dbfopen.c

ESRI SHAPE文件读/写源代码。SHAPE是GIS中的重要文件格式

/******************************************************************************
 * $Id: dbfopen.c,v 1.22 1999/12/15 13:47:24 warmerda Exp $
 *
 * Project:  Shapelib
 * Purpose:  Implementation of .dbf access API documented in dbf_api.html.
 * Author:   Frank Warmerdam, [e-mail]
 *
 ******************************************************************************
 * Copyright (c) 1999, Frank Warmerdam
 *
 * This software is available under the following "MIT Style" license,
 * or at the option of the licensee under the LGPL (see LICENSE.LGPL).  This
 * option is discussed in more detail in shapelib.html.
 *
 * --
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ******************************************************************************
 *
 * $Log: dbfopen.c,v $
 * Revision 1.22  1999/12/15 13:47:24  warmerda
 * Added stdlib.h to ensure that atof() is prototyped.
 *
 * Revision 1.21  1999/12/13 17:25:46  warmerda
 * Added support for upper case .DBF extention.
 *
 * Revision 1.20  1999/11/30 16:32:11  warmerda
 * Use atof() instead of sscanf().
 *
 * Revision 1.19  1999/11/05 14:12:04  warmerda
 * updated license terms
 *
 * Revision 1.18  1999/07/27 00:53:28  warmerda
 * ensure that whole old field value clear on write of string
 *
 * Revision 1.1  1999/07/05 18:58:07  warmerda
 * New
 *
 * Revision 1.17  1999/06/11 19:14:12  warmerda
 * Fixed some memory leaks.
 *
 * Revision 1.16  1999/06/11 19:04:11  warmerda
 * Remoted some unused variables.
 *
 * Revision 1.15  1999/05/11 03:19:28  warmerda
 * added new Tuple api, and improved extension handling - add from candrsn
 *
 * Revision 1.14  1999/05/04 15:01:48  warmerda
 * Added 'F' support.
 *
 * Revision 1.13  1999/03/23 17:38:59  warmerda
 * DBFAddField() now actually does return the new field number, or -1 if
 * it fails.
 *
 * Revision 1.12  1999/03/06 02:54:46  warmerda
 * Added logic to convert shapefile name to dbf filename in DBFOpen()
 * for convenience.
 *
 * Revision 1.11  1998/12/31 15:30:34  warmerda
 * Improved the interchangability of numeric and string attributes.  Add
 * white space trimming option for attributes.
 *
 * Revision 1.10  1998/12/03 16:36:44  warmerda
 * Use r+b instead of rb+ for binary access.
 *
 * Revision 1.9  1998/12/03 15:34:23  warmerda
 * Updated copyright message.
 *
 * Revision 1.8  1997/12/04 15:40:15  warmerda
 * Added newline character after field definitions.
 *
 * Revision 1.7  1997/03/06 14:02:10  warmerda
 * Ensure bUpdated is initialized.
 *
 * Revision 1.6  1996/02/12 04:54:41  warmerda
 * Ensure that DBFWriteAttribute() returns TRUE if it succeeds.
 *
 * Revision 1.5  1995/10/21  03:15:12  warmerda
 * Changed to use binary file access, and ensure that the
 * field name field is zero filled, and limited to 10 chars.
 *
 * Revision 1.4  1995/08/24  18:10:42  warmerda
 * Added use of SfRealloc() to avoid pre-ANSI realloc() functions such
 * as on the Sun.
 *
 * Revision 1.3  1995/08/04  03:15:16  warmerda
 * Fixed up header.
 *
 * Revision 1.2  1995/08/04  03:14:43  warmerda
 * Added header.
 */

static char rcsid[] = 
  "$Id: dbfopen.c,v 1.22 1999/12/15 13:47:24 warmerda Exp $";

#include "shapefil.h"

#include <math.h>
#include <stdlib.h>

typedef unsigned char uchar;

#ifndef FALSE
#  define FALSE		0
#  define TRUE		1
#endif

static int	nStringFieldLen = 0;
static char * pszStringField = NULL;

/************************************************************************/
/*                             SfRealloc()                              */
/*                                                                      */
/*      A realloc cover function that will access a NULL pointer as     */
/*      a valid input.                                                  */
/************************************************************************/

static void * SfRealloc( void * pMem, int nNewSize )

{
    if( pMem == NULL )
        return( (void *) malloc(nNewSize) );
    else
        return( (void *) realloc(pMem,nNewSize) );
}

/************************************************************************/
/*                           DBFWriteHeader()                           */
/*                                                                      */
/*      This is called to write out the file header, and field          */
/*      descriptions before writing any actual data records.  This      */
/*      also computes all the DBFDataSet field offset/size/decimals     */
/*      and so forth values.                                            */
/************************************************************************/

static void DBFWriteHeader(DBFHandle psDBF)

{
    uchar	abyHeader[XBASE_FLDHDR_SZ];
    int		i;

    if( !psDBF->bNoHeader )
        return;

    psDBF->bNoHeader = FALSE;

/* -------------------------------------------------------------------- */
/*	Initialize the file header information.				*/
/* -------------------------------------------------------------------- */
    for( i = 0; i < XBASE_FLDHDR_SZ; i++ )
        abyHeader[i] = 0;

    abyHeader[0] = 0x03;		/* memo field? - just copying 	*/

    /* date updated on close, record count preset at zero */

    abyHeader[8] = psDBF->nHeaderLength % 256;
    abyHeader[9] = psDBF->nHeaderLength / 256;
    
    abyHeader[10] = psDBF->nRecordLength % 256;
    abyHeader[11] = psDBF->nRecordLength / 256;

/* -------------------------------------------------------------------- */
/*      Write the initial 32 byte file header, and all the field        */
/*      descriptions.                                     		*/
/* -------------------------------------------------------------------- */
    fseek( psDBF->fp, 0, 0 );
    fwrite( abyHeader, XBASE_FLDHDR_SZ, 1, psDBF->fp );
    fwrite( psDBF->pszHeader, XBASE_FLDHDR_SZ, psDBF->nFields, psDBF->fp );

/* -------------------------------------------------------------------- */
/*      Write out the newline character if there is room for it.        */
/* -------------------------------------------------------------------- */
    if( psDBF->nHeaderLength > 32*psDBF->nFields + 32 )
    {
        char	cNewline;

        cNewline = 0x0d;
        fwrite( &cNewline, 1, 1, psDBF->fp );
    }
}

/************************************************************************/
/*                           DBFFlushRecord()                           */
/*                                                                      */
/*      Write out the current record if there is one.                   */
/************************************************************************/

static void DBFFlushRecord( DBFHandle psDBF )

{
    int		nRecordOffset;

    if( psDBF->bCurrentRecordModified && psDBF->nCurrentRecord > -1 )
    {
	psDBF->bCurrentRecordModified = FALSE;

	nRecordOffset = psDBF->nRecordLength * psDBF->nCurrentRecord 
	                                             + psDBF->nHeaderLength;

	fseek( psDBF->fp, nRecordOffset, 0 );
	fwrite( psDBF->pszCurrentRecord, psDBF->nRecordLength, 1, psDBF->fp );
    }
}

/************************************************************************/
/*                              DBFOpen()                               */
/*                                                                      */
/*      Open a .dbf file.                                               */
/************************************************************************/
   
DBFHandle DBFOpen( const char * pszFilename, const char * pszAccess )

{
    DBFHandle		psDBF;
    uchar		*pabyBuf;
    int			nFields, nRecords, nHeadLen, nRecLen, iField, i;
    char		*pszBasename, *pszFullname;

/* -------------------------------------------------------------------- */
/*      We only allow the access strings "rb" and "r+".                  */
/* -------------------------------------------------------------------- */
    if( strcmp(pszAccess,"r") != 0 && strcmp(pszAccess,"r+") != 0 
        && strcmp(pszAccess,"rb") != 0 && strcmp(pszAccess,"rb+") != 0
        && strcmp(pszAccess,"r+b") != 0 )
        return( NULL );

/* -------------------------------------------------------------------- */
/*	Compute the base (layer) name.  If there is any extension	*/
/*	on the passed in filename we will strip it off.			*/
/* -------------------------------------------------------------------- */
    pszBasename = (char *) malloc(strlen(pszFilename)+5);
    strcpy( pszBasename, pszFilename );
    for( i = strlen(pszBasename)-1; 
	 i > 0 && pszBasename[i] != '.' && pszBasename[i] != '/'
	       && pszBasename[i] != '\\';
	 i-- ) {}

    if( pszBasename[i] == '.' )
        pszBasename[i] = '\0';

    pszFullname = (char *) malloc(strlen(pszBasename) + 5);
    sprintf( pszFullname, "%s.dbf", pszBasename );
        
    psDBF = (DBFHandle) calloc( 1, sizeof(DBFInfo) );
    psDBF->fp = fopen( pszFullname, pszAccess );

    if( psDBF->fp == NULL )
    {
        sprintf( pszFullname, "%s.DBF", pszBasename );
        psDBF->fp = fopen(pszFullname, pszAccess );
    }
    
    free( pszBasename );
    free( pszFullname );
    
    if( psDBF->fp == NULL )
    {
        free( psDBF );
        return( NULL );
    }

    psDBF->bNoHeader = FALSE;
    psDBF->nCurrentRecord = -1;
    psDBF->bCurrentRecordModified = FALSE;

/* -------------------------------------------------------------------- */
/*  Read Table Header info                                              */
/* -------------------------------------------------------------------- */
    pabyBuf = (uchar *) malloc(500);
    fread( pabyBuf, 32, 1, psDBF->fp );

    psDBF->nRecords = nRecords = 
     pabyBuf[4] + pabyBuf[5]*256 + pabyBuf[6]*256*256 + pabyBuf[7]*256*256*256;

    psDBF->nHeaderLength = nHeadLen = pabyBuf[8] + pabyBuf[9]*256;
    psDBF->nRecordLength = nRecLen = pabyBuf[10] + pabyBuf[11]*256;
    
    psDBF->nFields = nFields = (nHeadLen - 32) / 32;

    psDBF->pszCurrentRecord = (char *) malloc(nRecLen);

/* -------------------------------------------------------------------- */
/*  Read in Field Definitions                                           */
/* -------------------------------------------------------------------- */
    
    pabyBuf = (uchar *) SfRealloc(pabyBuf,nHeadLen);
    psDBF->pszHeader = (char *) pabyBuf;

    fseek( psDBF->fp, 32, 0 );
    fread( pabyBuf, nHeadLen, 1, psDBF->fp );

    psDBF->panFieldOffset = (int *) malloc(sizeof(int) * nFields);
    psDBF->panFieldSize = (int *) malloc(sizeof(int) * nFields);
    psDBF->panFieldDecimals = (int *) malloc(sizeof(int) * nFields);
    psDBF->pachFieldType = (char *) malloc(sizeof(char) * nFields);

    for( iField = 0; iField < nFields; iField++ )
    {
	uchar		*pabyFInfo;

	pabyFInfo = pabyBuf+iField*32;

	if( pabyFInfo[11] == 'N' || pabyFInfo[11] == 'F' )
	{
	    psDBF->panFieldSize[iField] = pabyFInfo[16];
	    psDBF->panFieldDecimals[iField] = pabyFInfo[17];
	}
	else
	{
	    psDBF->panFieldSize[iField] = pabyFInfo[16] + pabyFInfo[17]*256;
	    psDBF->panFieldDecimals[iField] = 0;
	}

	psDBF->pachFieldType[iField] = (char) pabyFInfo[11];
	if( iField == 0 )
	    psDBF->panFieldOffset[iField] = 1;
	else
	    psDBF->panFieldOffset[iField] = 
	      psDBF->panFieldOffset[iField-1] + psDBF->panFieldSize[iField-1];
    }

    return( psDBF );
}

/************************************************************************/
/*                              DBFClose()                              */
/************************************************************************/

void	DBFClose(DBFHandle psDBF)
{
/* -------------------------------------------------------------------- */
/*      Write out header if not already written.                        */
/* -------------------------------------------------------------------- */
    if( psDBF->bNoHeader )
        DBFWriteHeader( psDBF );

    DBFFlushRecord( psDBF );

/* -------------------------------------------------------------------- */
/*      Update last access date, and number of records if we have	*/