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# gdalopen.cpp

    00001 /******************************************************************************
    00002  * Copyright (c) 1998, Frank Warmerdam
    00003  *
    00004  * Permission is hereby granted, free of charge, to any person obtaining a
    00005  * copy of this software and associated documentation files (the "Software"),
    00006  * to deal in the Software without restriction, including without limitation
    00007  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
    00008  * and/or sell copies of the Software, and to permit persons to whom the
    00009  * Software is furnished to do so, subject to the following conditions:
    00010  *
    00011  * The above copyright notice and this permission notice shall be included
    00012  * in all copies or substantial portions of the Software.
    00013  *
    00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
    00015  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    00017  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    00019  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    00020  * DEALINGS IN THE SOFTWARE.
    00021  ******************************************************************************
    00022  *
    00023  * gdalopen.c
    00024  *
    00025  * GDALOpen() function, and supporting functions.
    00026  *
    00027  *
    00028  * $Log: gdalopen_cpp-source.html,v $
    00028  * Revision 1.1  2000/09/25 20:50:11  warmerda
    00028  * New
    00028  *
    00029  * Revision 1.8  2000/04/21 21:55:53  warmerda
    00030  * set filename as description of GDALDatasets.
    00031  *
    00032  * Revision 1.7  2000/01/10 15:43:06  warmerda
    00033  * Fixed debug statement.
    00034  *
    00035  * Revision 1.6  2000/01/10 15:31:02  warmerda
    00036  * Added debug statement in GDALOpen.
    00037  *
    00038  * Revision 1.5  1999/11/11 21:59:07  warmerda
    00039  * added GetDriver() for datasets
    00040  *
    00041  * Revision 1.4  1999/10/01 14:44:02  warmerda
    00042  * added documentation
    00043  *
    00044  * Revision 1.3  1999/04/21 04:00:34  warmerda
    00045  * Initialize fp to NULL.
    00046  *
    00047  * Revision 1.2  1998/12/31 18:52:45  warmerda
    00048  * Use CPL memory functions (they are safe), and fixed up header reading.
    00049  *
    00050  * Revision 1.1  1998/12/03 18:31:45  warmerda
    00051  * New
    00052  *
    00053  */
    00054
    00055 #include "gdal_priv.h"
    00056 #include "cpl_conv.h"
    00057
    00058 /************************************************************************/
    00059 /* ==================================================================== */
    00060 /*                             GDALOpenInfo                             */
    00061 /* ==================================================================== */
    00062 /************************************************************************/
    00063
    00064 /************************************************************************/
    00065 /*                            GDALOpenInfo()                            */
    00066 /************************************************************************/
    00067
    00068 GDALOpenInfo::GDALOpenInfo( const char * pszFilenameIn, GDALAccess eAccessIn )
    00069
    00070 {
    00071     pszFilename = CPLStrdup( pszFilenameIn );
    00072
    00073     nHeaderBytes = 0;
    00074     pabyHeader = NULL;
    00075     bStatOK = FALSE;
    00076     eAccess = eAccessIn;
    00077     fp = NULL;
    00078
    00079 /* -------------------------------------------------------------------- */
    00080 /*      Collect information about the file.                             */
    00081 /* -------------------------------------------------------------------- */
    00082     if( VSIStat( pszFilename, &sStat ) == 0 )
    00083     {
    00084         bStatOK = TRUE;
    00085
    00086         if( VSI_ISREG( sStat.st_mode ) )
    00087         {
    00088             nHeaderBytes = MIN(1024,sStat.st_size);
    00089             pabyHeader = (GByte *) CPLCalloc(nHeaderBytes+1,1);
    00090
    00091             fp = VSIFOpen( pszFilename, "rb" );
    00092
    00093             if( fp != NULL )
    00094             {
    00095                 nHeaderBytes = VSIFRead( pabyHeader, 1, nHeaderBytes, fp );
    00096
    00097                 VSIRewind( fp );
    00098             }
    00099         }
    00100     }
    00101
    00102 }
    00103
    00104 /************************************************************************/
    00105 /*                           ~GDALOpenInfo()                            */
    00106 /************************************************************************/
    00107
    00108 GDALOpenInfo::~GDALOpenInfo()
    00109
    00110 {
    00111     VSIFree( pabyHeader );
    00112     CPLFree( pszFilename );
    00113
    00114     if( fp != NULL )
    00115         VSIFClose( fp );
    00116 }
    00117
    00118 /************************************************************************/
    00119 /*                              GDALOpen()                              */
    00120 /************************************************************************/
    00121
    00137 GDALDatasetH GDALOpen( const char * pszFilename, GDALAccess eAccess )
    00138
    00139 {
    00140     int         iDriver;
    00141     GDALDriverManager *poDM = GetGDALDriverManager();
    00142     GDALOpenInfo oOpenInfo( pszFilename, eAccess );
    00143
    00144     CPLErrorReset();
    00145
    00146     for( iDriver = 0; iDriver < poDM->GetDriverCount(); iDriver++ )
    00147     {
    00148         GDALDriver      *poDriver = poDM->GetDriver( iDriver );
    00149         GDALDataset     *poDS;
    00150
    00151         poDS = poDriver->pfnOpen( &oOpenInfo );
    00152         if( poDS != NULL )
    00153         {
    00154             poDS->SetDescription( pszFilename );
    00155
    00156             if( poDS->poDriver == NULL )
    00157                 poDS->poDriver = poDriver;
    00158
    00159             CPLDebug( "GDAL", "GDALOpen(%s) succeeds as %s.\n",
    00160                       pszFilename, poDriver->pszLongName );
    00161
    00162             return (GDALDatasetH) poDS;
    00163         }
    00164
    00165         if( CPLGetLastErrorNo() != 0 )
    00166             return NULL;
    00167     }
    00168
    00169     CPLError( CE_Failure, CPLE_OpenFailed,
    00170               "`%s' not recognised as a supported file format.\n",
    00171               pszFilename );
    00172
    00173     return NULL;
    00174 }
    00175