Ultrix3.1 bug in ioctl(2)?
Piet Tutelaers
rcpt at tuegate.tue.nl
Tue May 29 07:14:09 AEST 1990
The next program shows a bug I encountered in ULTRIX 3.1 when I tried to
install npasswd(1), a public replacement for passwd(1). The password should
obviously not be echo'ed when typed in by the user. To realise this the
program npasswd(1) uses ioctl() calls. The next program compiled with the
compile time flag -DULTRIX_BUG shows the essential part of npasswd(1) that
handles the disabling of the echoing. The program comes up with the next
error message:
getpass(save get): Not a typewriter
By trial and error we find out that the old fashioned gtty() and stty()
calls corrects the ill behaviour of the program (the shown message and no
echoing if the errors are ignored). This can be demonstrated by compiling
the program without the `-DULTRIX_BUG' option.
I consider this as a BUG, perhaps a known one. I would like to know if
ULTRIX 4.0 solves this problem? Who can test this?
-- Piet
rcpt at urc.tue.nl
------------------------------------noecho.c---------------------------
#include <errno.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/sgtty.h>
#include <stdio.h>
#include <fcntl.h>
#include "version.h"
char pbuf[16]; /* Password read buffer 1 */
/*
* passwd - change the password for a user.
*
* This program impliments the 'passwd' command.
*/
main(argc, argv)
int argc;
char *argv[];
{
void getpass();
getpass("New password: ");
}
struct sgttyb saved_tty_mode;
#define ERR -1
/*
* The system getpass() throws away all but the first 8 characters
* of a password string. If this isn't enough for you, use this
* routine instead. This code assumes that stdin is the terminal.
*/
void getpass(prompt)
char *prompt;
{
struct sgttyb saved, /* Saved tty characteristics */
noecho; /* No-echo tty characteristics */
char *index();
int tp;
static char ib[64]; /* Input buffer */
char *rc; /* Temp */
if ((tp = open("/dev/tty", O_RDONLY)) < 0)
{
perror("getpass(open)");
return;
}
#ifdef ULTRIX_BUG
if (ioctl(tp, TIOCGETP, &saved)==ERR)
{
perror("getpass(save get)");
return;
}
#else
gtty(tp, &saved);
#endif
#ifdef ULTRIX_BUG
if (ioctl(tp, TIOCGETP, &noecho)==ERR)
{
perror("getpass(noechoget)");
return;
}
#else
gtty(tp, &noecho);
#endif
noecho.sg_flags &= ~ECHO;
#ifdef ULTRIX_BUG
if (ioctl(tp, TIOCSETP, &noecho)==ERR)
{
perror("getpass(noecho set)");
return;
}
#else
stty(tp, &noecho);
#endif
fputs(prompt, stderr);
#ifdef ULTRIX_BUG
rc = fgets(ib, sizeof(ib), stdin);
#else
rc = read(tp, (char *)ib, (int) sizeof(ib));
#endif
putc('\n', stderr);
#ifdef ULTRIX_BUG
(void) ioctl(tp, TIOCSETP, &saved);
#else
stty(tp, &saved);
#endif
close(tp);
fprintf(stderr, "password was:%s\n", ib);
}
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