Don't loop endlessly on EOF

[unix-history] / usr / src / usr.bin / tset / term.c

/*-
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*/

#ifndef lint
static char sccsid[] = "@(#)term.c      5.4 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <errno.h>
#include <ttyent.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "extern.h"

char    tbuf[1024];                     /* Termcap entry. */

char    *askuser __P((char *));
char    *ttys __P((char *));

/*
* Figure out what kind of terminal we're dealing with, and then read in
* its termcap entry.
*/
char *
get_termcap_entry(userarg, tcapbufp)
       char *userarg, **tcapbufp;
{
       struct ttyent *t;
       int rval;
       char *p, *ttype, *ttypath;

       if (userarg) {
               ttype = userarg;
               goto found;
       }

       /* Try the environment. */
       if (ttype = getenv("TERM"))
               goto map;

       /* Try ttyname(3); check for dialup or other mapping. */
       if (ttypath = ttyname(STDERR_FILENO)) {
               if (p = rindex(ttypath, '/'))
                       ++p;
               else
                       p = ttypath;
               if ((t = getttynam(p))) {
                       ttype = t->ty_type;
                       goto map;
               }
       }

       /* If still undefined, use "unknown". */
       ttype = "unknown";

map:    ttype = mapped(ttype);

       /*
        * If not a path, remove TERMCAP from the environment so we get a
        * real entry from /etc/termcap.  This prevents us from being fooled
        * by out of date stuff in the environment.
        */
found:  if ((p = getenv("TERMCAP")) != NULL && *p != '/')
               unsetenv("TERMCAP");

       /*
        * ttype now contains a pointer to the type of the terminal.
        * If the first character is '?', ask the user.
        */
       if (ttype[0] == '?')
               ttype = askuser(ttype + 1);

       /* Find the termcap entry.  If it doesn't exist, ask the user. */
       while ((rval = tgetent(tbuf, ttype)) == 0) {
               (void)fprintf(stderr,
                   "tset: terminal type %s is unknown\n", ttype);
               ttype = askuser(NULL);
       }
       if (rval == -1)
               err("termcap: %s", strerror(errno ? errno : ENOENT));
       *tcapbufp = tbuf;
       return (ttype);
}

/* Prompt the user for a terminal type. */
char *
askuser(dflt)
       char *dflt;
{
       static char answer[256];
       char *p;

       /* We can get recalled; if so, don't continue uselessly. */
       if (feof(stdin) || ferror(stdin)) {
               (void)fprintf(stderr, "\n");
               exit(1);
       }
       for (;;) {
               if (dflt)
                       (void)fprintf(stderr, "Terminal type? [%s] ", dflt);
               else
                       (void)fprintf(stderr, "Terminal type? ");
               (void)fflush(stderr);

               if (fgets(answer, sizeof(answer), stdin) == NULL) {
                       if (dflt == NULL) {
                               (void)fprintf(stderr, "\n");
                               exit(1);
                       }
                       return (dflt);
               }

               if (p = index(answer, '\n'))
                       *p = '\0';
               return (answer[0] ? answer : dflt);
       }
}