lwgeom_in_flatgeobuf.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 (C) 2021 Björn Harrtell <bjorn@wololo.org>
 *
 **********************************************************************/
 
 
#include <assert.h>
 
#include "postgres.h"
 
#include "../postgis_config.h"
#include "lwgeom_pg.h"
#include "liblwgeom.h"
#include "lwgeom_cache.h"
#include "funcapi.h"
#include <executor/spi.h>
#include <utils/builtins.h>
#include "flatgeobuf.h"
 
static char *get_pgtype(uint8_t column_type) {
        switch (column_type) {
        case flatgeobuf_column_type_bool:
                return "boolean";
        case flatgeobuf_column_type_byte:
        case flatgeobuf_column_type_ubyte:
                return "smallint";
        case flatgeobuf_column_type_short:
                return "smallint";
        case flatgeobuf_column_type_int:
                return "integer";
        case flatgeobuf_column_type_uint:
        case flatgeobuf_column_type_long:
        case flatgeobuf_column_type_ulong:
                return "bigint";
        case flatgeobuf_column_type_float:
                return "real";
        case flatgeobuf_column_type_double:
                return "double precision";
        case flatgeobuf_column_type_datetime:
                return "timestamptz";
        case flatgeobuf_column_type_string:
                return "text";
        case flatgeobuf_column_type_binary:
                return "bytea";
        case flatgeobuf_column_type_json:
                return "jsonb";
        }
        elog(ERROR, "unknown column_type %d", column_type);
}
 
PG_FUNCTION_INFO_V1(pgis_tablefromflatgeobuf);
Datum pgis_tablefromflatgeobuf(PG_FUNCTION_ARGS)
{
        struct flatgeobuf_decode_ctx *ctx;
        text *schema_input;
        char *schema;
        text *table_input;
        char *table;
        char *format;
        char *sql;
        bytea *data;
        uint16_t i;
        char **column_defs;
        size_t column_defs_total_len;
        char *column_defs_str;
 
        if (PG_ARGISNULL(0))
                PG_RETURN_NULL();
        if (PG_ARGISNULL(1))
                PG_RETURN_NULL();
 
        schema_input = PG_GETARG_TEXT_P(0);
        schema = text_to_cstring(schema_input);
 
        table_input = PG_GETARG_TEXT_P(1);
        table = text_to_cstring(table_input);
 
        data = PG_GETARG_BYTEA_PP(2);
 
        ctx = palloc0(sizeof(*ctx));
        ctx->ctx = palloc0(sizeof(flatgeobuf_ctx));
        ctx->ctx->size = VARSIZE_ANY_EXHDR(data);
        POSTGIS_DEBUGF(3, "bytea data size is %ld", ctx->ctx->size);
        ctx->ctx->buf = lwalloc(ctx->ctx->size);
        memcpy(ctx->ctx->buf, VARDATA_ANY(data), ctx->ctx->size);
        ctx->ctx->offset = 0;
 
        flatgeobuf_check_magicbytes(ctx);
        flatgeobuf_decode_header(ctx->ctx);
 
        column_defs = palloc(sizeof(char *) * ctx->ctx->columns_size);
        column_defs_total_len = 0;
        POSTGIS_DEBUGF(2, "found %d columns", ctx->ctx->columns_size);
        for (i = 0; i < ctx->ctx->columns_size; i++) {
                flatgeobuf_column *column = ctx->ctx->columns[i];
                const char *name = column->name;
                uint8_t column_type = column->type;
                char *pgtype = get_pgtype(column_type);
                size_t len = strlen(name) + 1 + strlen(pgtype) + 1;
                column_defs[i] = palloc0(sizeof(char) * len);
                strcat(column_defs[i], name);
                strcat(column_defs[i], " ");
                strcat(column_defs[i], pgtype);
                column_defs_total_len += len;
        }
        column_defs_str = palloc0(sizeof(char) * column_defs_total_len + (ctx->ctx->columns_size * 2) + 2 + 1);
        if (ctx->ctx->columns_size > 0)
                strcat(column_defs_str, ", ");
        for (i = 0; i < ctx->ctx->columns_size; i++) {
                strcat(column_defs_str, column_defs[i]);
                if (i < ctx->ctx->columns_size - 1)
                        strcat(column_defs_str, ", ");
        }
 
        POSTGIS_DEBUGF(2, "column_defs_str %s", column_defs_str);
 
        format = "create table %s.%s (id int, geom geometry%s)";
        sql = palloc0(strlen(format) + strlen(schema) + strlen(table) + strlen(column_defs_str) + 1);
 
        sprintf(sql, format, schema, table, column_defs_str);
 
        POSTGIS_DEBUGF(3, "sql: %s", sql);
 
        if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "Failed to connect SPI");
 
        if (SPI_execute(sql, false, 0) != SPI_OK_UTILITY)
                elog(ERROR, "Failed to create table");
 
        if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "Failed to finish SPI");
 
        POSTGIS_DEBUG(3, "finished");
 
        PG_RETURN_NULL();
}
 
// https://stackoverflow.com/questions/11740256/refactor-a-pl-pgsql-function-to-return-the-output-of-various-select-queries
PG_FUNCTION_INFO_V1(pgis_fromflatgeobuf);
Datum pgis_fromflatgeobuf(PG_FUNCTION_ARGS)
{
        FuncCallContext *funcctx;
 
        TupleDesc tupdesc;
        bytea *data;
        MemoryContext oldcontext;
 
        struct flatgeobuf_decode_ctx *ctx;
 
        if (SRF_IS_FIRSTCALL()) {
                funcctx = SRF_FIRSTCALL_INIT();
                oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 
                funcctx->max_calls = 0;
 
                if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
                        ereport(ERROR,
                                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                         errmsg("function returning record called in context "
                                                        "that cannot accept type record")));
 
                data = PG_GETARG_BYTEA_PP(1);
 
                ctx = palloc0(sizeof(*ctx));
                ctx->tupdesc = tupdesc;
                ctx->ctx = palloc0(sizeof(flatgeobuf_ctx));
                ctx->ctx->size = VARSIZE_ANY_EXHDR(data);
                POSTGIS_DEBUGF(3, "VARSIZE_ANY_EXHDR %ld", ctx->ctx->size);
                ctx->ctx->buf = palloc(ctx->ctx->size);
                memcpy(ctx->ctx->buf, VARDATA_ANY(data), ctx->ctx->size);
                ctx->ctx->offset = 0;
                ctx->done = false;
                ctx->fid = 0;
 
                funcctx->user_fctx = ctx;
 
                if (ctx->ctx->size == 0) {
                        POSTGIS_DEBUG(2, "no data");
                        MemoryContextSwitchTo(oldcontext);
                        SRF_RETURN_DONE(funcctx);
                }
 
                flatgeobuf_check_magicbytes(ctx);
                flatgeobuf_decode_header(ctx->ctx);
 
                POSTGIS_DEBUGF(2, "header decoded now at offset %ld", ctx->ctx->offset);
 
                if (ctx->ctx->size == ctx->ctx->offset) {
                        POSTGIS_DEBUGF(2, "no feature data offset %ld", ctx->ctx->offset);
                        MemoryContextSwitchTo(oldcontext);
                        SRF_RETURN_DONE(funcctx);
                }
 
                // TODO: get table and verify structure against header
                MemoryContextSwitchTo(oldcontext);
        }
 
        funcctx = SRF_PERCALL_SETUP();
        ctx = funcctx->user_fctx;
 
        if (!ctx->done) {
                flatgeobuf_decode_row(ctx);
                POSTGIS_DEBUG(2, "Calling SRF_RETURN_NEXT");
                SRF_RETURN_NEXT(funcctx, ctx->result);
        } else {
                POSTGIS_DEBUG(2, "Calling SRF_RETURN_DONE");
                SRF_RETURN_DONE(funcctx);
        }
}