source: git/src/img.c @ 58f02ae

/* img.c
 * Routines for reading and writing Survex ".3d" image files
 * Copyright (C) 1993-2001 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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 "img.h"
#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)
#else
# define INT32_T long
# define TIMENA "Time not available."
# define TIMEFMT "%a,%Y.%m.%d %H:%M:%S %Z"
# define EXT_SVX_3D "3d"
# 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 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 ASSERT(X)

static long
get32(FILE *fh)
{
   long w = getc(fh);
   w |= (long)getc(fh) << 8l;
   w |= (long)getc(fh) << 16l;
   w |= (long)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);
}

#endif

#ifdef HAVE_ROUND
# include <math.h>
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

unsigned int img_output_version = 3;

#define TMPBUFLEN 256
static char tmpbuf[TMPBUFLEN];

#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

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

/* Read a line from a stream to a buffer. Any eol chars are removed
 * from the file and the length of the string excluding '\0' is returned */
static int
getline(char *buf, size_t len, FILE *fh)
{
   size_t i = 0;
   int ch;

   ch = getc(fh);
   while (ch != '\n' && ch != '\r' && ch != EOF && i < len - 1) {
      buf[i++] = ch;
      ch = getc(fh);
   }
   if (ch == '\n' || ch == '\r') {
      /* remove any further eol chars (for DOS text files) */
      do {
         ch = getc(fh);
      } while (ch == '\n' || ch == '\r');
      ungetc(ch, fh); /* we don't want it, so put it back */
   }
   buf[i] = '\0';
   return i;
}

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') {
      /* remove any further eol chars (for DOS text files) */
      do {
         ch = getc(fh);
      } while (ch == '\n' || ch == '\r');
      ungetc(ch, fh); /* we don't want it, so put it back */
   }
   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

img *
img_open_survey(const char *fnm, const char *survey)
{
   img *pimg;
   size_t len;

   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", NULL);
   if (pimg->fh == NULL) {
      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 */
   pimg->label_len = 0;

   pimg->survey = NULL;
   pimg->survey_len = 0;

   pimg->title = NULL;
   if (survey) {
      len = strlen(survey);
      if (len) {
         if (survey[len - 1] == '.') len--;
         if (len) {
            char *p;
            pimg->survey = osmalloc(len + 2);
            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 = osstrdup(p); /* FIXME: osstrdup for non IMG_HOSTED case */
            pimg->survey[len] = '.';
            pimg->survey[len + 1] = '\0';
         }
      }
      pimg->survey_len = len;
   }

   /* [version -1] 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 (len > LITLEN(EXT_SVX_POS) + 1 &&
       fnm[len - LITLEN(EXT_SVX_POS) - 1] == FNM_SEP_EXT &&
       strcmp(fnm + len - LITLEN(EXT_SVX_POS), EXT_SVX_POS) == 0) {
      pimg->version = -1;
      if (!survey) pimg->title = baseleaf_from_fnm(fnm);
      /* FIXME: osstrdup for non IMG_HOSTED case */
      pimg->datestamp = osstrdup(TIMENA);
      pimg->start = 0;
      return pimg;
   }

   getline(tmpbuf, TMPBUFLEN, pimg->fh); /* id string */
   if (strcmp(tmpbuf, "Survex 3D Image File") != 0) {
      img_errno = IMG_BADFORMAT;
      goto error;
   }

   getline(tmpbuf, TMPBUFLEN, pimg->fh); /* file format version */
   pimg->version = (tolower(*tmpbuf) == 'b'); /* binary file iff B/b prefix */
   /* knock off the 'B' or 'b' if it's there */
   if (strcmp(tmpbuf + pimg->version, "v0.01") == 0) {
      /* nothing special to do */
   } else if (pimg->version == 0 && tmpbuf[0] == 'v') {
      if (tmpbuf[1] < '2' || tmpbuf[1] > '3' || tmpbuf[2] != '\0') {
         img_errno = IMG_TOONEW;
         goto error;
      }
      pimg->version = tmpbuf[1] - '0';
   } else {
      img_errno = IMG_BADFORMAT;
      goto error;
   }

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

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

void
img_rewind(img *pimg)
{
   fseek(pimg->fh, pimg->start, SEEK_SET);
   clearerr(pimg->fh);
   /* [version -1] 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 */
   pimg->label_len = 0;
}

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);
      img_errno = IMG_CANTOPENOUT;
      return 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 > 2) ? 3 : 2;
      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 {
      /* output current date and time in format specified */
      strftime(tmpbuf, TMPBUFLEN, TIMEFMT, localtime(&tm));
      fputsnl(tmpbuf, pimg->fh);
   }
   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;

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

static int
read_coord(FILE *fh, img_point *pt)
{
   ASSERT(fh);
   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;
}

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

   if (pimg->version == 3) {
      int opt;
      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 */
      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;
            /* zero prefix using "0" */
            if (pimg->label_len <= 16) {
               img_errno = IMG_BADFORMAT;
               return img_BAD;
            }
            c = pimg->label_len - 16;
            opt &= 0x07;
            while (pimg->label_buf[c] != '.' || --opt > 0) {
               if (--c < 0) {
                  /* zero prefix using "0" */
                  img_errno = IMG_BADFORMAT;
                  return img_BAD;
               }
            }
            c++;
            pimg->label_buf[c] = '\0';
            pimg->label_len = c;
            goto again3;
         }
         if (opt == 15) {
            result = img_MOVE;
            break;
         }
         /* 16-31 mean remove (n - 15) characters from the prefix */
         pimg->label_len -= (opt - 15);
         /* zero prefix using 0 */
         if (pimg->label_len <= 0) {
            img_errno = IMG_BADFORMAT;
            return img_BAD;
         }
         goto again3;
       case 1: case 2: {
         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;
            }
         }

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

         result = opt & 0x40 ? img_LABEL : img_LINE;

         if (pimg->survey_len) {
            size_t l = pimg->survey_len;
            const char *s = pimg->label_buf;
            if (result == img_LINE) {
               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;
               }
            } else {
               if (strncmp(pimg->survey, s, l + 1) != 0) {
                  fseek(pimg->fh, 12, SEEK_CUR);
                  goto again3;
               }
            }
            pimg->label += l;
            /* skip the dot if there */
            if (*pimg->label) pimg->label++;
         }

         if (result == img_LINE && 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;
   } else 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 (fseek(pimg->fh, 12, SEEK_CUR) == -1) {
            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 (len >= (long)pimg->buf_len) {
            pimg->label = pimg->label_buf = xosrealloc(pimg->label_buf,
                                                       len + 1);
            if (!pimg->label_buf) {
               img_errno = IMG_OUTOFMEMORY;
               return img_BAD;
            }
            pimg->buf_len = len + 1;
         }
         if (fread(pimg->label_buf, len, 1, pimg->fh) != 1) {
            img_errno = feof(pimg->fh) ? IMG_BADFORMAT : IMG_READERROR;
            return img_BAD;
         }
         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 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 {
         /* Stop if nothing found */
         if (fscanf(pimg->fh, "%s", tmpbuf) < 1) return img_STOP;
         if (strcmp(tmpbuf, "move") == 0)
            result = img_MOVE;
         else if (strcmp(tmpbuf, "draw") == 0)
            result = img_LINE;
         else if (strcmp(tmpbuf, "line") == 0) {
            /* set flag to indicate to process second triplet as LINE */
            pimg->pending = 1;
            result = img_MOVE;
         } else if (strcmp(tmpbuf, "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(tmpbuf, "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) {
                  pimg->buf_len += pimg->buf_len;
                  pimg->label_buf = xosrealloc(pimg->label_buf, pimg->buf_len);
               }
               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++;

            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 {
      /* version -1: .pos file */
      size_t off;
      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;
         }
         pimg->buf_len += pimg->buf_len;
         pimg->label_buf = xosrealloc(pimg->label_buf, pimg->buf_len);
      }

      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;
   }
}

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;
   }

   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(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 (n >= pimg->buf_len) {
      char *p = xosrealloc(pimg->label_buf, n + 1);
      if (!p) return 0; /* FIXME: distinguish out of memory... */
      pimg->label_buf = p;
      pimg->buf_len = n + 1;
   }
   memcpy(pimg->label_buf + len, s + len, n - len + 1);

   return !ferror(pimg->fh);
}

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_MOVE:
         opt = 15;
         break;
       case img_LINE:
         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;
      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);
   }
}

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;
             case 3:
               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;
         img_errno = pimg->fRead ? IMG_READERROR : IMG_WRITEERROR;
      }
      osfree(pimg->label_buf);
      osfree(pimg);
   }
   return result;
}