lwgeom_in_geojson.c

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/**********************************************************************
 *
 * PostGIS - Spatial Types for PostgreSQL
 * http://postgis.net
 *
 * PostGIS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * PostGIS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with PostGIS.  If not, see <http://www.gnu.org/licenses/>.
 *
 **********************************************************************
 *
 * Copyright 2011 Kashif Rasul <kashif.rasul@gmail.com>
 *
 **********************************************************************/
 
 
#include <assert.h>
 
#include "postgres.h"
 
#include "../postgis_config.h"
#include "lwgeom_pg.h"
#include "liblwgeom.h"
#include "lwgeom_cache.h"
 
#if defined(HAVE_LIBJSON)
 
#include <json.h>
 
/* We don't include <utils/builtins.h> to avoid collisions with json-c/json.h */
static text*
cstring2text(const char *cstring)
{
        size_t len = strlen(cstring);
        text *result = (text *) palloc(len + VARHDRSZ);
        SET_VARSIZE(result, len + VARHDRSZ);
        memcpy(VARDATA(result), cstring, len);
 
        return result;
}
 
static char*
text2cstring(const text *textptr)
{
        size_t size = VARSIZE_ANY_EXHDR(textptr);
        char *str = lwalloc(size+1);
        memcpy(str, VARDATA(textptr), size);
        str[size]='\0';
        return str;
}
#endif
 
Datum geom_from_geojson(PG_FUNCTION_ARGS);
Datum postgis_libjson_version(PG_FUNCTION_ARGS);
 
PG_FUNCTION_INFO_V1(postgis_libjson_version);
Datum postgis_libjson_version(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBJSON
        PG_RETURN_NULL();
#else /* HAVE_LIBJSON  */
# ifdef JSON_C_VERSION
        const char *ver = json_c_version();
# else
        const char *ver = "UNKNOWN";
# endif
        text *result = cstring2text(ver);
        PG_RETURN_POINTER(result);
#endif
}
 
PG_FUNCTION_INFO_V1(geom_from_geojson);
Datum geom_from_geojson(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBJSON
        elog(ERROR, "You need JSON-C for ST_GeomFromGeoJSON");
        PG_RETURN_NULL();
#else /* HAVE_LIBJSON  */
 
        GSERIALIZED *geom;
        LWGEOM *lwgeom;
        text *geojson_input;
        char *geojson;
        char *srs = NULL;
        int32_t srid = WGS84_SRID;
 
        /* Get the geojson stream */
        if (PG_ARGISNULL(0))
                PG_RETURN_NULL();
 
        geojson_input = PG_GETARG_TEXT_P(0);
        geojson = text2cstring(geojson_input);
 
        lwgeom = lwgeom_from_geojson(geojson, &srs);
        if (!lwgeom)
        {
                /* Shouldn't get here */
                elog(ERROR, "lwgeom_from_geojson returned NULL");
                PG_RETURN_NULL();
        }
 
        if (srs)
        {
                srid = GetSRIDCacheBySRS(fcinfo, srs);
                lwfree(srs);
        }
 
        lwgeom_set_srid(lwgeom, srid);
        geom = geometry_serialize(lwgeom);
        lwgeom_free(lwgeom);
 
        PG_RETURN_POINTER(geom);
#endif
}