util-linux/util-linux-agetty-s-option.patch

git diff v2.18..HEAD login-utils/agetty.c login-utils/agetty.8

agetty: fix -s option (baud rate setup)
agetty: add -c to reuse cflags
agetty: add -s to reuse existing baud rate

diff --git a/login-utils/agetty.8 b/login-utils/agetty.8
index 8761374..084086f 100644
--- a/login-utils/agetty.8
+++ b/login-utils/agetty.8
@@ -3,7 +3,7 @@
 agetty \- alternative Linux getty
 
 .SH SYNOPSIS
-.BR "agetty " [\-8ihLmnUw]
+.BR "agetty " [\-c8ihLmnsUw]
 .RI "[-f " issue_file ]
 .RI "[-l " login_program ]
 .RI "[-I " init ]
@@ -12,16 +12,6 @@ agetty \- alternative Linux getty
 .I port
 .I baud_rate,...
 .RI [ term ]
-.br
-.BR "agetty " [\-8ihLmnw]
-.RI "[-f " issue_file ]
-.RI "[-l " login_program ]
-.RI "[-I " init ]
-.RI "[-t " timeout ]
-.RI "[-H " login_host ]
-.I baud_rate,...
-.I port
-.RI [ term ]
 
 .SH DESCRIPTION
 .ad
@@ -92,6 +82,10 @@ whatever init(8) may have set, and is inherited by login and the shell.
 .fi
 .ad
 .TP
+\-c
+Don't reset terminal cflags (control modes). See \fItermios(3)\fP for more
+details.
+.TP
 \-8
 Assume that the tty is 8-bit clean, hence disable parity detection.
 .TP
@@ -163,6 +157,10 @@ Force the line to be a local line with no need for carrier detect. This can
 be useful when you have a locally attached terminal where the serial line
 does not set the carrier detect signal.
 .TP
+\-s
+Try to keep the existing baud rate. The baud rates from
+the command line are used when agetty receives a BREAK character.
+.TP
 \-U
 Turn on support for detecting an uppercase only terminal.  This setting will
 detect a login name containing only capitals as indicating an uppercase
diff --git a/login-utils/agetty.c b/login-utils/agetty.c
index 39a1fd3..9d463ce 100644
--- a/login-utils/agetty.c
+++ b/login-utils/agetty.c
@@ -133,6 +133,8 @@ struct options {
 #define F_CUSTISSUE	(1<<6)		/* give alternative issue file */
 #define F_NOPROMPT	(1<<7)		/* don't ask for login name! */
 #define F_LCUC		(1<<8)		/* Support for *LCUC stty modes */
+#define F_KEEPSPEED	(1<<9)		/* Follow baud rate from kernel */
+#define F_KEEPCFLAGS	(1<<10)		/* Reuse c_cflags setup from kernel */
 
 /* Storage for things detected while the login name was read. */
 
@@ -203,7 +205,7 @@ void parse_args P_((int argc, char **argv, struct options *op));
 void parse_speeds P_((struct options *op, char *arg));
 void update_utmp P_((char *line));
 void open_tty P_((char *tty, struct termios *tp, int local));
-void termio_init P_((struct termios *tp, int speed, struct options *op));
+void termio_init P_((struct termios *tp, struct options *op));
 void auto_baud P_((struct termios *tp));
 void do_prompt P_((struct options *op, struct termios *tp));
 void next_speed P_((struct termios *tp, struct options *op));
@@ -297,7 +299,7 @@ main(argc, argv)
     tcsetpgrp(0, getpid());
     /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
     debug("calling termio_init\n");
-    termio_init(&termios, options.speeds[FIRST_SPEED], &options);
+    termio_init(&termios, &options);
 
     /* write the modem init string and DON'T flush the buffers */
     if (options.flags & F_INITSTRING) {
@@ -373,8 +375,11 @@ parse_args(argc, argv, op)
     extern int optind;			/* getopt */
     int     c;
 
-    while (isascii(c = getopt(argc, argv, "8I:LH:f:hil:mt:wUn"))) {
+    while (isascii(c = getopt(argc, argv, "8cI:LH:f:hil:mst:wUn"))) {
 	switch (c) {
+	case 'c':
+	    op->flags |= F_KEEPCFLAGS;
+	    break;
 	case '8':
 	    op->eightbits = 1;
 	    break;
@@ -443,6 +448,9 @@ parse_args(argc, argv, op)
 	case 'n':
 	    op->flags |= F_NOPROMPT;
 	    break;
+	case 's':
+	    op->flags |= F_KEEPSPEED;		/* keep kernel defined speed */
+	    break;
 	case 't':				/* time out */
 	    if ((op->timeout = atoi(optarg)) <= 0)
 		error(_("bad timeout value: %s"), optarg);
@@ -691,11 +699,17 @@ char gbuf[1024];
 char area[1024];
 
 void
-termio_init(tp, speed, op)
+termio_init(tp, op)
      struct termios *tp;
-     int     speed;
      struct options *op;
 {
+    speed_t ispeed, ospeed;
+
+    if (op->flags & F_KEEPSPEED) {
+	ispeed = cfgetispeed(tp);		/* save the original setting */
+	ospeed = cfgetospeed(tp);
+    } else
+	ospeed = ispeed = op->speeds[FIRST_SPEED];
 
     /*
      * Initial termios settings: 8-bit characters, raw-mode, blocking i/o.
@@ -706,14 +720,21 @@ termio_init(tp, speed, op)
     /* flush input and output queues, important for modems! */
     (void) tcflush(0, TCIOFLUSH);
 
-    tp->c_cflag = CS8 | HUPCL | CREAD;
-    cfsetispeed(tp, speed);
-    cfsetospeed(tp, speed);
+    tp->c_iflag = tp->c_lflag = tp->c_oflag = 0;
+
+    if (!(op->flags & F_KEEPCFLAGS))
+	tp->c_cflag = CS8 | HUPCL | CREAD | (tp->c_cflag & CLOCAL);
+
+    /* Note that the speed is stored in the c_cflag termios field, so we have
+     * set the speed always when the cflag se reseted.
+     */
+    cfsetispeed(tp, ispeed);
+    cfsetospeed(tp, ospeed);
+
     if (op->flags & F_LOCAL) {
 	tp->c_cflag |= CLOCAL;
     }
 
-    tp->c_iflag = tp->c_lflag = tp->c_oflag = 0;
 #ifdef HAVE_STRUCT_TERMIOS_C_LINE
     tp->c_line = 0;
 #endif
@@ -973,9 +994,18 @@ next_speed(tp, op)
      struct termios *tp;
      struct options *op;
 {
-    static int baud_index = FIRST_SPEED;/* current speed index */
+    static int baud_index = -1;
+
+    if (baud_index == -1)
+	/*
+	 * if the F_KEEPSPEED flags is set then the FIRST_SPEED is not
+	 * tested yet (see termio_init()).
+	 */
+	baud_index = (op->flags & F_KEEPSPEED) ? FIRST_SPEED :
+		                                 1 % op->numspeed;
+    else
+	baud_index = (baud_index + 1) % op->numspeed;
 
-    baud_index = (baud_index + 1) % op->numspeed;
     cfsetispeed(tp, op->speeds[baud_index]);
     cfsetospeed(tp, op->speeds[baud_index]);
     (void) tcsetattr(0, TCSANOW, tp);
@@ -1203,7 +1233,7 @@ bcode(s)
 void
 usage()
 {
-    fprintf(stderr, _("Usage: %s [-8hiLmUw] [-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 [-8hiLmsUw] [-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);
 }