/*
   File names management
*/

#include "common.h"
#include "file.h"

#define FREE	'-'
#define BUSY	'+'

/* Assign unique file name */
Global(CharPtr) AssignFileName(void) {
  int pos,c;
  FILE PNTR stream;
  stream=FileOpen(GetParam(SFS_FILES,"NAMES"),"r+b");
  /*
    The following code behaves differently
    when compiled by Borland C 3.1 and by cc (Unix)
    and the first char in the stream is '-'.
      pos=-1;
      fscanf(stream,"%*[+]%n",&pos);
      if (pos>=0) ...
    So we have use 'portable' solution...
  */
  for (pos=0; (c=fgetc(stream),c!=EOF); pos++)
    if (c==FREE) break;
  if (c==FREE) fseek(stream,pos,SEEK_SET);
  else {
    fseek(stream,0,SEEK_END);
    pos=(int)ftell(stream);
  }
  fputc(BUSY,stream);
  FileClose(stream);
  return GetParam(SFS_FILES,"FORMAT",pos);
}

/* Mark given file name as free */
Global(void) FreeFileName(CharPtr name) {
  int num;
  FILE PNTR stream;
  stream=FileOpen(GetParam(SFS_FILES,"NAMES"),"r+b");
  num=-1;
  sscanf(name,GetParamString(SFS_FILES,"FORMAT"),&num);
  if (num>=0)
    if (fseek(stream,num,SEEK_SET)==0)
      fputc(FREE,stream);
  FileClose(stream);
}