Line data    Source code

       1             : /******************************************************************************
       2             :  *
       3             :  * Project:  GeoTIFF Driver
       4             :  * Purpose:  GDAL GeoTIFF support.
       5             :  * Author:   Frank Warmerdam, warmerdam@pobox.com
       6             :  *
       7             :  ******************************************************************************
       8             :  * Copyright (c) 1998, 2002, Frank Warmerdam <warmerdam@pobox.com>
       9             :  * Copyright (c) 2007-2015, Even Rouault <even dot rouault at spatialys dot com>
      10             :  *
      11             :  * Permission is hereby granted, free of charge, to any person obtaining a
      12             :  * copy of this software and associated documentation files (the "Software"),
      13             :  * to deal in the Software without restriction, including without limitation
      14             :  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      15             :  * and/or sell copies of the Software, and to permit persons to whom the
      16             :  * Software is furnished to do so, subject to the following conditions:
      17             :  *
      18             :  * The above copyright notice and this permission notice shall be included
      19             :  * in all copies or substantial portions of the Software.
      20             :  *
      21             :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
      22             :  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
      23             :  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
      24             :  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
      25             :  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
      26             :  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
      27             :  * DEALINGS IN THE SOFTWARE.
      28             :  ****************************************************************************/
      29             : 
      30             : #ifndef FETCHBUFFERDIRECTIO_H_INCLUDED
      31             : #define FETCHBUFFERDIRECTIO_H_INCLUDED
      32             : 
      33             : #include "cpl_error.h"
      34             : #include "cpl_vsi.h"
      35             : #include "gdal.h"
      36             : 
      37             : /************************************************************************/
      38             : /*                        FetchBufferDirectIO                           */
      39             : /************************************************************************/
      40             : 
      41             : class FetchBufferDirectIO final
      42             : {
      43             :     VSILFILE *fp;
      44             :     GByte *pTempBuffer;
      45             :     size_t nTempBufferSize;
      46             : 
      47             :   public:
      48         613 :     FetchBufferDirectIO(VSILFILE *fpIn, GByte *pTempBufferIn,
      49             :                         size_t nTempBufferSizeIn)
      50         613 :         : fp(fpIn), pTempBuffer(pTempBufferIn),
      51         613 :           nTempBufferSize(nTempBufferSizeIn)
      52             :     {
      53         613 :     }
      54             : 
      55        9595 :     const GByte *FetchBytes(vsi_l_offset nOffset, int nPixels, int nDTSize,
      56             :                             bool bIsByteSwapped, bool bIsComplex, int nBlockId)
      57             :     {
      58        9595 :         if (!FetchBytes(pTempBuffer, nOffset, nPixels, nDTSize, bIsByteSwapped,
      59             :                         bIsComplex, nBlockId))
      60             :         {
      61          18 :             return nullptr;
      62             :         }
      63        9577 :         return pTempBuffer;
      64             :     }
      65             : 
      66        9595 :     bool FetchBytes(GByte *pabyDstBuffer, vsi_l_offset nOffset, int nPixels,
      67             :                     int nDTSize, bool bIsByteSwapped, bool bIsComplex,
      68             :                     int nBlockId)
      69             :     {
      70        9595 :         vsi_l_offset nSeekForward = 0;
      71       13801 :         if (nOffset <= VSIFTellL(fp) ||
      72        4206 :             (nSeekForward = nOffset - VSIFTellL(fp)) > nTempBufferSize)
      73             :         {
      74        7344 :             if (VSIFSeekL(fp, nOffset, SEEK_SET) != 0)
      75             :             {
      76           0 :                 CPLError(CE_Failure, CPLE_FileIO, "Cannot seek to block %d",
      77             :                          nBlockId);
      78           0 :                 return false;
      79             :             }
      80             :         }
      81             :         else
      82             :         {
      83        4502 :             while (nSeekForward > 0)
      84             :             {
      85        2251 :                 vsi_l_offset nToRead = nSeekForward;
      86        2251 :                 if (nToRead > nTempBufferSize)
      87           0 :                     nToRead = nTempBufferSize;
      88        2251 :                 if (VSIFReadL(pTempBuffer, static_cast<size_t>(nToRead), 1,
      89        2251 :                               fp) != 1)
      90             :                 {
      91           0 :                     CPLError(CE_Failure, CPLE_FileIO, "Cannot seek to block %d",
      92             :                              nBlockId);
      93           0 :                     return false;
      94             :                 }
      95        2251 :                 nSeekForward -= nToRead;
      96             :             }
      97             :         }
      98        9595 :         if (VSIFReadL(pabyDstBuffer, static_cast<size_t>(nPixels) * nDTSize, 1,
      99        9595 :                       fp) != 1)
     100             :         {
     101          18 :             CPLError(CE_Failure, CPLE_FileIO, "Missing data for block %d",
     102             :                      nBlockId);
     103          18 :             return false;
     104             :         }
     105             : 
     106        9577 :         if (bIsByteSwapped)
     107             :         {
     108        2318 :             if (bIsComplex)
     109        1213 :                 GDALSwapWords(pabyDstBuffer, nDTSize / 2, 2 * nPixels,
     110             :                               nDTSize / 2);
     111             :             else
     112        1105 :                 GDALSwapWords(pabyDstBuffer, nDTSize, nPixels, nDTSize);
     113             :         }
     114        9577 :         return true;
     115             :     }
     116             : 
     117             :     static const bool bMinimizeIO = true;
     118             : };
     119             : 
     120             : #endif  // FETCHBUFFERDIRECTIO_H_INCLUDED