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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 1.10  2002/04/16 13:11:48  warmerda
00028  * updated
00028  *
00029  * Revision 1.12  2001/12/12 17:21:21  warmerda
00030  * Use CPLStat instead of VSIStat().
00031  *
00032  * Revision 1.11  2001/08/20 13:40:28  warmerda
00033  * modified message on failure to open if not a file
00034  *
00035  * Revision 1.10  2001/07/18 04:04:30  warmerda
00036  * added CPL_CVSID
00037  *
00038  * Revision 1.9  2001/01/03 05:32:20  warmerda
00039  * avoid depending on VSIStatBuf file size for 2GB issues
00040  *
00041  * Revision 1.8  2000/04/21 21:55:53  warmerda
00042  * set filename as description of GDALDatasets.
00043  *
00044  * Revision 1.7  2000/01/10 15:43:06  warmerda
00045  * Fixed debug statement.
00046  *
00047  * Revision 1.6  2000/01/10 15:31:02  warmerda
00048  * Added debug statement in GDALOpen.
00049  *
00050  * Revision 1.5  1999/11/11 21:59:07  warmerda
00051  * added GetDriver() for datasets
00052  *
00053  * Revision 1.4  1999/10/01 14:44:02  warmerda
00054  * added documentation
00055  *
00056  * Revision 1.3  1999/04/21 04:00:34  warmerda
00057  * Initialize fp to NULL.
00058  *
00059  * Revision 1.2  1998/12/31 18:52:45  warmerda
00060  * Use CPL memory functions (they are safe), and fixed up header reading.
00061  *
00062  * Revision 1.1  1998/12/03 18:31:45  warmerda
00063  * New
00064  *
00065  */
00066 
00067 #include "gdal_priv.h"
00068 #include "cpl_conv.h"
00069 
00070 CPL_CVSID("$Id: gdalopen_cpp-source.html,v 1.10 2002/04/16 13:11:48 warmerda Exp $");
00071 
00072 /************************************************************************/
00073 /* ==================================================================== */
00074 /*                             GDALOpenInfo                             */
00075 /* ==================================================================== */
00076 /************************************************************************/
00077 
00078 /************************************************************************/
00079 /*                            GDALOpenInfo()                            */
00080 /************************************************************************/
00081 
00082 GDALOpenInfo::GDALOpenInfo( const char * pszFilenameIn, GDALAccess eAccessIn )
00083 
00084 {
00085     pszFilename = CPLStrdup( pszFilenameIn );
00086 
00087     nHeaderBytes = 0;
00088     pabyHeader = NULL;
00089     bStatOK = FALSE;
00090     eAccess = eAccessIn;
00091     fp = NULL;
00092     
00093 /* -------------------------------------------------------------------- */
00094 /*      Collect information about the file.                             */
00095 /* -------------------------------------------------------------------- */
00096     if( CPLStat( pszFilename, &sStat ) == 0 )
00097     {
00098         bStatOK = TRUE;
00099 
00100         if( VSI_ISREG( sStat.st_mode ) )
00101         {
00102             pabyHeader = (GByte *) CPLCalloc(1025,1);
00103 
00104             fp = VSIFOpen( pszFilename, "rb" );
00105 
00106             if( fp != NULL )
00107             {
00108                 nHeaderBytes = VSIFRead( pabyHeader, 1, 1024, fp );
00109 
00110                 VSIRewind( fp );
00111             }
00112         }
00113     }
00114 }
00115 
00116 /************************************************************************/
00117 /*                           ~GDALOpenInfo()                            */
00118 /************************************************************************/
00119 
00120 GDALOpenInfo::~GDALOpenInfo()
00121 
00122 {
00123     VSIFree( pabyHeader );
00124     CPLFree( pszFilename );
00125 
00126     if( fp != NULL )
00127         VSIFClose( fp );
00128 }
00129 
00130 /************************************************************************/
00131 /*                              GDALOpen()                              */
00132 /************************************************************************/
00133 
00149 GDALDatasetH GDALOpen( const char * pszFilename, GDALAccess eAccess )
00150 
00151 {
00152     int         iDriver;
00153     GDALDriverManager *poDM = GetGDALDriverManager();
00154     GDALOpenInfo oOpenInfo( pszFilename, eAccess );
00155 
00156     CPLErrorReset();
00157     
00158     for( iDriver = 0; iDriver < poDM->GetDriverCount(); iDriver++ )
00159     {
00160         GDALDriver      *poDriver = poDM->GetDriver( iDriver );
00161         GDALDataset     *poDS;
00162 
00163         poDS = poDriver->pfnOpen( &oOpenInfo );
00164         if( poDS != NULL )
00165         {
00166             poDS->SetDescription( pszFilename );
00167 
00168             if( poDS->poDriver == NULL )
00169                 poDS->poDriver = poDriver;
00170 
00171             CPLDebug( "GDAL", "GDALOpen(%s) succeeds as %s.\n",
00172                       pszFilename, poDriver->pszLongName );
00173 
00174             return (GDALDatasetH) poDS;
00175         }
00176 
00177         if( CPLGetLastErrorNo() != 0 )
00178             return NULL;
00179     }
00180 
00181     if( oOpenInfo.bStatOK )
00182         CPLError( CE_Failure, CPLE_OpenFailed,
00183                   "`%s' not recognised as a supported file format.\n",
00184                   pszFilename );
00185     else
00186         CPLError( CE_Failure, CPLE_OpenFailed,
00187                   "`%s' does not exist in the file system,\n"
00188                   "and is not recognised as a supported dataset name.\n",
00189                   pszFilename );
00190               
00191     return NULL;
00192 }
00193 

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