source: trunk/athena/bin/discuss/libds/tunix.c @ 22404

/*
 *
 *      Copyright (C) 1988, 1989 by the Massachusetts Institute of Technology
 *      Developed by the MIT Student Information Processing Board (SIPB).
 *      For copying information, see the file mit-copyright.h in this release.
 *
 */
/*
 *
 *      $Id: tunix.c,v 1.9 2006-03-10 07:11:38 ghudson Exp $
 *
 * tunix.c -- procedures to have tfiles work from unix files.
 *
 *
 */
#ifndef lint
static char rcsid_tunix_c[] =
    "$Id: tunix.c,v 1.9 2006-03-10 07:11:38 ghudson Exp $";
#endif /* lint */

#define min(A, B) ((A) < (B) ? (A) : (B))
#define NIL 0

#define SUCCESS 1

#include <stdio.h>
#include <stdlib.h>
#include <discuss/tfile.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>

#define NL '\n'

struct tunix_state {
     char last_char;
};

/*
 *
 * tunix () -- This is the handler procedure, that handles tfile requests.
 *
 */
int tunix (op, infop, info, argp, argn, result)
int op, *info, argn, *result;
char **infop, *argp;
{
     int numread,numwrite;
     struct tunix_state *ts;

     *result = 0;               /* optimist */
     ts = (struct tunix_state *) *infop;

     switch (op) {
     case TFOPEN:               /* argp is pointer to modes */
          return (0);

     case TFCLOSE:
          return (0);

     case TFREAD:
          numread = read (*info, argp, argn);
          if (numread < 0) {
               *result = errno;
               return (-1);
          }
          return(numread);

     case TFWRITE:
          numwrite = write (*info, argp, argn);
          if (numwrite < 0) {
               *result = errno;
               return (-1);
          }
          /* save last character written to file, so we can force NL */
          ts -> last_char = argp [numwrite-1];
          return(numwrite);

     case TFDESTROY:
          free (*infop);
          return (0);

     case TFCONTROL:
          if (argn == TFC_FORCE_NL) {                   /* force a NL at this point */
               if (ts -> last_char != NL) {
                    ts -> last_char = NL;
                    write (*info, &(ts -> last_char), 1);
               }
          }
          return (0);

     default:
          *result = EBADF;
          return (-1);
     }
}

/*
 *
 * unix_tfile (tfs, us)
 *
 */
tfile unix_tfile (desc)
int desc;
{
     struct stat buf;
     struct tunix_state *ts;

     if (fstat (desc, &buf) < 0)
          return (NIL);

     ts = (struct tunix_state *) malloc (sizeof (struct tunix_state));
     ts -> last_char = 0;

     return (tcreate ((int) buf.st_size, (char *) ts, desc, tunix));
}