agetty: 8 bit characters on the Linux console lead to input corruption

8 bit characters on the Linux console lead to input corruption (e.g.
German umlauts). This is easily reproducable by inserting a login name with
umlaut and typing backspace afterwards.

agetty supports tty parity, which leads to getty treating these characters
as a 7bit char with set parity.

This patch by Samuel Thibault adds a new option -8 which disables parity
detection for ttys not used for serial logins.

| Note: With this patch, 8bit characters are just silently dropped (that's
| the expected getty behavior), this is quite neat since you then don't
| even need to backspace your 8bit characters :)

Signed-off-by: LaMont Jones <lamont@mmjgroup.com>

diff --git a/login-utils/agetty.8 b/login-utils/agetty.8
index b1ade5feb99be5b275d5e764c31db1b86fd29e1d..5bde294b954d108ca3bed23ceb5f2cba62708b3d 100644 (file)
--- a/login-utils/agetty.8
+++ b/login-utils/agetty.8
@@ -3,7 +3,7 @@
 agetty \- alternative Linux getty
 
 .SH SYNOPSIS
-.BR "agetty " [\-ihLmnw]
+.BR "agetty " [\-8ihLmnw]
 .RI "[-f " issue_file ]
 .RI "[-l " login_program ]
 .RI "[-I " init ]
@@ -13,7 +13,7 @@ agetty \- alternative Linux getty
 .I baud_rate,...
 .RI [ term ]
 .br
-.BR "agetty " [\-ihLmnw]
+.BR "agetty " [\-8ihLmnw]
 .RI "[-f " issue_file ]
 .RI "[-l " login_program ]
 .RI "[-I " init ]
@@ -92,6 +92,9 @@ whatever init(8) may have set, and is inherited by login and the shell.
 .fi
 .ad
 .TP
+\-8
+Assume that the tty is 8-bit clean, hence disable parity detection.
+.TP
 \-h
 Enable hardware (RTS/CTS) flow control. It is left up to the
 application to disable software (XON/XOFF) flow protocol where

diff --git a/login-utils/agetty.c b/login-utils/agetty.c
index b7ae536f0e397f774d0ce5f593757aafcc9382ff..d5359d2c43bef60a6285c069d197a15157fbb8b6 100644 (file)
--- a/login-utils/agetty.c
+++ b/login-utils/agetty.c
@@ -154,6 +154,7 @@ struct options {
     char   *issue;                     /* alternative issue file */
     int     numspeed;                  /* number of baud rates to try */
     int     speeds[MAX_SPEED];         /* baud rates to be tried */
+    int     eightbits;                 /* assume 8bit-clean tty */
 };
 
 #define        F_PARSE         (1<<0)          /* process modem status messages */
@@ -411,8 +412,11 @@ parse_args(argc, argv, op)
     extern int optind;                 /* getopt */
     int     c;
 
-    while (isascii(c = getopt(argc, argv, "I:LH:f:hil:mt:wn"))) {
+    while (isascii(c = getopt(argc, argv, "8I:LH:f:hil:mt:wn"))) {
        switch (c) {
+       case '8':
+           op->eightbits = 1;
+           break;
        case 'I':
            if (!(op->initstring = malloc(strlen(optarg)))) {
                error(_("can't malloc initstring"));
@@ -1061,10 +1065,11 @@ char   *get_logname(op, cp, tp)
 
            if ((c == 0) && op->numspeed > 1)
                return (0);
-
            /* Do parity bit handling. */
 
-           if (c != (ascval = (c & 0177))) {   /* "parity" bit on ? */
+           if (op->eightbits) {
+               ascval = c;
+           } else if (c != (ascval = (c & 0177))) {    /* "parity" bit on */
                for (bits = 1, mask = 1; mask & 0177; mask <<= 1)
                    if (mask & ascval)
                        bits++;                 /* count "1" bits */
@@ -1225,7 +1230,7 @@ bcode(s)
 void
 usage()
 {
-    fprintf(stderr, _("Usage: %s [-hiLmw] [-l login_program] [-t timeout] [-I initstring] [-H login_host] baud_rate,... line [termtype]\nor\t[-hiLmw] [-l login_program] [-t timeout] [-I initstring] [-H login_host] line baud_rate,... [termtype]\n"), progname);
+    fprintf(stderr, _("Usage: %s [-8hiLmw] [-l login_program] [-t timeout] [-I initstring] [-H login_host] baud_rate,... line [termtype]\nor\t[-hiLmw] [-l login_program] [-t timeout] [-I initstring] [-H login_host] line baud_rate,... [termtype]\n"), progname);
     exit(1);
 }