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comparison: security/sandbox/chromium/base/strings/string_number_conversions.cc

security/sandbox/chromium/base/strings/string_number_conversions.cc

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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/strings/string_number_conversions.h"
6
7 #include <ctype.h>
8 #include <errno.h>
9 #include <stdlib.h>
10 #include <wctype.h>
11
12 #include <limits>
13
14 #include "base/logging.h"
15 #include "base/scoped_clear_errno.h"
16 #include "base/strings/utf_string_conversions.h"
17 #include "base/third_party/dmg_fp/dmg_fp.h"
18
19 namespace base {
20
21 namespace {
22
23 template <typename STR, typename INT, typename UINT, bool NEG>
24 struct IntToStringT {
25 // This is to avoid a compiler warning about unary minus on unsigned type.
26 // For example, say you had the following code:
27 // template <typename INT>
28 // INT abs(INT value) { return value < 0 ? -value : value; }
29 // Even though if INT is unsigned, it's impossible for value < 0, so the
30 // unary minus will never be taken, the compiler will still generate a
31 // warning. We do a little specialization dance...
32 template <typename INT2, typename UINT2, bool NEG2>
33 struct ToUnsignedT {};
34
35 template <typename INT2, typename UINT2>
36 struct ToUnsignedT<INT2, UINT2, false> {
37 static UINT2 ToUnsigned(INT2 value) {
38 return static_cast<UINT2>(value);
39 }
40 };
41
42 template <typename INT2, typename UINT2>
43 struct ToUnsignedT<INT2, UINT2, true> {
44 static UINT2 ToUnsigned(INT2 value) {
45 return static_cast<UINT2>(value < 0 ? -value : value);
46 }
47 };
48
49 // This set of templates is very similar to the above templates, but
50 // for testing whether an integer is negative.
51 template <typename INT2, bool NEG2>
52 struct TestNegT {};
53 template <typename INT2>
54 struct TestNegT<INT2, false> {
55 static bool TestNeg(INT2 value) {
56 // value is unsigned, and can never be negative.
57 return false;
58 }
59 };
60 template <typename INT2>
61 struct TestNegT<INT2, true> {
62 static bool TestNeg(INT2 value) {
63 return value < 0;
64 }
65 };
66
67 static STR IntToString(INT value) {
68 // log10(2) ~= 0.3 bytes needed per bit or per byte log10(2**8) ~= 2.4.
69 // So round up to allocate 3 output characters per byte, plus 1 for '-'.
70 const int kOutputBufSize = 3 * sizeof(INT) + 1;
71
72 // Allocate the whole string right away, we will right back to front, and
73 // then return the substr of what we ended up using.
74 STR outbuf(kOutputBufSize, 0);
75
76 bool is_neg = TestNegT<INT, NEG>::TestNeg(value);
77 // Even though is_neg will never be true when INT is parameterized as
78 // unsigned, even the presence of the unary operation causes a warning.
79 UINT res = ToUnsignedT<INT, UINT, NEG>::ToUnsigned(value);
80
81 for (typename STR::iterator it = outbuf.end();;) {
82 --it;
83 DCHECK(it != outbuf.begin());
84 *it = static_cast<typename STR::value_type>((res % 10) + '0');
85 res /= 10;
86
87 // We're done..
88 if (res == 0) {
89 if (is_neg) {
90 --it;
91 DCHECK(it != outbuf.begin());
92 *it = static_cast<typename STR::value_type>('-');
93 }
94 return STR(it, outbuf.end());
95 }
96 }
97 NOTREACHED();
98 return STR();
99 }
100 };
101
102 // Utility to convert a character to a digit in a given base
103 template<typename CHAR, int BASE, bool BASE_LTE_10> class BaseCharToDigit {
104 };
105
106 // Faster specialization for bases <= 10
107 template<typename CHAR, int BASE> class BaseCharToDigit<CHAR, BASE, true> {
108 public:
109 static bool Convert(CHAR c, uint8* digit) {
110 if (c >= '0' && c < '0' + BASE) {
111 *digit = c - '0';
112 return true;
113 }
114 return false;
115 }
116 };
117
118 // Specialization for bases where 10 < base <= 36
119 template<typename CHAR, int BASE> class BaseCharToDigit<CHAR, BASE, false> {
120 public:
121 static bool Convert(CHAR c, uint8* digit) {
122 if (c >= '0' && c <= '9') {
123 *digit = c - '0';
124 } else if (c >= 'a' && c < 'a' + BASE - 10) {
125 *digit = c - 'a' + 10;
126 } else if (c >= 'A' && c < 'A' + BASE - 10) {
127 *digit = c - 'A' + 10;
128 } else {
129 return false;
130 }
131 return true;
132 }
133 };
134
135 template<int BASE, typename CHAR> bool CharToDigit(CHAR c, uint8* digit) {
136 return BaseCharToDigit<CHAR, BASE, BASE <= 10>::Convert(c, digit);
137 }
138
139 // There is an IsWhitespace for wchars defined in string_util.h, but it is
140 // locale independent, whereas the functions we are replacing were
141 // locale-dependent. TBD what is desired, but for the moment let's not introduce
142 // a change in behaviour.
143 template<typename CHAR> class WhitespaceHelper {
144 };
145
146 template<> class WhitespaceHelper<char> {
147 public:
148 static bool Invoke(char c) {
149 return 0 != isspace(static_cast<unsigned char>(c));
150 }
151 };
152
153 template<> class WhitespaceHelper<char16> {
154 public:
155 static bool Invoke(char16 c) {
156 return 0 != iswspace(c);
157 }
158 };
159
160 template<typename CHAR> bool LocalIsWhitespace(CHAR c) {
161 return WhitespaceHelper<CHAR>::Invoke(c);
162 }
163
164 // IteratorRangeToNumberTraits should provide:
165 // - a typedef for iterator_type, the iterator type used as input.
166 // - a typedef for value_type, the target numeric type.
167 // - static functions min, max (returning the minimum and maximum permitted
168 // values)
169 // - constant kBase, the base in which to interpret the input
170 template<typename IteratorRangeToNumberTraits>
171 class IteratorRangeToNumber {
172 public:
173 typedef IteratorRangeToNumberTraits traits;
174 typedef typename traits::iterator_type const_iterator;
175 typedef typename traits::value_type value_type;
176
177 // Generalized iterator-range-to-number conversion.
178 //
179 static bool Invoke(const_iterator begin,
180 const_iterator end,
181 value_type* output) {
182 bool valid = true;
183
184 while (begin != end && LocalIsWhitespace(*begin)) {
185 valid = false;
186 ++begin;
187 }
188
189 if (begin != end && *begin == '-') {
190 if (!std::numeric_limits<value_type>::is_signed) {
191 valid = false;
192 } else if (!Negative::Invoke(begin + 1, end, output)) {
193 valid = false;
194 }
195 } else {
196 if (begin != end && *begin == '+') {
197 ++begin;
198 }
199 if (!Positive::Invoke(begin, end, output)) {
200 valid = false;
201 }
202 }
203
204 return valid;
205 }
206
207 private:
208 // Sign provides:
209 // - a static function, CheckBounds, that determines whether the next digit
210 // causes an overflow/underflow
211 // - a static function, Increment, that appends the next digit appropriately
212 // according to the sign of the number being parsed.
213 template<typename Sign>
214 class Base {
215 public:
216 static bool Invoke(const_iterator begin, const_iterator end,
217 typename traits::value_type* output) {
218 *output = 0;
219
220 if (begin == end) {
221 return false;
222 }
223
224 // Note: no performance difference was found when using template
225 // specialization to remove this check in bases other than 16
226 if (traits::kBase == 16 && end - begin > 2 && *begin == '0' &&
227 (*(begin + 1) == 'x' || *(begin + 1) == 'X')) {
228 begin += 2;
229 }
230
231 for (const_iterator current = begin; current != end; ++current) {
232 uint8 new_digit = 0;
233
234 if (!CharToDigit<traits::kBase>(*current, &new_digit)) {
235 return false;
236 }
237
238 if (current != begin) {
239 if (!Sign::CheckBounds(output, new_digit)) {
240 return false;
241 }
242 *output *= traits::kBase;
243 }
244
245 Sign::Increment(new_digit, output);
246 }
247 return true;
248 }
249 };
250
251 class Positive : public Base<Positive> {
252 public:
253 static bool CheckBounds(value_type* output, uint8 new_digit) {
254 if (*output > static_cast<value_type>(traits::max() / traits::kBase) ||
255 (*output == static_cast<value_type>(traits::max() / traits::kBase) &&
256 new_digit > traits::max() % traits::kBase)) {
257 *output = traits::max();
258 return false;
259 }
260 return true;
261 }
262 static void Increment(uint8 increment, value_type* output) {
263 *output += increment;
264 }
265 };
266
267 class Negative : public Base<Negative> {
268 public:
269 static bool CheckBounds(value_type* output, uint8 new_digit) {
270 if (*output < traits::min() / traits::kBase ||
271 (*output == traits::min() / traits::kBase &&
272 new_digit > 0 - traits::min() % traits::kBase)) {
273 *output = traits::min();
274 return false;
275 }
276 return true;
277 }
278 static void Increment(uint8 increment, value_type* output) {
279 *output -= increment;
280 }
281 };
282 };
283
284 template<typename ITERATOR, typename VALUE, int BASE>
285 class BaseIteratorRangeToNumberTraits {
286 public:
287 typedef ITERATOR iterator_type;
288 typedef VALUE value_type;
289 static value_type min() {
290 return std::numeric_limits<value_type>::min();
291 }
292 static value_type max() {
293 return std::numeric_limits<value_type>::max();
294 }
295 static const int kBase = BASE;
296 };
297
298 template<typename ITERATOR>
299 class BaseHexIteratorRangeToIntTraits
300 : public BaseIteratorRangeToNumberTraits<ITERATOR, int, 16> {
301 };
302
303 template<typename ITERATOR>
304 class BaseHexIteratorRangeToInt64Traits
305 : public BaseIteratorRangeToNumberTraits<ITERATOR, int64, 16> {
306 };
307
308 template<typename ITERATOR>
309 class BaseHexIteratorRangeToUInt64Traits
310 : public BaseIteratorRangeToNumberTraits<ITERATOR, uint64, 16> {
311 };
312
313 typedef BaseHexIteratorRangeToIntTraits<StringPiece::const_iterator>
314 HexIteratorRangeToIntTraits;
315
316 typedef BaseHexIteratorRangeToInt64Traits<StringPiece::const_iterator>
317 HexIteratorRangeToInt64Traits;
318
319 typedef BaseHexIteratorRangeToUInt64Traits<StringPiece::const_iterator>
320 HexIteratorRangeToUInt64Traits;
321
322 template<typename STR>
323 bool HexStringToBytesT(const STR& input, std::vector<uint8>* output) {
324 DCHECK_EQ(output->size(), 0u);
325 size_t count = input.size();
326 if (count == 0 || (count % 2) != 0)
327 return false;
328 for (uintptr_t i = 0; i < count / 2; ++i) {
329 uint8 msb = 0; // most significant 4 bits
330 uint8 lsb = 0; // least significant 4 bits
331 if (!CharToDigit<16>(input[i * 2], &msb) ||
332 !CharToDigit<16>(input[i * 2 + 1], &lsb))
333 return false;
334 output->push_back((msb << 4) | lsb);
335 }
336 return true;
337 }
338
339 template <typename VALUE, int BASE>
340 class StringPieceToNumberTraits
341 : public BaseIteratorRangeToNumberTraits<StringPiece::const_iterator,
342 VALUE,
343 BASE> {
344 };
345
346 template <typename VALUE>
347 bool StringToIntImpl(const StringPiece& input, VALUE* output) {
348 return IteratorRangeToNumber<StringPieceToNumberTraits<VALUE, 10> >::Invoke(
349 input.begin(), input.end(), output);
350 }
351
352 template <typename VALUE, int BASE>
353 class StringPiece16ToNumberTraits
354 : public BaseIteratorRangeToNumberTraits<StringPiece16::const_iterator,
355 VALUE,
356 BASE> {
357 };
358
359 template <typename VALUE>
360 bool String16ToIntImpl(const StringPiece16& input, VALUE* output) {
361 return IteratorRangeToNumber<StringPiece16ToNumberTraits<VALUE, 10> >::Invoke(
362 input.begin(), input.end(), output);
363 }
364
365 } // namespace
366
367 std::string IntToString(int value) {
368 return IntToStringT<std::string, int, unsigned int, true>::
369 IntToString(value);
370 }
371
372 string16 IntToString16(int value) {
373 return IntToStringT<string16, int, unsigned int, true>::
374 IntToString(value);
375 }
376
377 std::string UintToString(unsigned int value) {
378 return IntToStringT<std::string, unsigned int, unsigned int, false>::
379 IntToString(value);
380 }
381
382 string16 UintToString16(unsigned int value) {
383 return IntToStringT<string16, unsigned int, unsigned int, false>::
384 IntToString(value);
385 }
386
387 std::string Int64ToString(int64 value) {
388 return IntToStringT<std::string, int64, uint64, true>::
389 IntToString(value);
390 }
391
392 string16 Int64ToString16(int64 value) {
393 return IntToStringT<string16, int64, uint64, true>::IntToString(value);
394 }
395
396 std::string Uint64ToString(uint64 value) {
397 return IntToStringT<std::string, uint64, uint64, false>::
398 IntToString(value);
399 }
400
401 string16 Uint64ToString16(uint64 value) {
402 return IntToStringT<string16, uint64, uint64, false>::
403 IntToString(value);
404 }
405
406 std::string DoubleToString(double value) {
407 // According to g_fmt.cc, it is sufficient to declare a buffer of size 32.
408 char buffer[32];
409 dmg_fp::g_fmt(buffer, value);
410 return std::string(buffer);
411 }
412
413 bool StringToInt(const StringPiece& input, int* output) {
414 return StringToIntImpl(input, output);
415 }
416
417 bool StringToInt(const StringPiece16& input, int* output) {
418 return String16ToIntImpl(input, output);
419 }
420
421 bool StringToUint(const StringPiece& input, unsigned* output) {
422 return StringToIntImpl(input, output);
423 }
424
425 bool StringToUint(const StringPiece16& input, unsigned* output) {
426 return String16ToIntImpl(input, output);
427 }
428
429 bool StringToInt64(const StringPiece& input, int64* output) {
430 return StringToIntImpl(input, output);
431 }
432
433 bool StringToInt64(const StringPiece16& input, int64* output) {
434 return String16ToIntImpl(input, output);
435 }
436
437 bool StringToUint64(const StringPiece& input, uint64* output) {
438 return StringToIntImpl(input, output);
439 }
440
441 bool StringToUint64(const StringPiece16& input, uint64* output) {
442 return String16ToIntImpl(input, output);
443 }
444
445 bool StringToSizeT(const StringPiece& input, size_t* output) {
446 return StringToIntImpl(input, output);
447 }
448
449 bool StringToSizeT(const StringPiece16& input, size_t* output) {
450 return String16ToIntImpl(input, output);
451 }
452
453 bool StringToDouble(const std::string& input, double* output) {
454 // Thread-safe? It is on at least Mac, Linux, and Windows.
455 ScopedClearErrno clear_errno;
456
457 char* endptr = NULL;
458 *output = dmg_fp::strtod(input.c_str(), &endptr);
459
460 // Cases to return false:
461 // - If errno is ERANGE, there was an overflow or underflow.
462 // - If the input string is empty, there was nothing to parse.
463 // - If endptr does not point to the end of the string, there are either
464 // characters remaining in the string after a parsed number, or the string
465 // does not begin with a parseable number. endptr is compared to the
466 // expected end given the string's stated length to correctly catch cases
467 // where the string contains embedded NUL characters.
468 // - If the first character is a space, there was leading whitespace
469 return errno == 0 &&
470 !input.empty() &&
471 input.c_str() + input.length() == endptr &&
472 !isspace(input[0]);
473 }
474
475 // Note: if you need to add String16ToDouble, first ask yourself if it's
476 // really necessary. If it is, probably the best implementation here is to
477 // convert to 8-bit and then use the 8-bit version.
478
479 // Note: if you need to add an iterator range version of StringToDouble, first
480 // ask yourself if it's really necessary. If it is, probably the best
481 // implementation here is to instantiate a string and use the string version.
482
483 std::string HexEncode(const void* bytes, size_t size) {
484 static const char kHexChars[] = "0123456789ABCDEF";
485
486 // Each input byte creates two output hex characters.
487 std::string ret(size * 2, '\0');
488
489 for (size_t i = 0; i < size; ++i) {
490 char b = reinterpret_cast<const char*>(bytes)[i];
491 ret[(i * 2)] = kHexChars[(b >> 4) & 0xf];
492 ret[(i * 2) + 1] = kHexChars[b & 0xf];
493 }
494 return ret;
495 }
496
497 bool HexStringToInt(const StringPiece& input, int* output) {
498 return IteratorRangeToNumber<HexIteratorRangeToIntTraits>::Invoke(
499 input.begin(), input.end(), output);
500 }
501
502 bool HexStringToInt64(const StringPiece& input, int64* output) {
503 return IteratorRangeToNumber<HexIteratorRangeToInt64Traits>::Invoke(
504 input.begin(), input.end(), output);
505 }
506
507 bool HexStringToUInt64(const StringPiece& input, uint64* output) {
508 return IteratorRangeToNumber<HexIteratorRangeToUInt64Traits>::Invoke(
509 input.begin(), input.end(), output);
510 }
511
512 bool HexStringToBytes(const std::string& input, std::vector<uint8>* output) {
513 return HexStringToBytesT(input, output);
514 }
515
516 } // namespace base

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