rufus/file.c

/******************************************************************
    Copyright (C) 2009  Henrik Carlqvist
    Modified for Rufus/Windows (C) 2011  Pete Batard

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
******************************************************************/
#include <stdio.h>
#include <string.h>

#include "rufus.h"
#include "file.h"

int write_sectors(HANDLE hDrive, size_t SectorSize,
                  size_t StartSector, size_t nSectors,
                  const void *pBuf, size_t BufSize)
{
   LARGE_INTEGER ptr;
   DWORD dwSize;

   if(SectorSize * nSectors > BufSize)
   {
      uprintf("write_sectors: Buffer is too small\n");
      return 0;
   }

   ptr.QuadPart = StartSector*SectorSize;
   if(!SetFilePointerEx(hDrive, ptr, NULL, FILE_BEGIN))
   {
      uprintf("write_sectors: Could not access sector %d - %s\n", StartSector, WindowsErrorString());
      return 0;
   }

   if((!WriteFile(hDrive, pBuf, (DWORD)BufSize, &dwSize, NULL)) || (dwSize != BufSize))
   {
      uprintf("write_sectors: Write error - %s\n", WindowsErrorString());
      return 0;
   }

   return 1;
}

int read_sectors(HANDLE hDrive, size_t SectorSize,
                 size_t StartSector, size_t nSectors,
                 void *pBuf, size_t BufSize)
{
   LARGE_INTEGER ptr;
   DWORD dwSize;

   if(SectorSize * nSectors > BufSize)
   {
      uprintf("read_sectors: Buffer is too small\n");
      return 0;
   }

   ptr.QuadPart = StartSector*SectorSize;
   if(!SetFilePointerEx(hDrive, ptr, NULL, FILE_BEGIN))
   {
      uprintf("read_sectors: Could not access sector %d - %s\n", StartSector, WindowsErrorString());
      return 0;
   }

   if((!ReadFile(hDrive, pBuf, (DWORD)BufSize, &dwSize, NULL)) || (dwSize != BufSize))
   {
      uprintf("read_sectors: Read error - %s\n", WindowsErrorString());
      return 0;
   }

   return 1;
}

/* Use a bastardized fp that contains a Windows handle and the sector size */
int contains_data(FILE *fp, unsigned long ulPosition,
                  const void *pData, unsigned int uiLen)
{
   unsigned char aucBuf[MAX_DATA_LEN];
   HANDLE hDrive = (HANDLE)fp->_ptr;
   unsigned long ulSectorSize = (unsigned long)fp->_bufsiz;
   unsigned long ulStartSector, ulEndSector, ulNumSectors;

   ulStartSector = ulPosition/ulSectorSize;
   ulEndSector   = (ulPosition+uiLen+ulSectorSize-1)/ulSectorSize;
   ulNumSectors  = ulEndSector - ulStartSector;

   if((ulNumSectors*ulSectorSize) > MAX_DATA_LEN)
   {
      uprintf("Please increase MAX_DATA_LEN in file.h\n");
      return 0;
   }

   if(!read_sectors(hDrive, ulSectorSize, ulStartSector,
                     ulNumSectors, aucBuf, sizeof(aucBuf)))
      return 0;

   if(memcmp(pData, &aucBuf[ulPosition - ulStartSector*ulSectorSize], uiLen))
      return 0;
   return 1;
} /* contains_data */

/* May read/write the same sector many times, but compatible with existing ms-sys */
int write_data(FILE *fp, unsigned long ulPosition,
               const void *pData, unsigned int uiLen)
{
   unsigned char aucBuf[MAX_DATA_LEN];
   HANDLE hDrive = (HANDLE)fp->_ptr;
   unsigned long ulSectorSize = (unsigned long)fp->_bufsiz;
   unsigned long ulStartSector, ulEndSector, ulNumSectors;

   ulStartSector = ulPosition/ulSectorSize;
   ulEndSector   = (ulPosition+uiLen+ulSectorSize-1)/ulSectorSize;
   ulNumSectors  = ulEndSector - ulStartSector;

   if((ulNumSectors*ulSectorSize) > MAX_DATA_LEN)
   {
      uprintf("Please increase MAX_DATA_LEN in file.h\n");
      return 0;
   }

   /* Data to write may not be aligned on a sector boundary => read into a sector buffer first */
   if(!read_sectors(hDrive, ulSectorSize, ulStartSector,
                     ulNumSectors, aucBuf, sizeof(aucBuf)))
      return 0;

   if(!memcpy(&aucBuf[ulPosition - ulStartSector*ulSectorSize], pData, uiLen))
      return 0;

   if(!write_sectors(hDrive, ulSectorSize, ulStartSector,
                     ulNumSectors, aucBuf, sizeof(aucBuf)))
      return 0;
   return 1;
} /* write_data */