source: git/src/img.c @ 7cb7f91

/* img.c
 * Routines for reading and writing Survex ".3d" image files
 * Copyright (C) 1993-2004,2005,2006,2010,2011 Olly Betts
 *
 * This program 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.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <ctype.h>
#include <locale.h>

#include "img.h"

#ifndef IMG_API_VERSION
# define IMG_API_VERSION 0
#elif IMG_API_VERSION > 1
# error IMG_API_VERSION > 1 too new
#endif

#ifdef IMG_HOSTED
# include "debug.h"
# include "filelist.h"
# include "filename.h"
# include "message.h"
# include "useful.h"
# define TIMENA msg(/*Date and time not available.*/108)
# define TIMEFMT msg(/*%a,%Y.%m.%d %H:%M:%S %Z*/107)
# define INT32_T int32_t
#else
# define INT32_T int
# define TIMENA "Time not available."
# define TIMEFMT "%a,%Y.%m.%d %H:%M:%S %Z"
# define EXT_SVX_3D "3d"
# define EXT_SVX_POS "pos"
# define FNM_SEP_EXT '.'
# define METRES_PER_FOOT 0.3048 /* exact value */
# define xosmalloc(L) malloc((L))
# define xosrealloc(L,S) realloc((L),(S))
# define osfree(P) free((P))
# define ossizeof(T) sizeof(T)
/* in IMG_HOSTED mode, this tests if a filename refers to a directory */
# define fDirectory(X) 0
/* open file FNM with mode MODE, maybe using path PTH and/or extension EXT */
/* path isn't used in img.c, but EXT is */
# define fopenWithPthAndExt(PTH,FNM,EXT,MODE,X) fopen(FNM,MODE)
# define PUTC(C, FH) putc(C, FH)
# define GETC(FH) getc(FH)
# define fFalse 0
# define fTrue 1
# define bool int
/* dummy do {...} while(0) hack to permit stuff like
 * if (s) fputsnl(s,fh); else exit(1);
 * to work as intended
 */
# define fputsnl(S, FH) do {fputs((S), (FH)); PUTC('\n', (FH));} while(0)
# define SVX_ASSERT(X)

static INT32_T
get32(FILE *fh)
{
   INT32_T w = GETC(fh);
   w |= (INT32_T)GETC(fh) << 8l;
   w |= (INT32_T)GETC(fh) << 16l;
   w |= (INT32_T)GETC(fh) << 24l;
   return w;
}

static void
put32(long w, FILE *fh)
{
   PUTC((char)(w), fh);
   PUTC((char)(w >> 8l), fh);
   PUTC((char)(w >> 16l), fh);
   PUTC((char)(w >> 24l), fh);
}

static short
get16(FILE *fh)
{
   short w = GETC(fh);
   w |= (short)GETC(fh) << 8l;
   return w;
}

static void
put16(short w, FILE *fh)
{
   PUTC((char)(w), fh);
   PUTC((char)(w >> 8l), fh);
}

static char *
baseleaf_from_fnm(const char *fnm)
{
   const char *p;
   char *q;
   size_t len;

   p = fnm;
   q = strrchr(p, '/');
   if (q) p = q + 1;
   q = strrchr(p, '\\');
   if (q) p = q + 1;

   q = strrchr(p, FNM_SEP_EXT);
   if (q) len = (const char *)q - p; else len = strlen(p);

   q = xosmalloc(len + 1);
   if (!q) return NULL;
   memcpy(q, p, len);
   q[len] = '\0';
   return q;
}
#endif

static unsigned short
getu16(FILE *fh)
{
   return (unsigned short)get16(fh);
}

#include <math.h>
#ifdef HAVE_ROUND
extern double round(double); /* prototype is often missing... */
# define my_round round
#else
static double
my_round(double x) {
   if (x >= 0.0) return floor(x + 0.5);
   return ceil(x - 0.5);
}
#endif

/* portable case insensitive string compare */
#if defined(strcasecmp) || defined(HAVE_STRCASECMP)
# define my_strcasecmp strcasecmp
#else
/* What about top bit set chars? */
int my_strcasecmp(const char *s1, const char *s2) {
   register int c1, c2;
   do {
      c1 = *s1++;
      c2 = *s2++;
   } while (c1 && toupper(c1) == toupper(c2));
   /* now calculate real difference */
   return c1 - c2;
}
#endif

unsigned int img_output_version = IMG_VERSION_MAX;

#ifdef IMG_HOSTED
static enum {
   IMG_NONE = 0,
   IMG_FILENOTFOUND = /*Couldn't open data file `%s'*/24,
   IMG_OUTOFMEMORY  = /*Out of memory %.0s*/38,
   IMG_DIRECTORY    = /*Filename `%s' refers to directory*/44,
   IMG_CANTOPENOUT  = /*Failed to open output file `%s'*/47,
   IMG_BADFORMAT    = /*Bad 3d image file `%s'*/106,
   IMG_READERROR    = /*Error reading from file `%s'*/109,
   IMG_WRITEERROR   = /*Error writing to file `%s'*/110,
   IMG_TOONEW       = /*File `%s' has a newer format than this program can understand*/114
} img_errno = IMG_NONE;
#else
static img_errcode img_errno = IMG_NONE;
#endif

#define FILEID "Survex 3D Image File"

#define EXT_PLT "plt"
#define EXT_PLF "plf"
#define EXT_XYZ "xyz"

/* Attempt to string paste to ensure we are passed a literal string */
#define LITLEN(S) (sizeof(S"") - 1)

/* Fake "version numbers" for non-3d formats we can read. */
#define VERSION_CMAP_SHOT       -4
#define VERSION_CMAP_STATION    -3
#define VERSION_COMPASS_PLT     -2
#define VERSION_SURVEX_POS      -1

static char *
my_strdup(const char *str)
{
   char *p;
   size_t len = strlen(str) + 1;
   p = xosmalloc(len);
   if (p) memcpy(p, str, len);
   return p;
}

static char *
getline_alloc(FILE *fh)
{
   int ch;
   size_t i = 0;
   size_t len = 16;
   char *buf = xosmalloc(len);
   if (!buf) return NULL;

   ch = GETC(fh);
   while (ch != '\n' && ch != '\r' && ch != EOF) {
      buf[i++] = ch;
      if (i == len - 1) {
         char *p;
         len += len;
         p = xosrealloc(buf, len);
         if (!p) {
            osfree(buf);
            return NULL;
         }
         buf = p;
      }
      ch = GETC(fh);
   }
   if (ch == '\n' || ch == '\r') {
      int otherone = ch ^ ('\n' ^ '\r');
      ch = GETC(fh);
      /* if it's not the other eol character, put it back */
      if (ch != otherone) ungetc(ch, fh);
   }
   buf[i++] = '\0';
   return buf;
}

#ifndef IMG_HOSTED
img_errcode
img_error(void)
{
   return img_errno;
}
#else
int
img_error(void)
{
   return (int)img_errno;
}
#endif

static bool
check_label_space(img *pimg, size_t len)
{
   if (len > pimg->buf_len) {
      char *b = xosrealloc(pimg->label_buf, len);
      if (!b) return fFalse;
      pimg->label = (pimg->label - pimg->label_buf) + b;
      pimg->label_buf = b;
      pimg->buf_len = len;
   }
   return fTrue;
}

#define has_ext(F,L,E) ((L) > LITLEN(E) + 1 &&\
                        (F)[(L) - LITLEN(E) - 1] == FNM_SEP_EXT &&\
                        my_strcasecmp((F) + (L) - LITLEN(E), E) == 0)

img *
img_open_survey(const char *fnm, const char *survey)
{
   img *pimg;
   size_t len;
   char buf[LITLEN(FILEID) + 9];
   int ch;

   if (fDirectory(fnm)) {
      img_errno = IMG_DIRECTORY;
      return NULL;
   }

   pimg = (img *)xosmalloc(ossizeof(img));
   if (pimg == NULL) {
      img_errno = IMG_OUTOFMEMORY;
      return NULL;
   }

   pimg->buf_len = 257;
   pimg->label_buf = xosmalloc(pimg->buf_len);
   if (!pimg->label_buf) {
      osfree(pimg);
      img_errno = IMG_OUTOFMEMORY;
      return NULL;
   }

   pimg->fh = fopenWithPthAndExt("", fnm, EXT_SVX_3D, "rb", &(pimg->filename_opened));
   if (pimg->fh == NULL) {
      osfree(pimg->label_buf);
      osfree(pimg);
      img_errno = IMG_FILENOTFOUND;
      return NULL;
   }

   pimg->fRead = fTrue; /* reading from this file */
   img_errno = IMG_NONE;

   pimg->flags = 0;

   /* for version >= 3 we use label_buf to store the prefix for reuse */
   /* for VERSION_COMPASS_PLT, 0 value indicates we haven't
    * entered a survey yet */
   /* for VERSION_CMAP_SHOT, we store the last station here
    * to detect whether we MOVE or LINE */
   pimg->label_len = 0;
   pimg->label_buf[0] = '\0';

   pimg->survey = NULL;
   pimg->survey_len = 0;
   pimg->separator = '.';
#if IMG_API_VERSION == 0
   pimg->date1 = pimg->date2 = 0;
#else /* IMG_API_VERSION == 1 */
   pimg->days1 = pimg->days2 = -1;
#endif
   pimg->is_extended_elevation = 0;

   pimg->l = pimg->r = pimg->u = pimg->d = -1.0;

   pimg->title = pimg->datestamp = NULL;
   if (survey) {
      len = strlen(survey);
      if (len) {
         if (survey[len - 1] == '.') len--;
         if (len) {
            char *p;
            pimg->survey = xosmalloc(len + 2);
            if (!pimg->survey) {
               img_errno = IMG_OUTOFMEMORY;
               goto error;
            }
            memcpy(pimg->survey, survey, len);
            /* Set title to leaf survey name */
            pimg->survey[len] = '\0';
            p = strchr(pimg->survey, '.');
            if (p) p++; else p = pimg->survey;
            pimg->title = my_strdup(p);
            if (!pimg->title) {
               img_errno = IMG_OUTOFMEMORY;
               goto error;
            }
            pimg->survey[len] = '.';
            pimg->survey[len + 1] = '\0';
         }
      }
      pimg->survey_len = len;
   }

   /* [VERSION_COMPASS_PLT, VERSION_CMAP_STATION, VERSION_CMAP_SHOT] pending
    * IMG_LINE or IMG_MOVE - both have 4 added.
    * [VERSION_SURVEX_POS] already skipped heading line, or there wasn't one
    * [version 0] not in the middle of a 'LINE' command
    * [version >= 3] not in the middle of turning a LINE into a MOVE
    */
   pimg->pending = 0;

   len = strlen(fnm);
   if (has_ext(fnm, len, EXT_SVX_POS)) {
pos_file:
      pimg->version = VERSION_SURVEX_POS;
      if (!pimg->survey) pimg->title = baseleaf_from_fnm(fnm);
      pimg->datestamp = my_strdup(TIMENA);
      if (!pimg->datestamp) {
         img_errno = IMG_OUTOFMEMORY;
         goto error;
      }
      pimg->start = 0;
      return pimg;
   }

   if (has_ext(fnm, len, EXT_PLT) || has_ext(fnm, len, EXT_PLF)) {
      long fpos;
plt_file:
      pimg->version = VERSION_COMPASS_PLT;
      /* Spaces aren't legal in Compass station names, but dots are, so
       * use space as the level separator */
      pimg->separator = ' ';
      pimg->start = 0;
      if (!pimg->survey) pimg->title = baseleaf_from_fnm(fnm);
      pimg->datestamp = my_strdup(TIMENA);
      if (!pimg->datestamp) {
         img_errno = IMG_OUTOFMEMORY;
         goto error;
      }
      while (1) {
         ch = GETC(pimg->fh);
         switch (ch) {
          case '\x1a':
            fseek(pimg->fh, -1, SEEK_CUR);
            /* FALL THRU */
          case EOF:
            pimg->start = ftell(pimg->fh);
            return pimg;
          case 'N': {
            char *line, *q;
            fpos = ftell(pimg->fh) - 1;
            if (!pimg->survey) {
               /* FIXME : if there's only one survey in the file, it'd be nice
                * to use its description as the title here...
                */
               ungetc('N', pimg->fh);
               pimg->start = fpos;
               return pimg;
            }
            line = getline_alloc(pimg->fh);
            if (!line) {
               img_errno = IMG_OUTOFMEMORY;
               goto error;
            }
            len = 0;
            while (line[len] > 32) ++len;
            if (pimg->survey_len != len ||
                memcmp(line, pimg->survey, len) != 0) {
               osfree(line);
               continue;
            }
            q = strchr(line + len, 'C');
            if (q && q[1]) {
                osfree(pimg->title);
                pimg->title = my_strdup(q + 1);
            } else if (!pimg->title) {
                pimg->title = my_strdup(pimg->label);
            }
            osfree(line);
            if (!pimg->title) {
                img_errno = IMG_OUTOFMEMORY;
                goto error;
            }
            if (!pimg->start) pimg->start = fpos;
            fseek(pimg->fh, pimg->start, SEEK_SET);
            return pimg;
          }
          case 'M': case 'D':
            pimg->start = ftell(pimg->fh) - 1;
            break;
         }
         while (ch != '\n' && ch != '\r') {
            ch = GETC(pimg->fh);
         }
      }
   }

   if (has_ext(fnm, len, EXT_XYZ)) {
      char *line;
xyz_file:
      /* Spaces aren't legal in CMAP station names, but dots are, so
       * use space as the level separator. */
      pimg->separator = ' ';
      line = getline_alloc(pimg->fh);
      if (!line) {
         img_errno = IMG_OUTOFMEMORY;
         goto error;
      }
      /* FIXME: reparse date? */
      len = strlen(line);
      if (len > 59) line[59] = '\0';
      if (len > 45) {
         pimg->datestamp = my_strdup(line + 45);
      } else {
         pimg->datestamp = my_strdup(TIMENA);
      }
      if (strncmp(line, "  Cave Survey Data Processed by CMAP ",
                  LITLEN("  Cave Survey Data Processed by CMAP ")) == 0) {
         len = 0;
      } else {
         if (len > 45) {
            line[45] = '\0';
            len = 45;
         }
         while (len > 2 && line[len - 1] == ' ') --len;
         if (len > 2) {
            line[len] = '\0';
            pimg->title = my_strdup(line + 2);
         }
      }
      if (len <= 2) pimg->title = baseleaf_from_fnm(fnm);
      osfree(line);
      if (!pimg->datestamp || !pimg->title) {
         img_errno = IMG_OUTOFMEMORY;
         goto error;
      }
      line = getline_alloc(pimg->fh);
      if (!line) {
         img_errno = IMG_OUTOFMEMORY;
         goto error;
      }
      if (line[0] != ' ' || (line[1] != 'S' && line[1] != 'O')) {
         img_errno = IMG_BADFORMAT;
         goto error;
      }
      if (line[1] == 'S') {
         pimg->version = VERSION_CMAP_STATION;
      } else {
         pimg->version = VERSION_CMAP_SHOT;
      }
      osfree(line);
      line = getline_alloc(pimg->fh);
      if (!line) {
         img_errno = IMG_OUTOFMEMORY;
         goto error;
      }
      if (line[0] != ' ' || line[1] != '-') {
         img_errno = IMG_BADFORMAT;
         goto error;
      }
      osfree(line);
      pimg->start = ftell(pimg->fh);
      return pimg;
   }

   if (fread(buf, LITLEN(FILEID) + 1, 1, pimg->fh) != 1 ||
       memcmp(buf, FILEID"\n", LITLEN(FILEID) + 1) != 0) {
      if (fread(buf + LITLEN(FILEID) + 1, 8, 1, pimg->fh) == 1 &&
          memcmp(buf, FILEID"\r\nv0.01\r\n", LITLEN(FILEID) + 9) == 0) {
         /* v0 3d file with DOS EOLs */
         pimg->version = 0;
         goto v03d;
      }
      rewind(pimg->fh);
      if (buf[1] == ' ') {
         if (buf[0] == ' ') {
            /* Looks like a CMAP .xyz file ... */
            goto xyz_file;
         } else if (strchr("ZSNF", buf[0])) {
            /* Looks like a Compass .plt file ... */
            /* Almost certainly it'll start "Z " */
            goto plt_file;
         }
      }
      if (buf[0] == '(') {
         /* Looks like a Survex .pos file ... */
         goto pos_file;
      }
      img_errno = IMG_BADFORMAT;
      goto error;
   }

   /* check file format version */
   ch = GETC(pimg->fh);
   pimg->version = 0;
   if (tolower(ch) == 'b') {
      /* binary file iff B/b prefix */
      pimg->version = 1;
      ch = GETC(pimg->fh);
   }
   if (ch != 'v') {
      img_errno = IMG_BADFORMAT;
      goto error;
   }
   ch = GETC(pimg->fh);
   if (ch == '0') {
      if (fread(buf, 4, 1, pimg->fh) != 1 || memcmp(buf, ".01\n", 4) != 0) {
         img_errno = IMG_BADFORMAT;
         goto error;
      }
      /* nothing special to do */
   } else if (pimg->version == 0) {
      if (ch < '2' || ch > '0' + IMG_VERSION_MAX || GETC(pimg->fh) != '\n') {
         img_errno = IMG_TOONEW;
         goto error;
      }
      pimg->version = ch - '0';
   } else {
      img_errno = IMG_BADFORMAT;
      goto error;
   }

v03d:
   if (!pimg->title)
       pimg->title = getline_alloc(pimg->fh);
   else
       osfree(getline_alloc(pimg->fh));
   pimg->datestamp = getline_alloc(pimg->fh);
   if (!pimg->title || !pimg->datestamp) {
      img_errno = IMG_OUTOFMEMORY;
      error:
      osfree(pimg->title);
      osfree(pimg->datestamp);
      osfree(pimg->filename_opened);
      fclose(pimg->fh);
      osfree(pimg);
      return NULL;
   }

   pimg->start = ftell(pimg->fh);

   len = strlen(pimg->title);
   if (len > 11 && strcmp(pimg->title + len - 11, " (extended)") == 0) {
       pimg->title[len - 11] = '\0';
       pimg->is_extended_elevation = 1;
   }

   return pimg;
}

int
img_rewind(img *pimg)
{
   if (!pimg->fRead) {
      img_errno = IMG_WRITEERROR;
      return 0;
   }
   if (fseek(pimg->fh, pimg->start, SEEK_SET) != 0) {
      img_errno = IMG_READERROR;
      return 0;
   }
   clearerr(pimg->fh);
   /* [VERSION_SURVEX_POS] already skipped heading line, or there wasn't one
    * [version 0] not in the middle of a 'LINE' command
    * [version >= 3] not in the middle of turning a LINE into a MOVE */
   pimg->pending = 0;

   img_errno = IMG_NONE;

   /* for version >= 3 we use label_buf to store the prefix for reuse */
   /* for VERSION_COMPASS_PLT, 0 value indicates we haven't entered a survey
    * yet */
   /* for VERSION_CMAP_SHOT, we store the last station here to detect whether
    * we MOVE or LINE */
   pimg->label_len = 0;
   return 1;
}

img *
img_open_write(const char *fnm, char *title_buf, bool fBinary)
{
   time_t tm;
   img *pimg;

   fBinary = fBinary;

   if (fDirectory(fnm)) {
      img_errno = IMG_DIRECTORY;
      return NULL;
   }

   pimg = (img *)xosmalloc(ossizeof(img));
   if (pimg == NULL) {
      img_errno = IMG_OUTOFMEMORY;
      return NULL;
   }

   pimg->buf_len = 257;
   pimg->label_buf = xosmalloc(pimg->buf_len);
   if (!pimg->label_buf) {
      osfree(pimg);
      img_errno = IMG_OUTOFMEMORY;
      return NULL;
   }

   pimg->fh = fopen(fnm, "wb");
   if (!pimg->fh) {
      osfree(pimg->label_buf);
      osfree(pimg);
      img_errno = IMG_CANTOPENOUT;
      return NULL;
   }

   pimg->filename_opened = NULL;

   /* Output image file header */
   fputs("Survex 3D Image File\n", pimg->fh); /* file identifier string */
   if (img_output_version < 2) {
      pimg->version = 1;
      fputs("Bv0.01\n", pimg->fh); /* binary file format version number */
   } else {
      pimg->version = (img_output_version > IMG_VERSION_MAX) ? IMG_VERSION_MAX : img_output_version;
      fprintf(pimg->fh, "v%d\n", pimg->version); /* file format version no. */
   }
   fputsnl(title_buf, pimg->fh);
   tm = time(NULL);
   if (tm == (time_t)-1) {
      fputsnl(TIMENA, pimg->fh);
   } else {
      char date[256];
      /* output current date and time in format specified */
      strftime(date, 256, TIMEFMT, localtime(&tm));
      fputsnl(date, pimg->fh);
   }
#if 0
   if (img_output_version >= 5) {
       static const unsigned char codelengths[32] = {
           4,  8,  8,  16, 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
           0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0
       };
       fwrite(codelengths, 32, 1, pimg->fh);
   }
#endif
   pimg->fRead = fFalse; /* writing to this file */
   img_errno = IMG_NONE;

   /* for version >= 3 we use label_buf to store the prefix for reuse */
   pimg->label_buf[0] = '\0';
   pimg->label_len = 0;

#if IMG_API_VERSION == 0
   pimg->date1 = pimg->date2 = 0;
   pimg->olddate1 = pimg->olddate2 = 0;
#else /* IMG_API_VERSION == 1 */
   pimg->days1 = pimg->days2 = -1;
   pimg->olddays1 = pimg->olddays2 = -1;
#endif

   pimg->l = pimg->r = pimg->u = pimg->d = -1.0;

   pimg->n_legs = 0;
   pimg->length = 0.0;
   pimg->E = pimg->H = pimg->V = 0.0;

   /* Don't check for write errors now - let img_close() report them... */
   return pimg;
}

static void
read_xyz_station_coords(img_point *pt, const char *line)
{
   char num[12];
   memcpy(num, line + 6, 9);
   num[9] = '\0';
   pt->x = atof(num) / METRES_PER_FOOT;
   memcpy(num, line + 15, 9);
   pt->y = atof(num) / METRES_PER_FOOT;
   memcpy(num, line + 24, 8);
   num[8] = '\0';
   pt->z = atof(num) / METRES_PER_FOOT;
}

static void
read_xyz_shot_coords(img_point *pt, const char *line)
{
   char num[12];
   memcpy(num, line + 40, 10);
   num[10] = '\0';
   pt->x = atof(num) / METRES_PER_FOOT;
   memcpy(num, line + 50, 10);
   pt->y = atof(num) / METRES_PER_FOOT;
   memcpy(num, line + 60, 9);
   num[9] = '\0';
   pt->z = atof(num) / METRES_PER_FOOT;
}

static void
subtract_xyz_shot_deltas(img_point *pt, const char *line)
{
   char num[12];
   memcpy(num, line + 15, 9);
   num[9] = '\0';
   pt->x -= atof(num) / METRES_PER_FOOT;
   memcpy(num, line + 24, 8);
   num[8] = '\0';
   pt->y -= atof(num) / METRES_PER_FOOT;
   memcpy(num, line + 32, 8);
   pt->z -= atof(num) / METRES_PER_FOOT;
}

static int
read_coord(FILE *fh, img_point *pt)
{
   SVX_ASSERT(fh);
   SVX_ASSERT(pt);
   pt->x = get32(fh) / 100.0;
   pt->y = get32(fh) / 100.0;
   pt->z = get32(fh) / 100.0;
   if (ferror(fh) || feof(fh)) {
      img_errno = feof(fh) ? IMG_BADFORMAT : IMG_READERROR;
      return 0;
   }
   return 1;
}

static int
skip_coord(FILE *fh)
{
    return (fseek(fh, 12, SEEK_CUR) == 0);
}

static int
read_v3label(img *pimg)
{
   char *q;
   long len = GETC(pimg->fh);
   if (len == EOF) {
      img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
      return img_BAD;
   }
   if (len == 0xfe) {
      len += get16(pimg->fh);
      if (feof(pimg->fh)) {
         img_errno = IMG_BADFORMAT;
         return img_BAD;
      }
      if (ferror(pimg->fh)) {
         img_errno = IMG_READERROR;
         return img_BAD;
      }
   } else if (len == 0xff) {
      len = get32(pimg->fh);
      if (ferror(pimg->fh)) {
         img_errno = IMG_READERROR;
         return img_BAD;
      }
      if (feof(pimg->fh) || len < 0xfe + 0xffff) {
         img_errno = IMG_BADFORMAT;
         return img_BAD;
      }
   }

   if (!check_label_space(pimg, pimg->label_len + len + 1)) {
      img_errno = IMG_OUTOFMEMORY;
      return img_BAD;
   }
   q = pimg->label_buf + pimg->label_len;
   pimg->label_len += len;
   if (len && fread(q, len, 1, pimg->fh) != 1) {
      img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
      return img_BAD;
   }
   q[len] = '\0';
   return 0;
}

static int img_read_item_ascii(img *pimg, img_point *p);

int
img_read_item(img *pimg, img_point *p)
{
   int result;
   pimg->flags = 0;

   if (pimg->version >= 3) {
      int opt;
      pimg->l = pimg->r = pimg->u = pimg->d = -1.0;
      if (pimg->pending == 256) {
         pimg->pending = 0;
         return img_XSECT_END;
      }
      if (pimg->pending >= 0x80) {
         *p = pimg->mv;
         pimg->flags = (int)(pimg->pending) & 0x3f;
         pimg->pending = 0;
         return img_LINE;
      }
      again3: /* label to goto if we get a prefix, date, or lrud */
      pimg->label = pimg->label_buf;
      opt = GETC(pimg->fh);
      if (opt == EOF) {
         img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
         return img_BAD;
      }
      switch (opt >> 6) {
       case 0:
         if (opt == 0) {
            if (!pimg->label_len) return img_STOP; /* end of data marker */
            pimg->label_len = 0;
            goto again3;
         }
         if (opt < 15) {
            /* 1-14 mean trim that many levels from current prefix */
            int c;
            if (pimg->label_len <= 17) {
               /* zero prefix using "0" */
               img_errno = IMG_BADFORMAT;
               return img_BAD;
            }
            /* extra - 1 because label_len points to one past the end */
            c = pimg->label_len - 17 - 1;
            while (pimg->label_buf[c] != '.' || --opt > 0) {
               if (--c < 0) {
                  /* zero prefix using "0" */
                  img_errno = IMG_BADFORMAT;
                  return img_BAD;
               }
            }
            c++;
            pimg->label_len = c;
            goto again3;
         }
         if (opt == 15) {
            result = img_MOVE;
            break;
         }
         if (opt >= 0x20) {
             switch (opt) {
                 case 0x20: /* Single date */
                     if (pimg->version < 7) {
                         int date1 = get32(pimg->fh);
#if IMG_API_VERSION == 0
                         pimg->date2 = pimg->date1 = date1;
#else /* IMG_API_VERSION == 1 */
                         if (date1 != 0) {
                             pimg->days2 = pimg->days1 = (date1 / 86400) + 25567;
                         } else {
                             pimg->days2 = pimg->days1 = -1;
                         }
#endif
                     } else {
                         int days1 = (int)getu16(pimg->fh);
#if IMG_API_VERSION == 0
                         pimg->date2 = pimg->date1 = (days1 - 25567) * 86400;
#else /* IMG_API_VERSION == 1 */
                         pimg->days2 = pimg->days1 = days1;
#endif
                     }
                     break;
                 case 0x21: /* Date range (short for v7+) */
                     if (pimg->version < 7) {
                         INT32_T date1 = get32(pimg->fh);
                         INT32_T date2 = get32(pimg->fh);
#if IMG_API_VERSION == 0
                         pimg->date1 = date1;
                         pimg->date2 = date2;
#else /* IMG_API_VERSION == 1 */
                         pimg->days1 = (date1 / 86400) + 25567;
                         pimg->days2 = (date2 / 86400) + 25567;
#endif
                     } else {
                         int days1 = (int)getu16(pimg->fh);
                         int days2 = days1 + GETC(pimg->fh) + 1;
#if IMG_API_VERSION == 0
                         pimg->date1 = (days1 - 25567) * 86400;
                         pimg->date2 = (days2 - 25567) * 86400;
#else /* IMG_API_VERSION == 1 */
                         pimg->days1 = days1;
                         pimg->days2 = days2;
#endif
                     }
                     break;
                 case 0x22: /* Error info */
                     pimg->n_legs = get32(pimg->fh);
                     pimg->length = get32(pimg->fh) / 100.0;
                     pimg->E = get32(pimg->fh) / 100.0;
                     pimg->H = get32(pimg->fh) / 100.0;
                     pimg->V = get32(pimg->fh) / 100.0;
                     return img_ERROR_INFO;
                 case 0x23: { /* v7+: Date range (long) */
                     if (pimg->version < 7) {
                         img_errno = IMG_BADFORMAT;
                         return img_BAD;
                     }
                     int days1 = (int)getu16(pimg->fh);
                     int days2 = (int)getu16(pimg->fh);
#if IMG_API_VERSION == 0
                     pimg->date1 = (days1 - 25567) * 86400;
                     pimg->date2 = (days2 - 25567) * 86400;
#else /* IMG_API_VERSION == 1 */
                     pimg->days1 = days1;
                     pimg->days2 = days2;
#endif
                     break;
                 }
                 case 0x24: { /* v7+: No date info */
#if IMG_API_VERSION == 0
                     pimg->date1 = pimg->date2 = 0;
#else /* IMG_API_VERSION == 1 */
                     pimg->days1 = pimg->days2 = -1;
#endif
                     break;
                 }
                 case 0x30: case 0x31: /* LRUD */
                 case 0x32: case 0x33: /* Big LRUD! */
                     if (read_v3label(pimg) == img_BAD) return img_BAD;
                     pimg->flags = (int)opt & 0x01;
                     if (opt < 0x32) {
                         pimg->l = get16(pimg->fh) / 100.0;
                         pimg->r = get16(pimg->fh) / 100.0;
                         pimg->u = get16(pimg->fh) / 100.0;
                         pimg->d = get16(pimg->fh) / 100.0;
                     } else {
                         pimg->l = get32(pimg->fh) / 100.0;
                         pimg->r = get32(pimg->fh) / 100.0;
                         pimg->u = get32(pimg->fh) / 100.0;
                         pimg->d = get32(pimg->fh) / 100.0;
                     }
                     if (pimg->survey_len) {
                         size_t l = pimg->survey_len;
                         const char *s = pimg->label_buf;
                         if (strncmp(pimg->survey, s, l + 1) != 0) {
                             return img_XSECT_END;
                         }
                         pimg->label += l;
                         /* skip the dot if there */
                         if (*pimg->label) pimg->label++;
                     }
                     /* If this is the last cross-section in this passage, set
                      * pending so we return img_XSECT_END next time. */
                     if (pimg->flags & 0x01) {
                         pimg->pending = 256;
                         pimg->flags &= ~0x01;
                     }
                     return img_XSECT;
                 default: /* 0x25 - 0x2f and 0x34 - 0x3f are currently unallocated. */
                     img_errno = IMG_BADFORMAT;
                     return img_BAD;
             }
             goto again3;
         }
         /* 16-31 mean remove (n - 15) characters from the prefix */
         /* zero prefix using 0 */
         if (pimg->label_len <= (size_t)(opt - 15)) {
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         pimg->label_len -= (opt - 15);
         goto again3;
       case 1:
         if (read_v3label(pimg) == img_BAD) return img_BAD;

         result = img_LABEL;

         if (pimg->survey_len) {
            size_t l = pimg->survey_len;
            const char *s = pimg->label_buf;
            if (strncmp(pimg->survey, s, l + 1) != 0) {
               if (!skip_coord(pimg->fh)) return img_BAD;
               pimg->pending = 0;
               goto again3;
            }
            pimg->label += l;
            /* skip the dot if there */
            if (*pimg->label) pimg->label++;
         }

         pimg->flags = (int)opt & 0x3f;
         break;
       case 2:
         if (read_v3label(pimg) == img_BAD) return img_BAD;

         result = img_LINE;

         if (pimg->survey_len) {
            size_t l = pimg->survey_len;
            const char *s = pimg->label_buf;
            if (strncmp(pimg->survey, s, l) != 0 ||
                !(s[l] == '.' || s[l] == '\0')) {
               if (!read_coord(pimg->fh, &(pimg->mv))) return img_BAD;
               pimg->pending = 15;
               goto again3;
            }
            pimg->label += l;
            /* skip the dot if there */
            if (*pimg->label) pimg->label++;
         }

         if (pimg->pending) {
            *p = pimg->mv;
            if (!read_coord(pimg->fh, &(pimg->mv))) return img_BAD;
            pimg->pending = opt;
            return img_MOVE;
         }
         pimg->flags = (int)opt & 0x3f;
         break;
       default:
         img_errno = IMG_BADFORMAT;
         return img_BAD;
      }
      if (!read_coord(pimg->fh, p)) return img_BAD;
      pimg->pending = 0;
      return result;
   }

   pimg->label = pimg->label_buf;

   if (pimg->version > 0) {
      static long opt_lookahead = 0;
      static img_point pt = { 0.0, 0.0, 0.0 };
      long opt;
      again: /* label to goto if we get a cross */
      pimg->label[0] = '\0';

      if (pimg->version == 1) {
         if (opt_lookahead) {
            opt = opt_lookahead;
            opt_lookahead = 0;
         } else {
            opt = get32(pimg->fh);
         }
      } else {
         opt = GETC(pimg->fh);
      }

      if (feof(pimg->fh)) {
         img_errno = IMG_BADFORMAT;
         return img_BAD;
      }
      if (ferror(pimg->fh)) {
         img_errno = IMG_READERROR;
         return img_BAD;
      }

      switch (opt) {
       case -1: case 0:
         return img_STOP; /* end of data marker */
       case 1:
         /* skip coordinates */
         if (!skip_coord(pimg->fh)) {
            img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
            return img_BAD;
         }
         goto again;
       case 2: case 3: {
         char *q;
         int ch;
         result = img_LABEL;
         ch = GETC(pimg->fh);
         if (ch == EOF) {
            img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
            return img_BAD;
         }
         if (ch != '\\') ungetc(ch, pimg->fh);
         fgets(pimg->label_buf, 257, pimg->fh);
         if (feof(pimg->fh)) {
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         if (ferror(pimg->fh)) {
            img_errno = IMG_READERROR;
            return img_BAD;
         }
         q = pimg->label_buf + strlen(pimg->label_buf) - 1;
         if (*q != '\n') {
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         /* Ignore empty labels in some .3d files (caused by a bug) */
         if (q == pimg->label_buf) goto again;
         *q = '\0';
         pimg->flags = img_SFLAG_UNDERGROUND; /* no flags given... */
         if (opt == 2) goto done;
         break;
       }
       case 6: case 7: {
         long len;
         result = img_LABEL;

         if (opt == 7)
            pimg->flags = GETC(pimg->fh);
         else
            pimg->flags = img_SFLAG_UNDERGROUND; /* no flags given... */

         len = get32(pimg->fh);

         if (feof(pimg->fh)) {
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         if (ferror(pimg->fh)) {
            img_errno = IMG_READERROR;
            return img_BAD;
         }

         /* Ignore empty labels in some .3d files (caused by a bug) */
         if (len == 0) goto again;
         if (!check_label_space(pimg, len + 1)) {
            img_errno = IMG_OUTOFMEMORY;
            return img_BAD;
         }
         if (fread(pimg->label_buf, len, 1, pimg->fh) != 1) {
            img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
            return img_BAD;
         }
         pimg->label_buf[len] = '\0';
         break;
       }
       case 4:
         result = img_MOVE;
         break;
       case 5:
         result = img_LINE;
         break;
       default:
         switch ((int)opt & 0xc0) {
          case 0x80:
            pimg->flags = (int)opt & 0x3f;
            result = img_LINE;
            break;
          case 0x40: {
            char *q;
            pimg->flags = (int)opt & 0x3f;
            result = img_LABEL;
            if (!fgets(pimg->label_buf, 257, pimg->fh)) {
               img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
               return img_BAD;
            }
            q = pimg->label_buf + strlen(pimg->label_buf) - 1;
            /* Ignore empty-labels in some .3d files (caused by a bug) */
            if (q == pimg->label_buf) goto again;
            if (*q != '\n') {
               img_errno = IMG_BADFORMAT;
               return img_BAD;
            }
            *q = '\0';
            break;
          }
          case 0xc0:
            /* use this for an extra leg or station flag if we need it */
          default:
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         break;
      }

      if (!read_coord(pimg->fh, &pt)) return img_BAD;

      if (result == img_LABEL && pimg->survey_len) {
         if (strncmp(pimg->label_buf, pimg->survey, pimg->survey_len + 1) != 0)
            goto again;
         pimg->label += pimg->survey_len + 1;
      }

      done:
      *p = pt;

      if (result == img_MOVE && pimg->version == 1) {
         /* peek at next code and see if it's an old-style label */
         opt_lookahead = get32(pimg->fh);

         if (feof(pimg->fh)) {
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         if (ferror(pimg->fh)) {
            img_errno = IMG_READERROR;
            return img_BAD;
         }

         if (opt_lookahead == 2) return img_read_item(pimg, p);
      }

      return result;
   } else {
      /* We need to set the default locale for fscanf() to work on
       * numbers with "." as decimal point. */
      char * current_locale = my_strdup(setlocale(LC_NUMERIC, NULL));
      setlocale(LC_NUMERIC, "C");
      result = img_read_item_ascii(pimg, p);
      setlocale(LC_NUMERIC, current_locale);
      free(current_locale);
      return result;
   }
}

/* Handle all for ASCII formats so we can easily fix up the locale
 * so fscanf(), etc work on numbers with "." as decimal point. */
static int
img_read_item_ascii(img *pimg, img_point *p)
{
   int result;
   if (pimg->version == 0) {
      ascii_again:
      pimg->label[0] = '\0';
      if (feof(pimg->fh)) return img_STOP;
      if (pimg->pending) {
         pimg->pending = 0;
         result = img_LINE;
      } else {
         char cmd[7];
         /* Stop if nothing found */
         if (fscanf(pimg->fh, "%6s", cmd) < 1) return img_STOP;
         if (strcmp(cmd, "move") == 0)
            result = img_MOVE;
         else if (strcmp(cmd, "draw") == 0)
            result = img_LINE;
         else if (strcmp(cmd, "line") == 0) {
            /* set flag to indicate to process second triplet as LINE */
            pimg->pending = 1;
            result = img_MOVE;
         } else if (strcmp(cmd, "cross") == 0) {
            if (fscanf(pimg->fh, "%lf%lf%lf", &p->x, &p->y, &p->z) < 3) {
               img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
               return img_BAD;
            }
            goto ascii_again;
         } else if (strcmp(cmd, "name") == 0) {
            size_t off = 0;
            int ch = GETC(pimg->fh);
            if (ch == ' ') ch = GETC(pimg->fh);
            while (ch != ' ') {
               if (ch == '\n' || ch == EOF) {
                  img_errno = ferror(pimg->fh) ? IMG_READERROR : IMG_BADFORMAT;
                  return img_BAD;
               }
               if (off == pimg->buf_len) {
                  if (!check_label_space(pimg, pimg->buf_len * 2)) {
                     img_errno = IMG_OUTOFMEMORY;
                     return img_BAD;
                  }
               }
               pimg->label_buf[off++] = ch;
               ch = GETC(pimg->fh);
            }
            pimg->label_buf[off] = '\0';

            pimg->label = pimg->label_buf;
            if (pimg->label[0] == '\\') pimg->label++;

            pimg->flags = img_SFLAG_UNDERGROUND; /* default flags */

            result = img_LABEL;
         } else {
            img_errno = IMG_BADFORMAT;
            return img_BAD; /* unknown keyword */
         }
      }

      if (fscanf(pimg->fh, "%lf%lf%lf", &p->x, &p->y, &p->z) < 3) {
         img_errno = ferror(pimg->fh) ? IMG_READERROR : IMG_BADFORMAT;
         return img_BAD;
      }

      if (result == img_LABEL && pimg->survey_len) {
         if (strncmp(pimg->label, pimg->survey, pimg->survey_len + 1) != 0)
            goto ascii_again;
         pimg->label += pimg->survey_len + 1;
      }

      return result;
   } else if (pimg->version == VERSION_SURVEX_POS) {
      /* Survex .pos file */
      size_t off;
      pimg->flags = img_SFLAG_UNDERGROUND; /* default flags */
      againpos:
      off = 0;
      while (fscanf(pimg->fh, "(%lf,%lf,%lf ) ", &p->x, &p->y, &p->z) != 3) {
         int ch;
         if (ferror(pimg->fh)) {
            img_errno = IMG_READERROR;
            return img_BAD;
         }
         if (feof(pimg->fh)) return img_STOP;
         if (pimg->pending) {
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         pimg->pending = 1;
         /* ignore rest of line */
         do {
            ch = GETC(pimg->fh);
         } while (ch != '\n' && ch != '\r' && ch != EOF);
      }

      pimg->label_buf[0] = '\0';
      while (!feof(pimg->fh)) {
         if (!fgets(pimg->label_buf + off, pimg->buf_len - off, pimg->fh)) {
            img_errno = IMG_READERROR;
            return img_BAD;
         }

         off += strlen(pimg->label_buf + off);
         if (off && pimg->label_buf[off - 1] == '\n') {
            pimg->label_buf[off - 1] = '\0';
            break;
         }
         if (!check_label_space(pimg, pimg->buf_len * 2)) {
            img_errno = IMG_OUTOFMEMORY;
            return img_BAD;
         }
      }

      pimg->label = pimg->label_buf;

      if (pimg->label[0] == '\\') pimg->label++;

      if (pimg->survey_len) {
         size_t l = pimg->survey_len + 1;
         if (strncmp(pimg->survey, pimg->label, l) != 0) goto againpos;
         pimg->label += l;
      }

      return img_LABEL;
   } else if (pimg->version == VERSION_COMPASS_PLT) {
      /* Compass .plt file */
      if (pimg->pending > 0) {
         /* -1 signals we've entered the first survey we want to
          * read, and need to fudge lots if the first action is 'D'...
          */
         /* pending MOVE or LINE */
         int r = pimg->pending - 4;
         pimg->pending = 0;
         pimg->flags = 0;
         pimg->label[pimg->label_len] = '\0';
         return r;
      }

      while (1) {
         char *line;
         char *q;
         size_t len = 0;
         int ch = GETC(pimg->fh);

         switch (ch) {
            case '\x1a': case EOF: /* Don't insist on ^Z at end of file */
               return img_STOP;
            case 'X': case 'F': case 'S':
               /* bounding boX (marks end of survey), Feature survey, or
                * new Section - skip to next survey */
               if (pimg->survey) return img_STOP;
skip_to_N:
               while (1) {
                  do {
                     ch = GETC(pimg->fh);
                  } while (ch != '\n' && ch != '\r' && ch != EOF);
                  while (ch == '\n' || ch == '\r') ch = GETC(pimg->fh);
                  if (ch == 'N') break;
                  if (ch == '\x1a' || ch == EOF) return img_STOP;
               }
               /* FALLTHRU */
            case 'N':
               line = getline_alloc(pimg->fh);
               if (!line) {
                  img_errno = IMG_OUTOFMEMORY;
                  return img_BAD;
               }
               while (line[len] > 32) ++len;
               if (pimg->label_len == 0) pimg->pending = -1;
               if (!check_label_space(pimg, len + 1)) {
                  osfree(line);
                  img_errno = IMG_OUTOFMEMORY;
                  return img_BAD;
               }
               pimg->label_len = len;
               pimg->label = pimg->label_buf;
               memcpy(pimg->label, line, len);
               pimg->label[len] = '\0';
               osfree(line);
               break;
            case 'M': case 'D': {
               /* Move or Draw */
               long fpos = -1;
               if (pimg->survey && pimg->label_len == 0) {
                  /* We're only holding onto this line in case the first line
                   * of the 'N' is a 'D', so skip it for now...
                   */
                  goto skip_to_N;
               }
               if (ch == 'D' && pimg->pending == -1) {
                  if (pimg->survey) {
                     fpos = ftell(pimg->fh) - 1;
                     fseek(pimg->fh, pimg->start, SEEK_SET);
                     ch = GETC(pimg->fh);
                     pimg->pending = 0;
                  } else {
                     /* If a file actually has a 'D' before any 'M', then
                      * pretend the 'D' is an 'M' - one of the examples
                      * in the docs was like this! */
                     ch = 'M';
                  }
               }
               line = getline_alloc(pimg->fh);
               if (!line) {
                  img_errno = IMG_OUTOFMEMORY;
                  return img_BAD;
               }
               /* Compass stores coordinates as North, East, Up = (y,x,z)! */
               if (sscanf(line, "%lf%lf%lf", &p->y, &p->x, &p->z) != 3) {
                  osfree(line);
                  if (ferror(pimg->fh)) {
                     img_errno = IMG_READERROR;
                  } else {
                     img_errno = IMG_BADFORMAT;
                  }
                  return img_BAD;
               }
               p->x *= METRES_PER_FOOT;
               p->y *= METRES_PER_FOOT;
               p->z *= METRES_PER_FOOT;
               q = strchr(line, 'S');
               if (!q) {
                  osfree(line);
                  img_errno = IMG_BADFORMAT;
                  return img_BAD;
               }
               ++q;
               len = 0;
               while (q[len] > ' ') ++len;
               q[len] = '\0';
               len += 2; /* ' ' and '\0' */
               if (!check_label_space(pimg, pimg->label_len + len)) {
                  img_errno = IMG_OUTOFMEMORY;
                  return img_BAD;
               }
               pimg->label = pimg->label_buf;
               if (pimg->label_len) {
                   pimg->label[pimg->label_len] = ' ';
                   memcpy(pimg->label + pimg->label_len + 1, q, len - 1);
               } else {
                   memcpy(pimg->label, q, len - 1);
               }
               q += len - 1;
               /* Now read LRUD.  Technically, this is optional but virtually
                * all PLT files have it (with dummy negative values if no LRUD
                * was measured) and some versions of Compass can't read PLT
                * files without it!
                */
               while (*q && *q <= ' ') q++;
               if (*q == 'P') {
                   if (sscanf(q + 1, "%lf%lf%lf%lf",
                              &pimg->l, &pimg->r, &pimg->u, &pimg->d) != 4) {
                       osfree(line);
                       if (ferror(pimg->fh)) {
                           img_errno = IMG_READERROR;
                       } else {
                           img_errno = IMG_BADFORMAT;
                       }
                       return img_BAD;
                   }
                   pimg->l *= METRES_PER_FOOT;
                   pimg->r *= METRES_PER_FOOT;
                   pimg->u *= METRES_PER_FOOT;
                   pimg->d *= METRES_PER_FOOT;
               } else {
                   pimg->l = pimg->r = pimg->u = pimg->d = -1;
               }
               osfree(line);
               pimg->flags = img_SFLAG_UNDERGROUND; /* default flags */
               if (fpos != -1) {
                  fseek(pimg->fh, fpos, SEEK_SET);
               } else {
                  pimg->pending = (ch == 'M' ? img_MOVE : img_LINE) + 4;
               }
               return img_LABEL;
            }
            default:
               img_errno = IMG_BADFORMAT;
               return img_BAD;
         }
      }
   } else {
      /* CMAP .xyz file */
      char *line = NULL;
      char *q;
      size_t len;

      if (pimg->pending) {
         /* pending MOVE or LINE or LABEL or STOP */
         int r = pimg->pending - 4;
         /* Set label to empty - don't use "" as we adjust label relative
          * to label_buf when label_buf is reallocated. */
         pimg->label = pimg->label_buf + strlen(pimg->label_buf);
         pimg->flags = 0;
         if (r == img_LABEL) {
            /* nasty magic */
            read_xyz_shot_coords(p, pimg->label_buf + 16);
            subtract_xyz_shot_deltas(p, pimg->label_buf + 16);
            pimg->pending = img_STOP + 4;
            return img_MOVE;
         }

         pimg->pending = 0;

         if (r == img_STOP) {
            /* nasty magic */
            read_xyz_shot_coords(p, pimg->label_buf + 16);
            return img_LINE;
         }

         return r;
      }

      pimg->label = pimg->label_buf;
      do {
         osfree(line);
         if (feof(pimg->fh)) return img_STOP;
         line = getline_alloc(pimg->fh);
         if (!line) {
            img_errno = IMG_OUTOFMEMORY;
            return img_BAD;
         }
      } while (line[0] == ' ' || line[0] == '\0');
      if (line[0] == '\x1a') return img_STOP;

      len = strlen(line);
      if (pimg->version == VERSION_CMAP_STATION) {
         /* station variant */
         if (len < 37) {
            osfree(line);
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         memcpy(pimg->label, line, 6);
         q = memchr(pimg->label, ' ', 6);
         if (!q) q = pimg->label + 6;
         *q = '\0';

         read_xyz_station_coords(p, line);

         /* FIXME: look at prev for lines (line + 32, 5) */
         /* FIXME: duplicate stations... */
         return img_LABEL;
      } else {
         /* Shot variant */
         char old[8], new[8];
         if (len < 61) {
            osfree(line);
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }

         memcpy(old, line, 7);
         q = memchr(old, ' ', 7);
         if (!q) q = old + 7;
         *q = '\0';

         memcpy(new, line + 7, 7);
         q = memchr(new, ' ', 7);
         if (!q) q = new + 7;
         *q = '\0';

         pimg->flags = img_SFLAG_UNDERGROUND;

         if (strcmp(old, new) == 0) {
            pimg->pending = img_MOVE + 4;
            read_xyz_shot_coords(p, line);
            strcpy(pimg->label, new);
            osfree(line);
            return img_LABEL;
         }

         if (strcmp(old, pimg->label) == 0) {
            pimg->pending = img_LINE + 4;
            read_xyz_shot_coords(p, line);
            strcpy(pimg->label, new);
            osfree(line);
            return img_LABEL;
         }

         pimg->pending = img_LABEL + 4;
         read_xyz_shot_coords(p, line);
         strcpy(pimg->label, new);
         memcpy(pimg->label + 16, line, 70);

         osfree(line);
         return img_LABEL;
      }
   }
}

static int
write_v3label(img *pimg, int opt, const char *s)
{
   size_t len, n, dot;

   /* find length of common prefix */
   dot = 0;
   for (len = 0; s[len] == pimg->label_buf[len] && s[len] != '\0'; len++) {
      if (s[len] == '.') dot = len + 1;
   }

   SVX_ASSERT(len <= pimg->label_len);
   n = pimg->label_len - len;
   if (len == 0) {
      if (pimg->label_len) PUTC(0, pimg->fh);
   } else if (n <= 16) {
      if (n) PUTC(n + 15, pimg->fh);
   } else if (dot == 0) {
      if (pimg->label_len) PUTC(0, pimg->fh);
      len = 0;
   } else {
      const char *p = pimg->label_buf + dot;
      n = 1;
      for (len = pimg->label_len - dot - 17; len; len--) {
         if (*p++ == '.') n++;
      }
      if (n <= 14) {
         PUTC(n, pimg->fh);
         len = dot;
      } else {
         if (pimg->label_len) PUTC(0, pimg->fh);
         len = 0;
      }
   }

   n = strlen(s + len);
   PUTC(opt, pimg->fh);
   if (n < 0xfe) {
      PUTC(n, pimg->fh);
   } else if (n < 0xffff + 0xfe) {
      PUTC(0xfe, pimg->fh);
      put16((short)(n - 0xfe), pimg->fh);
   } else {
      PUTC(0xff, pimg->fh);
      put32(n, pimg->fh);
   }
   fwrite(s + len, n, 1, pimg->fh);

   n += len;
   pimg->label_len = n;
   if (!check_label_space(pimg, n + 1))
      return 0; /* FIXME: distinguish out of memory... */
   memcpy(pimg->label_buf + len, s + len, n - len + 1);

   return !ferror(pimg->fh);
}

static void
img_write_item_date(img *pimg)
{
    int same, unset;
    /* Only write dates when they've changed. */
#if IMG_API_VERSION == 0
    if (pimg->date1 == pimg->olddate1 && pimg->date2 == pimg->olddate2)
        return;

    same = (pimg->date1 == pimg->date2);
    unset = (pimg->date1 == 0);
#else /* IMG_API_VERSION == 1 */
    if (pimg->days1 == pimg->olddays1 && pimg->days2 == pimg->olddays2)
        return;

    same = (pimg->days1 == pimg->days2);
    unset = (pimg->days1 == -1);
#endif

    if (same) {
        if (img_output_version < 7) {
            PUTC(0x20, pimg->fh);
#if IMG_API_VERSION == 0
            put32(pimg->date1, pimg->fh);
#else /* IMG_API_VERSION == 1 */
            put32((pimg->days1 - 25567) * 86400, pimg->fh);
#endif
        } else {
            if (unset) {
                PUTC(0x24, pimg->fh);
            } else {
                PUTC(0x20, pimg->fh);
#if IMG_API_VERSION == 0
                put16(pimg->date1 / 86400 + 25567, pimg->fh);
#else /* IMG_API_VERSION == 1 */
                put16(pimg->days1, pimg->fh);
#endif
            }
        }
    } else {
        if (img_output_version < 7) {
            PUTC(0x21, pimg->fh);
#if IMG_API_VERSION == 0
            put32(pimg->date1, pimg->fh);
            put32(pimg->date2, pimg->fh);
#else /* IMG_API_VERSION == 1 */
            put32((pimg->days1 - 25567) * 86400, pimg->fh);
            put32((pimg->days2 - 25567) * 86400, pimg->fh);
#endif
        } else {
#if IMG_API_VERSION == 0
            int diff = (pimg->date2 - pimg->date1) / 86400;
            if (diff > 0 && diff <= 256) {
                PUTC(0x21, pimg->fh);
                put16(pimg->date1 / 86400 + 25567, pimg->fh);
                PUTC(diff - 1, pimg->fh);
            } else {
                PUTC(0x23, pimg->fh);
                put16(pimg->date1 / 86400 + 25567, pimg->fh);
                put16(pimg->date2 / 86400 + 25567, pimg->fh);
            }
#else /* IMG_API_VERSION == 1 */
            int diff = pimg->days2 - pimg->days1;
            if (diff > 0 && diff <= 256) {
                PUTC(0x21, pimg->fh);
                put16(pimg->days1, pimg->fh);
                PUTC(diff - 1, pimg->fh);
            } else {
                PUTC(0x23, pimg->fh);
                put16(pimg->days1, pimg->fh);
                put16(pimg->days2, pimg->fh);
            }
#endif
        }
    }
#if IMG_API_VERSION == 0
    pimg->olddate1 = pimg->date1;
    pimg->olddate2 = pimg->date2;
#else /* IMG_API_VERSION == 1 */
    pimg->olddays1 = pimg->days1;
    pimg->olddays2 = pimg->days2;
#endif
}

void
img_write_item(img *pimg, int code, int flags, const char *s,
               double x, double y, double z)
{
   if (!pimg) return;
   if (pimg->version >= 3) {
      int opt = 0;
      switch (code) {
       case img_LABEL:
         write_v3label(pimg, 0x40 | flags, s);
         opt = 0;
         break;
       case img_XSECT: {
         INT32_T l, r, u, d, max_dim;
         /* Need at least version 5 for img_XSECT. */
         if (pimg->version < 5) break;
         img_write_item_date(pimg);
         l = (INT32_T)my_round(pimg->l * 100.0);
         r = (INT32_T)my_round(pimg->r * 100.0);
         u = (INT32_T)my_round(pimg->u * 100.0);
         d = (INT32_T)my_round(pimg->d * 100.0);
         if (l < 0) l = -1;
         if (r < 0) r = -1;
         if (u < 0) u = -1;
         if (d < 0) d = -1;
         max_dim = max(max(l, r), max(u, d));
         flags &= 1;
         if (max_dim >= 32768) flags |= 2;
         write_v3label(pimg, 0x30 | flags, s);
         if (flags & 2) {
            /* Big passage!  Need to use 4 bytes. */
            put32(l, pimg->fh);
            put32(r, pimg->fh);
            put32(u, pimg->fh);
            put32(d, pimg->fh);
         } else {
            put16(l, pimg->fh);
            put16(r, pimg->fh);
            put16(u, pimg->fh);
            put16(d, pimg->fh);
         }
         return;
       }
       case img_MOVE:
         opt = 15;
         break;
       case img_LINE:
         if (pimg->version >= 4) {
             img_write_item_date(pimg);
         }
         write_v3label(pimg, 0x80 | flags, s ? s : "");
         opt = 0;
         break;
       default: /* ignore for now */
         return;
      }
      if (opt) PUTC(opt, pimg->fh);
      /* Output in cm */
      put32((INT32_T)my_round(x * 100.0), pimg->fh);
      put32((INT32_T)my_round(y * 100.0), pimg->fh);
      put32((INT32_T)my_round(z * 100.0), pimg->fh);
   } else {
      size_t len;
      INT32_T opt = 0;
      SVX_ASSERT(pimg->version > 0);
      switch (code) {
       case img_LABEL:
         if (pimg->version == 1) {
            /* put a move before each label */
            img_write_item(pimg, img_MOVE, 0, NULL, x, y, z);
            put32(2, pimg->fh);
            fputsnl(s, pimg->fh);
            return;
         }
         len = strlen(s);
         if (len > 255 || strchr(s, '\n')) {
            /* long label - not in early incarnations of v2 format, but few
             * 3d files will need these, so better not to force incompatibility
             * with a new version I think... */
            PUTC(7, pimg->fh);
            PUTC(flags, pimg->fh);
            put32(len, pimg->fh);
            fputs(s, pimg->fh);
         } else {
            PUTC(0x40 | (flags & 0x3f), pimg->fh);
            fputsnl(s, pimg->fh);
         }
         opt = 0;
         break;
       case img_MOVE:
         opt = 4;
         break;
       case img_LINE:
         if (pimg->version > 1) {
            opt = 0x80 | (flags & 0x3f);
            break;
         }
         opt = 5;
         break;
       default: /* ignore for now */
         return;
      }
      if (pimg->version == 1) {
         put32(opt, pimg->fh);
      } else {
         if (opt) PUTC(opt, pimg->fh);
      }
      /* Output in cm */
      put32((INT32_T)my_round(x * 100.0), pimg->fh);
      put32((INT32_T)my_round(y * 100.0), pimg->fh);
      put32((INT32_T)my_round(z * 100.0), pimg->fh);
   }
}

/* Write error information for the current traverse
 * n_legs is the number of legs in the traverse
 * length is the traverse length (in m)
 * E is the ratio of the observed misclosure to the theoretical one
 * H is the ratio of the observed horizontal misclosure to the theoretical one
 * V is the ratio of the observed vertical misclosure to the theoretical one
 */
void
img_write_errors(img *pimg, int n_legs, double length,
                 double E, double H, double V)
{
    PUTC(0x22, pimg->fh);
    put32(n_legs, pimg->fh);
    put32((INT32_T)my_round(length * 100.0), pimg->fh);
    put32((INT32_T)my_round(E * 100.0), pimg->fh);
    put32((INT32_T)my_round(H * 100.0), pimg->fh);
    put32((INT32_T)my_round(V * 100.0), pimg->fh);
}

int
img_close(img *pimg)
{
   int result = 1;
   if (pimg) {
      if (pimg->fh) {
         if (pimg->fRead) {
            osfree(pimg->survey);
            osfree(pimg->title);
            osfree(pimg->datestamp);
         } else {
            /* write end of data marker */
            switch (pimg->version) {
             case 1:
               put32((INT32_T)-1, pimg->fh);
               break;
             case 2:
               PUTC(0, pimg->fh);
               break;
             default:
               if (pimg->label_len) PUTC(0, pimg->fh);
               PUTC(0, pimg->fh);
               break;
            }
         }
         if (ferror(pimg->fh)) result = 0;
         if (fclose(pimg->fh)) result = 0;
         if (!result) img_errno = pimg->fRead ? IMG_READERROR : IMG_WRITEERROR;
      }
      osfree(pimg->label_buf);
      osfree(pimg->filename_opened);
      osfree(pimg);
   }
   return result;
}