ei.cfg Removal/Restore Utility

SUBMITTED BY: Guest

DATE: Dec. 4, 2013, 12:55 p.m.

FORMAT: C++

SIZE: 5.5 kB

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  1. /**
  2. * ei.cfg Removal/Restore Utility
  3. * Copyright (C) Kai Liu. Licensed under a standard BSD-style license.
  4. * CRC16 code was adapted from 7-Zip, which is licensed under the GPL.
  5. **/
  7. //#include <windows.h>
  9. #pragma intrinsic(memset, memcmp, memcpy)
  11. #define CB_WORK_RANGE (0x1000000)
  12. #define CCH_WORK_RANGE (CB_WORK_RANGE/sizeof(WCHAR))
  13. #define CCH_PATH_BUFFER (MAX_PATH << 1)
  16. typedef struct {
  17. UINT16 ident;
  18. UINT16 version;
  19. UINT8 checksum;
  20. UINT8 reserved;
  21. UINT16 serial;
  22. UINT16 crc;
  23. UINT16 crclen;
  24. UINT32 location;
  25. } UDFTAG, *PUDFTAG;
  27. typedef struct {
  28. UINT32 cbExtent;
  29. BYTE location[6];
  30. BYTE iu[6];
  31. } LONGALLOC, *PLONGALLOC;
  33. typedef struct {
  34. UDFTAG tag;
  35. UINT16 version;
  36. UINT8 characteristics;
  37. UINT8 cbIdentifier;
  38. LONGALLOC ICB;
  39. UINT16 cbIU;
  40. BYTE misc[2];
  41. } UDFFILEDESC, *PUDFFILEDESC;
  44. // CRC16 adapted from 7-Zip
  45. void Crc16GenerateTable();
  46. UINT16 Crc16Calc(const void *data, size_t size);
  47. // CRC16 adapted from 7-Zip
  50. #pragma comment(linker, "/version:1.1")
  51. #pragma comment(linker, "/entry:eicfg_remover")
  52. void eicfg_remover( )
  53. {
  54. PVOID pvBuffer = LocalAlloc(LMEM_FIXED, CB_WORK_RANGE);
  56. // Set up the OPENFILENAME structure
  58. TCHAR szFileName[CCH_PATH_BUFFER];
  60. OPENFILENAME ofn;
  61. ZeroMemory(&ofn, sizeof(ofn));
  62. ofn.lStructSize = sizeof(ofn);
  63. ofn.lpstrFilter = TEXT("ISO Image (*.iso)\0*.iso\0");
  64. ofn.lpstrFile = szFileName;
  65. ofn.lpstrFile[0] = 0;
  66. ofn.nMaxFile = CCH_PATH_BUFFER;
  67. ofn.Flags = OFN_DONTADDTORECENT | OFN_FILEMUSTEXIST | OFN_HIDEREADONLY;
  69. if (pvBuffer && GetOpenFileName(&ofn))
  70. {
  71. HANDLE hFile = CreateFile(
  72. ofn.lpstrFile,
  73. GENERIC_READ | GENERIC_WRITE,
  74. 0,
  75. NULL,
  76. OPEN_EXISTING,
  77. FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,
  78. NULL
  79. );
  81. UINT64 cbFile;
  82. DWORD cbOperation;
  84. if ( hFile != INVALID_HANDLE_VALUE &&
  85. GetFileSizeEx(hFile, (PLARGE_INTEGER)&cbFile) &&
  86. cbFile > CB_WORK_RANGE &&
  87. ReadFile(hFile, pvBuffer, CB_WORK_RANGE, &cbOperation, NULL) &&
  88. cbOperation == CB_WORK_RANGE )
  89. {
  90. PWSTR pszBuffer = pvBuffer;
  91. UINT32 posStart;
  92. PUDFFILEDESC pDesc = NULL;
  93. int i;
  95. // Locate the file name entry
  97. for (i = 0x100; i < CCH_WORK_RANGE - 0x100; ++i)
  98. {
  99. static const WCHAR szNeedle[] = L"ei.cfg";
  101. if (memcmp(pszBuffer + i, szNeedle, sizeof(szNeedle) - sizeof(WCHAR)) == 0)
  102. {
  103. posStart = i * sizeof(WCHAR) - sizeof(UDFFILEDESC);
  104. pDesc = (PUDFFILEDESC)((PBYTE)pvBuffer + posStart);
  106. if ( pDesc->tag.ident == 257 &&
  107. pDesc->tag.version == 2 &&
  108. pDesc->tag.reserved == 0 &&
  109. pDesc->tag.crclen == sizeof(UDFFILEDESC) - sizeof(UDFTAG) + (sizeof(szNeedle) - sizeof(WCHAR)) &&
  110. pDesc->cbIdentifier == sizeof(szNeedle) - 1 &&
  111. pDesc->cbIU == 0 &&
  112. (pDesc->characteristics == 0 || pDesc->characteristics == 5) )
  113. {
  114. // Passed sanity check
  115. break;
  116. }
  117. else
  118. {
  119. pDesc = NULL;
  120. }
  121. }
  122. }
  124. if (pDesc)
  125. {
  126. PBYTE pbRaw = (PBYTE)pDesc;
  128. // Toggle whether the file is deleted
  130. pDesc->characteristics = (pDesc->characteristics) ? 0 : 5;
  132. // Recalculate the descriptor CRC16
  134. Crc16GenerateTable();
  135. pDesc->tag.crc = Crc16Calc(&pDesc->version, pDesc->tag.crclen);
  137. // Recalculate the tag checksum
  139. pDesc->tag.checksum = 0;
  141. for (i = 0; i < 4; ++i)
  142. pDesc->tag.checksum += pbRaw[i];
  143. for (i = 5; i < 16; ++i)
  144. pDesc->tag.checksum += pbRaw[i];
  146. // Update the ISO file
  148. SetFilePointer(hFile, posStart, NULL, FILE_BEGIN);
  149. WriteFile(hFile, pDesc, sizeof(UDFFILEDESC), &cbOperation, NULL);
  151. MessageBox(
  152. NULL,
  153. (pDesc->characteristics) ? TEXT("ei.cfg removed") : TEXT("ei.cfg restored"),
  154. NULL,
  155. MB_ICONINFORMATION
  156. );
  157. }
  158. else
  159. {
  160. MessageBox(NULL, TEXT("ei.cfg not found."), NULL, MB_ICONERROR);
  161. }
  163. }
  164. else
  165. {
  166. MessageBox(NULL, TEXT("Input error."), NULL, MB_ICONERROR);
  167. }
  169. if (hFile != INVALID_HANDLE_VALUE)
  170. CloseHandle(hFile);
  171. }
  173. LocalFree(pvBuffer);
  174. ExitProcess(0);
  175. }
  178. // CRC16 adapted from 7-Zip
  179. #define CRC16_INIT_VAL 0
  180. #define CRC16_GET_DIGEST(crc) (crc)
  181. #define CRC16_UPDATE_BYTE(crc, b) (g_Crc16Table[(((crc) >> 8) ^ (b)) & 0xFF] ^ ((crc) << 8))
  183. #define kCrc16Poly 0x1021
  184. UINT16 g_Crc16Table[256];
  186. void Crc16GenerateTable()
  187. {
  188. UINT32 i;
  189. int j;
  190. for (i = 0; i < 256; i++)
  191. {
  192. UINT32 r = (i << 8);
  193. for (j = 8; j > 0; j--)
  194. r = ((r & 0x8000) ? ((r << 1) ^ kCrc16Poly) : (r << 1)) & 0xFFFF;
  195. g_Crc16Table[i] = (UINT16)r;
  196. }
  197. }
  199. UINT16 Crc16_Update(UINT16 v, const void *data, size_t size)
  200. {
  201. const BYTE *p = (const BYTE *)data;
  202. for (; size > 0 ; size--, p++)
  203. v = CRC16_UPDATE_BYTE(v, *p);
  204. return v;
  205. }
  207. UINT16 Crc16Calc(const void *data, size_t size)
  208. {
  209. return Crc16_Update(CRC16_INIT_VAL, data, size);
  210. }
  211. // CRC16 adapted from 7-Zip
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