X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/blobdiff_plain/e2c19b91957f97c7290af3b2127ff14e25b7e3e9..c6d444031eb2fcbf0551a3b7d5c366bb14a339c5:/usr/src/sys/kern/tty.c

diff --git a/usr/src/sys/kern/tty.c b/usr/src/sys/kern/tty.c
index 0e6925c82a..0bdaa200a9 100644
--- a/usr/src/sys/kern/tty.c
+++ b/usr/src/sys/kern/tty.c
@@ -1,21 +1,25 @@
-/*	tty.c	6.7	83/10/01	*/
+/*
+ * Copyright (c) 1982, 1986 Regents of the University of California.
+ * All rights reserved.  The Berkeley software License Agreement
+ * specifies the terms and conditions for redistribution.
+ *
+ *	@(#)tty.c	7.9 (Berkeley) %G%
+ */
 
 #include "../machine/reg.h"
 
-#include "../h/param.h"
-#include "../h/systm.h"
-#include "../h/dir.h"
-#include "../h/user.h"
-#include "../h/ioctl.h"
-#include "../h/tty.h"
-#include "../h/proc.h"
-#include "../h/inode.h"
-#include "../h/file.h"
-#include "../h/conf.h"
-#include "../h/buf.h"
-#include "../h/dk.h"
-#include "../h/uio.h"
-#include "../h/kernel.h"
+#include "param.h"
+#include "systm.h"
+#include "dir.h"
+#include "user.h"
+#include "ioctl.h"
+#include "tty.h"
+#include "proc.h"
+#include "file.h"
+#include "conf.h"
+#include "dkstat.h"
+#include "uio.h"
+#include "kernel.h"
 
 /*
  * Table giving parity for characters and indicating
@@ -102,6 +106,8 @@ struct	ttychars ttydefaults = {
 	CBRK,	CSUSP,	CDSUSP, CRPRNT, CFLUSH, CWERASE,CLNEXT
 };
 
+extern struct tty *constty;		/* temporary virtual console */
+
 ttychars(tp)
 	struct tty *tp;
 {
@@ -123,10 +129,10 @@ ttywflush(tp)
 ttywait(tp)
 	register struct tty *tp;
 {
-	register int s = spl5();
+	register int s = spltty();
 
 	while ((tp->t_outq.c_cc || tp->t_state&TS_BUSY) &&
-	    tp->t_state&TS_CARR_ON && tp->t_oproc) {	/* kludge for pty */
+	    tp->t_state&TS_CARR_ON && tp->t_oproc) {
 		(*tp->t_oproc)(tp);
 		tp->t_state |= TS_ASLEEP;
 		sleep((caddr_t)&tp->t_outq, TTOPRI);
@@ -142,7 +148,7 @@ ttyflush(tp, rw)
 {
 	register s;
 
-	s = spl6();
+	s = spltty();
 	if (rw & FREAD) {
 		while (getc(&tp->t_canq) >= 0)
 			;
@@ -158,7 +164,6 @@ ttyflush(tp, rw)
 	if (rw & FREAD) {
 		while (getc(&tp->t_rawq) >= 0)
 			;
-		tp->t_delct = 0;
 		tp->t_rocount = 0;
 		tp->t_rocol = 0;
 		tp->t_state &= ~TS_LOCAL;
@@ -183,7 +188,8 @@ ttyblock(tp)
 	 * Block further input iff:
 	 * Current input > threshold AND input is available to user program
 	 */
-	if (x >= TTYHOG/2 && (tp->t_delct>0 || (tp->t_flags&(RAW|CBREAK)))) {
+	if (x >= TTYHOG/2 && 
+	    ((tp->t_flags & (RAW|CBREAK)) || (tp->t_canq.c_cc > 0))) {
 		if (putc(tp->t_stopc, &tp->t_outq)==0) {
 			tp->t_state |= TS_TBLOCK;
 			ttstart(tp);
@@ -216,13 +222,9 @@ ttrstrt(tp)
 ttstart(tp)
 	register struct tty *tp;
 {
-	register s;
 
-	s = spl5();
-	if ((tp->t_state & (TS_TIMEOUT|TS_TTSTOP|TS_BUSY)) == 0 &&
-	    tp->t_oproc)		/* kludge for pty */
+	if (tp->t_oproc)		/* kludge for pty */
 		(*tp->t_oproc)(tp);
-	splx(s);
 }
 
 /*
@@ -238,10 +240,10 @@ ttioctl(tp, com, data, flag)
 	int s;
 	register int newflags;
 
+
 	/*
 	 * If the ioctl involves modification,
-	 * insist on being able to write the device,
-	 * and hang if in the background.
+	 * hang if in the background.
 	 */
 	switch (com) {
 
@@ -256,18 +258,17 @@ ttioctl(tp, com, data, flag)
 	case TIOCLBIC:
 	case TIOCLSET:
 	case TIOCSTI:
-#define bit(a) (1<<(a-1))
+	case TIOCSWINSZ:
 		while (tp->t_line == NTTYDISC &&
 		   u.u_procp->p_pgrp != tp->t_pgrp && tp == u.u_ttyp &&
 		   (u.u_procp->p_flag&SVFORK) == 0 &&
-		   !(u.u_procp->p_sigignore & bit(SIGTTOU)) &&
-		   !(u.u_procp->p_sigmask & bit(SIGTTOU))) {
+		   !(u.u_procp->p_sigignore & sigmask(SIGTTOU)) &&
+		   !(u.u_procp->p_sigmask & sigmask(SIGTTOU))) {
 			gsignal(u.u_procp->p_pgrp, SIGTTOU);
 			sleep((caddr_t)&lbolt, TTOPRI);
 		}
 		break;
 	}
-#undef	bit
 
 	/*
 	 * Process the ioctl.
@@ -286,20 +287,18 @@ ttioctl(tp, com, data, flag)
 
 		if ((unsigned) t >= nldisp)
 			return (ENXIO);
-		s = spl5();
-		if (tp->t_line)
+		if (t != tp->t_line) {
+			s = spltty();
 			(*linesw[tp->t_line].l_close)(tp);
-		if (t)
 			error = (*linesw[t].l_open)(dev, tp);
-		splx(s);
-		if (error) {
-			s = spl5();
-			if (tp->t_line)
+			if (error) {
 				(void) (*linesw[tp->t_line].l_open)(dev, tp);
+				splx(s);
+				return (error);
+			}
+			tp->t_line = t;
 			splx(s);
-			return (error);
 		}
-		tp->t_line = t;
 		break;
 	}
 
@@ -338,7 +337,7 @@ ttioctl(tp, com, data, flag)
 		break;
 
 	case TIOCSTOP:
-		s = spl5();
+		s = spltty();
 		if ((tp->t_state&TS_TTSTOP) == 0) {
 			tp->t_state |= TS_TTSTOP;
 			(*cdevsw[major(tp->t_dev)].d_stop)(tp, 0);
@@ -347,7 +346,7 @@ ttioctl(tp, com, data, flag)
 		break;
 
 	case TIOCSTART:
-		s = spl5();
+		s = spltty();
 		if ((tp->t_state&TS_TTSTOP) || (tp->t_flags&FLUSHO)) {
 			tp->t_state &= ~TS_TTSTOP;
 			tp->t_flags &= ~FLUSHO;
@@ -360,6 +359,8 @@ ttioctl(tp, com, data, flag)
 	 * Simulate typing of a character at the terminal.
 	 */
 	case TIOCSTI:
+		if (u.u_uid && (flag & FREAD) == 0)
+			return (EPERM);
 		if (u.u_uid && u.u_ttyp != tp)
 			return (EACCES);
 		(*linesw[tp->t_line].l_rint)(*(char *)data, tp);
@@ -374,7 +375,7 @@ ttioctl(tp, com, data, flag)
 		tp->t_ispeed = sg->sg_ispeed;
 		tp->t_ospeed = sg->sg_ospeed;
 		newflags = (tp->t_flags&0xffff0000) | (sg->sg_flags&0xffff);
-		s = spl5();
+		s = spltty();
 		if (tp->t_flags&RAW || newflags&RAW || com == TIOCSETP) {
 			ttywait(tp);
 			ttyflush(tp, FREAD);
@@ -461,18 +462,58 @@ ttioctl(tp, com, data, flag)
 		break;
 
 	case TIOCLGET:
-		*(int *)data = tp->t_flags >> 16;
+		*(int *)data = ((unsigned)tp->t_flags) >> 16;
 		break;
 
-	/* should allow SPGRP and GPGRP only if tty open for reading */
-	case TIOCSPGRP:
-		tp->t_pgrp = *(int *)data;
+	/*
+	 * Allow SPGRP only if tty is open for reading.
+	 * Quick check: if we can find a process in the new pgrp,
+	 * this user must own that process.
+	 * SHOULD VERIFY THAT PGRP IS IN USE AND IS THIS USER'S.
+	 */
+	case TIOCSPGRP: {
+		struct proc *p;
+		int pgrp = *(int *)data;
+
+		if (u.u_uid && (flag & FREAD) == 0)
+			return (EPERM);
+		p = pfind(pgrp);
+		if (p && p->p_pgrp == pgrp &&
+		    p->p_uid != u.u_uid && u.u_uid && !inferior(p))
+			return (EPERM);
+		tp->t_pgrp = pgrp;
 		break;
+	}
 
 	case TIOCGPGRP:
 		*(int *)data = tp->t_pgrp;
 		break;
 
+	case TIOCSWINSZ:
+		if (bcmp((caddr_t)&tp->t_winsize, data,
+		    sizeof (struct winsize))) {
+			tp->t_winsize = *(struct winsize *)data;
+			gsignal(tp->t_pgrp, SIGWINCH);
+		}
+		break;
+
+	case TIOCGWINSZ:
+		*(struct winsize *)data = tp->t_winsize;
+		break;
+
+	case TIOCCONS:
+		if (*(int *)data) {
+			if (constty != NULL)
+				return (EBUSY);
+#ifndef	UCONSOLE
+			if (!suser())
+				return (EPERM);
+#endif
+			constty = tp;
+		} else if (tp == constty)
+			constty == NULL;
+		break;
+
 	default:
 		return (-1);
 	}
@@ -498,13 +539,13 @@ ttselect(dev, rw)
 {
 	register struct tty *tp = &cdevsw[major(dev)].d_ttys[minor(dev)];
 	int nread;
-	int s = spl5();
+	int s = spltty();
 
 	switch (rw) {
 
 	case FREAD:
 		nread = ttnread(tp);
-		if (nread > 0)
+		if (nread > 0 || (tp->t_state & TS_CARR_ON) == 0)
 			goto win;
 		if (tp->t_rsel && tp->t_rsel->p_wchan == (caddr_t)&selwait)
 			tp->t_state |= TS_RCOLL;
@@ -529,6 +570,7 @@ win:
 }
 
 /*
+ * Initial open of tty, or (re)entry to line discipline.
  * Establish a process group for distribution of
  * quits and interrupts from the tty.
  */
@@ -548,12 +590,26 @@ ttyopen(dev, tp)
 		pp->p_pgrp = tp->t_pgrp;
 	}
 	tp->t_state &= ~TS_WOPEN;
-	tp->t_state |= TS_ISOPEN;
-	if (tp->t_line != NTTYDISC)
-		ttywflush(tp);
+	if ((tp->t_state & TS_ISOPEN) == 0) {
+		tp->t_state |= TS_ISOPEN;
+		bzero((caddr_t)&tp->t_winsize, sizeof(tp->t_winsize));
+		if (tp->t_line != NTTYDISC)
+			ttywflush(tp);
+	}
 	return (0);
 }
 
+/*
+ * "close" a line discipline
+ */
+ttylclose(tp)
+	register struct tty *tp;
+{
+
+	ttywflush(tp);
+	tp->t_line = 0;
+}
+
 /*
  * clean tp on last close
  */
@@ -561,19 +617,75 @@ ttyclose(tp)
 	register struct tty *tp;
 {
 
-	if (tp->t_line) {
-		ttywflush(tp);
-		tp->t_line = 0;
-		return;
-	}
+	if (constty == tp)
+		constty = NULL;
+	ttyflush(tp, FREAD|FWRITE);
 	tp->t_pgrp = 0;
-	ttywflush(tp);
 	tp->t_state = 0;
 }
 
+/*
+ * Handle modem control transition on a tty.
+ * Flag indicates new state of carrier.
+ * Returns 0 if the line should be turned off, otherwise 1.
+ */
+ttymodem(tp, flag)
+	register struct tty *tp;
+{
+
+	if ((tp->t_state&TS_WOPEN) == 0 && (tp->t_flags & MDMBUF)) {
+		/*
+		 * MDMBUF: do flow control according to carrier flag
+		 */
+		if (flag) {
+			tp->t_state &= ~TS_TTSTOP;
+			ttstart(tp);
+		} else if ((tp->t_state&TS_TTSTOP) == 0) {
+			tp->t_state |= TS_TTSTOP;
+			(*cdevsw[major(tp->t_dev)].d_stop)(tp, 0);
+		}
+	} else if (flag == 0) {
+		/*
+		 * Lost carrier.
+		 */
+		tp->t_state &= ~TS_CARR_ON;
+		if (tp->t_state & TS_ISOPEN) {
+			if ((tp->t_flags & NOHANG) == 0) {
+				gsignal(tp->t_pgrp, SIGHUP);
+				gsignal(tp->t_pgrp, SIGCONT);
+				ttyflush(tp, FREAD|FWRITE);
+				return (0);
+			}
+		}
+	} else {
+		/*
+		 * Carrier now on.
+		 */
+		tp->t_state |= TS_CARR_ON;
+		wakeup((caddr_t)&tp->t_rawq);
+	}
+	return (1);
+}
+
+/*
+ * Default modem control routine (for other line disciplines).
+ * Return argument flag, to turn off device on carrier drop.
+ */
+nullmodem(tp, flag)
+	register struct tty *tp;
+	int flag;
+{
+	
+	if (flag)
+		tp->t_state |= TS_CARR_ON;
+	else
+		tp->t_state &= ~TS_CARR_ON;
+	return (flag);
+}
+
 /*
  * reinput pending characters after state switch
- * call at spl5().
+ * call at spltty().
  */
 ttypend(tp)
 	register struct tty *tp;
@@ -638,7 +750,7 @@ ttyinput(c, tp)
 	 * Ignore any high bit added during
 	 * previous ttyinput processing.
 	 */
-	if ((tp->t_state&TS_TYPEN) == 0)
+	if ((tp->t_state&TS_TYPEN) == 0 && (t_flags&PASS8) == 0)
 		c &= 0177;
 	/*
 	 * Check for literal nexting very first
@@ -657,13 +769,13 @@ ttyinput(c, tp)
 	 */
 	if (tp->t_line == NTTYDISC) {
 		if (c == tp->t_lnextc) {
-			if (tp->t_flags&ECHO)
+			if (t_flags&ECHO)
 				ttyout("^\b", tp);
 			tp->t_state |= TS_LNCH;
 			goto endcase;
 		}
 		if (c == tp->t_flushc) {
-			if (tp->t_flags&FLUSHO)
+			if (t_flags&FLUSHO)
 				tp->t_flags &= ~FLUSHO;
 			else {
 				ttyflush(tp, FWRITE);
@@ -675,7 +787,7 @@ ttyinput(c, tp)
 			goto startoutput;
 		}
 		if (c == tp->t_suspc) {
-			if ((tp->t_flags&NOFLSH) == 0)
+			if ((t_flags&NOFLSH) == 0)
 				ttyflush(tp, FREAD);
 			ttyecho(c, tp);
 			gsignal(tp->t_pgrp, SIGTSTP);
@@ -703,13 +815,26 @@ ttyinput(c, tp)
 	 * Look for interrupt/quit chars.
 	 */
 	if (c == tp->t_intrc || c == tp->t_quitc) {
-		if ((tp->t_flags&NOFLSH) == 0)
+		if ((t_flags&NOFLSH) == 0)
 			ttyflush(tp, FREAD|FWRITE);
 		ttyecho(c, tp);
 		gsignal(tp->t_pgrp, c == tp->t_intrc ? SIGINT : SIGQUIT);
 		goto endcase;
 	}
 
+	if (tp->t_flags & LCASE && c <= 0177) {
+		if (tp->t_state&TS_BKSL) {
+			ttyrub(unputc(&tp->t_rawq), tp);
+			if (maptab[c])
+				c = maptab[c];
+			c |= 0200;
+			tp->t_state &= ~(TS_BKSL|TS_QUOT);
+		} else if (c >= 'A' && c <= 'Z')
+			c += 'a' - 'A';
+		else if (c == '\\')
+			tp->t_state |= TS_BKSL;
+	}
+
 	/*
 	 * Cbreak mode, don't process line editing
 	 * characters; check high water mark for wakeup.
@@ -718,7 +843,7 @@ ttyinput(c, tp)
 		if (tp->t_rawq.c_cc > TTYHOG) {
 			if (tp->t_outq.c_cc < TTHIWAT(tp) &&
 			    tp->t_line == NTTYDISC)
-				(void) ttyoutput(CTRL(g), tp);
+				(void) ttyoutput(CTRL('g'), tp);
 		} else if (putc(c, &tp->t_rawq) >= 0) {
 			ttwakeup(tp);
 			ttyecho(c, tp);
@@ -741,7 +866,7 @@ ttyinput(c, tp)
 		goto endcase;
 	}
 	if (c == tp->t_kill) {
-		if (tp->t_flags&CRTKIL &&
+		if (t_flags&CRTKIL &&
 		    tp->t_rawq.c_cc == tp->t_rocount) {
 			while (tp->t_rawq.c_cc)
 				ttyrub(unputc(&tp->t_rawq), tp);
@@ -792,7 +917,7 @@ ttyinput(c, tp)
 	 */
 	if (tp->t_rawq.c_cc+tp->t_canq.c_cc >= TTYHOG) {
 		if (tp->t_line == NTTYDISC)
-			(void) ttyoutput(CTRL(g), tp);
+			(void) ttyoutput(CTRL('g'), tp);
 		goto endcase;
 	}
 
@@ -816,7 +941,7 @@ ttyinput(c, tp)
 		}
 		i = tp->t_col;
 		ttyecho(c, tp);
-		if (c == tp->t_eofc && tp->t_flags&ECHO) {
+		if (c == tp->t_eofc && t_flags&ECHO) {
 			i = MIN(2, tp->t_col - i);
 			while (i > 0) {
 				(void) ttyoutput('\b', tp);
@@ -824,20 +949,17 @@ ttyinput(c, tp)
 			}
 		}
 	}
-
 endcase:
 	/*
 	 * If DEC-style start/stop is enabled don't restart
 	 * output until seeing the start character.
 	 */
-	if (tp->t_flags&DECCTQ && tp->t_state&TS_TTSTOP &&
+	if (t_flags&DECCTQ && tp->t_state&TS_TTSTOP &&
 	    tp->t_startc != tp->t_stopc)
 		return;
-
 restartoutput:
 	tp->t_state &= ~TS_TTSTOP;
 	tp->t_flags &= ~FLUSHO;
-
 startoutput:
 	ttstart(tp);
 }
@@ -882,7 +1004,7 @@ ttyoutput(c, tp)
 
 		c = 8 - (tp->t_col&7);
 		if ((tp->t_flags&FLUSHO) == 0) {
-			s = spl5();		/* don't interrupt tabs */
+			s = spltty();		/* don't interrupt tabs */
 			c -= b_to_q("        ", c, &tp->t_outq);
 			tk_nout += c;
 			splx(s);
@@ -956,9 +1078,11 @@ ttyoutput(c, tp)
 	case NEWLINE:
 		ctype = (tp->t_flags >> 8) & 03;
 		if (ctype == 1) { /* tty 37 */
-			if (*colp > 0)
-				c = max((((unsigned)*colp) >> 4) + 3,
-				    (unsigned)6);
+			if (*colp > 0) {
+				c = (((unsigned)*colp) >> 4) + 3;
+				if ((unsigned)c > 6)
+					c = 6;
+			}
 		} else if (ctype == 2) /* vt05 */
 			c = mstohz(100);
 		*colp = 0;
@@ -1013,30 +1137,29 @@ ttread(tp, uio)
 	register c, t_flags;
 	int s, first, error = 0;
 
-	if ((tp->t_state&TS_CARR_ON)==0)
-		return (EIO);
 loop:
 	/*
 	 * Take any pending input first.
 	 */
-	s = spl5();
+	s = spltty();
 	if (tp->t_flags&PENDIN)
 		ttypend(tp);
 	splx(s);
 
+	if ((tp->t_state&TS_CARR_ON)==0)
+		return (EIO);
+
 	/*
 	 * Hang process if it's in the background.
 	 */
-	while (tp == u.u_ttyp && u.u_procp->p_pgrp != tp->t_pgrp) {
-		if (u.u_signal[SIGTTIN] == SIG_IGN ||
-		    u.u_signal[SIGTTIN] == SIG_HOLD ||
-/*
-		    (u.u_procp->p_flag&SDETACH) ||
-*/
+	if (tp == u.u_ttyp && u.u_procp->p_pgrp != tp->t_pgrp) {
+		if ((u.u_procp->p_sigignore & sigmask(SIGTTIN)) ||
+		   (u.u_procp->p_sigmask & sigmask(SIGTTIN)) ||
 		    u.u_procp->p_flag&SVFORK)
 			return (EIO);
 		gsignal(u.u_procp->p_pgrp, SIGTTIN);
 		sleep((caddr_t)&lbolt, TTIPRI);
+		goto loop;
 	}
 	t_flags = tp->t_flags;
 
@@ -1046,7 +1169,7 @@ loop:
 	 * device interrupts when interrogating rawq.
 	 */
 	if (t_flags&RAW) {
-		s = spl5();
+		s = spltty();
 		if (tp->t_rawq.c_cc <= 0) {
 			if ((tp->t_state&TS_CARR_ON) == 0 ||
 			    (tp->t_state&TS_NBIO)) {
@@ -1073,7 +1196,7 @@ loop:
 	 * No input, sleep on rawq awaiting hardware
 	 * receipt and notification.
 	 */
-	s = spl5();
+	s = spltty();
 	if (qp->c_cc <= 0) {
 		if ((tp->t_state&TS_CARR_ON) == 0 ||
 		    (tp->t_state&TS_NBIO)) {
@@ -1094,21 +1217,6 @@ loop:
 	while ((c = getc(qp)) >= 0) {
 		if (t_flags&CRMOD && c == '\r')
 			c = '\n';
-		/*
-		 * Hack lower case simulation on
-		 * upper case only terminals.
-		 */
-		if (t_flags&LCASE && c <= 0177)
-			if (tp->t_state&TS_BKSL) {
-				if (maptab[c])
-					c = maptab[c];
-				tp->t_state &= ~TS_BKSL;
-			} else if (c >= 'A' && c <= 'Z')
-				c += 'a' - 'A';
-			else if (c == '\\') {
-				tp->t_state |= TS_BKSL;
-				continue;
-			}
 		/*
 		 * Check for delayed suspend character.
 		 */
@@ -1128,7 +1236,7 @@ loop:
 		/*
 		 * Give user character.
 		 */
- 		error = ureadc(c & 0177, uio);
+ 		error = ureadc(t_flags&PASS8 ? c : c & 0177, uio);
 		if (error)
 			break;
  		if (uio->uio_resid == 0)
@@ -1141,7 +1249,6 @@ loop:
 			break;
 		first = 0;
 	}
-	tp->t_state &= ~TS_BKSL;
 
 checktandem:
 	/*
@@ -1156,6 +1263,38 @@ checktandem:
 	return (error);
 }
 
+/*
+ * Check the output queue on tp for space for a kernel message
+ * (from uprintf/tprintf).  Allow some space over the normal
+ * hiwater mark so we don't lose messages due to normal flow
+ * control, but don't let the tty run amok.
+ * Sleeps here are not interruptible, but we return prematurely
+ * if new signals come in.
+ */
+ttycheckoutq(tp, wait)
+	register struct tty *tp;
+	int wait;
+{
+	int hiwat, s, oldsig;
+
+	hiwat = TTHIWAT(tp);
+	s = spltty();
+	oldsig = u.u_procp->p_sig;
+	if (tp->t_outq.c_cc > hiwat + 200)
+		while (tp->t_outq.c_cc > hiwat) {
+			ttstart(tp);
+			if (wait == 0 || u.u_procp->p_sig != oldsig) {
+				splx(s);
+				return (0);
+			}
+			timeout(wakeup, (caddr_t)&tp->t_outq, hz);
+			tp->t_state |= TS_ASLEEP;
+			sleep((caddr_t)&tp->t_outq, PZERO - 1);
+		}
+	splx(s);
+	return (1);
+}
+
 /*
  * Called from the device's write routine after it has
  * calculated the tty-structure given as argument.
@@ -1169,26 +1308,22 @@ ttwrite(tp, uio)
 	int i, hiwat, cnt, error, s;
 	char obuf[OBUFSIZ];
 
-	if ((tp->t_state&TS_CARR_ON) == 0)
-		return (EIO);
 	hiwat = TTHIWAT(tp);
 	cnt = uio->uio_resid;
 	error = 0;
 loop:
+	if ((tp->t_state&TS_CARR_ON) == 0)
+		return (EIO);
 	/*
 	 * Hang the process if it's in the background.
 	 */
-	while (u.u_procp->p_pgrp != tp->t_pgrp && tp == u.u_ttyp &&
+	if (u.u_procp->p_pgrp != tp->t_pgrp && tp == u.u_ttyp &&
 	    (tp->t_flags&TOSTOP) && (u.u_procp->p_flag&SVFORK)==0 &&
-	    u.u_signal[SIGTTOU] != SIG_IGN &&
-	    u.u_signal[SIGTTOU] != SIG_HOLD
-/*
-					     &&
-	    (u.u_procp->p_flag&SDETACH)==0) {
-*/
-	    ) {
+	    !(u.u_procp->p_sigignore & sigmask(SIGTTOU)) &&
+	    !(u.u_procp->p_sigmask & sigmask(SIGTTOU))) {
 		gsignal(u.u_procp->p_pgrp, SIGTTOU);
 		sleep((caddr_t)&lbolt, TTIPRI);
+		goto loop;
 	}
 
 	/*
@@ -1199,6 +1334,10 @@ loop:
 	 * in acquiring new space.
 	 */
 	while (uio->uio_resid > 0) {
+		if (tp->t_outq.c_cc > hiwat) {
+			cc = 0;
+			goto ovhiwat;
+		}
 		/*
 		 * Grab a hunk of data from the user.
 		 */
@@ -1206,7 +1345,7 @@ loop:
 		if (cc == 0) {
 			uio->uio_iovcnt--;
 			uio->uio_iov++;
-			if (uio->uio_iovcnt < 0)
+			if (uio->uio_iovcnt <= 0)
 				panic("ttwrite");
 			continue;
 		}
@@ -1216,8 +1355,6 @@ loop:
 		error = uiomove(cp, cc, UIO_WRITE, uio);
 		if (error)
 			break;
-		if (tp->t_outq.c_cc > hiwat)
-			goto ovhiwat;
 		if (tp->t_flags&FLUSHO)
 			continue;
 		/*
@@ -1234,6 +1371,13 @@ loop:
 					ttstart(tp);
 					sleep((caddr_t)&lbolt, TTOPRI);
 					tp->t_rocount = 0;
+					if (cc != 0) {
+						uio->uio_iov->iov_base -= cc;
+						uio->uio_iov->iov_len += cc;
+						uio->uio_resid += cc;
+						uio->uio_offset -= cc;
+					}
+					goto loop;
 				}
 				--cc;
 				if (tp->t_outq.c_cc > hiwat)
@@ -1263,10 +1407,16 @@ loop:
 				if (ce == 0) {
 					tp->t_rocount = 0;
 					if (ttyoutput(*cp, tp) >= 0) {
-						/* no c-lists, wait a bit */
-						ttstart(tp);
-						sleep((caddr_t)&lbolt, TTOPRI);
-						continue;
+					    /* no c-lists, wait a bit */
+					    ttstart(tp);
+					    sleep((caddr_t)&lbolt, TTOPRI);
+					    if (cc != 0) {
+					        uio->uio_iov->iov_base -= cc;
+					        uio->uio_iov->iov_len += cc;
+					        uio->uio_resid += cc;
+						uio->uio_offset -= cc;
+					    }
+					    goto loop;
 					}
 					cp++, cc--;
 					if (tp->t_flags&FLUSHO ||
@@ -1292,6 +1442,11 @@ loop:
 				/* out of c-lists, wait a bit */
 				ttstart(tp);
 				sleep((caddr_t)&lbolt, TTOPRI);
+				uio->uio_iov->iov_base -= cc;
+				uio->uio_iov->iov_len += cc;
+				uio->uio_resid += cc;
+				uio->uio_offset -= cc;
+				goto loop;
 			}
 			if (tp->t_flags&FLUSHO || tp->t_outq.c_cc > hiwat)
 				goto ovhiwat;
@@ -1301,23 +1456,24 @@ loop:
 	return (error);
 
 ovhiwat:
-	s = spl5();
 	if (cc != 0) {
 		uio->uio_iov->iov_base -= cc;
 		uio->uio_iov->iov_len += cc;
 		uio->uio_resid += cc;
 		uio->uio_offset -= cc;
 	}
+	ttstart(tp);
+	s = spltty();
 	/*
-	 * This can only occur if FLUSHO
-	 * is also set in t_flags.
+	 * This can only occur if FLUSHO is set in t_flags,
+	 * or if ttstart/oproc is synchronous (or very fast).
 	 */
 	if (tp->t_outq.c_cc <= hiwat) {
 		splx(s);
 		goto loop;
 	}
-	ttstart(tp);
 	if (tp->t_state&TS_NBIO) {
+		splx(s);
 		if (uio->uio_resid == cnt)
 			return (EWOULDBLOCK);
 		return (0);
@@ -1377,7 +1533,7 @@ ttyrub(c, tp)
 				ttyretype(tp);
 				return;
 			}
-			s = spl5();
+			s = spltty();
 			savecol = tp->t_col;
 			tp->t_state |= TS_CNTTB;
 			tp->t_flags |= FLUSHO;
@@ -1441,7 +1597,7 @@ ttyretype(tp)
 	if (tp->t_rprntc != 0377)
 		ttyecho(tp->t_rprntc, tp);
 	(void) ttyoutput('\n', tp);
-	s = spl5();
+	s = spltty();
 	for (cp = tp->t_canq.c_cf; cp; cp = nextc(&tp->t_canq, cp))
 		ttyecho(*cp, tp);
 	for (cp = tp->t_rawq.c_cf; cp; cp = nextc(&tp->t_rawq, cp))
@@ -1483,8 +1639,6 @@ ttyecho(c, tp)
 				c += 'A' - 1;
 		}
 	}
-	if ((tp->t_flags&LCASE) && (c >= 'A' && c <= 'Z'))
-		c += 'a' - 'A';
 	(void) ttyoutput(c&0177, tp);
 }
 
@@ -1525,17 +1679,3 @@ ttwakeup(tp)
 		gsignal(tp->t_pgrp, SIGIO); 
 	wakeup((caddr_t)&tp->t_rawq);
 }
-
-#if !defined(vax)
-scanc(size, cp, table, mask)
-	register int size;
-	register char *cp, table[];
-	register int mask;
-{
-	register int i = 0;
-
-	while ((table[*(u_char *)(cp + i)]&mask) == 0 && i < size)
-		i++;
-	return (size - i);
-}
-#endif