jetpack / vendor / wp-php-toolkit / reprint-server / src / class-gzip-output-stream.php

class-gzip-output-stream.php in Jetpack – WP Security, Backup, Speed, & Growth 16.3-a.7, at vendor/wp-php-toolkit/reprint-server/src/class-gzip-output-stream.php

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1	<?php
2
3	// Declared here rather than in export.php so it can live in this package's
4	// namespace. export.php is a global-namespace file of endpoint functions that
5	// callers reach by unqualified name.
6
7	namespace WordPress\Reprint\Server;
8
9	/**
10	* Incremental response writer.
11	*
12	* PHP 7.0 and newer can gzip each bounded write without buffering the whole
13	* response. PHP 5.6 lacks the incremental zlib API, so it sends the same
14	* multipart stream without a Content-Encoding header.
15	*
16	* PHP-side gzip also gives outbound WAF rules that do not decode
17	* Content-Encoding the encoded byte stream; server-level compression can run
18	* after those rules inspect the body.
19	*/
20	class GzipOutputStream
21	{
22	private $deflate_ctx;
23	/** @var bool */
24	private $enabled = true;
25
26	public function __construct(bool $enabled = true)
27	{
28	$this->enabled = $enabled
29	&& function_exists('deflate_init')
30	&& function_exists('deflate_add');
31	if ($this->enabled) {
32	$this->deflate_ctx = deflate_init(ZLIB_ENCODING_GZIP, ["level" => 6]);
33	if ($this->deflate_ctx === false) {
34	throw new \RuntimeException(
35	"deflate_init() failed — zlib may be misconfigured"
36	);
37	}
38	if (!headers_sent()) {
39	@header("Content-Encoding: gzip");
40	}
41	}
42	}
43
44	/**
45	* Writes data without forcing a sync point.
46	*
47	* Uses ZLIB_NO_FLUSH so the compressor can build back-references across
48	* multiple write() calls, producing significantly better compression
49	* ratios than ZLIB_SYNC_FLUSH on every call. Data still flows out
50	* whenever zlib's internal buffer fills — the decompressor on the other
51	* end will decompress incrementally.
52	*
53	* Call sync() after each complete multipart part to guarantee the client
54	* can decompress everything emitted so far.
55	*/
56	public function write(string $data): void
57	{
58	if (!$this->enabled) {
59	echo $data;
60	return;
61	}
62	$compressed = deflate_add(
63	$this->deflate_ctx,
64	$data,
65	ZLIB_NO_FLUSH
66	);
67	if ($compressed === false) {
68	throw new \RuntimeException("deflate_add() failed during gzip write");
69	}
70	if ($compressed !== "") {
71	echo $compressed;
72	}
73	}
74
75	/**
76	* Forces a sync flush so the client can decompress all data written so far.
77	*/
78	public function sync(): void
79	{
80	if (!$this->enabled) {
81	flush();
82	return;
83	}
84	$compressed = deflate_add(
85	$this->deflate_ctx,
86	"",
87	ZLIB_SYNC_FLUSH
88	);
89	if ($compressed === false) {
90	throw new \RuntimeException("deflate_add() failed during gzip sync");
91	}
92	if ($compressed !== "") {
93	echo $compressed;
94	}
95	flush();
96	}
97
98	/**
99	* Finalizes the gzip stream with ZLIB_FINISH.
100	*/
101	public function finish(): void
102	{
103	if (!$this->enabled) {
104	flush();
105	return;
106	}
107	$final = deflate_add($this->deflate_ctx, "", ZLIB_FINISH);
108	if ($final === false) {
109	throw new \RuntimeException("deflate_add() failed during gzip finish");
110	}
111	if ($final !== "") {
112	echo $final;
113	}
114	flush();
115	}
116	}
117