139 lines
3.2 KiB
C++
139 lines
3.2 KiB
C++
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//+-------------------------------------------------------------------------
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//
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// Microsoft Windows
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// Copyright (C) Microsoft Corporation, 1992 - 1992.
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//
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// File: header.cxx
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//
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// Contents: Code to manage MSF header
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//
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// Classes: Defined in header.hxx
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//
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//--------------------------------------------------------------------------
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#include "msfhead.cxx"
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#include "h/dfver.h"
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// Function set [uArg] to the byte order of the machine.
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//
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// it will return 0xFFFE on Little Endian (== the disk order)
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// and 0xFEFF on Big Endian
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const BYTE abDiskByteOrder[]= {0xFE, 0xFF};
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inline void SetMachineByteOrder(USHORT *pUShort)
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{
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memcpy(pUShort, abDiskByteOrder, sizeof(abDiskByteOrder));
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}
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CMSFHeader::CMSFHeader(USHORT uSectorShift)
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{
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msfAssert((CSECTFATREAL != CSECTFAT) || (sizeof(CMSFHeader) == HEADERSIZE));
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_uSectorShift = uSectorShift;
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_uMiniSectorShift = MINISECTORSHIFT;
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_ulMiniSectorCutoff = MINISTREAMSIZE;
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_clid = IID_NULL;
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SetMachineByteOrder(&_uByteOrder);
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_uMinorVersion = rmm;
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_uDllVersion = rmj;
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for (SECT sect = 0; sect < CSECTFAT; sect ++)
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{
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_sectFat[sect] = FREESECT;
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}
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SetDifLength(0);
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SetDifStart(ENDOFCHAIN);
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SetFatLength(1);
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SetFatStart(SECTFAT);
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SetDirStart(SECTDIR);
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SetMiniFatLength(0);
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SetMiniFatStart(ENDOFCHAIN);
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_signature = 0;
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_usReserved = 0;
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_ulReserved1 = _ulReserved2 = 0;
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// Write DocFile signature
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memcpy(abSig, SIGSTG, CBSIGSTG);
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}
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//+---------------------------------------------------------------------------
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//
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// Function: CheckSignature, private
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//
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// Synopsis: Checks the given memory against known signatures
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//
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// Arguments: [pb] - Pointer to memory to check
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//
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// Returns: S_OK - Current signature
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// S_FALSE - Beta 2 signature, but still successful
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// Appropriate status code
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//
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//----------------------------------------------------------------------------
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//Identifier for first bytes of Beta 2 Docfiles
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const BYTE SIGSTG_B2[] = {0x0e, 0x11, 0xfc, 0x0d, 0xd0, 0xcf, 0x11, 0xe0};
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const BYTE CBSIGSTG_B2 = sizeof(SIGSTG_B2);
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SCODE CheckSignature(BYTE *pb)
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{
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SCODE sc;
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msfDebugOut((DEB_ITRACE, "In CheckSignature(%p)\n", pb));
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// Check for ship Docfile signature first
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if (memcmp(pb, SIGSTG, CBSIGSTG) == 0)
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sc = S_OK;
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// Check for Beta 2 Docfile signature
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else if (memcmp(pb, SIGSTG_B2, CBSIGSTG_B2) == 0)
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sc = S_FALSE;
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else
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sc = STG_E_INVALIDHEADER;
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msfDebugOut((DEB_ITRACE, "Out CheckSignature => %lX\n", sc));
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return sc;
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}
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//+-------------------------------------------------------------------------
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//
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// Method: CMSFHeader::Validate, public
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//
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// Synopsis: Validate a header.
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//
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// Returns: S_OK if header is valid.
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//
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//--------------------------------------------------------------------------
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SCODE CMSFHeader::Validate(VOID) const
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{
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SCODE sc;
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sc = CheckSignature((BYTE *)abSig);
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if (sc == S_OK)
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{
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// Check file format verson number
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if (GetDllVersion() > rmj)
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return STG_E_OLDDLL;
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// check for unreasonably large SectorShift
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if (GetSectorShift() > MAXSECTORSHIFT)
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return STG_E_DOCFILECORRUPT;
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}
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return sc;
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}
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