shpopen.c

/******************************************************************************
 * $Id: shpopen.c,v 1.76 2017-09-10 10:11:36 erouault Exp $
 *
 * Project:  Shapelib
 * Purpose:  Implementation of core Shapefile read/write functions.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 1999, 2001, Frank Warmerdam
 * Copyright (c) 2011-2013, Even Rouault <even dot rouault at mines-paris dot org>
 *
 * This software is available under the following "MIT Style" license,
 * or at the option of the licensee under the LGPL (see COPYING).  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: shpopen.c,v $
 * Revision 1.76  2017-09-10 10:11:36  erouault
 * * shpopen.c: resync with GDAL copy. Make sure to zero terminate all
 * error messages. And fix regression regarding re-writing the last shape
 * of a file (https://trac.osgeo.org/gdal/ticket/7031)
 *
 * Revision 1.75  2016-12-05 12:44:05  erouault
 * * Major overhaul of Makefile build system to use autoconf/automake.
 *
 * * Warning fixes in contrib/
 *
 * Revision 1.74  2016-12-04 15:30:15  erouault
 * * shpopen.c, dbfopen.c, shptree.c, shapefil.h: resync with
 * GDAL Shapefile driver. Mostly cleanups. SHPObject and DBFInfo
 * structures extended with new members. New functions:
 * DBFSetLastModifiedDate, SHPOpenLLEx, SHPRestoreSHX,
 * SHPSetFastModeReadObject
 *
 * * sbnsearch.c: new file to implement original ESRI .sbn spatial
 * index reading. (no write support). New functions:
 * SBNOpenDiskTree, SBNCloseDiskTree, SBNSearchDiskTree,
 * SBNSearchDiskTreeInteger, SBNSearchFreeIds
 *
 * * Makefile, makefile.vc, CMakeLists.txt, shapelib.def: updates
 * with new file and symbols.
 *
 * * commit: helper script to cvs commit
 *
 * Revision 1.73  2012-01-24 22:33:01  fwarmerdam
 * fix memory leak on failure to open .shp (gdal #4410)
 *
 * Revision 1.72  2011-12-11 22:45:28  fwarmerdam
 * fix failure return from SHPOpenLL.
 *
 * Revision 1.71  2011-09-15 03:33:58  fwarmerdam
 * fix missing cast (#2344)
 *
 * Revision 1.70  2011-07-24 05:59:25  fwarmerdam
 * minimize use of CPLError in favor of SAHooks.Error()
 *
 * Revision 1.69  2011-07-24 03:24:22  fwarmerdam
 * fix memory leaks in error cases creating shapefiles (#2061)
 *
 * Revision 1.68  2010-08-27 23:42:52  fwarmerdam
 * add SHPAPI_CALL attribute in code
 *
 * Revision 1.67  2010-07-01 08:15:48  fwarmerdam
 * do not error out on an object with zero vertices
 *
 * Revision 1.66  2010-07-01 07:58:57  fwarmerdam
 * minor cleanup of error handling
 *
 * Revision 1.65  2010-07-01 07:27:13  fwarmerdam
 * white space formatting adjustments
 *
 * Revision 1.64  2010-01-28 11:34:34  fwarmerdam
 * handle the shape file length limits more gracefully (#3236)
 *
 * Revision 1.63  2010-01-28 04:04:40  fwarmerdam
 * improve numerical accuracy of SHPRewind() algs (gdal #3363)
 *
 * Revision 1.62  2010-01-17 05:34:13  fwarmerdam
 * Remove asserts on x/y being null (#2148).
 *
 * Revision 1.61  2010-01-16 05:07:42  fwarmerdam
 * allow 0/nulls in shpcreateobject (#2148)
 *
 * Revision 1.60  2009-09-17 20:50:02  bram
 * on Win32, define snprintf as alias to _snprintf
 *
 * Revision 1.59  2008-03-14 05:25:31  fwarmerdam
 * Correct crash on buggy geometries (gdal #2218)
 *
 * Revision 1.58  2008/01/08 23:28:26  bram
 * on line 2095, use a float instead of a double to avoid a compiler warning
 *
 * Revision 1.57  2007/12/06 07:00:25  fwarmerdam
 * dbfopen now using SAHooks for fileio
 *
 * Revision 1.56  2007/12/04 20:37:56  fwarmerdam
 * preliminary implementation of hooks api for io and errors
 *
 * Revision 1.55  2007/11/21 22:39:56  fwarmerdam
 * close shx file in readonly mode (GDAL #1956)
 *
 * Revision 1.54  2007/11/15 00:12:47  mloskot
 * Backported recent changes from GDAL (Ticket #1415) to Shapelib.
 *
 * Revision 1.53  2007/11/14 22:31:08  fwarmerdam
 * checks after mallocs to detect for corrupted/voluntary broken shapefiles.
 * http://trac.osgeo.org/gdal/ticket/1991
 *
 * Revision 1.52  2007/06/21 15:58:33  fwarmerdam
 * fix for SHPRewindObject when rings touch at one vertex (gdal #976)
 *
 * Revision 1.51  2006/09/04 15:24:01  fwarmerdam
 * Fixed up log message for 1.49.
 *
 * Revision 1.50  2006/09/04 15:21:39  fwarmerdam
 * fix of last fix
 *
 * Revision 1.49  2006/09/04 15:21:00  fwarmerdam
 * MLoskot: Added stronger test of Shapefile reading failures, e.g. truncated
 * files.  The problem was discovered by Tim Sutton and reported here
 *   https://svn.qgis.org/trac/ticket/200
 *
 * Revision 1.48  2006/01/26 15:07:32  fwarmerdam
 * add bMeasureIsUsed flag from Craig Bruce: Bug 1249
 *
 * Revision 1.47  2006/01/04 20:07:23  fwarmerdam
 * In SHPWriteObject() make sure that the record length is updated
 * when rewriting an existing record.
 *
 * Revision 1.46  2005/02/11 17:17:46  fwarmerdam
 * added panPartStart[0] validation
 *
 * Revision 1.45  2004/09/26 20:09:48  fwarmerdam
 * const correctness changes
 *
 * Revision 1.44  2003/12/29 00:18:39  fwarmerdam
 * added error checking for failed IO and optional CPL error reporting
 *
 * Revision 1.43  2003/12/01 16:20:08  warmerda
 * be careful of zero vertex shapes
 *
 * Revision 1.42  2003/12/01 14:58:27  warmerda
 * added degenerate object check in SHPRewindObject()
 *
 * Revision 1.41  2003/07/08 15:22:43  warmerda
 * avoid warning
 *
 * Revision 1.40  2003/04/21 18:30:37  warmerda
 * added header write/update public methods
 *
 * Revision 1.39  2002/08/26 06:46:56  warmerda
 * avoid c++ comments
 *
 * Revision 1.38  2002/05/07 16:43:39  warmerda
 * Removed debugging printf()
 *
 * Revision 1.37  2002/04/10 17:35:22  warmerda
 * fixed bug in ring reversal code
 *
 * Revision 1.36  2002/04/10 16:59:54  warmerda
 * added SHPRewindObject
 *
 * Revision 1.35  2001/12/07 15:10:44  warmerda
 * fix if .shx fails to open
 *
 * Revision 1.34  2001/11/01 16:29:55  warmerda
 * move pabyRec into SHPInfo for thread safety
 *
 * Revision 1.33  2001/07/03 12:18:15  warmerda
 * Improved cleanup if SHX not found, provided by Riccardo Cohen.
 *
 * Revision 1.32  2001/06/22 01:58:07  warmerda
 * be more careful about establishing initial bounds in face of NULL shapes
 *
 * Revision 1.31  2001/05/31 19:35:29  warmerda
 * added support for writing null shapes
 *
 * Revision 1.30  2001/05/28 12:46:29  warmerda
 * Add some checking on reasonableness of record count when opening.
 *
 * Revision 1.29  2001/05/23 13:36:52  warmerda
 * added use of SHPAPI_CALL
 *
 * Revision 1.28  2001/02/06 22:25:06  warmerda
 * fixed memory leaks when SHPOpen() fails
 *
 * Revision 1.27  2000/07/18 15:21:33  warmerda
 * added better enforcement of -1 for append in SHPWriteObject
 *
 * Revision 1.26  2000/02/16 16:03:51  warmerda
 * added null shape support
 *
 * Revision 1.25  1999/12/15 13:47:07  warmerda
 * Fixed record size settings in .shp file (was 4 words too long)
 * Added stdlib.h.
 *
 * Revision 1.24  1999/11/05 14:12:04  warmerda
 * updated license terms
 *
 * Revision 1.23  1999/07/27 00:53:46  warmerda
 * added support for rewriting shapes
 *
 * Revision 1.22  1999/06/11 19:19:11  warmerda
 * Cleanup pabyRec static buffer on SHPClose().
 *
 * Revision 1.21  1999/06/02 14:57:56  kshih
 * Remove unused variables
 *
 * Revision 1.20  1999/04/19 21:04:17  warmerda
 * Fixed syntax error.
 *
 * Revision 1.19  1999/04/19 21:01:57  warmerda
 * Force access string to binary in SHPOpen().
 *
 * Revision 1.18  1999/04/01 18:48:07  warmerda
 * Try upper case extensions if lower case doesn't work.
 *
 * Revision 1.17  1998/12/31 15:29:39  warmerda
 * Disable writing measure values to multipatch objects if
 * DISABLE_MULTIPATCH_MEASURE is defined.
 *
 * Revision 1.16  1998/12/16 05:14:33  warmerda
 * Added support to write MULTIPATCH.  Fixed reading Z coordinate of
 * MULTIPATCH. Fixed record size written for all feature types.
 *
 * Revision 1.15  1998/12/03 16:35:29  warmerda
 * r+b is proper binary access string, not rb+.
 *
 * Revision 1.14  1998/12/03 15:47:56  warmerda
 * Fixed setting of nVertices in SHPCreateObject().
 *
 * Revision 1.13  1998/12/03 15:33:54  warmerda
 * Made SHPCalculateExtents() separately callable.
 *
 * Revision 1.12  1998/11/11 20:01:50  warmerda
 * Fixed bug writing ArcM/Z, and PolygonM/Z for big endian machines.
 *
 * Revision 1.11  1998/11/09 20:56:44  warmerda
 * Fixed up handling of file wide bounds.
 *
 * Revision 1.10  1998/11/09 20:18:51  warmerda
 * Converted to support 3D shapefiles, and use of SHPObject.
 *
 * Revision 1.9  1998/02/24 15:09:05  warmerda
 * Fixed memory leak.
 *
 * Revision 1.8  1997/12/04 15:40:29  warmerda
 * Fixed byte swapping of record number, and record length fields in the
 * .shp file.
 *
 * Revision 1.7  1995/10/21 03:15:58  warmerda
 * Added support for binary file access, the magic cookie 9997
 * and tried to improve the int32 selection logic for 16bit systems.
 *
 * Revision 1.6  1995/09/04  04:19:41  warmerda
 * Added fix for file bounds.
 *
 * Revision 1.5  1995/08/25  15:16:44  warmerda
 * Fixed a couple of problems with big endian systems ... one with bounds
 * and the other with multipart polygons.
 *
 * Revision 1.4  1995/08/24  18:10:17  warmerda
 * Switch to use SfRealloc() to avoid problems with pre-ANSI realloc()
 * functions (such as on the Sun).
 *
 * Revision 1.3  1995/08/23  02:23:15  warmerda
 * Added support for reading bounds, and fixed up problems in setting the
 * file wide bounds.
 *
 * Revision 1.2  1995/08/04  03:16:57  warmerda
 * Added header.
 *
 */

#include "shapefil.h"

#include <math.h>
#include <limits.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>

SHP_CVSID("$Id: shpopen.c,v 1.76 2017-09-10 10:11:36 erouault Exp $")

typedef unsigned char uchar;

#if UINT_MAX == 65535
typedef unsigned long	      int32;
#else
typedef unsigned int	      int32;
#endif

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

#define ByteCopy( a, b, c )	memcpy( b, a, c )
#ifndef MAX
#  define MIN(a,b)      ((a<b) ? a : b)
#  define MAX(a,b)      ((a>b) ? a : b)
#endif

#ifndef USE_CPL
#if defined(_MSC_VER)
# if _MSC_VER < 1900
#     define snprintf _snprintf
# endif
#elif defined(WIN32) || defined(_WIN32)
#  ifndef snprintf
#     define snprintf _snprintf
#  endif
#endif
#endif

#ifndef CPL_UNUSED
#if defined(__GNUC__) && __GNUC__ >= 4
#  define CPL_UNUSED __attribute((__unused__))
#else
#  define CPL_UNUSED
#endif
#endif  

#if defined(CPL_LSB)
#define bBigEndian FALSE
#elif defined(CPL_MSB)
#define bBigEndian TRUE
#else
static int 	bBigEndian;
#endif

/************************************************************************/
/*                              SwapWord()                              */
/*                                                                      */
/*      Swap a 2, 4 or 8 byte word.                                     */
/************************************************************************/

static void	SwapWord( int length, void * wordP )

{
    int		i;
    uchar	temp;

    for( i=0; i < length/2; i++ )
    {
	temp = ((uchar *) wordP)[i];
	((uchar *)wordP)[i] = ((uchar *) wordP)[length-i-1];
	((uchar *) wordP)[length-i-1] = temp;
    }
}

/************************************************************************/
/*                             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) );
}

/************************************************************************/
/*                          SHPWriteHeader()                            */
/*                                                                      */
/*      Write out a header for the .shp and .shx files as well as the	*/
/*	contents of the index (.shx) file.				*/
/************************************************************************/

void SHPAPI_CALL SHPWriteHeader( SHPHandle psSHP )

{
    uchar     	abyHeader[100] = { 0 };
    int		i;
    int32	i32;
    double	dValue;
    int32	*panSHX;

    if (psSHP->fpSHX == NULL)
    {
        psSHP->sHooks.Error( "SHPWriteHeader failed : SHX file is closed");
        return;
    }

/* -------------------------------------------------------------------- */
/*      Prepare header block for .shp file.                             */
/* -------------------------------------------------------------------- */

    abyHeader[2] = 0x27;				/* magic cookie */
    abyHeader[3] = 0x0a;

    i32 = psSHP->nFileSize/2;				/* file size */
    ByteCopy( &i32, abyHeader+24, 4 );
    if( !bBigEndian ) SwapWord( 4, abyHeader+24 );

    i32 = 1000;						/* version */
    ByteCopy( &i32, abyHeader+28, 4 );
    if( bBigEndian ) SwapWord( 4, abyHeader+28 );

    i32 = psSHP->nShapeType;				/* shape type */
    ByteCopy( &i32, abyHeader+32, 4 );
    if( bBigEndian ) SwapWord( 4, abyHeader+32 );

    dValue = psSHP->adBoundsMin[0];			/* set bounds */
    ByteCopy( &dValue, abyHeader+36, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+36 );

    dValue = psSHP->adBoundsMin[1];
    ByteCopy( &dValue, abyHeader+44, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+44 );

    dValue = psSHP->adBoundsMax[0];
    ByteCopy( &dValue, abyHeader+52, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+52 );

    dValue = psSHP->adBoundsMax[1];
    ByteCopy( &dValue, abyHeader+60, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+60 );

    dValue = psSHP->adBoundsMin[2];			/* z */
    ByteCopy( &dValue, abyHeader+68, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+68 );

    dValue = psSHP->adBoundsMax[2];
    ByteCopy( &dValue, abyHeader+76, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+76 );

    dValue = psSHP->adBoundsMin[3];			/* m */
    ByteCopy( &dValue, abyHeader+84, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+84 );

    dValue = psSHP->adBoundsMax[3];
    ByteCopy( &dValue, abyHeader+92, 8 );
    if( bBigEndian ) SwapWord( 8, abyHeader+92 );

/* -------------------------------------------------------------------- */
/*      Write .shp file header.                                         */
/* -------------------------------------------------------------------- */
    if( psSHP->sHooks.FSeek( psSHP->fpSHP, 0, 0 ) != 0
        || psSHP->sHooks.FWrite( abyHeader, 100, 1, psSHP->fpSHP ) != 1 )
    {
        char szErrorMsg[200];

        snprintf( szErrorMsg, sizeof(szErrorMsg),
                 "Failure writing .shp header: %s", strerror(errno) );
        szErrorMsg[sizeof(szErrorMsg)-1] = '\0';
        psSHP->sHooks.Error( szErrorMsg );
        return;
    }

/* -------------------------------------------------------------------- */
/*      Prepare, and write .shx file header.                            */
/* -------------------------------------------------------------------- */
    i32 = (psSHP->nRecords * 2 * sizeof(int32) + 100)/2;   /* file size */
    ByteCopy( &i32, abyHeader+24, 4 );
    if( !bBigEndian ) SwapWord( 4, abyHeader+24 );

    if( psSHP->sHooks.FSeek( psSHP->fpSHX, 0, 0 ) != 0
        || psSHP->sHooks.FWrite( abyHeader, 100, 1, psSHP->fpSHX ) != 1 )
    {
        char szErrorMsg[200];

        snprintf( szErrorMsg, sizeof(szErrorMsg),
                 "Failure writing .shx header: %s", strerror(errno) );
        szErrorMsg[sizeof(szErrorMsg)-1] = '\0';
        psSHP->sHooks.Error( szErrorMsg );

        return;
    }

/* -------------------------------------------------------------------- */
/*      Write out the .shx contents.                                    */
/* -------------------------------------------------------------------- */
    panSHX = (int32 *) malloc(sizeof(int32) * 2 * psSHP->nRecords);
    if( panSHX == NULL )
    {
        psSHP->sHooks.Error( "Failure allocatin panSHX" );
        return;
    }

    for( i = 0; i < psSHP->nRecords; i++ )
    {
        panSHX[i*2  ] = psSHP->panRecOffset[i]/2;
        panSHX[i*2+1] = psSHP->panRecSize[i]/2;
        if( !bBigEndian ) SwapWord( 4, panSHX+i*2 );
        if( !bBigEndian ) SwapWord( 4, panSHX+i*2+1 );
    }

    if( (int)psSHP->sHooks.FWrite( panSHX, sizeof(int32)*2, psSHP->nRecords, psSHP->fpSHX )
        != psSHP->nRecords )
    {
        char szErrorMsg[200];

        snprintf( szErrorMsg, sizeof(szErrorMsg),
                 "Failure writing .shx contents: %s", strerror(errno) );
        szErrorMsg[sizeof(szErrorMsg)-1] = '\0';
        psSHP->sHooks.Error( szErrorMsg );
    }

    free( panSHX );

/* -------------------------------------------------------------------- */
/*      Flush to disk.                                                  */
/* -------------------------------------------------------------------- */
    psSHP->sHooks.FFlush( psSHP->fpSHP );
    psSHP->sHooks.FFlush( psSHP->fpSHX );
}

/************************************************************************/
/*                              SHPOpen()                               */
/************************************************************************/

SHPHandle SHPAPI_CALL
SHPOpen( const char * pszLayer, const char * pszAccess )

{
    SAHooks sHooks;

    SASetupDefaultHooks( &sHooks );

    return SHPOpenLL( pszLayer, pszAccess, &sHooks );
}

/************************************************************************/
/*                              SHPOpen()                               */
/*                                                                      */
/*      Open the .shp and .shx files based on the basename of the       */
/*      files or either file name.                                      */
/************************************************************************/

SHPHandle SHPAPI_CALL
SHPOpenLL( const char * pszLayer, const char * pszAccess, SAHooks *psHooks )

{
    char        *pszFullname, *pszBasename;
    SHPHandle       psSHP;

    uchar       *pabyBuf;
    int         i;
    double      dValue;
    int         bLazySHXLoading = FALSE;
    size_t nFullnameLen;

/* -------------------------------------------------------------------- */
/*      Ensure the access string is one of the legal ones.  We          */
/*      ensure the result string indicates binary to avoid common       */
/*      problems on Windows.                                            */
/* -------------------------------------------------------------------- */
    if( strcmp(pszAccess,"rb+") == 0 || strcmp(pszAccess,"r+b") == 0
        || strcmp(pszAccess,"r+") == 0 )
        pszAccess = "r+b";
    else
    {
        bLazySHXLoading = strchr(pszAccess, 'l') != NULL;
        pszAccess = "rb";
    }

/* -------------------------------------------------------------------- */
/*  Establish the byte order on this machine.           */
/* -------------------------------------------------------------------- */
#if !defined(bBigEndian)
    i = 1;
    if( *((uchar *) &i) == 1 )
        bBigEndian = FALSE;
    else
        bBigEndian = TRUE;
#endif

/* -------------------------------------------------------------------- */
/*  Initialize the info structure.                  */
/* -------------------------------------------------------------------- */
    psSHP = (SHPHandle) calloc(sizeof(SHPInfo),1);

    psSHP->bUpdated = FALSE;
    memcpy( &(psSHP->sHooks), psHooks, sizeof(SAHooks) );

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

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

/* -------------------------------------------------------------------- */
/*  Open the .shp and .shx files.  Note that files pulled from  */
/*  a PC to Unix with upper case filenames won't work!      */
/* -------------------------------------------------------------------- */
    nFullnameLen = strlen(pszBasename) + 5;
    pszFullname = (char *) malloc(nFullnameLen);
    snprintf( pszFullname, nFullnameLen, "%s.shp", pszBasename ) ;
    psSHP->fpSHP = psSHP->sHooks.FOpen(pszFullname, pszAccess );
    if( psSHP->fpSHP == NULL )
    {
        snprintf( pszFullname, nFullnameLen, "%s.SHP", pszBasename );
        psSHP->fpSHP = psSHP->sHooks.FOpen(pszFullname, pszAccess );
    }

    if( psSHP->fpSHP == NULL )
    {
        size_t nMessageLen = strlen(pszBasename)*2+256;
        char *pszMessage = (char *) malloc(nMessageLen);
        snprintf( pszMessage, nMessageLen, "Unable to open %s.shp or %s.SHP.",
                  pszBasename, pszBasename );
        psHooks->Error( pszMessage );
        free( pszMessage );

        free( psSHP );
        free( pszBasename );
        free( pszFullname );

        return NULL;
    }

    snprintf( pszFullname, nFullnameLen, "%s.shx", pszBasename );
    psSHP->fpSHX =  psSHP->sHooks.FOpen(pszFullname, pszAccess );
    if( psSHP->fpSHX == NULL )
    {
        snprintf( pszFullname, nFullnameLen, "%s.SHX", pszBasename );
        psSHP->fpSHX = psSHP->sHooks.FOpen(pszFullname, pszAccess );
    }

    if( psSHP->fpSHX == NULL )
    {
        size_t nMessageLen = strlen(pszBasename)*2+256;
        char *pszMessage = (char *) malloc(nMessageLen);
        snprintf( pszMessage, nMessageLen, "Unable to open %s.shx or %s.SHX."
                  "Try --config SHAPE_RESTORE_SHX true to restore or create it",
                  pszBasename, pszBasename );
        psHooks->Error( pszMessage );
        free( pszMessage );

        psSHP->sHooks.FClose( psSHP->fpSHP );
        free( psSHP );
        free( pszBasename );
        free( pszFullname );
        return( NULL );
    }

    free( pszFullname );
    free( pszBasename );

/* -------------------------------------------------------------------- */
/*  Read the file size from the SHP file.               */
/* -------------------------------------------------------------------- */
    pabyBuf = (uchar *) malloc(100);
    psSHP->sHooks.FRead( pabyBuf, 100, 1, psSHP->fpSHP );

    psSHP->nFileSize = ((unsigned int)pabyBuf[24]<<24)|(pabyBuf[25]<<16)|
                        (pabyBuf[26]<<8)|pabyBuf[27];
    if( psSHP->nFileSize < UINT_MAX / 2 )
        psSHP->nFileSize *= 2;
    else
        psSHP->nFileSize = (UINT_MAX / 2) * 2;

/* -------------------------------------------------------------------- */
/*  Read SHX file Header info                                           */
/* -------------------------------------------------------------------- */
    if( psSHP->sHooks.FRead( pabyBuf, 100, 1, psSHP->fpSHX ) != 1
        || pabyBuf[0] != 0
        || pabyBuf[1] != 0
        || pabyBuf[2] != 0x27
        || (pabyBuf[3] != 0x0a && pabyBuf[3] != 0x0d) )
    {
        psSHP->sHooks.Error( ".shx file is unreadable, or corrupt." );
        psSHP->sHooks.FClose( psSHP->fpSHP );
        psSHP->sHooks.FClose( psSHP->fpSHX );
        free( pabyBuf );
        free( psSHP );

        return( NULL );
    }

    psSHP->nRecords = pabyBuf[27]|(pabyBuf[26]<<8)|(pabyBuf[25]<<16)|
                      ((pabyBuf[24] & 0x7F)<<24);
    psSHP->nRecords = (psSHP->nRecords - 50) / 4;

    psSHP->nShapeType = pabyBuf[32];

    if( psSHP->nRecords < 0 || psSHP->nRecords > 256000000 )
    {
        char szErrorMsg[200];

        snprintf( szErrorMsg, sizeof(szErrorMsg),
                 "Record count in .shp header is %d, which seems\n"
                 "unreasonable.  Assuming header is corrupt.",
                 psSHP->nRecords );
        szErrorMsg[sizeof(szErrorMsg)-1] = '\0';
        psSHP->sHooks.Error( szErrorMsg );
        psSHP->sHooks.FClose( psSHP->fpSHP );
        psSHP->sHooks.FClose( psSHP->fpSHX );
        free( psSHP );
        free(pabyBuf);

        return( NULL );
    }

    /* If a lot of records are advertized, check that the file is big enough */
    /* to hold them */
    if( psSHP->nRecords >= 1024 * 1024 )
    {
        SAOffset nFileSize;
        psSHP->sHooks.FSeek( psSHP->fpSHX, 0, 2 );
        nFileSize = psSHP->sHooks.FTell( psSHP->fpSHX );
        if( nFileSize > 100 &&
            nFileSize/2 < (SAOffset)(psSHP->nRecords * 4 + 50) )
        {
            psSHP->nRecords = (int)((nFileSize - 100) / 8);
        }
        psSHP->sHooks.FSeek( psSHP->fpSHX, 100, 0 );
    }

/* -------------------------------------------------------------------- */
/*      Read the bounds.                                                */
/* -------------------------------------------------------------------- */
    if( bBigEndian ) SwapWord( 8, pabyBuf+36 );
    memcpy( &dValue, pabyBuf+36, 8 );
    psSHP->adBoundsMin[0] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+44 );
    memcpy( &dValue, pabyBuf+44, 8 );
    psSHP->adBoundsMin[1] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+52 );
    memcpy( &dValue, pabyBuf+52, 8 );
    psSHP->adBoundsMax[0] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+60 );
    memcpy( &dValue, pabyBuf+60, 8 );
    psSHP->adBoundsMax[1] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+68 );     /* z */
    memcpy( &dValue, pabyBuf+68, 8 );
    psSHP->adBoundsMin[2] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+76 );
    memcpy( &dValue, pabyBuf+76, 8 );
    psSHP->adBoundsMax[2] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+84 );     /* z */
    memcpy( &dValue, pabyBuf+84, 8 );
    psSHP->adBoundsMin[3] = dValue;

    if( bBigEndian ) SwapWord( 8, pabyBuf+92 );
    memcpy( &dValue, pabyBuf+92, 8 );
    psSHP->adBoundsMax[3] = dValue;

    free( pabyBuf );

/* -------------------------------------------------------------------- */
/*  Read the .shx file to get the offsets to each record in     */
/*  the .shp file.                          */
/* -------------------------------------------------------------------- */
    psSHP->nMaxRecords = psSHP->nRecords;

    psSHP->panRecOffset = (unsigned int *)
        malloc(sizeof(unsigned int) * MAX(1,psSHP->nMaxRecords) );
    psSHP->panRecSize = (unsigned int *)
        malloc(sizeof(unsigned int) * MAX(1,psSHP->nMaxRecords) );
    if( bLazySHXLoading )
        pabyBuf = NULL;
    else
        pabyBuf = (uchar *) malloc(8 * MAX(1,psSHP->nRecords) );

    if (psSHP->panRecOffset == NULL ||
        psSHP->panRecSize == NULL ||
        (!bLazySHXLoading && pabyBuf == NULL))
    {
        char szErrorMsg[200];

        snprintf( szErrorMsg, sizeof(szErrorMsg),
                "Not enough memory to allocate requested memory (nRecords=%d).\n"
                "Probably broken SHP file",
                psSHP->nRecords );
        szErrorMsg[sizeof(szErrorMsg)-1] = '\0';
        psSHP->sHooks.Error( szErrorMsg );
        psSHP->sHooks.FClose( psSHP->fpSHP );
        psSHP->sHooks.FClose( psSHP->fpSHX );
        if (psSHP->panRecOffset) free( psSHP->panRecOffset );
        if (psSHP->panRecSize) free( psSHP->panRecSize );
        if (pabyBuf) free( pabyBuf );
        free( psSHP );
        return( NULL );
    }

    if( bLazySHXLoading )
    {
        memset(psSHP->panRecOffset, 0, sizeof(unsigned int) * MAX(1,psSHP->nMaxRecords) );
        memset(psSHP->panRecSize, 0, sizeof(unsigned int) * MAX(1,psSHP->nMaxRecords) );
        return( psSHP );
    }

    if( (int) psSHP->sHooks.FRead( pabyBuf, 8, psSHP->nRecords, psSHP->fpSHX )
        != psSHP->nRecords )
    {
        char szErrorMsg[200];

        snprintf( szErrorMsg, sizeof(szErrorMsg),
                 "Failed to read all values for %d records in .shx file: %s.",
                 psSHP->nRecords, strerror(errno) );
        szErrorMsg[sizeof(szErrorMsg)-1] = '\0';
        psSHP->sHooks.Error( szErrorMsg );

        /* SHX is short or unreadable for some reason. */
        psSHP->sHooks.FClose( psSHP->fpSHP );
        psSHP->sHooks.FClose( psSHP->fpSHX );
        free( psSHP->panRecOffset );
        free( psSHP->panRecSize );
        free( pabyBuf );
        free( psSHP );

        return( NULL );
    }

    /* In read-only mode, we can close the SHX now */
    if (strcmp(pszAccess, "rb") == 0)
    {
        psSHP->sHooks.FClose( psSHP->fpSHX );
        psSHP->fpSHX = NULL;
    }

    for( i = 0; i < psSHP->nRecords; i++ )
    {
        unsigned int        nOffset, nLength;

        memcpy( &nOffset, pabyBuf + i * 8, 4 );
        if( !bBigEndian ) SwapWord( 4, &nOffset );

        memcpy( &nLength, pabyBuf + i * 8 + 4, 4 );
        if( !bBigEndian ) SwapWord( 4, &nLength );

        if( nOffset > (unsigned int)INT_MAX )
        {
            char str[128];
            snprintf( str, sizeof(str),
                    "Invalid offset for entity %d", i);
            str[sizeof(str)-1] = '\0';

            psSHP->sHooks.Error( str );
            SHPClose(psSHP);
            free( pabyBuf );
            return NULL;
        }
        if( nLength > (unsigned int)(INT_MAX / 2 - 4) )
        {
            char str[128];
            snprintf( str, sizeof(str),
                    "Invalid length for entity %d", i);
            str[sizeof(str)-1] = '\0';

            psSHP->sHooks.Error( str );
            SHPClose(psSHP);
            free( pabyBuf );
            return NULL;
        }
        psSHP->panRecOffset[i] = nOffset*2;
        psSHP->panRecSize[i] = nLength*2;
    }
    free( pabyBuf );

    return( psSHP );
}

/************************************************************************/
/*                              SHPOpenLLEx()                           */
/*                                                                      */
/*      Open the .shp and .shx files based on the basename of the       */
/*      files or either file name. It generally invokes SHPRestoreSHX() */
/*      in case when bRestoreSHX equals true.                           */
/************************************************************************/

SHPHandle SHPAPI_CALL
SHPOpenLLEx( const char * pszLayer, const char * pszAccess, SAHooks *psHooks,
            int bRestoreSHX )

{
    if ( !bRestoreSHX ) return SHPOpenLL ( pszLayer, pszAccess, psHooks );
    else
    {
        if ( SHPRestoreSHX ( pszLayer, pszAccess, psHooks ) )
        {
            return SHPOpenLL ( pszLayer, pszAccess, psHooks );
        }
    }

    return( NULL );
}

/************************************************************************/
/*                              SHPRestoreSHX()                         */
/*                                                                      */
/*      Restore .SHX file using associated .SHP file.                   */
/*                                                                      */
/************************************************************************/

int       SHPAPI_CALL
SHPRestoreSHX ( const char * pszLayer, const char * pszAccess, SAHooks *psHooks )

{
    char            *pszFullname, *pszBasename;
    SAFile          fpSHP, fpSHX;


    uchar           *pabyBuf;
    int             i;
    size_t          nFullnameLen;
    unsigned int    nSHPFilesize;

    size_t          nMessageLen;
    char            *pszMessage;

    unsigned int    nCurrentRecordOffset = 0;
    unsigned int    nCurrentSHPOffset = 100;
    size_t          nRealSHXContentSize = 100;

    const char      pszSHXAccess[] = "w+b";
    char            *pabySHXHeader;
    char            abyReadedRecord[8];
    unsigned int    niRecord = 0;
    unsigned int    nRecordLength = 0;
    unsigned int    nRecordOffset = 50;

/* -------------------------------------------------------------------- */
/*      Ensure the access string is one of the legal ones.  We          */
/*      ensure the result string indicates binary to avoid common       */
/*      problems on Windows.                                            */
/* -------------------------------------------------------------------- */
    if( strcmp(pszAccess,"rb+") == 0 || strcmp(pszAccess,"r+b") == 0
        || strcmp(pszAccess,"r+") == 0 )
        pszAccess = "r+b";
    else
    {
        pszAccess = "rb";
    }

/* -------------------------------------------------------------------- */
/*  Establish the byte order on this machine.                           */
/* -------------------------------------------------------------------- */
#if !defined(bBigEndian)
    i = 1;
    if( *((uchar *) &i) == 1 )
        bBigEndian = FALSE;
    else
        bBigEndian = TRUE;
#endif

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

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

/* -------------------------------------------------------------------- */
/*  Open the .shp file.  Note that files pulled from                    */
/*  a PC to Unix with upper case filenames won't work!                  */
/* -------------------------------------------------------------------- */
    nFullnameLen = strlen(pszBasename) + 5;
    pszFullname = (char *) malloc(nFullnameLen);
    snprintf( pszFullname, nFullnameLen, "%s.shp", pszBasename ) ;