head.c

Go to the documentation of this file.

/*****************************************************************************
 *
 * MODULE:       Vector library
 *
 * AUTHOR(S):    Original author CERL, probably Dave Gerdes.
 *               Update to GRASS 5.7 Radim Blazek.
 *
 * PURPOSE:      Lower level functions for reading/writing/manipulating vectors.
 *
 * SPDX-FileCopyrightText: 2001 GRASS Development Team
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 *****************************************************************************/
 
#include <inttypes.h>
#include <sys/types.h>
#include <string.h>
#include <grass/vector.h>
 
int dig__write_head(struct Map_info *Map)
{
    unsigned char buf[10];
    long length = GV_COOR_HEAD_SIZE;
 
    G_debug(1, "dig__write_head()");
 
    dig_set_cur_port(&(Map->head.port));
    dig_fseek(&(Map->dig_fp), 0L, 0);
 
    /* bytes 1 - 5 */
    buf[0] = Map->head.coor_version.major;
    buf[1] = Map->head.coor_version.minor;
    buf[2] = Map->head.coor_version.back_major;
    buf[3] = Map->head.coor_version.back_minor;
 
    buf[4] = Map->head.port.byte_order;
    if (0 >= dig__fwrite_port_C((char *)buf, 5, &(Map->dig_fp)))
        return (0);
 
    /* increase header size for new vectors, already set in V1_open_new_nat() */
    length = Map->head.head_size;
 
    /* bytes 6 - 9 : header size */
    if (0 >= dig__fwrite_port_L(&length, 1, &(Map->dig_fp)))
        return (0);
 
    /* byte 10 : dimension 2D or 3D */
    buf[0] = Map->head.with_z;
    if (0 >= dig__fwrite_port_C((char *)buf, 1, &(Map->dig_fp)))
        return (0);
 
    /* bytes 11 - 18 : size of coordinate file */
    G_debug(1, "write coor size (%" PRId64 ") to head", Map->head.size);
    if (Map->head.head_size >= GV_COOR_HEAD_SIZE + 4) {
        if (Map->head.size > PORT_LONG_MAX) {
            /* can only happen when sizeof(off_t) == 8 */
            if (0 >= dig__fwrite_port_O(&(Map->head.size), 1, &(Map->dig_fp),
                                        sizeof(off_t)))
                return (0);
        }
        else {
            /* write twice to fill the space and set offset (account for
             * sizeof(off_t) == 4) */
            if (0 >=
                dig__fwrite_port_O(&(Map->head.size), 1, &(Map->dig_fp), 4))
                return (0);
            if (0 >=
                dig__fwrite_port_O(&(Map->head.size), 1, &(Map->dig_fp), 4))
                return (0);
        }
    }
    else {
        /* old vector with shorter coor head size got modified */
        /* bytes 11 - 14 : size of coordinate file */
        if (0 >= dig__fwrite_port_O(&(Map->head.size), 1, &(Map->dig_fp), 4))
            return (0);
    }
 
    G_debug(2, "coor body offset %" PRId64, dig_ftell(&(Map->dig_fp)));
 
    return 1;
}
 
int dig__read_head(struct Map_info *Map)
{
    unsigned char buf[10];
    struct Port_info port;
 
    G_debug(2, "dig__read_head(): name = '%s'", Map->name);
    dig_fseek(&(Map->dig_fp), 0L, 0);
 
    /* bytes 1 - 5 */
    if (0 >= dig__fread_port_C((char *)buf, 5, &(Map->dig_fp)))
        return (0);
    Map->head.coor_version.major = buf[0];
    Map->head.coor_version.minor = buf[1];
    Map->head.coor_version.back_major = buf[2];
    Map->head.coor_version.back_minor = buf[3];
    Map->head.port.byte_order = buf[4];
 
    G_debug(
        2,
        "Coor header: file version %d.%d , supported from GRASS version %d.%d",
        Map->head.coor_version.major, Map->head.coor_version.minor,
        Map->head.coor_version.back_major, Map->head.coor_version.back_minor);
 
    G_debug(2, "  byte order %d", Map->head.port.byte_order);
 
    /* check version numbers */
    if (Map->head.coor_version.major > GV_COOR_VER_MAJOR ||
        Map->head.coor_version.minor > GV_COOR_VER_MINOR) {
        /* The file was created by GRASS library with higher version than this
         * one */
 
        if (Map->head.coor_version.back_major > GV_COOR_VER_MAJOR ||
            Map->head.coor_version.back_minor > GV_COOR_VER_MINOR) {
            /* This version of GRASS lib is lower than the oldest which can read
             * this format */
            G_fatal_error("Vector 'coor' format version %d.%d is not supported "
                          "by this version of GRASS. "
                          "Update your GRASS.",
                          Map->head.coor_version.major,
                          Map->head.coor_version.minor);
            return (-1);
        }
 
        G_warning(
            "Your GRASS version does not fully support vector format %d.%d."
            " Consider to upgrade GRASS.",
            Map->head.coor_version.major, Map->head.coor_version.minor);
    }
 
    dig_init_portable(&port, Map->head.port.byte_order);
    dig_set_cur_port(&port);
 
    /* bytes 6 - 9 : header size */
    if (0 >= dig__fread_port_L(&(Map->head.head_size), 1, &(Map->dig_fp)))
        return (0);
    G_debug(2, "  header size %ld", Map->head.head_size);
 
    /* byte 10 : dimension 2D or 3D */
    if (0 >= dig__fread_port_C((char *)buf, 1, &(Map->dig_fp)))
        return (0);
    Map->head.with_z = buf[0];
    G_debug(2, "  with_z %d", Map->head.with_z);
 
    /* Map->head.size holds stats value */
    if (Map->head.size > PORT_LONG_MAX &&
        Map->head.head_size >= GV_COOR_HEAD_SIZE + 4) {
        /* bytes 11 - 18 : size of coordinate file */
        if (0 >= dig__fread_port_O(&(Map->head.size), 1, &(Map->dig_fp),
                                   sizeof(off_t)))
            return (0);
    }
    else {
        /* bytes 11 - 14 : size of coordinate file */
        if (0 >= dig__fread_port_O(&(Map->head.size), 1, &(Map->dig_fp), 4))
            return (0);
    }
    G_debug(2, "  coor size %" PRId64, Map->head.size);
 
    /* Go to end of header, file may be written by new version of GRASS with
     * longer header */
 
    dig_fseek(&(Map->dig_fp), Map->head.head_size, SEEK_SET);
 
    return (1);
}