Decoder::castInteger() - Code Metrics - Inspection of "Extended the range of supported integers from -PHP..." - s9e/Bencode - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( 923e94...00c6d3 )

by Josh

created 2021-09-12 21:14 UTC

Decoder::castInteger() A

↳ Parent: Decoder

Complexity

Conditions	4
Paths	4

Size

Total Lines	20
Code Lines	9

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	9
CRAP Score	4

Importance

Changes

Metric	Value
cc	4
eloc	9
c	0
b	0
f	0
nc	4
nop	2
dl	0
loc	20
ccs	9
cts	9
cp	1
crap	4
rs	9.9666

<?php declare(strict_types=1);

/**
* @package   s9e\Bencode
* @copyright Copyright (c) 2014-2021 The s9e authors
* @license   http://www.opensource.org/licenses/mit-license.php The MIT License
*/
namespace s9e\Bencode;

use ArrayObject;
use const PHP_INT_MAX, PHP_INT_MIN;
use function is_float, str_contains, strcmp, strlen, strspn, substr;
use s9e\Bencode\Exceptions\ComplianceError;
use s9e\Bencode\Exceptions\DecodingException;

class Decoder
{
	/**
	* @var string Bencoded string being decoded
	*/
	protected string $bencoded;

	/**
	* @var int Length of the bencoded string
	*/
	protected int $len;

	/**
	* @var int Safe rightmost boundary
	*/
	protected int $max;

	/**
	* @var int Position of the cursor while decoding
	*/
	protected int $offset = 0;

	public static function decode(string $bencoded): ArrayObject|array|int|string
	{
		$decoder = new static($bencoded);
		$value   = $decoder->decodeAnything();

		$decoder->checkCursorPosition();

		return $value;
	}

	protected function __construct(string $bencoded)
	{
		$this->bencoded = $bencoded;
		$this->len      = strlen($bencoded);

		$this->computeSafeBoundary();
		$this->checkBoundary();
	}

	/**
	* Cast given string as an integer and check for clamping
	*/
	protected function castInteger(string $string, bool $negative): int
	{
		if ($negative)
		{
			$value = (int) "-$string";
			if ($value === PHP_INT_MIN)
			{
				$this->checkIntegerOverflow("-$string");
			}
		}
		else
		{
			$value = (int) $string;
			if ($value === PHP_INT_MAX)
			{
				$this->checkIntegerOverflow($string);
			}
		}

		return $value;
	}

	protected function checkBoundary(): void
	{
		if ($this->max < 1)
		{
			throw match (substr($this->bencoded, 0, 1))
			{
				'-', 'e' => new DecodingException('Illegal character',     0),
				''       => new DecodingException('Premature end of data', 0),
				default  => new DecodingException('Premature end of data', $this->len - 1)
			};
		}
	}

	/**
	* Check the cursor's position after decoding is done
	*/
	protected function checkCursorPosition(): void
	{
		if ($this->offset !== $this->len)
		{
			if ($this->offset > $this->len)
			{
				throw new DecodingException('Premature end of data', $this->len - 1);
			}

			$this->complianceError('Superfluous content', $this->offset);
		}
	}

	protected function checkDictionaryCompliance(int $offset, string $key, string $lastKey): void
	{
		$cmp = strcmp($key, $lastKey);
		if ($cmp <= 0)
		{
			$msg = ($cmp === 0) ? 'Duplicate' : 'Out of order';
			$this->complianceError($msg . " dictionary entry '" . $key . "'", $offset);
		}
	}

	protected function checkIntegerOverflow(string $str): void
	{
		if (is_float(+$str))
		{
			throw new DecodingException('Integer overflow', $this->offset - 1 - strlen($str));
		}
	}

	protected function complianceError(string $message, int $offset): void
	{
		throw new ComplianceError($message, $offset);
	}

	/**
	* Adjust the rightmost boundary to the last safe character that can start a value
	*
	* Will rewind the boundary to skip the rightmost digits, optionally preceded by "i" or "i-"
	*/
	protected function computeSafeBoundary(): void
	{
		$boundary = $this->len - 1;
		do
		{
			$c = substr($this->bencoded, $boundary, 1);
		}
		while (str_contains('0123456789', $c) && --$boundary >= 0);

		$this->max = match ($c)
		{
			'-'     => $boundary - 2,
			'i'     => $boundary - 1,
			default => $boundary
		};
	}

	protected function decodeAnything(): ArrayObject|array|int|string
	{
		return match ($this->bencoded[$this->offset])
		{
			'd'     => $this->decodeDictionary(),
			'i'     => $this->decodeInteger(),
			'l'     => $this->decodeList(),
			default => $this->decodeString()
		};
	}

	protected function decodeDictionary(): ArrayObject
	{
		$values  = [];
		$lastKey = null;

		++$this->offset;
		while ($this->offset <= $this->max)
		{
			if ($this->bencoded[$this->offset] === 'e')
			{
				++$this->offset;

				return new ArrayObject($values, ArrayObject::ARRAY_AS_PROPS);
			}

			$offset = $this->offset;
			$key    = $this->decodeString();
			if (isset($lastKey))
			{
				$this->checkDictionaryCompliance($offset, $key, $lastKey);
			}
			if ($this->offset > $this->max)
			{
				break;
			}
			$values[$key] = $this->decodeAnything();
			$lastKey      = $key;
		}

		throw new DecodingException('Premature end of data', $this->len - 1);
	}

	protected function decodeInteger(): int
	{
		$negative = ($this->bencoded[++$this->offset] === '-');
		if ($negative && $this->bencoded[++$this->offset] === '0')
		{
			$this->complianceError('Illegal character', $this->offset);
		}

		return $this->castInteger($this->readDigits('e'), $negative);
	}

	protected function decodeList(): array
	{
		++$this->offset;

		$list = [];
		while ($this->offset <= $this->max)
		{
			if ($this->bencoded[$this->offset] === 'e')
			{
				++$this->offset;

				return $list;
			}

			$list[] = $this->decodeAnything();
		}

		throw new DecodingException('Premature end of data', $this->len - 1);
	}

	protected function decodeString(): string
	{
		$len = (int) $this->readDigits(':');
		if ($this->offset + $len >= PHP_INT_MAX)
		{
			throw new DecodingException('String length overflow', $this->offset - 1 - strlen((string) $len));
		}

		$string = substr($this->bencoded, $this->offset, $len);
		$this->offset += $len;

		return $string;
	}

	protected function readDigits(string $terminator): string
	{
		// Digits sorted by decreasing frequency as observed on a random sample of torrent files
		$spn = strspn($this->bencoded, '4615302879', $this->offset);
		if (!$spn)
		{
			throw new DecodingException('Illegal character', $this->offset);
		}
		if ($this->bencoded[$this->offset] === '0' && $spn !== 1)
		{
			$this->complianceError('Illegal character', 1 + $this->offset);
		}

		$string = substr($this->bencoded, $this->offset, $spn);

		$this->offset += $spn;
		if ($this->bencoded[$this->offset] !== $terminator)
		{
			throw new DecodingException('Illegal character', $this->offset);
		}
		++$this->offset;

		return $string;
	}
}

1		<?php declare(strict_types=1);
2
3		/**
4		* @package s9e\Bencode
5		* @copyright Copyright (c) 2014-2021 The s9e authors
6		* @license http://www.opensource.org/licenses/mit-license.php The MIT License
7		*/
8		namespace s9e\Bencode;
9
10		use ArrayObject;
11		use const PHP_INT_MAX, PHP_INT_MIN;
12		use function is_float, str_contains, strcmp, strlen, strspn, substr;
13		use s9e\Bencode\Exceptions\ComplianceError;
14		use s9e\Bencode\Exceptions\DecodingException;
15
16		class Decoder
17		{
18		/**
19		* @var string Bencoded string being decoded
20		*/
21		protected string $bencoded;
22
23		/**
24		* @var int Length of the bencoded string
25		*/
26		protected int $len;
27
28		/**
29		* @var int Safe rightmost boundary
30		*/
31		protected int $max;
32
33		/**
34		* @var int Position of the cursor while decoding
35		*/
36		protected int $offset = 0;
37
38	70	public static function decode(string $bencoded): ArrayObject\|array\|int\|string
39		{
40	70	$decoder = new static($bencoded);
41	58	$value = $decoder->decodeAnything();
42
43	30	$decoder->checkCursorPosition();
44
45	22	return $value;
46		}
47
48	70	protected function __construct(string $bencoded)
49		{
50	70	$this->bencoded = $bencoded;
51	70	$this->len = strlen($bencoded);
52
53	70	$this->computeSafeBoundary();
54	70	$this->checkBoundary();
55	58	}
56
57		/**
58		* Cast given string as an integer and check for clamping
59		*/
60	16	protected function castInteger(string $string, bool $negative): int
61		{
62	16	if ($negative)
63		{
64	2	$value = (int) "-$string";
65	2	if ($value === PHP_INT_MIN)
66		{
67	2	$this->checkIntegerOverflow("-$string");
68		}
69		}
70		else
71		{
72	14	$value = (int) $string;
73	14	if ($value === PHP_INT_MAX)
74		{
75	2	$this->checkIntegerOverflow($string);
76		}
77		}
78
79	15	return $value;
80		}
81
82	70	protected function checkBoundary(): void
83		{
84	70	if ($this->max < 1)
85		{
86	12	throw match (substr($this->bencoded, 0, 1))
87		{
88	2	'-', 'e' => new DecodingException('Illegal character', 0),
89	1	'' => new DecodingException('Premature end of data', 0),
90	9	default => new DecodingException('Premature end of data', $this->len - 1)
91		};
92		}
93	58	}
94
95		/**
96		* Check the cursor's position after decoding is done
97		*/
98	30	protected function checkCursorPosition(): void
99		{
100	30	if ($this->offset !== $this->len)
101		{
102	8	if ($this->offset > $this->len)
103		{
104	3	throw new DecodingException('Premature end of data', $this->len - 1);
105		}
106
107	5	$this->complianceError('Superfluous content', $this->offset);
108		}
109	22	}
110
111	7	protected function checkDictionaryCompliance(int $offset, string $key, string $lastKey): void
112		{
113	7	$cmp = strcmp($key, $lastKey);
114	7	if ($cmp <= 0)
115		{
116	4	$msg = ($cmp === 0) ? 'Duplicate' : 'Out of order';
117	4	$this->complianceError($msg . " dictionary entry '" . $key . "'", $offset);
118		}
119	3	}
120
121	3	protected function checkIntegerOverflow(string $str): void
122		{
123	3	if (is_float(+$str))
124		{
125	1	throw new DecodingException('Integer overflow', $this->offset - 1 - strlen($str));
126		}
127	2	}
128
129	13	protected function complianceError(string $message, int $offset): void
130		{
131	13	throw new ComplianceError($message, $offset);
132		}
133
134		/**
135		* Adjust the rightmost boundary to the last safe character that can start a value
136		*
137		* Will rewind the boundary to skip the rightmost digits, optionally preceded by "i" or "i-"
138		*/
139	70	protected function computeSafeBoundary(): void
140		{
141	70	$boundary = $this->len - 1;
142		do
143		{
144	70	$c = substr($this->bencoded, $boundary, 1);
145		}
146	70	while (str_contains('0123456789', $c) && --$boundary >= 0);
147
148	70	$this->max = match ($c)
149		{
150	8	'-' => $boundary - 2,
151	6	'i' => $boundary - 1,
152	56	default => $boundary
153		};
154	70	}
155
156	58	protected function decodeAnything(): ArrayObject\|array\|int\|string
157		{
158	58	return match ($this->bencoded[$this->offset])
159		{
160	16	'd' => $this->decodeDictionary(),
161	22	'i' => $this->decodeInteger(),
162	15	'l' => $this->decodeList(),
163	46	default => $this->decodeString()
164		};
165		}
166
167	16	protected function decodeDictionary(): ArrayObject
168		{
169	16	$values = [];
170	16	$lastKey = null;
171
172	16	++$this->offset;
173	16	while ($this->offset <= $this->max)
174		{
175	16	if ($this->bencoded[$this->offset] === 'e')
176		{
177	7	++$this->offset;
178
179	7	return new ArrayObject($values, ArrayObject::ARRAY_AS_PROPS);
180		}
181
182	15	$offset = $this->offset;
183	15	$key = $this->decodeString();
184	14	if (isset($lastKey))
185		{
186	7	$this->checkDictionaryCompliance($offset, $key, $lastKey);
187		}
188	14	if ($this->offset > $this->max)
189		{
190	1	break;
191		}
192	13	$values[$key] = $this->decodeAnything();
193	10	$lastKey = $key;
194		}
195
196	1	throw new DecodingException('Premature end of data', $this->len - 1);
197		}
198
199	22	protected function decodeInteger(): int
200		{
201	22	$negative = ($this->bencoded[++$this->offset] === '-');
202	22	if ($negative && $this->bencoded[++$this->offset] === '0')
203		{
204	1	$this->complianceError('Illegal character', $this->offset);
205		}
206
207	21	return $this->castInteger($this->readDigits('e'), $negative);
208		}
209
210	15	protected function decodeList(): array
211		{
212	15	++$this->offset;
213
214	15	$list = [];
215	15	while ($this->offset <= $this->max)
216		{
217	14	if ($this->bencoded[$this->offset] === 'e')
218		{
219	8	++$this->offset;
220
221	8	return $list;
222		}
223
224	11	$list[] = $this->decodeAnything();
225		}
226
227	5	throw new DecodingException('Premature end of data', $this->len - 1);
228		}
229
230	37	protected function decodeString(): string
231		{
232	37	$len = (int) $this->readDigits(':');
233	29	if ($this->offset + $len >= PHP_INT_MAX)
234		{
235	1	throw new DecodingException('String length overflow', $this->offset - 1 - strlen((string) $len));
236		}
237
238	28	$string = substr($this->bencoded, $this->offset, $len);
239	28	$this->offset += $len;
240
241	28	return $string;
242		}
243
244	50	protected function readDigits(string $terminator): string
245		{
246		// Digits sorted by decreasing frequency as observed on a random sample of torrent files
247	50	$spn = strspn($this->bencoded, '4615302879', $this->offset);
248	50	if (!$spn)
249		{
250	7	throw new DecodingException('Illegal character', $this->offset);
251		}
252	45	if ($this->bencoded[$this->offset] === '0' && $spn !== 1)
253		{
254	3	$this->complianceError('Illegal character', 1 + $this->offset);
255		}
256
257	42	$string = substr($this->bencoded, $this->offset, $spn);
258
259	42	$this->offset += $spn;
260	42	if ($this->bencoded[$this->offset] !== $terminator)
261		{
262	5	throw new DecodingException('Illegal character', $this->offset);
263		}
264	37	++$this->offset;
265
266	37	return $string;
267		}
268		}

s9e / Bencode

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Decoder::castInteger() A

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