wpsynchro / src / Database / SerializedStringHandler.php

SerializedStringHandler.php in WP Synchro – The Ultimate WordPress Migration Tool trunk, at src/Database/SerializedStringHandler.php

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1	<?php
2
3	namespace WPSynchro\Database;
4
5	use WPSynchro\Database\Exception\SerializedStringException;
6
7	/**
8	* Handle serialized strings
9	*/
10	class SerializedStringHandler
11	{
12	const STRING_START_PART = 's:';
13	const STRING_TOKENIZE_LENGTH = 2;
14	const STRING_END_PART = '";';
15	const MAX_TIME_ALLOWED = 500; // ms
16
17	/**
18	* Do search/replaces in serialized data
19	* @throws SerializedStringException Throws exception when serialized string is broken and no search/replace could be done
20	*/
21	public function searchReplaceSerialized(string &$data, array $search_replaces)
22	{
23	$start_time = microtime(true);
24	$rounds = 0;
25	$offset = 0;
26	$last_offset = -1;
27	while (($data_pos = strpos($data, self::STRING_START_PART, $offset)) !== false) {
28	$rounds++;
29	// Make sure we dont do endless loops, if the serialized content is broken
30	if ($offset == $last_offset) {
31	throw new SerializedStringException('Skipping serialized value that is broken, so no search/replaces could be done in this value.', 0, $data);
32	}
33	$last_offset = $offset;
34
35	// Every some rounds, we just check that we have not spent more time here than we should.
36	if ($rounds % 10000 == 0) {
37	$current_time = microtime(true);
38	$time_spent_in_ms = ($current_time - $start_time) * 1000;
39	if ($time_spent_in_ms > self::MAX_TIME_ALLOWED) {
40	// Likely that something is broken, so we break
41	throw new SerializedStringException(
42	'Skipping large serialized value that could not be search/replaced within reasonable time. First part of string:',
43	0,
44	substr($data, 0, 200)
45	);
46	}
47	}
48
49	// Get string length
50	$length_start_pos = $data_pos + self::STRING_TOKENIZE_LENGTH;
51	$length_end_pos = strpos($data, ':', $length_start_pos);
52	$length_length = $length_end_pos - $length_start_pos;
53	$expected_string_length = substr($data, $length_start_pos, $length_length);
54
55	// Get string value
56	$string_start_pos = $length_start_pos + $length_length + 2;
57	$string_end_pos = $string_start_pos + $expected_string_length;
58	$string_length = $string_end_pos - $string_start_pos;
59
60	// Check that string ends there and if not, something is wrong and we abort
61	if (substr($data, $string_end_pos, 2) !== self::STRING_END_PART) {
62	throw new SerializedStringException('Skipping serialized value that is broken, so no search/replaces could be done in this value.', 0, $data);
63	}
64
65	$string_value = substr($data, $string_start_pos, $string_length);
66
67	// Set new offset
68	$data_end = $string_end_pos + 2;
69	$offset = $data_end;
70
71	// Do search/replace in string value
72	$string_value_replaced = $string_value;
73	$search_replace_changed_string = false;
74	foreach ($search_replaces as $replaces) {
75	$replaces_actually_done = 0;
76	$string_value_replaced = str_replace($replaces->from, $replaces->to, $string_value_replaced, $replaces_actually_done);
77	if ($replaces_actually_done > 0) {
78	$search_replace_changed_string = true;
79	}
80	}
81
82	// Change the string in the data, if it was changed
83	if ($search_replace_changed_string) {
84	$new_string = self::STRING_START_PART . strlen($string_value_replaced) . ':"' . $string_value_replaced . self::STRING_END_PART;
85	$new_string_length = strlen($new_string);
86	$data = substr_replace(
87	$data,
88	$new_string,
89	$data_pos,
90	$data_end - $data_pos
91	);
92
93	// Adjust our current position in serialized string, if the replaced string was longer or shorter
94	$offset += $new_string_length - ($data_end - $data_pos);
95	}
96	}
97	}
98	}
99