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+ Fixed bounds checking in SFileSetFilePointer

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Ladislav Zezula
2016-05-03 16:33:49 +02:00
parent 881ea60a01
commit 3224eac75e
2 changed files with 161 additions and 50 deletions
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98
src/SFileReadFile.cpp
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@@ -801,9 +801,10 @@ DWORD WINAPI SFileGetFileSize(HANDLE hFile, LPDWORD pdwFileSizeHigh)
DWORD WINAPI SFileSetFilePointer(HANDLE hFile, LONG lFilePos, LONG * plFilePosHigh, DWORD dwMoveMethod)
{
TMPQFile * hf = (TMPQFile *)hFile;
ULONGLONG FilePosition;
ULONGLONG MoveOffset;
DWORD dwFilePosHi;
ULONGLONG OldPosition;
ULONGLONG NewPosition;
ULONGLONG FileSize;
ULONGLONG DeltaPos;
// If the hFile is not a valid file handle, return an error.
if(!IsValidFileHandle(hFile))
@@ -812,33 +813,47 @@ DWORD WINAPI SFileSetFilePointer(HANDLE hFile, LONG lFilePos, LONG * plFilePosHi
return SFILE_INVALID_POS;
}
// Retrieve the file size for handling the limits
if(hf->pStream != NULL)
{
FileStream_GetSize(hf->pStream, &FileSize);
}
else
{
FileSize = SFileGetFileSize(hFile, NULL);
}
// Handle the NULL and non-NULL values of plFilePosHigh
// Non-NULL: The DeltaPos is combined from lFilePos and *lpFilePosHigh
// NULL: The DeltaPos is sign-extended value of lFilePos
DeltaPos = (plFilePosHigh != NULL) ? MAKE_OFFSET64(plFilePosHigh[0], lFilePos) : (ULONGLONG)(LONGLONG)lFilePos;
// Get the relative point where to move from
switch(dwMoveMethod)
{
case FILE_BEGIN:
FilePosition = 0;
// Move relative to the file begin.
OldPosition = 0;
break;
case FILE_CURRENT:
// Retrieve the current file position
if(hf->pStream != NULL)
{
FileStream_GetPos(hf->pStream, &FilePosition);
FileStream_GetPos(hf->pStream, &OldPosition);
}
else
{
FilePosition = hf->dwFilePos;
OldPosition = hf->dwFilePos;
}
break;
case FILE_END:
if(hf->pStream != NULL)
{
FileStream_GetSize(hf->pStream, &FilePosition);
}
else
{
FilePosition = SFileGetFileSize(hFile, NULL);
}
// Move relative to the end of the file
OldPosition = FileSize;
break;
default:
@@ -846,47 +861,36 @@ DWORD WINAPI SFileSetFilePointer(HANDLE hFile, LONG lFilePos, LONG * plFilePosHi
return SFILE_INVALID_POS;
}
// Now get the move offset. Note that both values form
// a signed 64-bit value (a file pointer can be moved backwards)
if(plFilePosHigh != NULL)
dwFilePosHi = *plFilePosHigh;
else
dwFilePosHi = (lFilePos & 0x80000000) ? 0xFFFFFFFF : 0;
MoveOffset = MAKE_OFFSET64(dwFilePosHi, lFilePos);
// Calculate the new position
NewPosition = OldPosition + DeltaPos;
// Now calculate the new file pointer
// Do not allow the file pointer to overflow
FilePosition = ((FilePosition + MoveOffset) >= FilePosition) ? (FilePosition + MoveOffset) : 0;
// If moving backward, don't allow the new position go negative
if((LONGLONG)DeltaPos < 0)
{
if(NewPosition > FileSize)
NewPosition = 0;
}
// If moving forward, don't allow the new position go past the end of the file
else
{
if(NewPosition > FileSize)
NewPosition = FileSize;
}
// Now apply the file pointer to the file
if(hf->pStream != NULL)
{
// Apply the new file position
if(!FileStream_Read(hf->pStream, &FilePosition, NULL, 0))
if(!FileStream_Read(hf->pStream, &NewPosition, NULL, 0))
return SFILE_INVALID_POS;
// Return the new file position
if(plFilePosHigh != NULL)
*plFilePosHigh = (LONG)(FilePosition >> 32);
return (DWORD)FilePosition;
}
else
{
// Files in MPQ can't be bigger than 4 GB.
// We don't allow to go past 4 GB
if(FilePosition >> 32)
{
SetLastError(ERROR_INVALID_PARAMETER);
return SFILE_INVALID_POS;
}
// Change the file position
hf->dwFilePos = (DWORD)FilePosition;
// Return the new file position
if(plFilePosHigh != NULL)
*plFilePosHigh = 0;
return (DWORD)FilePosition;
hf->dwFilePos = (DWORD)NewPosition;
}
}
// Return the new file position
if(plFilePosHigh != NULL)
*plFilePosHigh = (LONG)(NewPosition >> 32);
return (DWORD)NewPosition;
}