plus_struct.c

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/*****************************************************************************
 *
 * MODULE:       Vector library
 *
 * AUTHOR(S):    Dave Gerdes, CERL.
 *               Update to GRASS 5.7 Radim Blazek.
 *
 * PURPOSE:      Lower level functions for reading/writing/manipulating vectors.
 *
 * COPYRIGHT:    (C) 2001 by the GRASS Development Team
 *
 *               This program is free software under the GNU General Public
 *               License (>=v2). Read the file COPYING that comes with GRASS
 *               for details.
 *
 *****************************************************************************/
 
#include <inttypes.h>
#include <sys/types.h>
#include <string.h>
#include <grass/vector.h>
#include <grass/glocale.h>
#include <grass/version.h>
 
/*
 * Routines for reading and writing Dig+ structures.
 * return 0 on success, -1 on failure of whatever kind
 * if you don't want it written out, then don't call these routines
 * ie  check for deleted status before calling a write routine
 * in as much as it would be nice to hide that code in here,
 * this is a library routine and we chose to make it dependent on
 * as few external files as possible
 */
 
/*  These routines assume ptr->alloc_lines  is valid
 *   Make sure it is initialized before calling
 */
 
/*
 *  Internally, my default variables for lines/areas/nodes/isles  are type
 *  plus_t  which is typedefed as short.  This limits the current version
 *  to no more than 32K lines, nodes etc. (excluding points)
 *  All in the name of future expansion, I have converted these values to
 *  longs in the dig_plus data file.
 *
 *  NOTE: 3.10 changes plus_t to  ints.
 *    This assumes that any reasonable machine will use 4 bytes to
 *    store an int.  The mapdev code is not guaranteed to work if
 *    plus_t is changed to a type that is larger than an int.
 */
int dig_Rd_P_node(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int cnt, n_edges;
    struct P_node *ptr;
 
    G_debug(4, "dig_Rd_P_node()");
 
    if (0 >= dig__fread_port_P(&cnt, 1, fp))
        return (-1);
 
    if (cnt == 0) { /* dead */
        G_debug(4, "    node is dead");
        Plus->Node[n] = NULL;
        return 0;
    }
 
    ptr = dig_alloc_node();
    ptr->n_lines = cnt;
 
    if (dig_node_alloc_line(ptr, ptr->n_lines) == -1) {
        dig_free_node(ptr);
        return -1;
    }
 
    if (ptr->n_lines) {
        if (0 >= dig__fread_port_P(ptr->lines, ptr->n_lines, fp)) {
            dig_free_node(ptr);
            return (-1);
        }
        if (0 >= dig__fread_port_F(ptr->angles, ptr->n_lines, fp)) {
            dig_free_node(ptr);
            return (-1);
        }
    }
 
    if (Plus->with_z) {
        if (0 >= dig__fread_port_P(&n_edges, 1, fp)) { /* reserved for edges */
            dig_free_node(ptr);
            return (-1);
        }
    }
    /* here will be edges */
 
    if (0 >= dig__fread_port_D(&(ptr->x), 1, fp)) {
        dig_free_node(ptr);
        return (-1);
    }
    if (0 >= dig__fread_port_D(&(ptr->y), 1, fp)) {
        dig_free_node(ptr);
        return (-1);
    }
 
    if (Plus->with_z) {
        if (0 >= dig__fread_port_D(&(ptr->z), 1, fp)) {
            dig_free_node(ptr);
            return (-1);
        }
    }
    else
        ptr->z = 0;
 
    Plus->Node[n] = ptr;
 
    return (0);
}
 
int dig_Wr_P_node(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int i, n_edges = 0;
    struct P_node *ptr;
 
    G_debug(4, "dig_Wr_P_node()");
    ptr = Plus->Node[n];
 
    /* If NULL i.e. dead write just 0 instead of number of lines */
    if (ptr == NULL) {
        G_debug(4, "    node is dead -> write 0 only");
        i = 0;
        if (0 >= dig__fwrite_port_P(&i, 1, fp))
            return (-1);
        return 0;
    }
 
    if (0 >= dig__fwrite_port_P(&(ptr->n_lines), 1, fp))
        return (-1);
 
    if (ptr->n_lines) {
        if (0 >= dig__fwrite_port_P(ptr->lines, ptr->n_lines, fp))
            return (-1);
        if (0 >= dig__fwrite_port_F(ptr->angles, ptr->n_lines, fp))
            return (-1);
    }
 
    if (Plus->with_z)
        if (0 >= dig__fwrite_port_P(&n_edges, 1, fp)) /* reserved for edges */
            return (-1);
 
    /* here will be edges */
 
    if (0 >= dig__fwrite_port_D(&(ptr->x), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_D(&(ptr->y), 1, fp))
        return (-1);
 
    if (Plus->with_z)
        if (0 >= dig__fwrite_port_D(&(ptr->z), 1, fp))
            return (-1);
 
    return (0);
}
 
int dig_Rd_P_line(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int n_edges;
    char tp;
    struct P_line *ptr;
 
    G_debug(4, "dig_Rd_P_line()");
 
    if (0 >= dig__fread_port_C(&tp, 1, fp))
        return (-1);
 
    if (tp == 0) { /* dead */
        G_debug(4, "    line is dead");
        Plus->Line[n] = NULL;
        return 0;
    }
 
    ptr = dig_alloc_line();
 
    /* type */
    ptr->type = dig_type_from_store(tp);
    G_debug(5, "    line type  %d -> %d", tp, ptr->type);
 
    /* offset */
    if (0 >= dig__fread_port_O(&(ptr->offset), 1, fp, Plus->off_t_size))
        goto free_exit_failure;
 
    if (ptr->type == GV_POINT) {
        ptr->topo = NULL;
    }
    else {
        ptr->topo = dig_alloc_topo(ptr->type);
    }
 
    /* centroids */
    if (ptr->type & GV_CENTROID) {
        struct P_topo_c *topo = (struct P_topo_c *)ptr->topo;
 
        if (0 >= dig__fread_port_P(&(topo->area), 1, fp))
            goto free_exit_failure;
    }
    /* lines */
    else if (ptr->type & GV_LINE) {
        struct P_topo_l *topo = (struct P_topo_l *)ptr->topo;
 
        if (0 >= dig__fread_port_P(&(topo->N1), 1, fp))
            goto free_exit_failure;
        if (0 >= dig__fread_port_P(&(topo->N2), 1, fp))
            goto free_exit_failure;
    }
    /* boundaries */
    else if (ptr->type & GV_BOUNDARY) {
        struct P_topo_b *topo = (struct P_topo_b *)ptr->topo;
 
        if (0 >= dig__fread_port_P(&(topo->N1), 1, fp))
            goto free_exit_failure;
        if (0 >= dig__fread_port_P(&(topo->N2), 1, fp))
            goto free_exit_failure;
        if (0 >= dig__fread_port_P(&(topo->left), 1, fp))
            goto free_exit_failure;
        if (0 >= dig__fread_port_P(&(topo->right), 1, fp))
            goto free_exit_failure;
    }
    /* faces */
    else if ((ptr->type & GV_FACE) &&
             Plus->with_z) { /* reserved for face edges */
        struct P_topo_f *topo = (struct P_topo_f *)ptr->topo;
 
        if (0 >= dig__fread_port_I(&n_edges, 1, fp))
            goto free_exit_failure;
 
        /* here will be list of edges */
 
        /* left / right volume */
        if (0 >= dig__fread_port_P(&(topo->left), 1, fp))
            goto free_exit_failure;
        if (0 >= dig__fread_port_P(&(topo->left), 1, fp))
            goto free_exit_failure;
    }
    /* kernels */
    else if ((ptr->type & GV_KERNEL) &&
             Plus->with_z) { /* reserved for kernel (volume number) */
        struct P_topo_k *topo = (struct P_topo_k *)ptr->topo;
 
        if (0 >= dig__fread_port_P(&(topo->volume), 1, fp))
            goto free_exit_failure;
    }
 
    Plus->Line[n] = ptr;
 
    return (0);
 
free_exit_failure:
    dig_free_line(ptr);
    return -1;
}
 
int dig_Wr_P_line(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int n_edges = 0;
    char ch;
    struct P_line *ptr;
 
    G_debug(4, "dig_Wr_P_line() line = %d", n);
 
    ptr = Plus->Line[n];
 
    /* if NULL i.e. dead write just 0 instead of type */
    if (ptr == NULL) {
        G_debug(4, "    line is dead -> write 0 only");
        ch = 0;
        if (0 >= dig__fwrite_port_C(&ch, 1, fp))
            return (-1);
        return 0;
    }
 
    /* type */
    ch = (char)dig_type_to_store(ptr->type);
    G_debug(5, "    line type  %d -> %d", ptr->type, ch);
    if (0 >= dig__fwrite_port_C(&ch, 1, fp))
        return (-1);
 
    /* offset */
    if (0 >= dig__fwrite_port_O(&(ptr->offset), 1, fp, Plus->off_t_size))
        return (-1);
 
    if (!ptr->topo)
        return (0);
 
    /* nothing else for points */
 
    /* centroids */
    if (ptr->type & GV_CENTROID) {
        struct P_topo_c *topo = (struct P_topo_c *)ptr->topo;
 
        if (0 >= dig__fwrite_port_P(&(topo->area), 1, fp))
            return (-1);
    }
    /* lines */
    else if (ptr->type & GV_LINE) {
        struct P_topo_l *topo = (struct P_topo_l *)ptr->topo;
 
        if (0 >= dig__fwrite_port_P(&(topo->N1), 1, fp))
            return (-1);
        if (0 >= dig__fwrite_port_P(&(topo->N2), 1, fp))
            return (-1);
    }
    /* boundaries */
    else if (ptr->type & GV_BOUNDARY) {
        struct P_topo_b *topo = (struct P_topo_b *)ptr->topo;
 
        if (0 >= dig__fwrite_port_P(&(topo->N1), 1, fp))
            return (-1);
        if (0 >= dig__fwrite_port_P(&(topo->N2), 1, fp))
            return (-1);
        if (0 >= dig__fwrite_port_P(&(topo->left), 1, fp))
            return (-1);
        if (0 >= dig__fwrite_port_P(&(topo->right), 1, fp))
            return (-1);
    }
    /* faces */
    else if ((ptr->type & GV_FACE) && Plus->with_z) { /* reserved for face */
        struct P_topo_f *topo = (struct P_topo_f *)ptr->topo;
 
        if (0 >= dig__fwrite_port_I(&n_edges, 1, fp))
            return (-1);
 
        /* here will be list of edges */
 
        /* left / right volume / hole */
        if (0 >= dig__fwrite_port_P(&(topo->left), 1, fp))
            return (-1);
        if (0 >= dig__fwrite_port_P(&(topo->right), 1, fp))
            return (-1);
    }
    /* kernels */
    else if ((ptr->type & GV_KERNEL) &&
             Plus->with_z) { /* reserved for kernel (volume number) */
        struct P_topo_k *topo = (struct P_topo_k *)ptr->topo;
 
        /* volume */
        if (0 >= dig__fwrite_port_P(&(topo->volume), 1, fp))
            return (-1);
    }
 
    return (0);
}
 
int dig_Rd_P_area(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int cnt;
    struct P_area *ptr;
 
    G_debug(4, "dig_Rd_P_area(): n = %d", n);
 
    if (0 >= dig__fread_port_P(&cnt, 1, fp))
        return (-1);
 
    if (cnt == 0) { /* dead */
        Plus->Area[n] = NULL;
        return 0;
    }
 
    ptr = dig_alloc_area();
 
    /* boundaries */
    ptr->n_lines = cnt;
 
    if (dig_area_alloc_line(ptr, ptr->n_lines) == -1) {
        dig_free_area(ptr);
        return -1;
    }
 
    if (ptr->n_lines) {
        if (0 >= dig__fread_port_P(ptr->lines, ptr->n_lines, fp)) {
            dig_free_area(ptr);
            return -1;
        }
    }
 
    /* isles */
    if (0 >= dig__fread_port_P(&(ptr->n_isles), 1, fp)) {
        dig_free_area(ptr);
        return -1;
    }
 
    if (dig_area_alloc_isle(ptr, ptr->n_isles) == -1) {
        dig_free_area(ptr);
        return -1;
    }
 
    if (ptr->n_isles) {
        if (0 >= dig__fread_port_P(ptr->isles, ptr->n_isles, fp)) {
            dig_free_area(ptr);
            return -1;
        }
    }
    /* centroid */
    if (0 >= dig__fread_port_P(&(ptr->centroid), 1, fp)) {
        dig_free_area(ptr);
        return -1;
    }
 
    Plus->Area[n] = ptr;
 
    return (0);
}
 
int dig_Wr_P_area(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int i;
    struct P_area *ptr;
 
    ptr = Plus->Area[n];
 
    /* If NULL i.e. dead write just 0 instead of number of lines */
    if (ptr == NULL) {
        i = 0;
        if (0 >= dig__fwrite_port_P(&i, 1, fp))
            return (-1);
        return 0;
    }
 
    /* boundaries */
    if (0 >= dig__fwrite_port_P(&(ptr->n_lines), 1, fp))
        return (-1);
 
    if (ptr->n_lines)
        if (0 >= dig__fwrite_port_P(ptr->lines, ptr->n_lines, fp))
            return -1;
 
    /* isles */
    if (0 >= dig__fwrite_port_P(&(ptr->n_isles), 1, fp))
        return (-1);
 
    if (ptr->n_isles)
        if (0 >= dig__fwrite_port_P(ptr->isles, ptr->n_isles, fp))
            return -1;
 
    /* centroid */
    if (0 >= dig__fwrite_port_P(&(ptr->centroid), 1, fp))
        return (-1);
 
    return (0);
}
 
int dig_Rd_P_isle(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int cnt;
    struct P_isle *ptr;
 
    G_debug(4, "dig_Rd_P_isle()");
 
    if (0 >= dig__fread_port_P(&cnt, 1, fp))
        return (-1);
 
    if (cnt == 0) { /* dead */
        Plus->Isle[n] = NULL;
        return 0;
    }
 
    ptr = dig_alloc_isle();
 
    /* boundaries */
    ptr->n_lines = cnt;
 
    if (dig_isle_alloc_line(ptr, ptr->n_lines) == -1) {
        dig_free_isle(ptr);
        return -1;
    }
 
    if (ptr->n_lines) {
        if (0 >= dig__fread_port_P(ptr->lines, ptr->n_lines, fp)) {
            dig_free_isle(ptr);
            return -1;
        }
    }
 
    /* area */
    if (0 >= dig__fread_port_P(&(ptr->area), 1, fp)) {
        dig_free_isle(ptr);
        return -1;
    }
 
    Plus->Isle[n] = ptr;
 
    return (0);
}
 
int dig_Wr_P_isle(struct Plus_head *Plus, int n, struct gvfile *fp)
{
    int i;
    struct P_isle *ptr;
 
    ptr = Plus->Isle[n];
 
    /* If NULL i.e. dead write just 0 instead of number of lines */
    if (ptr == NULL) {
        i = 0;
        if (0 >= dig__fwrite_port_P(&i, 1, fp))
            return (-1);
        return 0;
    }
 
    /* lines */
    if (0 >= dig__fwrite_port_P(&(ptr->n_lines), 1, fp))
        return (-1);
 
    if (ptr->n_lines)
        if (0 >= dig__fwrite_port_P(ptr->lines, ptr->n_lines, fp))
            return -1;
 
    /* area */
    if (0 >= dig__fwrite_port_P(&(ptr->area), 1, fp))
        return (-1);
 
    return (0);
}
 
/*!
   \brief Read Plus_head from file
 
   \param fp pointer to gvfile structure
   \param[in,out] ptr pointer to Plus_head structure
 
   \return -1 error
   \return  0 OK
 */
int dig_Rd_Plus_head(struct gvfile *fp, struct Plus_head *ptr)
{
    unsigned char buf[5];
    int byte_order;
 
    dig_rewind(fp);
 
    /* bytes 1 - 5 */
    if (0 >= dig__fread_port_C((char *)buf, 5, fp))
        return (-1);
    ptr->version.topo.major = buf[0];
    ptr->version.topo.minor = buf[1];
    ptr->version.topo.back_major = buf[2];
    ptr->version.topo.back_minor = buf[3];
    byte_order = buf[4];
 
    G_debug(
        2,
        "Topo header: file version %d.%d , supported from GRASS version %d.%d",
        ptr->version.topo.major, ptr->version.topo.minor,
        ptr->version.topo.back_major, ptr->version.topo.back_minor);
 
    G_debug(2, "  byte order %d", byte_order);
 
    /* check version numbers */
    if (ptr->version.topo.major > GV_TOPO_VER_MAJOR ||
        ptr->version.topo.minor > GV_TOPO_VER_MINOR) {
        /* The file was created by GRASS library with higher version than this
         * one */
 
        if (ptr->version.topo.back_major > GV_TOPO_VER_MAJOR ||
            ptr->version.topo.back_minor > GV_TOPO_VER_MINOR) {
            /* This version of GRASS lib is lower than the oldest which can read
             * this format */
            G_debug(1, "Topology format version %d.%d", ptr->version.topo.major,
                    ptr->version.topo.minor);
            G_fatal_error(_("This version of GRASS (%d.%d) is too old to read "
                            "this topology format."
                            " Try to rebuild topology or upgrade GRASS to at "
                            "least version %d."),
                          GRASS_VERSION_MAJOR, GRASS_VERSION_MINOR,
                          GRASS_VERSION_MAJOR + 1);
            return (-1);
        }
 
        G_warning(_("Your GRASS version does not fully support topology format "
                    "%d.%d of the vector."
                    " Consider to rebuild topology or upgrade GRASS."),
                  ptr->version.topo.major, ptr->version.topo.minor);
    }
    if (ptr->version.topo.major < GV_TOPO_VER_MAJOR ||
        (ptr->version.topo.major == GV_TOPO_VER_MAJOR &&
         ptr->version.topo.minor < GV_TOPO_VER_MINOR)) {
        /* The file was created by GRASS library with lower version than this
         * one */
 
        /* This version of GRASS lib can not read this old format */
        G_warning(
            _("Old topology format version %d.%d is not supported by this "
              "release."
              " Try to rebuild topology using v.build or v.build.all module."),
            ptr->version.topo.major, ptr->version.topo.minor);
        return (-1);
    }
 
    /* init Port_info structure and set as default */
    dig_init_portable(&(ptr->port), byte_order);
    dig_set_cur_port(&(ptr->port));
 
    /* bytes 6 - 9 : header size */
    if (0 >= dig__fread_port_L(&(ptr->head_size), 1, fp))
        return (-1);
    G_debug(2, "  header size %ld", ptr->head_size);
 
    /* determine required offset size from header size */
    /* this is not safe in case new fields get added in later versions */
    /* better: add a new field with off_t_size after byte_order? */
    if (ptr->head_size >= 142 + 32) /* keep in sync with dig_Wr_Plus_head() */
        ptr->off_t_size = 8;
    else
        ptr->off_t_size = 4;
 
    if (sizeof(off_t) < (size_t)ptr->off_t_size) {
        G_warning(_("Vector exceeds supported file size limit"));
        return (-1);
    }
 
    G_debug(2, "topo off_t size = %d", ptr->off_t_size);
 
    /* byte 10 : dimension 2D or 3D */
    if (0 >= dig__fread_port_C((char *)buf, 1, fp))
        return (-1);
    ptr->with_z = buf[0];
    G_debug(2, "  with_z %d", ptr->with_z);
 
    /* bytes 11 - 58 : bound box */
    if (0 >= dig__fread_port_D(&(ptr->box.N), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_D(&(ptr->box.S), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_D(&(ptr->box.E), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_D(&(ptr->box.W), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_D(&(ptr->box.T), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_D(&(ptr->box.B), 1, fp))
        return (-1);
 
    /* bytes 59 - 86 : number of structures */
    if (0 >= dig__fread_port_P(&(ptr->n_nodes), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_edges), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_lines), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_areas), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_isles), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_volumes), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_holes), 1, fp))
        return (-1);
 
    /* bytes 87 - 110 : number of line types */
    if (0 >= dig__fread_port_P(&(ptr->n_plines), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_llines), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_blines), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_clines), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_flines), 1, fp))
        return (-1);
    if (0 >= dig__fread_port_P(&(ptr->n_klines), 1, fp))
        return (-1);
 
    /* bytes 111 - 138 : Offset */
    if (0 >= dig__fread_port_O(&(ptr->Node_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fread_port_O(&(ptr->Edge_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fread_port_O(&(ptr->Line_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fread_port_O(&(ptr->Area_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fread_port_O(&(ptr->Isle_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fread_port_O(&(ptr->Volume_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fread_port_O(&(ptr->Hole_offset), 1, fp, ptr->off_t_size))
        return (-1);
 
    /* bytes 139 - 142 : Coor size and time */
    if (0 >= dig__fread_port_O(&(ptr->coor_size), 1, fp, ptr->off_t_size))
        return (-1);
 
    G_debug(2, "  coor size %" PRId64, ptr->coor_size);
 
    dig_fseek(fp, ptr->head_size, SEEK_SET);
 
    return (0);
}
 
/*!
   \brief Write Plus_head to file
 
   ptr->off_t_size is used for both coor and topo files, but their sizes
   (ptr->coor_size for coor and no variable for topo) can be different. If
   either file is greater than PORT_LONG_MAX, ptr->off_t_size must be 8. This
   function determines this value of ptr->off_t_size and writes it to the file.
 
   \param fp pointer to gvfile structure
   \param[in,out] ptr pointer to Plus_head structure
 
   \return -1 error
   \return  0 OK
 */
int dig_Wr_Plus_head(struct gvfile *fp, struct Plus_head *ptr)
{
    unsigned char buf[10];
    long length = 142;
 
    dig_rewind(fp);
    dig_set_cur_port(&(ptr->port));
 
    /* bytes 1 - 5 */
    buf[0] = GV_TOPO_VER_MAJOR;
    buf[1] = GV_TOPO_VER_MINOR;
    buf[2] = GV_TOPO_EARLIEST_MAJOR;
    buf[3] = GV_TOPO_EARLIEST_MINOR;
    buf[4] = ptr->port.byte_order;
    if (0 >= dig__fwrite_port_C((char *)buf, 5, fp))
        return (-1);
 
    /* determine required offset size from coor file size */
    if (ptr->coor_size > (off_t)PORT_LONG_MAX) {
        /* can only happen when sizeof(off_t) == 8 */
        ptr->off_t_size = 8;
    }
    else if (ptr->off_t_size == 0) {
        /* calculate the total size of topo file to get the correct off_t_size
         * if coor file is less than PORT_LONG_MAX */
        off_t size = length;
        int i;
 
        for (i = 1; i <= ptr->n_nodes; i++) {
            /* from dig_Wr_P_node() */
            struct P_node *p = ptr->Node[i];
 
            if (p == NULL)
                size += 4;
            else {
                size += 20 + 8 * p->n_lines;
                if (ptr->with_z)
                    size += 12;
            }
        }
 
        for (i = 1; i <= ptr->n_lines; i++) {
            /* from dig_Wr_P_line() */
            struct P_line *p = ptr->Line[i];
 
            if (p == NULL)
                size += 1;
            else {
                /* for now, off_t_size = 4 */
                size += 5;
                if (p->type & GV_CENTROID)
                    size += 4;
                else if (p->type & GV_LINE)
                    size += 8;
                else if (p->type & GV_BOUNDARY)
                    size += 16;
                else if ((p->type & GV_FACE) && ptr->with_z)
                    size += 12;
                else if ((p->type & GV_KERNEL) && ptr->with_z)
                    size += 4;
            }
        }
 
        for (i = 1; i <= ptr->n_areas; i++) {
            /* from dig_Wr_P_area() */
            struct P_area *p = ptr->Area[i];
 
            if (p == NULL)
                size += 4;
            else
                size += 12 + 4 * p->n_lines + 4 * p->n_isles;
        }
 
        for (i = 1; i <= ptr->n_isles; i++) {
            /* from dig_Wr_P_isle() */
            struct P_isle *p = ptr->Isle[i];
 
            if (p == NULL)
                size += 4;
            else
                size += 8 + 4 * p->n_lines;
        }
 
        ptr->off_t_size = size > (off_t)PORT_LONG_MAX ? 8 : 4;
    }
 
    /* add a new field with off_t_size after byte_order? */
 
    /* adjust header size for large files */
    if (ptr->off_t_size == 8) {
        /* 7 offset values and coor file size: add 8 * 4 */
        length += 32;
    }
 
    /* bytes 6 - 9 : header size */
    if (0 >= dig__fwrite_port_L(&length, 1, fp))
        return (0);
 
    /* byte 10 : dimension 2D or 3D */
    buf[0] = ptr->with_z;
    if (0 >= dig__fwrite_port_C((char *)buf, 1, fp))
        return (0);
 
    /* bytes 11 - 58 : bound box */
    if (0 >= dig__fwrite_port_D(&(ptr->box.N), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_D(&(ptr->box.S), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_D(&(ptr->box.E), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_D(&(ptr->box.W), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_D(&(ptr->box.T), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_D(&(ptr->box.B), 1, fp))
        return (-1);
 
    /* bytes 59 - 86 : number of structures */
    if (0 >= dig__fwrite_port_P(&(ptr->n_nodes), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_edges), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_lines), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_areas), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_isles), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_volumes), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_holes), 1, fp))
        return (-1);
 
    /* bytes 87 - 110 : number of line types */
    if (0 >= dig__fwrite_port_P(&(ptr->n_plines), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_llines), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_blines), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_clines), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_flines), 1, fp))
        return (-1);
    if (0 >= dig__fwrite_port_P(&(ptr->n_klines), 1, fp))
        return (-1);
 
    /* bytes 111 - 138 : Offset */
    if (0 >= dig__fwrite_port_O(&(ptr->Node_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fwrite_port_O(&(ptr->Edge_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fwrite_port_O(&(ptr->Line_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fwrite_port_O(&(ptr->Area_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fwrite_port_O(&(ptr->Isle_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fwrite_port_O(&(ptr->Volume_offset), 1, fp, ptr->off_t_size))
        return (-1);
    if (0 >= dig__fwrite_port_O(&(ptr->Hole_offset), 1, fp, ptr->off_t_size))
        return (-1);
 
    /* bytes 139 - 142 : Coor size and time */
    if (0 >= dig__fwrite_port_O(&(ptr->coor_size), 1, fp, ptr->off_t_size))
        return (-1);
 
    G_debug(2, "topo body offset %" PRId64, dig_ftell(fp));
 
    return (0);
}