01-08/phperkaigi-2023-tokens-q1/index.html +++ b/services/nuldoc/public/blog/posts/2025-01-08/phperkaigi-2023-tokens-q1/index.html @@ -167,7 +167,8 @@ まずはトークンを得る方法を解説抜きで説明する。次のように実行する。 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span>$ echo "#iwillblog" | php Q1.png >/dev/null</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code>$ echo "#iwillblog" | php Q1.png >/dev/null +</code></pre> </div> <p> 無事に実行できていれば「#ModernPHPisStaticallyTypedLanguage」というトークンが得られる。 @@ -181,7 +182,8 @@ まずは素直に画像として見てみよう。全体は QR コードになっている。適当な QR コードリーダで読み込むと、次のようなテキストが表示されるはずだ。 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span>Guess password. $ echo "password" | php Q1.png >/dev/null</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code>Guess password. $ echo "password" | php Q1.png >/dev/null +</code></pre> </div> <p> メッセージは、この画像の実行方法とこの問題でやるべきこと (パスワードの推測) を示している。 @@ -196,8 +198,9 @@ 不正なパスワードを使って実行してみると、次のようなエラーメッセージが表示される。 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span>$ echo "foo" | php Q1.png >/dev/null</span></span> -<span class="line"><span>401 Unauthorized</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code>$ echo "foo" | php Q1.png >/dev/null +401 Unauthorized +</code></pre> </div> <p> すでに <a href="#section--how-to-solve">「解き方」の節</a> で示したように、パスワードである PHPer トークンは「#iwillblog」である。これを与えて実行すると正解のトークンが得られる。 @@ -267,23 +270,25 @@ <code>strings</code> コマンドを使うと、隠されたデータを簡単に閲覧できる。 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span>IHDR</span></span> -<span class="line"><span>-HHc</span></span> -<span class="line"><span><PLTE</span></span> -<span class="line"><span>IDATx</span></span> -<span class="line"><span>IEND</span></span> -<span class="line"><span><?php</span></span> -<span class="line"><span>error_reporting(-1);</span></span> -<span class="line"><span>$b = unpack('C*', file_get_contents(__FILE__));</span></span> -<span class="line"><span>$w = $b[20]+2;</span></span> -<span class="line"><span>$h = $b[24]+2;</span></span> -<span class="line"><span>// (以下略)</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code>IHDR +-HHc +<PLTE +IDATx +IEND +<?php +error_reporting(-1); +$b = unpack('C*', file_get_contents(__FILE__)); +$w = $b[20]+2; +$h = $b[24]+2; +// (以下略) +</code></pre> </div> <p> <code>IHDR</code> や <code>IEND</code> が PNG 画像の一部で、<code><?php</code> からが実際のプログラムになっている。もちろんこれを PHP プログラムとして動かすと、PHP タグより前にある PNG 画像としてのデータはそのまま標準出力へと出力されてしまう。それを防ぐため、QR コードを読み込んだときの実行方法 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span>Guess password. $ echo "password" | php Q1.png >/dev/null</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code>Guess password. $ echo "password" | php Q1.png >/dev/null +</code></pre> </div> <p> には標準出力を捨てるよう <code>>/dev/null</code> と指定されている。 @@ -298,107 +303,108 @@ 画像の正体がわかったところで、画像に隠されていた PHP プログラムについて見ていこう。先ほどは一部しか記載しなかったので、全体を載せる。なお、ある程度ゴルフしながら書いたので、空白こそ残しているものの可読性は非常に低いことと思う。 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span style="color:#D73A49"><?</span><span style="color:#005CC5">php</span></span> -<span class="line"><span style="color:#005CC5">error_reporting</span><span style="color:#24292E">(</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">);</span></span> -<span class="line"><span style="color:#24292E">$b </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> unpack</span><span style="color:#24292E">(</span><span style="color:#032F62">'C*'</span><span style="color:#24292E">, </span><span style="color:#005CC5">file_get_contents</span><span style="color:#24292E">(</span><span style="color:#005CC5">__FILE__</span><span style="color:#24292E">));</span></span> -<span class="line"><span style="color:#24292E">$w </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $b[</span><span style="color:#005CC5">20</span><span style="color:#24292E">]</span><span style="color:#D73A49">+</span><span style="color:#005CC5">2</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$h </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $b[</span><span style="color:#005CC5">24</span><span style="color:#24292E">]</span><span style="color:#D73A49">+</span><span style="color:#005CC5">2</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$cs </span><span style="color:#D73A49">=</span><span style="color:#24292E"> [];</span></span> -<span class="line"><span style="color:#D73A49">for</span><span style="color:#24292E"> ($y </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">; $y </span><span style="color:#D73A49"><</span><span style="color:#24292E"> $h; $y</span><span style="color:#D73A49">++</span><span style="color:#24292E">)</span></span> -<span class="line"><span style="color:#D73A49"> for</span><span style="color:#24292E"> ($x </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">; $x </span><span style="color:#D73A49"><</span><span style="color:#24292E"> $w; $x</span><span style="color:#D73A49">++</span><span style="color:#24292E">)</span></span> -<span class="line"><span style="color:#24292E"> $cs[$y</span><span style="color:#D73A49">*</span><span style="color:#24292E">$w </span><span style="color:#D73A49">+</span><span style="color:#24292E"> $x] </span><span style="color:#D73A49">=</span><span style="color:#24292E"> ($x</span><span style="color:#D73A49">*</span><span style="color:#24292E">$y </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 0</span><span style="color:#D73A49"> ||</span><span style="color:#24292E"> $x </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $w</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#D73A49"> ||</span><span style="color:#24292E"> $y </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $h</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">)</span></span> -<span class="line"><span style="color:#D73A49"> ?</span><span style="color:#005CC5"> 0</span></span> -<span class="line"><span style="color:#D73A49"> :</span><span style="color:#24292E"> $b[</span><span style="color:#005CC5">122</span><span style="color:#D73A49">+</span><span style="color:#24292E">($y</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">)</span><span style="color:#D73A49">*</span><span style="color:#24292E">($w</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">)</span><span style="color:#D73A49">+</span><span style="color:#24292E">$x</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">];</span></span> -<span class="line"><span style="color:#24292E">$i </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> stream_isatty</span><span style="color:#24292E">(</span><span style="color:#005CC5">STDIN</span><span style="color:#24292E">)</span></span> -<span class="line"><span style="color:#D73A49"> ?</span><span style="color:#24292E"> []</span></span> -<span class="line"><span style="color:#D73A49"> :</span><span style="color:#005CC5"> array_map</span><span style="color:#24292E">(</span><span style="color:#005CC5">ord</span><span style="color:#24292E">(</span><span style="color:#D73A49">...</span><span style="color:#24292E">), </span><span style="color:#005CC5">str_split</span><span style="color:#24292E">(</span><span style="color:#005CC5">trim</span><span style="color:#24292E">((</span><span style="color:#D73A49">string</span><span style="color:#24292E">) </span><span style="color:#005CC5">fgets</span><span style="color:#24292E">(</span><span style="color:#005CC5">STDIN</span><span style="color:#24292E">))));</span></span> -<span class="line"><span style="color:#24292E">$m </span><span style="color:#D73A49">=</span><span style="color:#24292E"> [];</span></span> -<span class="line"><span style="color:#24292E">$pc </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 1</span><span style="color:#D73A49">*</span><span style="color:#24292E">$w</span><span style="color:#D73A49">+</span><span style="color:#005CC5">1</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$dp </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$cc </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 1</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$c0 </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 1</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$b </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$ns </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E">$o </span><span style="color:#D73A49">=</span><span style="color:#032F62"> ''</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#D73A49">while</span><span style="color:#24292E"> (</span><span style="color:#005CC5">true</span><span style="color:#24292E">) {</span></span> -<span class="line"><span style="color:#24292E"> $ns</span><span style="color:#D73A49">++</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($ns </span><span style="color:#D73A49">></span><span style="color:#005CC5"> 1e5</span><span style="color:#24292E">) {</span></span> -<span class="line"><span style="color:#005CC5"> echo</span><span style="color:#032F62"> "infinite loop detected</span><span style="color:#005CC5">\n</span><span style="color:#032F62">"</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#D73A49"> break</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E"> $c1 </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $cs[$pc];</span></span> -<span class="line"><span style="color:#24292E"> $y </span><span style="color:#D73A49">=</span><span style="color:#24292E"> (</span><span style="color:#005CC5">6</span><span style="color:#D73A49"> +</span><span style="color:#005CC5"> intdiv</span><span style="color:#24292E">($c1</span><span style="color:#D73A49">-</span><span style="color:#005CC5">2</span><span style="color:#24292E">, </span><span style="color:#005CC5">3</span><span style="color:#24292E">) </span><span style="color:#D73A49">-</span><span style="color:#005CC5"> intdiv</span><span style="color:#24292E">($c0</span><span style="color:#D73A49">-</span><span style="color:#005CC5">2</span><span style="color:#24292E">, </span><span style="color:#005CC5">3</span><span style="color:#24292E">)) </span><span style="color:#D73A49">%</span><span style="color:#005CC5"> 6</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E"> $x </span><span style="color:#D73A49">=</span><span style="color:#24292E"> (</span><span style="color:#005CC5">3</span><span style="color:#D73A49"> +</span><span style="color:#24292E"> $c1</span><span style="color:#D73A49">%</span><span style="color:#005CC5">3</span><span style="color:#D73A49"> -</span><span style="color:#24292E"> $c0</span><span style="color:#D73A49">%</span><span style="color:#005CC5">3</span><span style="color:#24292E">) </span><span style="color:#D73A49">%</span><span style="color:#005CC5"> 3</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#D73A49"> match</span><span style="color:#24292E"> (($c0 </span><span style="color:#D73A49">!==</span><span style="color:#005CC5"> 1</span><span style="color:#24292E">) </span><span style="color:#D73A49">*</span><span style="color:#24292E"> ($c1 </span><span style="color:#D73A49">!==</span><span style="color:#005CC5"> 1</span><span style="color:#24292E">) </span><span style="color:#D73A49">*</span><span style="color:#24292E"> ($y</span><span style="color:#D73A49">*</span><span style="color:#005CC5">3</span><span style="color:#D73A49"> +</span><span style="color:#24292E"> $x)) {</span></span> -<span class="line"><span style="color:#005CC5"> 1</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $m[] </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $b,</span></span> -<span class="line"><span style="color:#005CC5"> 2</span><span style="color:#D73A49"> =></span><span style="color:#005CC5"> array_pop</span><span style="color:#24292E">($m),</span></span> -<span class="line"><span style="color:#005CC5"> 3</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $m[] </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> array_pop</span><span style="color:#24292E">($m) </span><span style="color:#D73A49">+</span><span style="color:#005CC5"> array_pop</span><span style="color:#24292E">($m),</span></span> -<span class="line"><span style="color:#005CC5"> 4</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $m[] </span><span style="color:#D73A49">=</span><span style="color:#24292E"> (</span><span style="color:#D73A49">fn</span><span style="color:#24292E">($x, $y) => $y </span><span style="color:#D73A49">-</span><span style="color:#24292E"> $x)(</span><span style="color:#005CC5">array_pop</span><span style="color:#24292E">($m), </span><span style="color:#005CC5">array_pop</span><span style="color:#24292E">($m)),</span></span> -<span class="line"><span style="color:#005CC5"> 5</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $m[] </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> array_pop</span><span style="color:#24292E">($m) </span><span style="color:#D73A49">*</span><span style="color:#005CC5"> array_pop</span><span style="color:#24292E">($m),</span></span> -<span class="line"><span style="color:#005CC5"> 8</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $m[] </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> array_pop</span><span style="color:#24292E">($m) </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 0</span><span style="color:#D73A49"> ?</span><span style="color:#005CC5"> 1</span><span style="color:#D73A49"> :</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">,</span></span> -<span class="line"><span style="color:#005CC5"> 11</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $cc </span><span style="color:#D73A49">*=</span><span style="color:#005CC5"> pow</span><span style="color:#24292E">(</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">, </span><span style="color:#005CC5">array_pop</span><span style="color:#24292E">($m)),</span></span> -<span class="line"><span style="color:#005CC5"> 12</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $m[] </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $m[</span><span style="color:#005CC5">count</span><span style="color:#24292E">($m)</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">],</span></span> -<span class="line"><span style="color:#005CC5"> 13</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $m </span><span style="color:#D73A49">=</span><span style="color:#24292E"> (</span><span style="color:#D73A49">fn</span><span style="color:#24292E">($n, $d, $m, $l) => [</span></span> -<span class="line"><span style="color:#D73A49"> ...</span><span style="color:#005CC5">array_slice</span><span style="color:#24292E">($m, </span><span style="color:#005CC5">0</span><span style="color:#24292E">, $l</span><span style="color:#D73A49">-</span><span style="color:#24292E">$d),</span></span> -<span class="line"><span style="color:#D73A49"> ...</span><span style="color:#005CC5">array_reverse</span><span style="color:#24292E">([</span></span> -<span class="line"><span style="color:#D73A49"> ...</span><span style="color:#005CC5">array_reverse</span><span style="color:#24292E">(</span><span style="color:#005CC5">array_slice</span><span style="color:#24292E">($m, $l</span><span style="color:#D73A49">-</span><span style="color:#24292E">$d, $d</span><span style="color:#D73A49">-</span><span style="color:#24292E">$n)),</span></span> -<span class="line"><span style="color:#D73A49"> ...</span><span style="color:#005CC5">array_reverse</span><span style="color:#24292E">(</span><span style="color:#005CC5">array_slice</span><span style="color:#24292E">($m, $l</span><span style="color:#D73A49">-</span><span style="color:#24292E">$n)),</span></span> -<span class="line"><span style="color:#24292E"> ]),</span></span> -<span class="line"><span style="color:#24292E"> ])(</span><span style="color:#005CC5">array_pop</span><span style="color:#24292E">($m), </span><span style="color:#005CC5">array_pop</span><span style="color:#24292E">($m), $m, </span><span style="color:#005CC5">count</span><span style="color:#24292E">($m)),</span></span> -<span class="line"><span style="color:#005CC5"> 15</span><span style="color:#D73A49"> =></span><span style="color:#D73A49"> !</span><span style="color:#005CC5">empty</span><span style="color:#24292E">($i) </span><span style="color:#D73A49">and</span><span style="color:#24292E"> $m[] </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> array_shift</span><span style="color:#24292E">($i),</span></span> -<span class="line"><span style="color:#005CC5"> 16</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $o </span><span style="color:#D73A49">.=</span><span style="color:#005CC5"> sprintf</span><span style="color:#24292E">(</span><span style="color:#032F62">'%d'</span><span style="color:#24292E">, </span><span style="color:#005CC5">array_pop</span><span style="color:#24292E">($m)),</span></span> -<span class="line"><span style="color:#005CC5"> 17</span><span style="color:#D73A49"> =></span><span style="color:#24292E"> $o </span><span style="color:#D73A49">.=</span><span style="color:#005CC5"> sprintf</span><span style="color:#24292E">(</span><span style="color:#032F62">'%c'</span><span style="color:#24292E">, </span><span style="color:#005CC5">array_pop</span><span style="color:#24292E">($m)),</span></span> -<span class="line"><span style="color:#D73A49"> default</span><span style="color:#D73A49"> =></span><span style="color:#032F62"> 'nop'</span><span style="color:#24292E">,</span></span> -<span class="line"><span style="color:#24292E"> };</span></span> -<span class="line"><span style="color:#24292E"> $c0 </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $c1;</span></span> -<span class="line"><span style="color:#D73A49"> for</span><span style="color:#24292E"> ($j </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">; $j </span><span style="color:#D73A49"><</span><span style="color:#005CC5"> 8</span><span style="color:#24292E">; $j</span><span style="color:#D73A49">++</span><span style="color:#24292E">) {</span></span> -<span class="line"><span style="color:#24292E"> $v </span><span style="color:#D73A49">=</span><span style="color:#24292E"> [];</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($c1 </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 1</span><span style="color:#24292E">) {</span></span> -<span class="line"><span style="color:#24292E"> $x </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $pc </span><span style="color:#D73A49">%</span><span style="color:#24292E"> $w;</span></span> -<span class="line"><span style="color:#24292E"> $y </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> intdiv</span><span style="color:#24292E">($pc, $w);</span></span> -<span class="line"><span style="color:#24292E"> $e </span><span style="color:#D73A49">=</span><span style="color:#24292E"> [($y</span><span style="color:#D73A49">+</span><span style="color:#005CC5">1</span><span style="color:#24292E">)</span><span style="color:#D73A49">*</span><span style="color:#24292E">$w</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">, ($h</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">)</span><span style="color:#D73A49">*</span><span style="color:#24292E">$w</span><span style="color:#D73A49">+</span><span style="color:#24292E">$x, $y</span><span style="color:#D73A49">*</span><span style="color:#24292E">$w, $x][$dp];</span></span> -<span class="line"><span style="color:#24292E"> $z </span><span style="color:#D73A49">=</span><span style="color:#24292E"> [</span><span style="color:#005CC5">1</span><span style="color:#24292E">, $w, </span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">, </span><span style="color:#D73A49">-</span><span style="color:#24292E">$w][$dp];</span></span> -<span class="line"><span style="color:#D73A49"> for</span><span style="color:#24292E"> ($ep </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $pc; $ep </span><span style="color:#D73A49">!==</span><span style="color:#24292E"> $e; $ep </span><span style="color:#D73A49">+=</span><span style="color:#24292E"> $z)</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($cs[$ep] </span><span style="color:#D73A49">!==</span><span style="color:#005CC5"> 1</span><span style="color:#24292E">) </span><span style="color:#D73A49">break</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E"> $ep </span><span style="color:#D73A49">-=</span><span style="color:#24292E"> $z;</span></span> -<span class="line"><span style="color:#24292E"> $pc </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $ep;</span></span> -<span class="line"><span style="color:#24292E"> } </span><span style="color:#D73A49">else</span><span style="color:#24292E"> {</span></span> -<span class="line"><span style="color:#24292E"> $q </span><span style="color:#D73A49">=</span><span style="color:#24292E"> [$pc];</span></span> -<span class="line"><span style="color:#24292E"> $ep </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $pc;</span></span> -<span class="line"><span style="color:#D73A49"> while</span><span style="color:#24292E"> (</span><span style="color:#D73A49">!</span><span style="color:#005CC5">empty</span><span style="color:#24292E">($q)) {</span></span> -<span class="line"><span style="color:#24292E"> $qq </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> array_pop</span><span style="color:#24292E">($q);</span></span> -<span class="line"><span style="color:#24292E"> $v[$qq] </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> true</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#D73A49"> foreach</span><span style="color:#24292E"> ([$qq</span><span style="color:#D73A49">+</span><span style="color:#005CC5">1</span><span style="color:#24292E">, $qq</span><span style="color:#D73A49">+</span><span style="color:#24292E">$w, $qq</span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">, $qq</span><span style="color:#D73A49">-</span><span style="color:#24292E">$w] </span><span style="color:#D73A49">as</span><span style="color:#24292E"> $qp) {</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($cs[$qp] </span><span style="color:#D73A49">!==</span><span style="color:#24292E"> $c1) </span><span style="color:#D73A49">continue</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> (</span><span style="color:#005CC5">isset</span><span style="color:#24292E">($v[$qp])) </span><span style="color:#D73A49">continue</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E"> $q[] </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $qp;</span></span> -<span class="line"><span style="color:#24292E"> $qx </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $qp </span><span style="color:#D73A49">%</span><span style="color:#24292E"> $w;</span></span> -<span class="line"><span style="color:#24292E"> $qy </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> intdiv</span><span style="color:#24292E">($qp, $w);</span></span> -<span class="line"><span style="color:#24292E"> $x </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $ep </span><span style="color:#D73A49">%</span><span style="color:#24292E"> $w;</span></span> -<span class="line"><span style="color:#24292E"> $y </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> intdiv</span><span style="color:#24292E">($ep, $w);</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> (</span></span> -<span class="line"><span style="color:#24292E"> ($dp </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 0</span><span style="color:#D73A49"> &&</span><span style="color:#24292E"> ($x </span><span style="color:#D73A49"><</span><span style="color:#24292E"> $qx </span><span style="color:#D73A49">||</span><span style="color:#24292E"> ($x </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $qx </span><span style="color:#D73A49">&&</span><span style="color:#24292E"> ($y</span><span style="color:#D73A49"><=></span><span style="color:#24292E">$qy) </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $cc)))</span></span> -<span class="line"><span style="color:#D73A49"> ||</span><span style="color:#24292E"> ($dp </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 1</span><span style="color:#D73A49"> &&</span><span style="color:#24292E"> ($y </span><span style="color:#D73A49"><</span><span style="color:#24292E"> $qy </span><span style="color:#D73A49">||</span><span style="color:#24292E"> ($y </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $qy </span><span style="color:#D73A49">&&</span><span style="color:#24292E"> ($qx</span><span style="color:#D73A49"><=></span><span style="color:#24292E">$x) </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $cc)))</span></span> -<span class="line"><span style="color:#D73A49"> ||</span><span style="color:#24292E"> ($dp </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 2</span><span style="color:#D73A49"> &&</span><span style="color:#24292E"> ($qx </span><span style="color:#D73A49"><</span><span style="color:#24292E"> $x </span><span style="color:#D73A49">||</span><span style="color:#24292E"> ($qx </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $x </span><span style="color:#D73A49">&&</span><span style="color:#24292E"> ($qy</span><span style="color:#D73A49"><=></span><span style="color:#24292E">$y) </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $cc)))</span></span> -<span class="line"><span style="color:#D73A49"> ||</span><span style="color:#24292E"> ($dp </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 3</span><span style="color:#D73A49"> &&</span><span style="color:#24292E"> ($qy </span><span style="color:#D73A49"><</span><span style="color:#24292E"> $y </span><span style="color:#D73A49">||</span><span style="color:#24292E"> ($qy </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $y </span><span style="color:#D73A49">&&</span><span style="color:#24292E"> ($x</span><span style="color:#D73A49"><=></span><span style="color:#24292E">$qx) </span><span style="color:#D73A49">===</span><span style="color:#24292E"> $cc)))</span></span> -<span class="line"><span style="color:#24292E"> )</span></span> -<span class="line"><span style="color:#24292E"> $ep </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $qp;</span></span> -<span class="line"><span style="color:#24292E"> }</span></span> -<span class="line"><span style="color:#24292E"> }</span></span> -<span class="line"><span style="color:#24292E"> }</span></span> -<span class="line"><span style="color:#24292E"> $np </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $ep </span><span style="color:#D73A49">+</span><span style="color:#24292E"> [</span><span style="color:#005CC5">1</span><span style="color:#24292E">, $w, </span><span style="color:#D73A49">-</span><span style="color:#005CC5">1</span><span style="color:#24292E">, </span><span style="color:#D73A49">-</span><span style="color:#24292E">$w][$dp];</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($cs[$np] </span><span style="color:#D73A49">!==</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">) {</span></span> -<span class="line"><span style="color:#24292E"> $b </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> count</span><span style="color:#24292E">(</span><span style="color:#005CC5">array_keys</span><span style="color:#24292E">($v));</span></span> -<span class="line"><span style="color:#24292E"> $pc </span><span style="color:#D73A49">=</span><span style="color:#24292E"> $np;</span></span> -<span class="line"><span style="color:#D73A49"> break</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#24292E"> }</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($j </span><span style="color:#D73A49">===</span><span style="color:#005CC5"> 7</span><span style="color:#24292E">) </span><span style="color:#D73A49">break</span><span style="color:#005CC5"> 2</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($j </span><span style="color:#D73A49">%</span><span style="color:#005CC5"> 2</span><span style="color:#D73A49"> ===</span><span style="color:#005CC5"> 0</span><span style="color:#24292E">) $cc </span><span style="color:#D73A49">=</span><span style="color:#D73A49"> -</span><span style="color:#24292E">$cc;</span></span> -<span class="line"><span style="color:#D73A49"> if</span><span style="color:#24292E"> ($j </span><span style="color:#D73A49">%</span><span style="color:#005CC5"> 2</span><span style="color:#D73A49"> ===</span><span style="color:#005CC5"> 1</span><span style="color:#24292E">) $dp </span><span style="color:#D73A49">=</span><span style="color:#24292E"> ($dp</span><span style="color:#D73A49">+</span><span style="color:#005CC5">1</span><span style="color:#24292E">) </span><span style="color:#D73A49">%</span><span style="color:#005CC5"> 4</span><span style="color:#24292E">;</span></span> -<span class="line"><span style="color:#6A737D">// The original Piet image is wrong: it outputs 403 error for invalid passwords.</span></span> -<span class="line"><span style="color:#6A737D">// Failure of authentication should be notified by 401, not 403.</span></span> -<span class="line"><span style="color:#6A737D">// I noticed that one month before PHPerKaigi, but I could not read or write (paint)</span></span> -<span class="line"><span style="color:#6A737D">// Piet any longer at that time.</span></span> -<span class="line"><span style="color:#005CC5">fwrite</span><span style="color:#24292E">(</span><span style="color:#005CC5">STDERR</span><span style="color:#24292E">, </span><span style="color:#005CC5">str_replace</span><span style="color:#24292E">(</span><span style="color:#032F62">'403 Forbidden'</span><span style="color:#24292E">, </span><span style="color:#032F62">'401 Unauthorized'</span><span style="color:#24292E">, $o));</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code><span style="color: #6e7781"><?php</span> +<span style="color: #953800">error_reporting</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">);</span> +<span style="color: #0550ae">$b</span> <span style="color: #0550ae">=</span> <span style="color: #953800">unpack</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0a3069">'C*'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">file_get_contents</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #cf222e">__FILE__</span><span style="color: #24292f;background-color: #f6f8fa">));</span> +<span style="color: #0550ae">$w</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$b</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">20</span><span style="color: #24292f;background-color: #f6f8fa">]</span><span style="color: #0550ae">+</span><span style="color: #0550ae">2</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$h</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$b</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">24</span><span style="color: #24292f;background-color: #f6f8fa">]</span><span style="color: #0550ae">+</span><span style="color: #0550ae">2</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$cs</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">[];</span> +<span style="color: #cf222e">for</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$y</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$y</span> <span style="color: #0550ae"><</span> <span style="color: #0550ae">$h</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$y</span><span style="color: #0550ae">++</span><span style="color: #24292f;background-color: #f6f8fa">)</span> + <span style="color: #cf222e">for</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$x</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$x</span> <span style="color: #0550ae"><</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$x</span><span style="color: #0550ae">++</span><span style="color: #24292f;background-color: #f6f8fa">)</span> + <span style="color: #0550ae">$cs</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$y</span><span style="color: #0550ae">*</span><span style="color: #0550ae">$w</span> <span style="color: #0550ae">+</span> <span style="color: #0550ae">$x</span><span style="color: #24292f;background-color: #f6f8fa">]</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$x</span><span style="color: #0550ae">*</span><span style="color: #0550ae">$y</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">0</span> <span style="color: #0550ae">||</span> <span style="color: #0550ae">$x</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$w</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span> <span style="color: #0550ae">||</span> <span style="color: #0550ae">$y</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$h</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> + <span style="color: #0550ae">?</span> <span style="color: #0550ae">0</span> + <span style="color: #0550ae">:</span> <span style="color: #0550ae">$b</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">122</span><span style="color: #0550ae">+</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$y</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span><span style="color: #0550ae">*</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$w</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span><span style="color: #0550ae">+</span><span style="color: #0550ae">$x</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">];</span> +<span style="color: #0550ae">$i</span> <span style="color: #0550ae">=</span> <span style="color: #953800">stream_isatty</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">STDIN</span><span style="color: #24292f;background-color: #f6f8fa">)</span> + <span style="color: #0550ae">?</span> <span style="color: #24292f;background-color: #f6f8fa">[]</span> + <span style="color: #0550ae">:</span> <span style="color: #953800">array_map</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">ord</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">...</span><span style="color: #24292f;background-color: #f6f8fa">),</span> <span style="color: #953800">str_split</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">trim</span><span style="color: #24292f;background-color: #f6f8fa">((</span><span style="color: #24292f;background-color: #f6f8fa">string</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #953800">fgets</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">STDIN</span><span style="color: #24292f;background-color: #f6f8fa">))));</span> +<span style="color: #0550ae">$m</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">[];</span> +<span style="color: #0550ae">$pc</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">1</span><span style="color: #0550ae">*</span><span style="color: #0550ae">$w</span><span style="color: #0550ae">+</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$dp</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$cc</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$c0</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$b</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$ns</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #0550ae">$o</span> <span style="color: #0550ae">=</span> <span style="color: #0a3069">''</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #cf222e">while</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">true</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #0550ae">$ns</span><span style="color: #0550ae">++</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$ns</span> <span style="color: #0550ae">></span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">e5</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #cf222e">echo</span> <span style="color: #0a3069">"infinite loop detected</span><span style="color: #0a3069">\n</span><span style="color: #0a3069">"</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">break</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$c1</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$cs</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$pc</span><span style="color: #24292f;background-color: #f6f8fa">];</span> + <span style="color: #0550ae">$y</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">6</span> <span style="color: #0550ae">+</span> <span style="color: #953800">intdiv</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$c1</span><span style="color: #0550ae">-</span><span style="color: #0550ae">2</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">3</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">-</span> <span style="color: #953800">intdiv</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$c0</span><span style="color: #0550ae">-</span><span style="color: #0550ae">2</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">3</span><span style="color: #24292f;background-color: #f6f8fa">))</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">6</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$x</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">3</span> <span style="color: #0550ae">+</span> <span style="color: #0550ae">$c1</span><span style="color: #0550ae">%</span><span style="color: #0550ae">3</span> <span style="color: #0550ae">-</span> <span style="color: #0550ae">$c0</span><span style="color: #0550ae">%</span><span style="color: #0550ae">3</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">3</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">match</span> <span style="color: #24292f;background-color: #f6f8fa">((</span><span style="color: #0550ae">$c0</span> <span style="color: #0550ae">!==</span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">*</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$c1</span> <span style="color: #0550ae">!==</span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">*</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$y</span><span style="color: #0550ae">*</span><span style="color: #0550ae">3</span> <span style="color: #0550ae">+</span> <span style="color: #0550ae">$x</span><span style="color: #24292f;background-color: #f6f8fa">))</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #0550ae">1</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$b</span><span style="color: #24292f;background-color: #f6f8fa">,</span> + <span style="color: #0550ae">2</span> <span style="color: #0550ae">=></span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">),</span> + <span style="color: #0550ae">3</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">+</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">),</span> + <span style="color: #0550ae">4</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #cf222e">fn</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$x</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$y</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$y</span> <span style="color: #0550ae">-</span> <span style="color: #0550ae">$x</span><span style="color: #24292f;background-color: #f6f8fa">)(</span><span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">),</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)),</span> + <span style="color: #0550ae">5</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">*</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">),</span> + <span style="color: #0550ae">8</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">0</span> <span style="color: #0550ae">?</span> <span style="color: #0550ae">1</span> <span style="color: #0550ae">:</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">,</span> + <span style="color: #0550ae">11</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$cc</span> <span style="color: #0550ae">*=</span> <span style="color: #953800">pow</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)),</span> + <span style="color: #0550ae">12</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #953800">count</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">],</span> + <span style="color: #0550ae">13</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$m</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #cf222e">fn</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$n</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$d</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$l</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">=></span> <span style="color: #24292f;background-color: #f6f8fa">[</span> + <span style="color: #0550ae">...</span><span style="color: #953800">array_slice</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$l</span><span style="color: #0550ae">-</span><span style="color: #0550ae">$d</span><span style="color: #24292f;background-color: #f6f8fa">),</span> + <span style="color: #0550ae">...</span><span style="color: #953800">array_reverse</span><span style="color: #24292f;background-color: #f6f8fa">([</span> + <span style="color: #0550ae">...</span><span style="color: #953800">array_reverse</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">array_slice</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$l</span><span style="color: #0550ae">-</span><span style="color: #0550ae">$d</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$d</span><span style="color: #0550ae">-</span><span style="color: #0550ae">$n</span><span style="color: #24292f;background-color: #f6f8fa">)),</span> + <span style="color: #0550ae">...</span><span style="color: #953800">array_reverse</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">array_slice</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$l</span><span style="color: #0550ae">-</span><span style="color: #0550ae">$n</span><span style="color: #24292f;background-color: #f6f8fa">)),</span> + <span style="color: #24292f;background-color: #f6f8fa">]),</span> + <span style="color: #24292f;background-color: #f6f8fa">])(</span><span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">),</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">),</span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">count</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)),</span> + <span style="color: #0550ae">15</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">!</span><span style="color: #cf222e">empty</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$i</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #cf222e">and</span> <span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #953800">array_shift</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$i</span><span style="color: #24292f;background-color: #f6f8fa">),</span> + <span style="color: #0550ae">16</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$o</span> <span style="color: #0550ae">.</span><span style="color: #0550ae">=</span> <span style="color: #953800">sprintf</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0a3069">'%d'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)),</span> + <span style="color: #0550ae">17</span> <span style="color: #0550ae">=></span> <span style="color: #0550ae">$o</span> <span style="color: #0550ae">.</span><span style="color: #0550ae">=</span> <span style="color: #953800">sprintf</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0a3069">'%c'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$m</span><span style="color: #24292f;background-color: #f6f8fa">)),</span> + <span style="color: #cf222e">default</span> <span style="color: #0550ae">=></span> <span style="color: #0a3069">'nop'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> + <span style="color: #24292f;background-color: #f6f8fa">};</span> + <span style="color: #0550ae">$c0</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$c1</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">for</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$j</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$j</span> <span style="color: #0550ae"><</span> <span style="color: #0550ae">8</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$j</span><span style="color: #0550ae">++</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #0550ae">$v</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">[];</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$c1</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #0550ae">$x</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$pc</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$y</span> <span style="color: #0550ae">=</span> <span style="color: #953800">intdiv</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$pc</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">);</span> + <span style="color: #0550ae">$e</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">[(</span><span style="color: #0550ae">$y</span><span style="color: #0550ae">+</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span><span style="color: #0550ae">*</span><span style="color: #0550ae">$w</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$h</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span><span style="color: #0550ae">*</span><span style="color: #0550ae">$w</span><span style="color: #0550ae">+</span><span style="color: #0550ae">$x</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$y</span><span style="color: #0550ae">*</span><span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$x</span><span style="color: #24292f;background-color: #f6f8fa">][</span><span style="color: #0550ae">$dp</span><span style="color: #24292f;background-color: #f6f8fa">];</span> + <span style="color: #0550ae">$z</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">-</span><span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">][</span><span style="color: #0550ae">$dp</span><span style="color: #24292f;background-color: #f6f8fa">];</span> + <span style="color: #cf222e">for</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$ep</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$pc</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$ep</span> <span style="color: #0550ae">!==</span> <span style="color: #0550ae">$e</span><span style="color: #24292f;background-color: #f6f8fa">;</span> <span style="color: #0550ae">$ep</span> <span style="color: #0550ae">+=</span> <span style="color: #0550ae">$z</span><span style="color: #24292f;background-color: #f6f8fa">)</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$cs</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$ep</span><span style="color: #24292f;background-color: #f6f8fa">]</span> <span style="color: #0550ae">!==</span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #cf222e">break</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$ep</span> <span style="color: #0550ae">-=</span> <span style="color: #0550ae">$z</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$pc</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$ep</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #24292f;background-color: #f6f8fa">}</span> <span style="color: #cf222e">else</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #0550ae">$q</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$pc</span><span style="color: #24292f;background-color: #f6f8fa">];</span> + <span style="color: #0550ae">$ep</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$pc</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">while</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">!</span><span style="color: #cf222e">empty</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$q</span><span style="color: #24292f;background-color: #f6f8fa">))</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #0550ae">$qq</span> <span style="color: #0550ae">=</span> <span style="color: #953800">array_pop</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$q</span><span style="color: #24292f;background-color: #f6f8fa">);</span> + <span style="color: #0550ae">$v</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$qq</span><span style="color: #24292f;background-color: #f6f8fa">]</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">true</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">foreach</span> <span style="color: #24292f;background-color: #f6f8fa">([</span><span style="color: #0550ae">$qq</span><span style="color: #0550ae">+</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$qq</span><span style="color: #0550ae">+</span><span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$qq</span><span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$qq</span><span style="color: #0550ae">-</span><span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">]</span> <span style="color: #cf222e">as</span> <span style="color: #0550ae">$qp</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$cs</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$qp</span><span style="color: #24292f;background-color: #f6f8fa">]</span> <span style="color: #0550ae">!==</span> <span style="color: #0550ae">$c1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #cf222e">continue</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #cf222e">isset</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$v</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$qp</span><span style="color: #24292f;background-color: #f6f8fa">]))</span> <span style="color: #cf222e">continue</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$q</span><span style="color: #24292f;background-color: #f6f8fa">[]</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$qp</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$qx</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$qp</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$qy</span> <span style="color: #0550ae">=</span> <span style="color: #953800">intdiv</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$qp</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">);</span> + <span style="color: #0550ae">$x</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$ep</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #0550ae">$y</span> <span style="color: #0550ae">=</span> <span style="color: #953800">intdiv</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$ep</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">);</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span> + <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$dp</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">0</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$x</span> <span style="color: #0550ae"><</span> <span style="color: #0550ae">$qx</span> <span style="color: #0550ae">||</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$x</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$qx</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$y</span><span style="color: #0550ae"><=></span><span style="color: #0550ae">$qy</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$cc</span><span style="color: #24292f;background-color: #f6f8fa">)))</span> + <span style="color: #0550ae">||</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$dp</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">1</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$y</span> <span style="color: #0550ae"><</span> <span style="color: #0550ae">$qy</span> <span style="color: #0550ae">||</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$y</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$qy</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$qx</span><span style="color: #0550ae"><=></span><span style="color: #0550ae">$x</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$cc</span><span style="color: #24292f;background-color: #f6f8fa">)))</span> + <span style="color: #0550ae">||</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$dp</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">2</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$qx</span> <span style="color: #0550ae"><</span> <span style="color: #0550ae">$x</span> <span style="color: #0550ae">||</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$qx</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$x</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$qy</span><span style="color: #0550ae"><=></span><span style="color: #0550ae">$y</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$cc</span><span style="color: #24292f;background-color: #f6f8fa">)))</span> + <span style="color: #0550ae">||</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$dp</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">3</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$qy</span> <span style="color: #0550ae"><</span> <span style="color: #0550ae">$y</span> <span style="color: #0550ae">||</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$qy</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$y</span> <span style="color: #0550ae">&&</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$x</span><span style="color: #0550ae"><=></span><span style="color: #0550ae">$qx</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">$cc</span><span style="color: #24292f;background-color: #f6f8fa">)))</span> + <span style="color: #24292f;background-color: #f6f8fa">)</span> + <span style="color: #0550ae">$ep</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$qp</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #24292f;background-color: #f6f8fa">}</span> + <span style="color: #24292f;background-color: #f6f8fa">}</span> + <span style="color: #24292f;background-color: #f6f8fa">}</span> + <span style="color: #0550ae">$np</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$ep</span> <span style="color: #0550ae">+</span> <span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">-</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">-</span><span style="color: #0550ae">$w</span><span style="color: #24292f;background-color: #f6f8fa">][</span><span style="color: #0550ae">$dp</span><span style="color: #24292f;background-color: #f6f8fa">];</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$cs</span><span style="color: #24292f;background-color: #f6f8fa">[</span><span style="color: #0550ae">$np</span><span style="color: #24292f;background-color: #f6f8fa">]</span> <span style="color: #0550ae">!==</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #24292f;background-color: #f6f8fa">{</span> + <span style="color: #0550ae">$b</span> <span style="color: #0550ae">=</span> <span style="color: #953800">count</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">array_keys</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$v</span><span style="color: #24292f;background-color: #f6f8fa">));</span> + <span style="color: #0550ae">$pc</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">$np</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">break</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #24292f;background-color: #f6f8fa">}</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$j</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">7</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #cf222e">break</span> <span style="color: #0550ae">2</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$j</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">2</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">0</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">$cc</span> <span style="color: #0550ae">=</span> <span style="color: #0550ae">-</span><span style="color: #0550ae">$cc</span><span style="color: #24292f;background-color: #f6f8fa">;</span> + <span style="color: #cf222e">if</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$j</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">2</span> <span style="color: #0550ae">===</span> <span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">$dp</span> <span style="color: #0550ae">=</span> <span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0550ae">$dp</span><span style="color: #0550ae">+</span><span style="color: #0550ae">1</span><span style="color: #24292f;background-color: #f6f8fa">)</span> <span style="color: #0550ae">%</span> <span style="color: #0550ae">4</span><span style="color: #24292f;background-color: #f6f8fa">;</span> +<span style="color: #6e7781">// The original Piet image is wrong: it outputs 403 error for invalid passwords.</span> +<span style="color: #6e7781">// Failure of authentication should be notified by 401, not 403.</span> +<span style="color: #6e7781">// I noticed that one month before PHPerKaigi, but I could not read or write (paint)</span> +<span style="color: #6e7781">// Piet any longer at that time.</span> +<span style="color: #953800">fwrite</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">STDERR</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">str_replace</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0a3069">'403 Forbidden'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0a3069">'401 Unauthorized'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$o</span><span style="color: #24292f;background-color: #f6f8fa">));</span> +</code></pre> </div> <p> これは一体なんなのか。ずばり、難解プログラミング言語の一つ Piet のインタプリタである。Piet はピエト・モンドリアン (『赤・青・黄のコンポジション』などで知られる抽象画家) の作品にインスピレーションを受けて作られた、画像をソースコードとするプログラミング言語である。インタプリタは画像の各ピクセルの上を進みながら、色等に応じて特定の処理をおこなっていく。ここでは詳しい言語仕様については解説しないので、気になる方は <a href="https://ja.wikipedia.org/wiki/Piet" rel="noreferrer" target="_blank">Wikipedia の記事「Piet」</a> などを参照してほしい。 @@ -407,7 +413,8 @@ プログラムの冒頭にあるこの箇所 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span style="color:#24292E">$b </span><span style="color:#D73A49">=</span><span style="color:#005CC5"> unpack</span><span style="color:#24292E">(</span><span style="color:#032F62">'C*'</span><span style="color:#24292E">, </span><span style="color:#005CC5">file_get_contents</span><span style="color:#24292E">(</span><span style="color:#005CC5">__FILE__</span><span style="color:#24292E">));</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code><span style="color: #0550ae">$b</span> <span style="color: #0550ae">=</span> <span style="color: #953800">unpack</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0a3069">'C*'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">file_get_contents</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #cf222e">__FILE__</span><span style="color: #24292f;background-color: #f6f8fa">));</span> +</code></pre> </div> <p> で <code>__FILE__</code> つまりこの画像ファイルを読み込んでいる。先ほど Piet は画像をソースコードにしていると説明した。そう、今回の問題の画像ファイル <code>Q1.png</code> は、PHP 製 Piet インタプリタであると同時に、Piet のソースコード画像でもあるのだ。QR コード中央のカラフルな部分が Piet の命令になっている。 @@ -459,11 +466,12 @@ ところで、先ほど掲載した Piet のインタプリタのソースコード末尾には次のような箇所がある。 </p> <div class="codeblock"> - <pre class="shiki github-light" style="background-color:#f5f5f5;color:#24292e" tabindex="0"><code><span class="line"><span style="color:#6A737D">// The original Piet image is wrong: it outputs 403 error for invalid passwords.</span></span> -<span class="line"><span style="color:#6A737D">// Failure of authentication should be notified by 401, not 403.</span></span> -<span class="line"><span style="color:#6A737D">// I noticed that one month before PHPerKaigi, but I could not read or write (paint)</span></span> -<span class="line"><span style="color:#6A737D">// Piet any longer at that time.</span></span> -<span class="line"><span style="color:#005CC5">fwrite</span><span style="color:#24292E">(</span><span style="color:#005CC5">STDERR</span><span style="color:#24292E">, </span><span style="color:#005CC5">str_replace</span><span style="color:#24292E">(</span><span style="color:#032F62">'403 Forbidden'</span><span style="color:#24292E">, </span><span style="color:#032F62">'401 Unauthorized'</span><span style="color:#24292E">, $o));</span></span></code></pre> + <pre class="highlight" style="background-color:#f5f5f5"><code><span style="color: #6e7781">// The original Piet image is wrong: it outputs 403 error for invalid passwords.</span> +<span style="color: #6e7781">// Failure of authentication should be notified by 401, not 403.</span> +<span style="color: #6e7781">// I noticed that one month before PHPerKaigi, but I could not read or write (paint)</span> +<span style="color: #6e7781">// Piet any longer at that time.</span> +<span style="color: #953800">fwrite</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #953800">STDERR</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #953800">str_replace</span><span style="color: #24292f;background-color: #f6f8fa">(</span><span style="color: #0a3069">'403 Forbidden'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0a3069">'401 Unauthorized'</span><span style="color: #24292f;background-color: #f6f8fa">,</span> <span style="color: #0550ae">$o</span><span style="color: #24292f;background-color: #f6f8fa">));</span> +</code></pre> </div> <p> コメントにも書かれているが、この Piet のソースコード画像には誤りがあった。本来 HTTP のステータスコードを真似るのなら、認証の失敗には 401 を返さなければならない。しかし、Piet のソースは 403 を返すように書いてしまっていた。そのことに私が気付いたのは PHPerKaigi 2023 が開催されるひと月前で、その時点で私はこの Piet のソースコードを (ちょうどこの記事でそうなっているのと同じように) 読解できなくなっていた。さらに悪いことに、正しいメッセージ「401 Unauthorized」は元の「403 Forbidden」よりも3文字長い。3文字出力が長くなるということは、それだけ Piet で塗るべきピクセルが増えることを意味する。もはや3文字追加で出力するだけの余白はこの画像に残されていなかった (と思う。腕ききの Piet プログラマならできるかもしれないので挑戦してみてほしい)。 |