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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 

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