C++ VSIFReadL函数代码示例

int OGRGPXDataSource::Open( const char * pszFilename, int bUpdateIn)

{
    if (bUpdateIn)
    {
        CPLError(CE_Failure, CPLE_NotSupported,
                    "OGR/GPX driver does not support opening a file in update mode");
        return FALSE;
    }
#ifdef HAVE_EXPAT
    pszName = CPLStrdup( pszFilename );

/* -------------------------------------------------------------------- */
/*      Determine what sort of object this is.                          */
/* -------------------------------------------------------------------- */
    VSIStatBufL sStatBuf;

    if( VSIStatL( pszFilename, &sStatBuf ) != 0 )
        return FALSE;
    
    if( VSI_ISDIR(sStatBuf.st_mode) )
        return FALSE;

    VSILFILE* fp = VSIFOpenL(pszFilename, "r");
    if (fp == NULL)
        return FALSE;
    
    validity = GPX_VALIDITY_UNKNOWN;
    CPLFree(pszVersion);
    pszVersion = NULL;
    bUseExtensions = FALSE;
    nElementsRead = 0;
    
    XML_Parser oParser = OGRCreateExpatXMLParser();
    oCurrentParser = oParser;
    XML_SetUserData(oParser, this);
    XML_SetElementHandler(oParser, ::startElementValidateCbk, NULL);
    XML_SetCharacterDataHandler(oParser, ::dataHandlerValidateCbk);
    
    char aBuf[BUFSIZ];
    int nDone;
    unsigned int nLen;
    int nCount = 0;
    
    /* Begin to parse the file and look for the <gpx> element */
    /* It *MUST* be the first element of an XML file */
    /* So once we have read the first element, we know if we can */
    /* handle the file or not with that driver */
    do
    {
        nDataHandlerCounter = 0;
        nLen = (unsigned int) VSIFReadL( aBuf, 1, sizeof(aBuf), fp );
        nDone = VSIFEofL(fp);
        if (XML_Parse(oParser, aBuf, nLen, nDone) == XML_STATUS_ERROR)
        {
            if (nLen <= BUFSIZ-1)
                aBuf[nLen] = 0;
            else
                aBuf[BUFSIZ-1] = 0;
            if (strstr(aBuf, "<?xml") && strstr(aBuf, "<gpx"))
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                        "XML parsing of GPX file failed : %s at line %d, column %d",
                        XML_ErrorString(XML_GetErrorCode(oParser)),
                        (int)XML_GetCurrentLineNumber(oParser),
                        (int)XML_GetCurrentColumnNumber(oParser));
            }
            validity = GPX_VALIDITY_INVALID;
            break;
        }
        if (validity == GPX_VALIDITY_INVALID)
        {
            break;
        }
        else if (validity == GPX_VALIDITY_VALID)
        {
            /* If we have recognized the <gpx> element, now we try */
            /* to recognize if they are <extensions> tags */
            /* But we stop to look for after an arbitrary number of tags */
            if (bUseExtensions)
                break;
            else if (nElementsRead > 200)
                break;
        }
        else
        {
            /* After reading 50 * BUFSIZE bytes, and not finding whether the file */
            /* is GPX or not, we give up and fail silently */
            nCount ++;
            if (nCount == 50)
                break;
        }
    } while (!nDone && nLen > 0 );
    
    XML_ParserFree(oParser);
    
    VSIFCloseL(fp);
    
    if (validity == GPX_VALIDITY_VALID)
    {
//.........这里部分代码省略.........

void E00GRIDDataset::ReadMetadata()

{
    if (bHasReadMetadata)
        return;

    bHasReadMetadata = TRUE;

    if (e00ReadPtr == NULL)
    {
        int nRoundedBlockXSize = ((nRasterXSize + VALS_PER_LINE - 1) /
                                                VALS_PER_LINE) * VALS_PER_LINE;
        vsi_l_offset nValsToSkip =
                               (vsi_l_offset)nRasterYSize * nRoundedBlockXSize;
        vsi_l_offset nLinesToSkip = nValsToSkip / VALS_PER_LINE;
        int nBytesPerLine = VALS_PER_LINE * E00_FLOAT_SIZE + nBytesEOL;
        vsi_l_offset nPos = nDataStart + nLinesToSkip * nBytesPerLine;
        VSIFSeekL(fp, nPos, SEEK_SET);
    }
    else
    {
        nLastYOff = -1;

        const unsigned int BUFFER_SIZE = 65536;
        const unsigned int NEEDLE_SIZE = 3*5;
        const unsigned int nToRead = BUFFER_SIZE - NEEDLE_SIZE;
        char* pabyBuffer = (char*)CPLCalloc(1, BUFFER_SIZE+NEEDLE_SIZE);
        int nRead;
        int bEOGFound = FALSE;

        VSIFSeekL(fp, 0, SEEK_END);
        vsi_l_offset nEndPos = VSIFTellL(fp);
        if (nEndPos > BUFFER_SIZE)
            nEndPos -= BUFFER_SIZE;
        else
            nEndPos = 0;
        VSIFSeekL(fp, nEndPos, SEEK_SET);

#define GOTO_NEXT_CHAR() \
    i ++; \
    if (pabyBuffer[i] == 13 || pabyBuffer[i] == 10) \
    { \
        i++; \
        if (pabyBuffer[i] == 10) \
            i++; \
    } \

        while ((nRead = VSIFReadL(pabyBuffer, 1, nToRead, fp)) != 0)
        {
            int i;
            for(i = 0; i < nRead; i++)
            {
                if (pabyBuffer[i] == 'E')
                {
                    GOTO_NEXT_CHAR();
                    if (pabyBuffer[i] == 'O')
                    {
                        GOTO_NEXT_CHAR();
                        if (pabyBuffer[i] == 'G')
                        {
                            GOTO_NEXT_CHAR();
                            if (pabyBuffer[i] == '~')
                            {
                                GOTO_NEXT_CHAR();
                                if (pabyBuffer[i] == '}')
                                {
                                    bEOGFound = TRUE;
                                    break;
                                }
                            }
                        }
                    }
                }
            }

            if (bEOGFound)
            {
                VSIFSeekL(fp, VSIFTellL(fp) - nRead + i + 1, SEEK_SET);
                e00ReadPtr->iInBufPtr = 0;
                e00ReadPtr->szInBuf[0] = '\0';
                break;
            }

            if (nEndPos == 0)
                break;

            if ((unsigned int)nRead == nToRead)
            {
                memmove(pabyBuffer + nToRead, pabyBuffer, NEEDLE_SIZE);
                if (nEndPos >= (vsi_l_offset)nToRead)
                    nEndPos -= nToRead;
                else
                    nEndPos = 0;
                VSIFSeekL(fp, nEndPos, SEEK_SET);
            }
            else
                break;
        }
        CPLFree(pabyBuffer);
        if (!bEOGFound)
//.........这里部分代码省略.........

CPLErr OZIRasterBand::IReadBlock( int nBlockXOff, int nBlockYOff,
                                  void * pImage )

{
    OZIDataset *poGDS = (OZIDataset *) poDS;

    int nBlock = nBlockYOff * nXBlocks + nBlockXOff;

    VSIFSeekL(poGDS->fp, poGDS->panZoomLevelOffsets[nZoomLevel] +
                         12 + 1024 + 4 * nBlock, SEEK_SET);
    int nPointer = ReadInt(poGDS->fp, poGDS->bOzi3, poGDS->nKeyInit);
    if (nPointer < 0  || (vsi_l_offset)nPointer >= poGDS->nFileSize)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Invalid offset for block (%d, %d) : %d",
                 nBlockXOff, nBlockYOff, nPointer);
        return CE_Failure;
    }
    int nNextPointer = ReadInt(poGDS->fp, poGDS->bOzi3, poGDS->nKeyInit);
    if (nNextPointer <= nPointer + 16  ||
        (vsi_l_offset)nNextPointer >= poGDS->nFileSize)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Invalid next offset for block (%d, %d) : %d",
                 nBlockXOff, nBlockYOff, nNextPointer);
        return CE_Failure;
    }

    VSIFSeekL(poGDS->fp, nPointer, SEEK_SET);

    int nToRead = nNextPointer - nPointer;
    GByte* pabyZlibBuffer = (GByte*)CPLMalloc(nToRead);
    if (VSIFReadL(pabyZlibBuffer, nToRead, 1, poGDS->fp) != 1)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Not enough byte read for block (%d, %d)",
                 nBlockXOff, nBlockYOff);
        CPLFree(pabyZlibBuffer);
        return CE_Failure;
    }

    if (poGDS->bOzi3)
        OZIDecrypt(pabyZlibBuffer, 16, poGDS->nKeyInit);

    if (pabyZlibBuffer[0] != 0x78 ||
        pabyZlibBuffer[1] != 0xDA)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Bad ZLIB signature for block (%d, %d) : 0x%02X 0x%02X",
                 nBlockXOff, nBlockYOff, pabyZlibBuffer[0], pabyZlibBuffer[1]);
        CPLFree(pabyZlibBuffer);
        return CE_Failure;
    }

    z_stream      stream;
    stream.zalloc = (alloc_func)0;
    stream.zfree = (free_func)0;
    stream.opaque = (voidpf)0;
    stream.next_in = pabyZlibBuffer + 2;
    stream.avail_in = nToRead - 2;

    int err = inflateInit2(&(stream), -MAX_WBITS);

    int i;
    for(i=0;i<64 && err == Z_OK;i++)
    {
        stream.next_out = (Bytef*)pImage + (63 - i) * 64;
        stream.avail_out = 64;
        err = inflate(& (stream), Z_NO_FLUSH);
        if (err != Z_OK && err != Z_STREAM_END)
            break;

        if (pabyTranslationTable)
        {
            int j;
            GByte* ptr = ((GByte*)pImage) + (63 - i) * 64;
            for(j=0;j<64;j++)
            {
                *ptr = pabyTranslationTable[*ptr];
                ptr ++;
            }
        }
    }

    inflateEnd(&stream);

    CPLFree(pabyZlibBuffer);

    return (err == Z_OK || err == Z_STREAM_END) ? CE_None : CE_Failure;
}

int OGRIdrisiDataSource::Open( const char * pszFilename )

{
    pszName = CPLStrdup( pszFilename );

    VSILFILE* fpVCT = VSIFOpenL(pszFilename, "rb");
    if (fpVCT == NULL)
        return FALSE;

    char* pszWTKString = NULL;

// --------------------------------------------------------------------
//      Look for .vdc file
// --------------------------------------------------------------------
    const char* pszVDCFilename = CPLResetExtension(pszFilename, "vdc");
    VSILFILE* fpVDC = VSIFOpenL(pszVDCFilename, "rb");
    if (fpVDC == NULL)
    {
        pszVDCFilename = CPLResetExtension(pszFilename, "VDC");
        fpVDC = VSIFOpenL(pszVDCFilename, "rb");
    }

    char** papszVDC = NULL;
    if (fpVDC != NULL)
    {
        VSIFCloseL(fpVDC);
        fpVDC = NULL;

        CPLPushErrorHandler(CPLQuietErrorHandler);
        papszVDC = CSLLoad2(pszVDCFilename, 1024, 256, NULL);
        CPLPopErrorHandler();
        CPLErrorReset();
    }

    OGRwkbGeometryType eType = wkbUnknown;

    if (papszVDC != NULL)
    {
        CSLSetNameValueSeparator( papszVDC, ":" );

        const char *pszVersion = CSLFetchNameValue( papszVDC, "file format " );

        if( pszVersion == NULL || !EQUAL( pszVersion, "IDRISI Vector A.1" ) )
        {
            CSLDestroy( papszVDC );
            VSIFCloseL(fpVCT);
            return FALSE;
        }

        const char *pszRefSystem
            = CSLFetchNameValue( papszVDC, "ref. system " );
        const char *pszRefUnits = CSLFetchNameValue( papszVDC, "ref. units  " );

        if (pszRefSystem != NULL && pszRefUnits != NULL)
            IdrisiGeoReference2Wkt( pszFilename, pszRefSystem, pszRefUnits,
                                    &pszWTKString);
    }

    GByte chType;
    if (VSIFReadL(&chType, 1, 1, fpVCT) != 1)
    {
        VSIFCloseL(fpVCT);
        CSLDestroy( papszVDC );
        return FALSE;
    }

    if (chType == 1)
        eType = wkbPoint;
    else if (chType == 2)
        eType = wkbLineString;
    else if (chType == 3)
        eType = wkbPolygon;
    else
    {
        CPLError( CE_Failure, CPLE_AppDefined, "Unsupport geometry type : %d",
                  static_cast<int>(chType) );
        VSIFCloseL(fpVCT);
        CSLDestroy( papszVDC );
        return FALSE;
    }

    const char *pszMinX = CSLFetchNameValue( papszVDC, "min. X      " );
    const char *pszMaxX = CSLFetchNameValue( papszVDC, "max. X      " );
    const char *pszMinY = CSLFetchNameValue( papszVDC, "min. Y      " );
    const char *pszMaxY = CSLFetchNameValue( papszVDC, "max. Y      " );

    OGRIdrisiLayer* poLayer = new OGRIdrisiLayer(pszFilename,
                                                 CPLGetBasename(pszFilename),
                                                 fpVCT, eType, pszWTKString);
    papoLayers = static_cast<OGRLayer**>( CPLMalloc(sizeof(OGRLayer*)) );
    papoLayers[nLayers ++] = poLayer;

    if( pszMinX != NULL && pszMaxX != NULL && pszMinY != NULL &&
        pszMaxY != NULL)
    {
        poLayer->SetExtent(
            CPLAtof(pszMinX), CPLAtof(pszMinY), CPLAtof(pszMaxX),
            CPLAtof(pszMaxY) );
    }

//.........这里部分代码省略.........

OGRDataSource *OGRPGeoDriver::Open( const char * pszFilename,
                                    int bUpdate )

{
    OGRPGeoDataSource     *poDS;

    if( !EQUALN(pszFilename,"PGEO:",5) 
        && !EQUAL(CPLGetExtension(pszFilename),"mdb") )
        return NULL;

    if( !EQUALN(pszFilename,"PGEO:",5) &&
        EQUAL(CPLGetExtension(pszFilename),"mdb") )
    {
        VSILFILE* fp = VSIFOpenL(pszFilename, "rb");
        if (!fp)
            return NULL;
        GByte* pabyHeader = (GByte*) CPLMalloc(100000);
        VSIFReadL(pabyHeader, 100000, 1, fp);
        VSIFCloseL(fp);

        /* Look for GDB_GeomColumns table */
        const GByte pabyNeedle[] = { 'G', 0, 'D', 0, 'B', 0, '_', 0, 'G', 0, 'e', 0, 'o', 0, 'm', 0, 'C', 0, 'o', 0, 'l', 0, 'u', 0, 'm', 0, 'n', 0, 's' };
        int bFound = FALSE;
        for(int i=0;i<100000 - (int)sizeof(pabyNeedle);i++)
        {
            if (memcmp(pabyHeader + i, pabyNeedle, sizeof(pabyNeedle)) == 0)
            {
                bFound = TRUE;
                break;
            }
        }
        CPLFree(pabyHeader);
        if (!bFound)
            return NULL;
    }

#ifndef WIN32
    // Try to register MDB Tools driver
    //
    // ODBCINST.INI NOTE:
    // This operation requires write access to odbcinst.ini file
    // located in directory pointed by ODBCINISYS variable.
    // Usually, it points to /etc, so non-root users can overwrite this
    // setting ODBCINISYS with location they have write access to, e.g.:
    // $ export ODBCINISYS=$HOME/etc
    // $ touch $ODBCINISYS/odbcinst.ini
    //
    // See: http://www.unixodbc.org/internals.html
    //
    if ( !InstallMdbDriver() )
    {
        CPLError( CE_Warning, CPLE_AppDefined, 
                  "Unable to install MDB driver for ODBC, MDB access may not supported.\n" );
    }
    else
        CPLDebug( "PGeo", "MDB Tools driver installed successfully!");

#endif /* ndef WIN32 */

    // Open data source
    poDS = new OGRPGeoDataSource();

    if( !poDS->Open( pszFilename, bUpdate, TRUE ) )
    {
        delete poDS;
        return NULL;
    }
    else
        return poDS;
}

CPLErr HF2RasterBand::IReadBlock( int nBlockXOff, int nLineYOff,
                                  void * pImage )

{
    HF2Dataset *poGDS = (HF2Dataset *) poDS;

    int nXBlocks = (nRasterXSize + nBlockXSize - 1) / nBlockXSize;
    int nYBlocks = (nRasterYSize + nBlockXSize - 1) / nBlockXSize;
    
    if (!poGDS->LoadBlockMap())
        return CE_Failure;
    
    if (pafBlockData == NULL)
    {
        pafBlockData = (float*)VSIMalloc3(nXBlocks * sizeof(float), poGDS->nTileSize, poGDS->nTileSize);
        if (pafBlockData == NULL)
            return CE_Failure;
    }
    
    nLineYOff = nRasterYSize - 1 - nLineYOff;

    int nBlockYOff = nLineYOff / nBlockXSize;
    int nYOffInTile = nLineYOff % nBlockXSize;

    if (nBlockYOff != nLastBlockYOff)
    {
        nLastBlockYOff = nBlockYOff;

        memset(pafBlockData, 0, nXBlocks * sizeof(float) * nBlockXSize * nBlockXSize);

        /* 4 * nBlockXSize is the upper bound */
        void* pabyData = CPLMalloc( 4 * nBlockXSize );

        int nxoff;
        for(nxoff = 0; nxoff < nXBlocks; nxoff++)
        {
            VSIFSeekL(poGDS->fp, poGDS->panBlockOffset[(nYBlocks - 1 - nBlockYOff) * nXBlocks + nxoff], SEEK_SET);
            float fScale, fOff;
            VSIFReadL(&fScale, 4, 1, poGDS->fp);
            VSIFReadL(&fOff, 4, 1, poGDS->fp);
            CPL_LSBPTR32(&fScale);
            CPL_LSBPTR32(&fOff);
    
            int nTileWidth = MIN(nBlockXSize, nRasterXSize - nxoff * nBlockXSize);
            int nTileHeight = MIN(nBlockXSize, nRasterYSize - nBlockYOff * nBlockXSize);
            
            int j;
            for(j=0;j<nTileHeight;j++)
            {
                GByte nWordSize;
                VSIFReadL(&nWordSize, 1, 1, poGDS->fp);
                if (nWordSize != 1 && nWordSize != 2 && nWordSize != 4)
                {
                    CPLError(CE_Failure, CPLE_AppDefined,
                             "Unexpected word size : %d", (int)nWordSize);
                    break;
                }

                GInt32 nVal;
                VSIFReadL(&nVal, 4, 1, poGDS->fp);
                CPL_LSBPTR32(&nVal);
                VSIFReadL(pabyData, nWordSize * (nTileWidth - 1), 1, poGDS->fp);
#if defined(CPL_MSB)
                if (nWordSize > 1)
                    GDALSwapWords(pabyData, nWordSize, nTileWidth - 1, nWordSize);
#endif

                pafBlockData[nxoff * nBlockXSize * nBlockXSize + j * nBlockXSize + 0] = nVal * fScale + fOff;
                int i;
                for(i=1;i<nTileWidth;i++)
                {
                    if (nWordSize == 1)
                        nVal += ((char*)pabyData)[i-1];
                    else if (nWordSize == 2)
                        nVal += ((GInt16*)pabyData)[i-1];
                    else
                        nVal += ((GInt32*)pabyData)[i-1];
                    pafBlockData[nxoff * nBlockXSize * nBlockXSize + j * nBlockXSize + i] = nVal * fScale + fOff;
                }
            }
        }

        CPLFree(pabyData);
    }

    int nTileWidth = MIN(nBlockXSize, nRasterXSize - nBlockXOff * nBlockXSize);
    memcpy(pImage, pafBlockData + nBlockXOff * nBlockXSize * nBlockXSize +
                                  nYOffInTile * nBlockXSize,
           nTileWidth * sizeof(float));

    return CE_None;
}

static tsize_t
_tiffReadProc(thandle_t th, tdata_t buf, tsize_t size)
{
    GDALTiffHandle* psGTH = (GDALTiffHandle*) th;
    return VSIFReadL( buf, 1, size, psGTH->fpL );
}

int OGRHTFDataSource::Open( const char * pszFilename, int bUpdateIn)

{
    if (bUpdateIn)
    {
        return FALSE;
    }

    pszName = CPLStrdup( pszFilename );

// -------------------------------------------------------------------- 
//      Does this appear to be a .htf file?
// --------------------------------------------------------------------

    VSILFILE* fp = VSIFOpenL(pszFilename, "rb");
    if (fp == NULL)
        return FALSE;

    char szBuffer[11];
    int nbRead = (int)VSIFReadL(szBuffer, 1, sizeof(szBuffer) - 1, fp);
    szBuffer[nbRead] = '\0';

    int bIsHTF = strcmp(szBuffer, "HTF HEADER") == 0;
    if (!bIsHTF)
    {
        VSIFCloseL(fp);
        return FALSE;
    }

    VSIFSeekL(fp, 0, SEEK_SET);

    const char* pszLine;
    int bEndOfHTFHeader = FALSE;
    int bIsSouth = FALSE;
    int bGeodeticDatumIsWGS84 = FALSE;
    int bIsUTM = FALSE;
    int nZone = 0;
    int nLines = 0;
    int bHasSWEasting = FALSE, bHasSWNorthing = FALSE, bHasNEEasting = FALSE, bHasNENorthing = FALSE;
    double dfSWEasting = 0, dfSWNorthing = 0, dfNEEasting = 0, dfNENorthing = 0;
    std::vector<CPLString> aosMD;
    int nTotalSoundings = 0;
    while( (pszLine = CPLReadLine2L(fp, 1024, NULL)) != NULL)
    {
        nLines ++;
        if (nLines == 1000)
        {
            break;
        }
        if (*pszLine == ';' || *pszLine == '\0')
            continue;

        if (strcmp(pszLine, "END OF HTF HEADER") == 0)
        {
            bEndOfHTFHeader = TRUE;
            break;
        }

        aosMD.push_back(pszLine);

        if (strncmp(pszLine, "GEODETIC DATUM: ", 16) == 0)
        {
            if (strcmp(pszLine + 16, "WG84") == 0 ||
                strcmp(pszLine + 16, "WGS84") == 0)
                bGeodeticDatumIsWGS84 = TRUE;
            else
            {
                VSIFCloseL(fp);
                CPLError(CE_Failure, CPLE_NotSupported,
                         "Unsupported datum : %s", pszLine + 16);
                return FALSE;
            }
        }
        else if (strncmp(pszLine, "NE LATITUDE: -", 14) == 0)
            bIsSouth = TRUE;
        else if (strncmp(pszLine, "GRID REFERENCE SYSTEM: ", 23) == 0)
        {
            if (strncmp(pszLine + 23, "UTM", 3) == 0)
                bIsUTM = TRUE;
            else
            {
                VSIFCloseL(fp);
                CPLError(CE_Failure, CPLE_NotSupported,
                         "Unsupported grid : %s", pszLine + 23);
                return FALSE;
            }
        }
        else if (strncmp(pszLine, "GRID ZONE: ", 11) == 0)
        {
            nZone = atoi(pszLine + 11);
        }
        else if (strncmp(pszLine, "SW GRID COORDINATE - EASTING: ", 30) == 0)
        {
            bHasSWEasting = TRUE;
            dfSWEasting = atof(pszLine + 30);
        }
        else if (strncmp(pszLine, "SW GRID COORDINATE - NORTHING: ", 31) == 0)
        {
            bHasSWNorthing = TRUE;
            dfSWNorthing = atof(pszLine + 31);
//.........这里部分代码省略.........

GDALDataset *XPMDataset::Open( GDALOpenInfo * poOpenInfo )

{
/* -------------------------------------------------------------------- */
/*      First we check to see if the file has the expected header       */
/*      bytes.  For now we expect the XPM file to start with a line     */
/*      containing the letters XPM, and to have "static" in the         */
/*      header.                                                         */
/* -------------------------------------------------------------------- */
    if( poOpenInfo->nHeaderBytes < 32 
        || strstr((const char *) poOpenInfo->pabyHeader,"XPM") == NULL 
        || strstr((const char *) poOpenInfo->pabyHeader,"static") == NULL )
        return NULL;

    if( poOpenInfo->eAccess == GA_Update )
    {
        CPLError( CE_Failure, CPLE_NotSupported, 
                  "The XPM driver does not support update access to existing"
                  " files." );
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Read the whole file into a memory strings.                      */
/* -------------------------------------------------------------------- */
    unsigned int nFileSize;
    char *pszFileContents;
    VSILFILE *fp = VSIFOpenL( poOpenInfo->pszFilename, "rb" );
    if( fp == NULL )
        return NULL;

    VSIFSeekL( fp, 0, SEEK_END );
    nFileSize = VSIFTellL( fp );
    
    pszFileContents = (char *) VSIMalloc(nFileSize+1);
    if( pszFileContents == NULL )
    {
        CPLError( CE_Failure, CPLE_OutOfMemory, 
                  "Insufficient memory for loading XPM file %s into memory.", 
                  poOpenInfo->pszFilename );
        VSIFCloseL(fp);
        return NULL;
    }
    pszFileContents[nFileSize] = '\0';
    
    VSIFSeekL( fp, 0, SEEK_SET );

    if( VSIFReadL( pszFileContents, 1, nFileSize, fp ) != nFileSize)
    {
        CPLFree( pszFileContents );
        CPLError( CE_Failure, CPLE_FileIO, 
                  "Failed to read all %d bytes from file %s.",
                  nFileSize, poOpenInfo->pszFilename );
        VSIFCloseL(fp);
        return NULL;
    }
    
    VSIFCloseL(fp);
    fp = NULL;

/* -------------------------------------------------------------------- */
/*      Convert into a binary image.                                    */
/* -------------------------------------------------------------------- */
    GByte *pabyImage;
    int   nXSize, nYSize;
    GDALColorTable *poCT = NULL;

    CPLErrorReset();

    pabyImage = ParseXPM( pszFileContents, &nXSize, &nYSize, &poCT );
    CPLFree( pszFileContents );

    if( pabyImage == NULL )
    {
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Create a corresponding GDALDataset.                             */
/* -------------------------------------------------------------------- */
    XPMDataset 	*poDS;

    poDS = new XPMDataset();

/* -------------------------------------------------------------------- */
/*      Capture some information from the file that is of interest.     */
/* -------------------------------------------------------------------- */
    poDS->nRasterXSize = nXSize;
    poDS->nRasterYSize = nYSize;

/* -------------------------------------------------------------------- */
/*      Create band information objects.                                */
/* -------------------------------------------------------------------- */
    MEMRasterBand *poBand;

    poBand = new MEMRasterBand( poDS, 1, pabyImage, GDT_Byte, 1, nXSize, 
                                TRUE );
    poBand->SetColorTable( poCT );
    poDS->SetBand( 1, poBand );

//.........这里部分代码省略.........

GDALDataset *BTDataset::Open( GDALOpenInfo * poOpenInfo )

{
/* -------------------------------------------------------------------- */
/*      Verify that this is some form of binterr file.                  */
/* -------------------------------------------------------------------- */
    if( poOpenInfo->nHeaderBytes < 256)
        return NULL;

    if( strncmp( (const char *) poOpenInfo->pabyHeader, "binterr", 7 ) != 0 )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Create the dataset.                                             */
/* -------------------------------------------------------------------- */
    BTDataset  *poDS;

    poDS = new BTDataset();
 
    memcpy( poDS->abyHeader, poOpenInfo->pabyHeader, 256 );

/* -------------------------------------------------------------------- */
/*      Get the version.                                                */
/* -------------------------------------------------------------------- */
    char szVersion[4];

    strncpy( szVersion, (char *) (poDS->abyHeader + 7), 3 );
    szVersion[3] = '\0';
    poDS->nVersionCode = (int) (atof(szVersion) * 10);

/* -------------------------------------------------------------------- */
/*      Extract core header information, being careful about the        */
/*      version.                                                        */
/* -------------------------------------------------------------------- */
    GInt32 nIntTemp;
    GInt16 nDataSize;
    GDALDataType eType;

    memcpy( &nIntTemp, poDS->abyHeader + 10, 4 );
    poDS->nRasterXSize = CPL_LSBWORD32( nIntTemp );
    
    memcpy( &nIntTemp, poDS->abyHeader + 14, 4 );
    poDS->nRasterYSize = CPL_LSBWORD32( nIntTemp );

    if (!GDALCheckDatasetDimensions(poDS->nRasterXSize, poDS->nRasterYSize))
    {
        delete poDS;
        return NULL;
    }

    memcpy( &nDataSize, poDS->abyHeader+18, 2 );
    nDataSize = CPL_LSBWORD16( nDataSize );

    if( poDS->abyHeader[20] != 0 && nDataSize == 4 )
        eType = GDT_Float32;
    else if( poDS->abyHeader[20] == 0 && nDataSize == 4 )
        eType = GDT_Int32;
    else if( poDS->abyHeader[20] == 0 && nDataSize == 2 )
        eType = GDT_Int16;
    else
    {
        CPLError( CE_Failure, CPLE_AppDefined, 
                  ".bt file data type unknown, got datasize=%d.", 
                  nDataSize );
        delete poDS;
        return NULL;
    }

    /*
        rcg, apr 7/06: read offset 62 for vert. units.
        If zero, assume 1.0 as per spec.

    */
    memcpy( &poDS->m_fVscale, poDS->abyHeader + 62, 4 );
    CPL_LSBPTR32(&poDS->m_fVscale);
    if(poDS->m_fVscale == 0.0f)
        poDS->m_fVscale = 1.0f; 

/* -------------------------------------------------------------------- */
/*      Try to read a .prj file if it is indicated.                     */
/* -------------------------------------------------------------------- */
    OGRSpatialReference oSRS;						

    if( poDS->nVersionCode >= 12 && poDS->abyHeader[60] != 0 )
    {
        const char  *pszPrjFile = CPLResetExtension( poOpenInfo->pszFilename, 
                                                     "prj" );
        VSILFILE *fp;

        fp = VSIFOpenL( pszPrjFile, "rt" );
        if( fp != NULL )
        {
            char *pszBuffer, *pszBufPtr;
            int  nBufMax = 10000;
            int nBytes;

            pszBuffer = (char *) CPLMalloc(nBufMax);
            nBytes = VSIFReadL( pszBuffer, 1, nBufMax-1, fp );
            VSIFCloseL( fp );

//.........这里部分代码省略.........

GDALDataset *ELASDataset::Open( GDALOpenInfo * poOpenInfo )

{
    if( !Identify(poOpenInfo) )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Create a corresponding GDALDataset.                             */
/* -------------------------------------------------------------------- */
    ELASDataset 	*poDS;
    const char	 	*pszAccess;

    if( poOpenInfo->eAccess == GA_Update )
        pszAccess = "r+b";
    else
        pszAccess = "rb";

    poDS = new ELASDataset();

    poDS->fp = VSIFOpenL( poOpenInfo->pszFilename, pszAccess );
    if( poDS->fp == NULL )
    {
        CPLError( CE_Failure, CPLE_OpenFailed,
                  "Attempt to open `%s' with acces `%s' failed.\n",
                  poOpenInfo->pszFilename, pszAccess );
        delete poDS;
        return NULL;
    }

    poDS->eAccess = poOpenInfo->eAccess;

/* -------------------------------------------------------------------- */
/*      Read the header information.                                    */
/* -------------------------------------------------------------------- */
    poDS->bHeaderModified = FALSE;
    if( VSIFReadL( &(poDS->sHeader), 1024, 1, poDS->fp ) != 1 )
    {
        CPLError( CE_Failure, CPLE_FileIO,
                  "Attempt to read 1024 byte header filed on file %s\n",
                  poOpenInfo->pszFilename );
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Extract information of interest from the header.                */
/* -------------------------------------------------------------------- */
    int		nStart, nEnd, nELASDataType, nBytesPerSample;
    
    poDS->nLineOffset = CPL_MSBWORD32( poDS->sHeader.NBPR );

    nStart = CPL_MSBWORD32( poDS->sHeader.IL );
    nEnd = CPL_MSBWORD32( poDS->sHeader.LL );
    poDS->nRasterYSize = nEnd - nStart + 1;

    nStart = CPL_MSBWORD32( poDS->sHeader.IE );
    nEnd = CPL_MSBWORD32( poDS->sHeader.LE );
    poDS->nRasterXSize = nEnd - nStart + 1;

    poDS->nBands = CPL_MSBWORD32( poDS->sHeader.NC );

    if (!GDALCheckDatasetDimensions(poDS->nRasterXSize, poDS->nRasterYSize) ||
        !GDALCheckBandCount(poDS->nBands, FALSE))
    {
        delete poDS;
        return NULL;
    }

    nELASDataType = (poDS->sHeader.IH19[2] & 0x7e) >> 2;
    nBytesPerSample = poDS->sHeader.IH19[3];
    
    if( nELASDataType == 0 && nBytesPerSample == 1 )
        poDS->eRasterDataType = GDT_Byte;
    else if( nELASDataType == 1 && nBytesPerSample == 1 )
        poDS->eRasterDataType = GDT_Byte;
    else if( nELASDataType == 16 && nBytesPerSample == 4 )
        poDS->eRasterDataType = GDT_Float32;
    else if( nELASDataType == 17 && nBytesPerSample == 8 )
        poDS->eRasterDataType = GDT_Float64;
    else
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Unrecognised image data type %d, with BytesPerSample=%d.\n",
                  nELASDataType, nBytesPerSample );
        return NULL;
    }
    
/* -------------------------------------------------------------------- */
/*	Band offsets are always multiples of 256 within a multi-band	*/
/*	scanline of data.						*/
/* -------------------------------------------------------------------- */
    poDS->nBandOffset =
        (poDS->nRasterXSize * GDALGetDataTypeSize(poDS->eRasterDataType)/8);

    if( poDS->nBandOffset % 256 != 0 )
    {
        poDS->nBandOffset =
            poDS->nBandOffset - (poDS->nBandOffset % 256) + 256;
    }

//.........这里部分代码省略.........

GDALDataset *LCPDataset::Open( GDALOpenInfo * poOpenInfo )

{
/* -------------------------------------------------------------------- */
/*      Verify that this is a FARSITE LCP file    */
/* -------------------------------------------------------------------- */
    if( !Identify( poOpenInfo ) )
        return NULL;
        
/* -------------------------------------------------------------------- */
/*      Confirm the requested access is supported.                      */
/* -------------------------------------------------------------------- */
    if( poOpenInfo->eAccess == GA_Update )
    {
        CPLError( CE_Failure, CPLE_NotSupported, 
                  "The LCP driver does not support update access to existing"
                  " datasets.\n" );
        return NULL;
    }
    
/* -------------------------------------------------------------------- */
/*      Create a corresponding GDALDataset.                             */
/* -------------------------------------------------------------------- */
    LCPDataset  *poDS;
    VSILFILE        *fpImage;

    fpImage = VSIFOpenL(poOpenInfo->pszFilename, "rb");
    if (fpImage == NULL)
        return NULL;

    poDS = new LCPDataset();
    poDS->fpImage = fpImage;

/* -------------------------------------------------------------------- */
/*      Read the header and extract some information.                   */
/* -------------------------------------------------------------------- */
   int bHaveCrownFuels, bHaveGroundFuels;
   int nBands, i;
   long nWidth = -1, nHeight = -1;
   int nTemp, nTemp2;
   char szTemp[32];
   char* pszList;

   VSIFSeekL( poDS->fpImage, 0, SEEK_SET );
   if (VSIFReadL( poDS->pachHeader, 1, LCP_HEADER_SIZE, poDS->fpImage ) != LCP_HEADER_SIZE)
   {
       CPLError(CE_Failure, CPLE_FileIO, "File too short");
       delete poDS;
       return NULL;
   }

   nWidth = CPL_LSBINT32PTR (poDS->pachHeader + 4164);
   nHeight = CPL_LSBINT32PTR (poDS->pachHeader + 4168);

   poDS->nRasterXSize = nWidth;
   poDS->nRasterYSize = nHeight;

   if (!GDALCheckDatasetDimensions(poDS->nRasterXSize, poDS->nRasterYSize))
   {
       delete poDS;
       return NULL;
   }

   // crown fuels = canopy height, canopy base height, canopy bulk density
   // 21 = have them, 20 = don't have them
   bHaveCrownFuels = ( CPL_LSBINT32PTR (poDS->pachHeader + 0) - 20 );
   // ground fuels = duff loading, coarse woody
   bHaveGroundFuels = ( CPL_LSBINT32PTR (poDS->pachHeader + 4) - 20 );

   if( bHaveCrownFuels )
   {
       if( bHaveGroundFuels )
           nBands = 10;
       else
           nBands = 8;
   }
   else
   {
       if( bHaveGroundFuels )
           nBands = 7;
       else
           nBands = 5;
   }

   // add dataset-level metadata

   nTemp = CPL_LSBINT32PTR (poDS->pachHeader + 8);
   sprintf(szTemp, "%d", nTemp);
   poDS->SetMetadataItem( "LATITUDE", szTemp );

   nTemp = CPL_LSBINT32PTR (poDS->pachHeader + 4204);
   if ( nTemp == 0 )
      poDS->SetMetadataItem( "LINEAR_UNIT", "Meters" );
   if ( nTemp == 1 )
      poDS->SetMetadataItem( "LINEAR_UNIT", "Feet" );

   poDS->pachHeader[LCP_HEADER_SIZE-1] = '\0';
   poDS->SetMetadataItem( "DESCRIPTION", poDS->pachHeader + 6804 );


//.........这里部分代码省略.........

static tsize_t
_tiffReadProc(thandle_t fd, tdata_t buf, tsize_t size)
{
    return VSIFReadL( buf, 1, size, (VSILFILE *) fd );
}

GDALDataset *GS7BGDataset::Open( GDALOpenInfo * poOpenInfo )

{
    if( !Identify(poOpenInfo) )
    {
        return NULL;
    }

    /* ------------------------------------------------------------------- */
    /*      Create a corresponding GDALDataset.                            */
    /* ------------------------------------------------------------------- */
    GS7BGDataset    *poDS = new GS7BGDataset();

    /* ------------------------------------------------------------------- */
    /*      Open file with large file API.                                 */
    /* ------------------------------------------------------------------- */
    poDS->eAccess = poOpenInfo->eAccess;
    if( poOpenInfo->eAccess == GA_ReadOnly )
        poDS->fp = VSIFOpenL( poOpenInfo->pszFilename, "rb" );
    else
        poDS->fp = VSIFOpenL( poOpenInfo->pszFilename, "r+b" );

    if( poDS->fp == NULL )
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_OpenFailed,
            "VSIFOpenL(%s) failed unexpectedly.",
            poOpenInfo->pszFilename );
        return NULL;
    }

    /* ------------------------------------------------------------------- */
    /*      Read the header. The Header section must be the first section  */
    /*      in the file.                                                   */
    /* ------------------------------------------------------------------- */
    if( VSIFSeekL( poDS->fp, 0, SEEK_SET ) != 0 )
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_FileIO,
                "Unable to seek to start of grid file header.\n" );
        return NULL;
    }

    GInt32 nTag;
    GInt32 nSize;
    GInt32 nVersion;

    if( VSIFReadL( (void *)&nTag, sizeof(GInt32), 1, poDS->fp ) != 1 )
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_FileIO, "Unable to read Tag.\n" );
        return NULL;
    }

    CPL_LSBPTR32( &nTag );

    if(nTag != nHEADER_TAG)
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_FileIO, "Header tag not found.\n" );
        return NULL;
    }

    if( VSIFReadL( (void *)&nSize, sizeof(GInt32), 1, poDS->fp ) != 1 )
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_FileIO,
            "Unable to read file section size.\n" );
        return NULL;
    }

    CPL_LSBPTR32( &nSize );

    if( VSIFReadL( (void *)&nVersion, sizeof(GInt32), 1, poDS->fp ) != 1 )
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_FileIO,
            "Unable to read file version.\n" );
        return NULL;
    }

    CPL_LSBPTR32( &nVersion );

    if(nVersion != 1 && nVersion != 2)
    {
        delete poDS;
        CPLError( CE_Failure, CPLE_FileIO, 
                  "Incorrect file version (%d).", nVersion );
        return NULL;
    }

    // advance until the grid tag is found
    while(nTag != nGRID_TAG)
    {
        if( VSIFReadL( (void *)&nTag, sizeof(GInt32), 1, poDS->fp ) != 1 )
        {
            delete poDS;
            CPLError( CE_Failure, CPLE_FileIO, "Unable to read Tag.\n" );
            return NULL;
        }
//.........这里部分代码省略.........

GDALDataset *KRODataset::Open( GDALOpenInfo * poOpenInfo )

{
    if( !Identify( poOpenInfo ) )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Create a corresponding GDALDataset.                             */
/* -------------------------------------------------------------------- */
    KRODataset *poDS = new KRODataset();
    poDS->eAccess = poOpenInfo->eAccess;

/* -------------------------------------------------------------------- */
/*      Open the file.                                                  */
/* -------------------------------------------------------------------- */
    if( poOpenInfo->eAccess == GA_ReadOnly )
        poDS->fpImage = VSIFOpenL( poOpenInfo->pszFilename, "rb" );
    else
        poDS->fpImage = VSIFOpenL( poOpenInfo->pszFilename, "rb+" );

    if( poDS->fpImage == NULL )
    {
        delete poDS;
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Read the file header.                                           */
/* -------------------------------------------------------------------- */
    char achHeader[20] = { '\0' };
    CPL_IGNORE_RET_VAL(VSIFReadL( achHeader, 1, 20, poDS->fpImage ));

    int nXSize;
    memcpy(&nXSize, achHeader + 4, 4);
    CPL_MSBPTR32( &nXSize );

    int nYSize = 0;
    memcpy(&nYSize, achHeader + 8, 4);
    CPL_MSBPTR32( &nYSize );

    int nDepth = 0;
    memcpy(&nDepth, achHeader + 12, 4);
    CPL_MSBPTR32( &nDepth );

    int nComp = 0;
    memcpy(&nComp, achHeader + 16, 4);
    CPL_MSBPTR32( &nComp );

    if( !GDALCheckDatasetDimensions(nXSize, nYSize) ||
        !GDALCheckBandCount(nComp, FALSE) )
    {
        delete poDS;
        return NULL;
    }

    poDS->nRasterXSize = nXSize;
    poDS->nRasterYSize = nYSize;

    GDALDataType eDT = GDT_Unknown;
    if( nDepth == 8 )
    {
        eDT = GDT_Byte;
    }
    else if( nDepth == 16 )
    {
        eDT = GDT_UInt16;
    }
    else if( nDepth == 32 )
    {
        eDT = GDT_Float32;
    }
    else
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Unhandled depth : %d", nDepth );
        delete poDS;
        return NULL;
    }

    const int nDataTypeSize = nDepth / 8;

    if( nComp == 0 || nDataTypeSize == 0 ||
        poDS->nRasterXSize > INT_MAX / (nComp * nDataTypeSize) )
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Too large width / number of bands" );
        delete poDS;
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Create bands.                                                   */
/* -------------------------------------------------------------------- */
    CPLErrorReset();
    for( int iBand = 0; iBand < nComp; iBand++ )
    {
        RawRasterBand *poBand =
            new RawRasterBand( poDS, iBand+1, poDS->fpImage,
                               20 + nDataTypeSize * iBand,
                               nComp * nDataTypeSize,
//.........这里部分代码省略.........