SkBase64.cpp 4.8 KB

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  1. /*
  2. * Copyright 2006 The Android Open Source Project
  3. *
  4. * Use of this source code is governed by a BSD-style license that can be
  5. * found in the LICENSE file.
  6. */
  7. #include "include/utils/SkBase64.h"
  8. #define DecodePad -2
  9. #define EncodePad 64
  10. static const char default_encode[] =
  11. "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
  12. "abcdefghijklmnopqrstuvwxyz"
  13. "0123456789+/=";
  14. static const signed char decodeData[] = {
  15. 62, -1, -1, -1, 63,
  16. 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, DecodePad, -1, -1,
  17. -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
  18. 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
  19. -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  20. 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
  21. };
  22. SkBase64::SkBase64() : fLength((size_t) -1), fData(nullptr) {
  23. }
  24. #if defined _WIN32 // disable 'two', etc. may be used without having been initialized
  25. #pragma warning ( push )
  26. #pragma warning ( disable : 4701 )
  27. #endif
  28. SkBase64::Error SkBase64::decode(const void* srcPtr, size_t size, bool writeDestination) {
  29. unsigned char* dst = (unsigned char*) fData;
  30. const unsigned char* dstStart = (const unsigned char*) fData;
  31. const unsigned char* src = (const unsigned char*) srcPtr;
  32. bool padTwo = false;
  33. bool padThree = false;
  34. const unsigned char* end = src + size;
  35. while (src < end) {
  36. unsigned char bytes[4];
  37. int byte = 0;
  38. do {
  39. unsigned char srcByte = *src++;
  40. if (srcByte == 0)
  41. goto goHome;
  42. if (srcByte <= ' ')
  43. continue; // treat as white space
  44. if (srcByte < '+' || srcByte > 'z')
  45. return kBadCharError;
  46. signed char decoded = decodeData[srcByte - '+'];
  47. bytes[byte] = decoded;
  48. if (decoded < 0) {
  49. if (decoded == DecodePad)
  50. goto handlePad;
  51. return kBadCharError;
  52. } else
  53. byte++;
  54. if (*src)
  55. continue;
  56. if (byte == 0)
  57. goto goHome;
  58. if (byte == 4)
  59. break;
  60. handlePad:
  61. if (byte < 2)
  62. return kPadError;
  63. padThree = true;
  64. if (byte == 2)
  65. padTwo = true;
  66. break;
  67. } while (byte < 4);
  68. int two = 0;
  69. int three = 0;
  70. if (writeDestination) {
  71. int one = (uint8_t) (bytes[0] << 2);
  72. two = bytes[1];
  73. one |= two >> 4;
  74. two = (uint8_t) ((two << 4) & 0xFF);
  75. three = bytes[2];
  76. two |= three >> 2;
  77. three = (uint8_t) ((three << 6) & 0xFF);
  78. three |= bytes[3];
  79. SkASSERT(one < 256 && two < 256 && three < 256);
  80. *dst = (unsigned char) one;
  81. }
  82. dst++;
  83. if (padTwo)
  84. break;
  85. if (writeDestination)
  86. *dst = (unsigned char) two;
  87. dst++;
  88. if (padThree)
  89. break;
  90. if (writeDestination)
  91. *dst = (unsigned char) three;
  92. dst++;
  93. }
  94. goHome:
  95. fLength = dst - dstStart;
  96. return kNoError;
  97. }
  98. #if defined _WIN32
  99. #pragma warning ( pop )
  100. #endif
  101. size_t SkBase64::Encode(const void* srcPtr, size_t length, void* dstPtr, const char* encodeMap) {
  102. const char* encode;
  103. if (nullptr == encodeMap) {
  104. encode = default_encode;
  105. } else {
  106. encode = encodeMap;
  107. }
  108. const unsigned char* src = (const unsigned char*) srcPtr;
  109. unsigned char* dst = (unsigned char*) dstPtr;
  110. if (dst) {
  111. size_t remainder = length % 3;
  112. const unsigned char* end = &src[length - remainder];
  113. while (src < end) {
  114. unsigned a = *src++;
  115. unsigned b = *src++;
  116. unsigned c = *src++;
  117. int d = c & 0x3F;
  118. c = (c >> 6 | b << 2) & 0x3F;
  119. b = (b >> 4 | a << 4) & 0x3F;
  120. a = a >> 2;
  121. *dst++ = encode[a];
  122. *dst++ = encode[b];
  123. *dst++ = encode[c];
  124. *dst++ = encode[d];
  125. }
  126. if (remainder > 0) {
  127. int k1 = 0;
  128. int k2 = EncodePad;
  129. int a = (uint8_t) *src++;
  130. if (remainder == 2)
  131. {
  132. int b = *src++;
  133. k1 = b >> 4;
  134. k2 = (b << 2) & 0x3F;
  135. }
  136. *dst++ = encode[a >> 2];
  137. *dst++ = encode[(k1 | a << 4) & 0x3F];
  138. *dst++ = encode[k2];
  139. *dst++ = encode[EncodePad];
  140. }
  141. }
  142. return (length + 2) / 3 * 4;
  143. }
  144. SkBase64::Error SkBase64::decode(const char* src, size_t len) {
  145. Error err = decode(src, len, false);
  146. SkASSERT(err == kNoError);
  147. if (err != kNoError)
  148. return err;
  149. fData = new char[fLength]; // should use sk_malloc/sk_free
  150. decode(src, len, true);
  151. return kNoError;
  152. }