new vi

1 files changed, 865 insertions, 0 deletions

diff --git a/usr.bin/vi/common/key.c b/usr.bin/vi/common/key.c
new file mode 100644
index 00000000000..0ff6da0d8d3
--- /dev/null
+++ b/usr.bin/vi/common/key.c
@@ -0,0 +1,865 @@
+/*-
+ * Copyright (c) 1991, 1993, 1994
+ *	The Regents of the University of California.  All rights reserved.
+ * Copyright (c) 1991, 1993, 1994, 1995, 1996
+ *	Keith Bostic.  All rights reserved.
+ *
+ * See the LICENSE file for redistribution information.
+ */
+
+#include "config.h"
+
+#ifndef lint
+static const char sccsid[] = "@(#)key.c	10.30 (Berkeley) 4/3/96";
+#endif /* not lint */
+
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <sys/time.h>
+
+#include <bitstring.h>
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "common.h"
+#include "../vi/vi.h"
+
+static int	v_event_append __P((SCR *, EVENT *));
+static int	v_event_grow __P((SCR *, int));
+static int	v_key_cmp __P((const void *, const void *));
+static void	v_keyval __P((SCR *, int, scr_keyval_t));
+static void	v_sync __P((SCR *, int));
+
+/*
+ * !!!
+ * Historic vi always used:
+ *
+ *	^D: autoindent deletion
+ *	^H: last character deletion
+ *	^W: last word deletion
+ *	^Q: quote the next character (if not used in flow control).
+ *	^V: quote the next character
+ *
+ * regardless of the user's choices for these characters.  The user's erase
+ * and kill characters worked in addition to these characters.  Nvi wires
+ * down the above characters, but in addition permits the VEOF, VERASE, VKILL
+ * and VWERASE characters described by the user's termios structure.
+ *
+ * Ex was not consistent with this scheme, as it historically ran in tty
+ * cooked mode.  This meant that the scroll command and autoindent erase
+ * characters were mapped to the user's EOF character, and the character
+ * and word deletion characters were the user's tty character and word
+ * deletion characters.  This implementation makes it all consistent, as
+ * described above for vi.
+ *
+ * !!!
+ * This means that all screens share a special key set.
+ */
+KEYLIST keylist[] = {
+	{K_BACKSLASH,	  '\\'},	/*  \ */
+	{K_CARAT,	   '^'},	/*  ^ */
+	{K_CNTRLD,	'\004'},	/* ^D */
+	{K_CNTRLR,	'\022'},	/* ^R */
+	{K_CNTRLT,	'\024'},	/* ^T */
+	{K_CNTRLZ,	'\032'},	/* ^Z */
+	{K_COLON,	   ':'},	/*  : */
+	{K_CR,		  '\r'},	/* \r */
+	{K_ESCAPE,	'\033'},	/* ^[ */
+	{K_FORMFEED,	  '\f'},	/* \f */
+	{K_HEXCHAR,	'\030'},	/* ^X */
+	{K_NL,		  '\n'},	/* \n */
+	{K_RIGHTBRACE,	   '}'},	/*  } */
+	{K_RIGHTPAREN,	   ')'},	/*  ) */
+	{K_TAB,		  '\t'},	/* \t */
+	{K_VERASE,	  '\b'},	/* \b */
+	{K_VKILL,	'\025'},	/* ^U */
+	{K_VLNEXT,	'\021'},	/* ^Q */
+	{K_VLNEXT,	'\026'},	/* ^V */
+	{K_VWERASE,	'\027'},	/* ^W */
+	{K_ZERO,	   '0'},	/*  0 */
+
+#define	ADDITIONAL_CHARACTERS	4
+	{K_NOTUSED, 0},			/* VEOF, VERASE, VKILL, VWERASE */
+	{K_NOTUSED, 0},
+	{K_NOTUSED, 0},
+	{K_NOTUSED, 0},
+};
+static int nkeylist =
+    (sizeof(keylist) / sizeof(keylist[0])) - ADDITIONAL_CHARACTERS;
+
+/*
+ * v_key_init --
+ *	Initialize the special key lookup table.
+ *
+ * PUBLIC: int v_key_init __P((SCR *));
+ */
+int
+v_key_init(sp)
+	SCR *sp;
+{
+	CHAR_T ch;
+	GS *gp;
+	KEYLIST *kp;
+	int cnt;
+
+	gp = sp->gp;
+
+	/*
+	 * XXX
+	 * 8-bit only, for now.  Recompilation should get you any 8-bit
+	 * character set, as long as nul isn't a character.
+	 */
+	(void)setlocale(LC_ALL, "");
+#if __linux__
+	/*
+	 * In libc 4.5.26, setlocale(LC_ALL, ""), doesn't setup the table
+	 * for ctype(3c) correctly.  This bug is fixed in libc 4.6.x.
+	 *
+	 * This code works around this problem for libc 4.5.x users.
+	 * Note that this code is harmless if you're using libc 4.6.x.
+	 */
+	(void)setlocale(LC_CTYPE, "");
+#endif
+	v_key_ilookup(sp);
+
+	v_keyval(sp, K_CNTRLD, KEY_VEOF);
+	v_keyval(sp, K_VERASE, KEY_VERASE);
+	v_keyval(sp, K_VKILL, KEY_VKILL);
+	v_keyval(sp, K_VWERASE, KEY_VWERASE);
+
+	/* Sort the special key list. */
+	qsort(keylist, nkeylist, sizeof(keylist[0]), v_key_cmp);
+
+	/* Initialize the fast lookup table. */
+	for (gp->max_special = 0, kp = keylist, cnt = nkeylist; cnt--; ++kp) {
+		if (gp->max_special < kp->value)
+			gp->max_special = kp->value;
+		if (kp->ch <= MAX_FAST_KEY)
+			gp->special_key[kp->ch] = kp->value;
+	}
+
+	/* Find a non-printable character to use as a message separator. */
+	for (ch = 1; ch <= MAX_CHAR_T; ++ch)
+		if (!isprint(ch)) {
+			gp->noprint = ch;
+			break;
+		}
+	if (ch != gp->noprint) {
+		msgq(sp, M_ERR, "079|No non-printable character found");
+		return (1);
+	}
+	return (0);
+}
+
+/*
+ * v_keyval --
+ *	Set key values.
+ *
+ * We've left some open slots in the keylist table, and if these values exist,
+ * we put them into place.  Note, they may reset (or duplicate) values already
+ * in the table, so we check for that first.
+ */
+static void
+v_keyval(sp, val, name)
+	SCR *sp;
+	int val;
+	scr_keyval_t name;
+{
+	KEYLIST *kp;
+	CHAR_T ch;
+	int dne;
+
+	/* Get the key's value from the screen. */
+	if (sp->gp->scr_keyval(sp, name, &ch, &dne))
+		return;
+	if (dne)
+		return;
+
+	/* Check for duplication. */
+	for (kp = keylist; kp->value != K_NOTUSED; ++kp)
+		if (kp->ch == ch) {
+			kp->value = val;
+			return;
+		}
+
+	/* Add a new entry. */
+	if (kp->value == K_NOTUSED) {
+		keylist[nkeylist].ch = ch;
+		keylist[nkeylist].value = val;
+		++nkeylist;
+	}
+}
+
+/*
+ * v_key_ilookup --
+ *	Build the fast-lookup key display array.
+ *
+ * PUBLIC: void v_key_ilookup __P((SCR *));
+ */
+void
+v_key_ilookup(sp)
+	SCR *sp;
+{
+	CHAR_T ch, *p, *t;
+	GS *gp;
+	size_t len;
+
+	for (gp = sp->gp, ch = 0; ch <= MAX_FAST_KEY; ++ch)
+		for (p = gp->cname[ch].name, t = v_key_name(sp, ch),
+		    len = gp->cname[ch].len = sp->clen; len--;)
+			*p++ = *t++;
+}
+
+/*
+ * v_key_len --
+ *	Return the length of the string that will display the key.
+ *	This routine is the backup for the KEY_LEN() macro.
+ *
+ * PUBLIC: size_t v_key_len __P((SCR *, ARG_CHAR_T));
+ */
+size_t
+v_key_len(sp, ch)
+	SCR *sp;
+	ARG_CHAR_T ch;
+{
+	(void)v_key_name(sp, ch);
+	return (sp->clen);
+}
+
+/*
+ * v_key_name --
+ *	Return the string that will display the key.  This routine
+ *	is the backup for the KEY_NAME() macro.
+ *
+ * PUBLIC: CHAR_T *v_key_name __P((SCR *, ARG_CHAR_T));
+ */
+CHAR_T *
+v_key_name(sp, ach)
+	SCR *sp;
+	ARG_CHAR_T ach;
+{
+	static const CHAR_T hexdigit[] = "0123456789abcdef";
+	static const CHAR_T octdigit[] = "01234567";
+	CHAR_T ch, *chp, mask;
+	size_t len;
+	int cnt, shift;
+
+	ch = ach;
+
+	/* See if the character was explicitly declared printable or not. */
+	if ((chp = O_STR(sp, O_PRINT)) != NULL)
+		for (; *chp != '\0'; ++chp)
+			if (*chp == ch)
+				goto pr;
+	if ((chp = O_STR(sp, O_NOPRINT)) != NULL)
+		for (; *chp != '\0'; ++chp)
+			if (*chp == ch)
+				goto nopr;
+
+	/*
+	 * Historical (ARPA standard) mappings.  Printable characters are left
+	 * alone.  Control characters less than 0x20 are represented as '^'
+	 * followed by the character offset from the '@' character in the ASCII
+	 * character set.  Del (0x7f) is represented as '^' followed by '?'.
+	 *
+	 * XXX
+	 * The following code depends on the current locale being identical to
+	 * the ASCII map from 0x40 to 0x5f (since 0x1f + 0x40 == 0x5f).  I'm
+	 * told that this is a reasonable assumption...
+	 *
+	 * XXX
+	 * This code will only work with CHAR_T's that are multiples of 8-bit
+	 * bytes.
+	 *
+	 * XXX
+	 * NB: There's an assumption here that all printable characters take
+	 * up a single column on the screen.  This is not always correct.
+	 */
+	if (isprint(ch)) {
+pr:		sp->cname[0] = ch;
+		len = 1;
+		goto done;
+	}
+nopr:	if (iscntrl(ch) && (ch < 0x20 || ch == 0x7f)) {
+		sp->cname[0] = '^';
+		sp->cname[1] = ch == 0x7f ? '?' : '@' + ch;
+		len = 2;
+	} else if (O_ISSET(sp, O_OCTAL)) {
+#define	BITS	(sizeof(CHAR_T) * 8)
+#define	SHIFT	(BITS - BITS % 3)
+#define	TOPMASK	(BITS % 3 == 2 ? 3 : 1) << (BITS - BITS % 3)
+		sp->cname[0] = '\\';
+		sp->cname[1] = octdigit[(ch & TOPMASK) >> SHIFT];
+		shift = SHIFT - 3;
+		for (len = 2, mask = 7 << (SHIFT - 3),
+		    cnt = BITS / 3; cnt-- > 0; mask >>= 3, shift -= 3)
+			sp->cname[len++] = octdigit[(ch & mask) >> shift];
+	} else {
+		sp->cname[0] = '\\';
+		sp->cname[1] = 'x';
+		for (len = 2, chp = (u_int8_t *)&ch,
+		    cnt = sizeof(CHAR_T); cnt-- > 0; ++chp) {
+			sp->cname[len++] = hexdigit[(*chp & 0xf0) >> 4];
+			sp->cname[len++] = hexdigit[*chp & 0x0f];
+		}
+	}
+done:	sp->cname[sp->clen = len] = '\0';
+	return (sp->cname);
+}
+
+/*
+ * v_key_val --
+ *	Fill in the value for a key.  This routine is the backup
+ *	for the KEY_VAL() macro.
+ *
+ * PUBLIC: int v_key_val __P((SCR *, ARG_CHAR_T));
+ */
+int
+v_key_val(sp, ch)
+	SCR *sp;
+	ARG_CHAR_T ch;
+{
+	KEYLIST k, *kp;
+
+	k.ch = ch;
+	kp = bsearch(&k, keylist, nkeylist, sizeof(keylist[0]), v_key_cmp);
+	return (kp == NULL ? K_NOTUSED : kp->value);
+}
+
+/*
+ * v_event_push --
+ *	Push events/keys onto the front of the buffer.
+ *
+ * There is a single input buffer in ex/vi.  Characters are put onto the
+ * end of the buffer by the terminal input routines, and pushed onto the
+ * front of the buffer by various other functions in ex/vi.  Each key has
+ * an associated flag value, which indicates if it has already been quoted,
+ * and if it is the result of a mapping or an abbreviation.
+ *
+ * PUBLIC: int v_event_push __P((SCR *, EVENT *, CHAR_T *, size_t, u_int));
+ */
+int
+v_event_push(sp, p_evp, p_s, nitems, flags)
+	SCR *sp;
+	EVENT *p_evp;			/* Push event. */
+	CHAR_T *p_s;			/* Push characters. */
+	size_t nitems;			/* Number of items to push. */
+	u_int flags;			/* CH_* flags. */
+{
+	EVENT *evp;
+	GS *gp;
+	size_t total;
+
+	/* If we have room, stuff the items into the buffer. */
+	gp = sp->gp;
+	if (nitems <= gp->i_next ||
+	    (gp->i_event != NULL && gp->i_cnt == 0 && nitems <= gp->i_nelem)) {
+		if (gp->i_cnt != 0)
+			gp->i_next -= nitems;
+		goto copy;
+	}
+
+	/*
+	 * If there are currently items in the queue, shift them up,
+	 * leaving some extra room.  Get enough space plus a little
+	 * extra.
+	 */
+#define	TERM_PUSH_SHIFT	30
+	total = gp->i_cnt + gp->i_next + nitems + TERM_PUSH_SHIFT;
+	if (total >= gp->i_nelem && v_event_grow(sp, MAX(total, 64)))
+		return (1);
+	if (gp->i_cnt)
+		MEMMOVE(gp->i_event + TERM_PUSH_SHIFT + nitems,
+		    gp->i_event + gp->i_next, gp->i_cnt);
+	gp->i_next = TERM_PUSH_SHIFT;
+
+	/* Put the new items into the queue. */
+copy:	gp->i_cnt += nitems;
+	for (evp = gp->i_event + gp->i_next; nitems--; ++evp) {
+		if (p_evp != NULL)
+			*evp = *p_evp++;
+		else {
+			evp->e_event = E_CHARACTER;
+			evp->e_c = *p_s++;
+			evp->e_value = KEY_VAL(sp, evp->e_c);
+			F_INIT(&evp->e_ch, flags);
+		}
+	}
+	return (0);
+}
+
+/*
+ * v_event_append --
+ *	Append events onto the tail of the buffer.
+ */
+static int
+v_event_append(sp, argp)
+	SCR *sp;
+	EVENT *argp;
+{
+	CHAR_T *s;			/* Characters. */
+	EVENT *evp;
+	GS *gp;
+	size_t nevents;			/* Number of events. */
+
+	/* Grow the buffer as necessary. */
+	nevents = argp->e_event == E_STRING ? argp->e_len : 1;
+	gp = sp->gp;
+	if (gp->i_event == NULL ||
+	    nevents > gp->i_nelem - (gp->i_next + gp->i_cnt))
+		v_event_grow(sp, MAX(nevents, 64));
+	evp = gp->i_event + gp->i_next + gp->i_cnt;
+	gp->i_cnt += nevents;
+
+	/* Transform strings of characters into single events. */
+	if (argp->e_event == E_STRING)
+		for (s = argp->e_csp; nevents--; ++evp) {
+			evp->e_event = E_CHARACTER;
+			evp->e_c = *s++;
+			evp->e_value = KEY_VAL(sp, evp->e_c);
+			evp->e_flags = 0;
+		}
+	else
+		*evp = *argp;
+	return (0);
+}
+
+/* Remove events from the queue. */
+#define	QREM(len) {							\
+	if ((gp->i_cnt -= len) == 0)					\
+		gp->i_next = 0;						\
+	else								\
+		gp->i_next += len;					\
+}
+
+/*
+ * v_event_get --
+ *	Return the next event.
+ *
+ * !!!
+ * The flag EC_NODIGIT probably needs some explanation.  First, the idea of
+ * mapping keys is that one or more keystrokes act like a function key.
+ * What's going on is that vi is reading a number, and the character following
+ * the number may or may not be mapped (EC_MAPCOMMAND).  For example, if the
+ * user is entering the z command, a valid command is "z40+", and we don't want
+ * to map the '+', i.e. if '+' is mapped to "xxx", we don't want to change it
+ * into "z40xxx".  However, if the user enters "35x", we want to put all of the
+ * characters through the mapping code.
+ *
+ * Historical practice is a bit muddled here.  (Surprise!)  It always permitted
+ * mapping digits as long as they weren't the first character of the map, e.g.
+ * ":map ^A1 xxx" was okay.  It also permitted the mapping of the digits 1-9
+ * (the digit 0 was a special case as it doesn't indicate the start of a count)
+ * as the first character of the map, but then ignored those mappings.  While
+ * it's probably stupid to map digits, vi isn't your mother.
+ *
+ * The way this works is that the EC_MAPNODIGIT causes term_key to return the
+ * end-of-digit without "looking" at the next character, i.e. leaving it as the
+ * user entered it.  Presumably, the next term_key call will tell us how the
+ * user wants it handled.
+ *
+ * There is one more complication.  Users might map keys to digits, and, as
+ * it's described above, the commands:
+ *
+ *	:map g 1G
+ *	d2g
+ *
+ * would return the keys "d2<end-of-digits>1G", when the user probably wanted
+ * "d21<end-of-digits>G".  So, if a map starts off with a digit we continue as
+ * before, otherwise, we pretend we haven't mapped the character, and return
+ * <end-of-digits>.
+ *
+ * Now that that's out of the way, let's talk about Energizer Bunny macros.
+ * It's easy to create macros that expand to a loop, e.g. map x 3x.  It's
+ * fairly easy to detect this example, because it's all internal to term_key.
+ * If we're expanding a macro and it gets big enough, at some point we can
+ * assume it's looping and kill it.  The examples that are tough are the ones
+ * where the parser is involved, e.g. map x "ayyx"byy.  We do an expansion
+ * on 'x', and get "ayyx"byy.  We then return the first 4 characters, and then
+ * find the looping macro again.  There is no way that we can detect this
+ * without doing a full parse of the command, because the character that might
+ * cause the loop (in this case 'x') may be a literal character, e.g. the map
+ * map x "ayy"xyy"byy is perfectly legal and won't cause a loop.
+ *
+ * Historic vi tried to detect looping macros by disallowing obvious cases in
+ * the map command, maps that that ended with the same letter as they started
+ * (which wrongly disallowed "map x 'x"), and detecting macros that expanded
+ * too many times before keys were returned to the command parser.  It didn't
+ * get many (most?) of the tricky cases right, however, and it was certainly
+ * possible to create macros that ran forever.  And, even if it did figure out
+ * what was going on, the user was usually tossed into ex mode.  Finally, any
+ * changes made before vi realized that the macro was recursing were left in
+ * place.  We recover gracefully, but the only recourse the user has in an
+ * infinite macro loop is to interrupt.
+ *
+ * !!!
+ * It is historic practice that mapping characters to themselves as the first
+ * part of the mapped string was legal, and did not cause infinite loops, i.e.
+ * ":map! { {^M^T" and ":map n nz." were known to work.  The initial, matching
+ * characters were returned instead of being remapped.
+ *
+ * !!!
+ * It is also historic practice that the macro "map ] ]]^" caused a single ]
+ * keypress to behave as the command ]] (the ^ got the map past the vi check
+ * for "tail recursion").  Conversely, the mapping "map n nn^" went recursive.
+ * What happened was that, in the historic vi, maps were expanded as the keys
+ * were retrieved, but not all at once and not centrally.  So, the keypress ]
+ * pushed ]]^ on the stack, and then the first ] from the stack was passed to
+ * the ]] command code.  The ]] command then retrieved a key without entering
+ * the mapping code.  This could bite us anytime a user has a map that depends
+ * on secondary keys NOT being mapped.  I can't see any possible way to make
+ * this work in here without the complete abandonment of Rationality Itself.
+ *
+ * XXX
+ * The final issue is recovery.  It would be possible to undo all of the work
+ * that was done by the macro if we entered a record into the log so that we
+ * knew when the macro started, and, in fact, this might be worth doing at some
+ * point.  Given that this might make the log grow unacceptably (consider that
+ * cursor keys are done with maps), for now we leave any changes made in place.
+ *
+ * PUBLIC: int v_event_get __P((SCR *, EVENT *, int, u_int32_t));
+ */
+int
+v_event_get(sp, argp, timeout, flags)
+	SCR *sp;
+	EVENT *argp;
+	int timeout;
+	u_int32_t flags;
+{
+	EVENT *evp, ev;
+	GS *gp;
+	SEQ *qp;
+	int init_nomap, ispartial, istimeout, remap_cnt;
+
+	gp = sp->gp;
+
+	/* If simply checking for interrupts, argp may be NULL. */
+	if (argp == NULL)
+		argp = &ev;
+
+retry:	istimeout = remap_cnt = 0;
+
+	/*
+	 * If the queue isn't empty and we're timing out for characters,
+	 * return immediately.
+	 */
+	if (gp->i_cnt != 0 && LF_ISSET(EC_TIMEOUT))
+		return (0);
+
+	/*
+	 * If the queue is empty, we're checking for interrupts, or we're
+	 * timing out for characters, get more events.
+	 */
+	if (gp->i_cnt == 0 || LF_ISSET(EC_INTERRUPT | EC_TIMEOUT)) {
+		/*
+		 * If we're reading new characters, check any scripting
+		 * windows for input.
+		 */
+		if (F_ISSET(gp, G_SCRIPT) && sscr_input(sp))
+			return (1);
+loop:		if (gp->scr_event(sp, argp,
+		    LF_ISSET(EC_INTERRUPT | EC_QUOTED | EC_RAW), timeout))
+			return (1);
+		switch (argp->e_event) {
+		case E_ERR:
+		case E_SIGHUP:
+		case E_SIGTERM:
+			/*
+			 * Fatal conditions cause the file to be synced to
+			 * disk immediately.
+			 */
+			v_sync(sp, RCV_ENDSESSION | RCV_PRESERVE |
+			    (argp->e_event == E_SIGTERM ? 0: RCV_EMAIL));
+			return (1);
+		case E_TIMEOUT:
+			istimeout = 1;
+			break;
+		case E_INTERRUPT:
+			/* Set the global interrupt flag. */
+			F_SET(sp->gp, G_INTERRUPTED);
+
+			/*
+			 * If the caller was interested in interrupts, return
+			 * immediately.
+			 */
+			if (LF_ISSET(EC_INTERRUPT))
+				return (0);
+			goto append;
+		default:
+append:			if (v_event_append(sp, argp))
+				return (1);
+			break;
+		}
+	}
+
+	/*
+	 * If the caller was only interested in interrupts or timeouts, return
+	 * immediately.  (We may have gotten characters, and that's okay, they
+	 * were queued up for later use.)
+	 */
+	if (LF_ISSET(EC_INTERRUPT | EC_TIMEOUT))
+		return (0);
+	 
+newmap:	evp = &gp->i_event[gp->i_next];
+
+	/* 
+	 * If the next event in the queue isn't a character event, return
+	 * it, we're done.
+	 */
+	if (evp->e_event != E_CHARACTER) {
+		*argp = *evp;
+		QREM(1);
+		return (0);
+	}
+	
+	/*
+	 * If the key isn't mappable because:
+	 *
+	 *	+ ... the timeout has expired
+	 *	+ ... it's not a mappable key
+	 *	+ ... neither the command or input map flags are set
+	 *	+ ... there are no maps that can apply to it
+	 *
+	 * return it forthwith.
+	 */
+	if (istimeout || F_ISSET(&evp->e_ch, CH_NOMAP) ||
+	    !LF_ISSET(EC_MAPCOMMAND | EC_MAPINPUT) ||
+	    evp->e_c < MAX_BIT_SEQ && !bit_test(gp->seqb, evp->e_c))
+		goto nomap;
+
+	/* Search the map. */
+	qp = seq_find(sp, NULL, evp, NULL, gp->i_cnt,
+	    LF_ISSET(EC_MAPCOMMAND) ? SEQ_COMMAND : SEQ_INPUT, &ispartial);
+
+	/*
+	 * If get a partial match, get more characters and retry the map.
+	 * If time out without further characters, return the characters
+	 * unmapped.
+	 *
+	 * !!!
+	 * <escape> characters are a problem.  Cursor keys start with <escape>
+	 * characters, so there's almost always a map in place that begins with
+	 * an <escape> character.  If we timeout <escape> keys in the same way
+	 * that we timeout other keys, the user will get a noticeable pause as
+	 * they enter <escape> to terminate input mode.  If key timeout is set
+	 * for a slow link, users will get an even longer pause.  Nvi used to
+	 * simply timeout <escape> characters at 1/10th of a second, but this
+	 * loses over PPP links where the latency is greater than 100Ms.
+	 */
+	if (ispartial) {
+		if (O_ISSET(sp, O_TIMEOUT))
+			timeout = (evp->e_value == K_ESCAPE ?
+			    O_VAL(sp, O_ESCAPETIME) :
+			    O_VAL(sp, O_KEYTIME)) * 100;
+		else
+			timeout = 0;
+		goto loop;
+	}
+
+	/* If no map, return the character. */
+	if (qp == NULL) {
+nomap:		if (!isdigit(evp->e_c) && LF_ISSET(EC_MAPNODIGIT))
+			goto not_digit;
+		*argp = *evp;
+		QREM(1);
+		return (0);
+	}
+
+	/*
+	 * If looking for the end of a digit string, and the first character
+	 * of the map is it, pretend we haven't seen the character.
+	 */
+	if (LF_ISSET(EC_MAPNODIGIT) &&
+	    qp->output != NULL && !isdigit(qp->output[0])) {
+not_digit:	argp->e_c = CH_NOT_DIGIT;
+		argp->e_value = K_NOTUSED;
+		argp->e_event = E_CHARACTER;
+		F_INIT(&argp->e_ch, 0);
+		return (0);
+	}
+
+	/* Find out if the initial segments are identical. */
+	init_nomap = !e_memcmp(qp->output, &gp->i_event[gp->i_next], qp->ilen);
+
+	/* Delete the mapped characters from the queue. */
+	QREM(qp->ilen);
+
+	/* If keys mapped to nothing, go get more. */
+	if (qp->output == NULL)
+		goto retry;
+
+	/* If remapping characters... */
+	if (O_ISSET(sp, O_REMAP)) {
+		/*
+		 * Periodically check for interrupts.  Always check the first
+		 * time through, because it's possible to set up a map that
+		 * will return a character every time, but will expand to more,
+		 * e.g. "map! a aaaa" will always return a 'a', but we'll never
+		 * get anywhere useful.
+		 */
+		if ((++remap_cnt == 1 || remap_cnt % 10 == 0) &&
+		    (gp->scr_event(sp, &ev,
+		    EC_INTERRUPT, 0) || ev.e_event == E_INTERRUPT)) {
+			F_SET(sp->gp, G_INTERRUPTED);
+			argp->e_event = E_INTERRUPT;
+			return (0);
+		}
+
+		/*
+		 * If an initial part of the characters mapped, they are not
+		 * further remapped -- return the first one.  Push the rest
+		 * of the characters, or all of the characters if no initial
+		 * part mapped, back on the queue.
+		 */
+		if (init_nomap) {
+			if (v_event_push(sp, NULL, qp->output + qp->ilen,
+			    qp->olen - qp->ilen, CH_MAPPED))
+				return (1);
+			if (v_event_push(sp, NULL,
+			    qp->output, qp->ilen, CH_NOMAP | CH_MAPPED))
+				return (1);
+			evp = &gp->i_event[gp->i_next];
+			goto nomap;
+		}
+		if (v_event_push(sp, NULL, qp->output, qp->olen, CH_MAPPED))
+			return (1);
+		goto newmap;
+	}
+
+	/* Else, push the characters on the queue and return one. */
+	if (v_event_push(sp, NULL, qp->output, qp->olen, CH_MAPPED | CH_NOMAP))
+		return (1);
+
+	goto nomap;
+}
+
+/*
+ * v_sync --
+ *	Walk the screen lists, sync'ing files to their backup copies.
+ */
+static void
+v_sync(sp, flags)
+	SCR *sp;
+	int flags;
+{
+	GS *gp;
+
+	gp = sp->gp;
+	for (sp = gp->dq.cqh_first; sp != (void *)&gp->dq; sp = sp->q.cqe_next)
+		rcv_sync(sp, flags);
+	for (sp = gp->hq.cqh_first; sp != (void *)&gp->hq; sp = sp->q.cqe_next)
+		rcv_sync(sp, flags);
+}
+
+/*
+ * v_event_err --
+ *	Unexpected event.
+ *
+ * PUBLIC: void v_event_err __P((SCR *, EVENT *));
+ */
+void
+v_event_err(sp, evp)
+	SCR *sp;
+	EVENT *evp;
+{
+	switch (evp->e_event) {
+	case E_CHARACTER:
+		msgq(sp, M_ERR, "276|Unexpected character event");
+		break;
+	case E_EOF:
+		msgq(sp, M_ERR, "277|Unexpected end-of-file event");
+		break;
+	case E_INTERRUPT:
+		msgq(sp, M_ERR, "279|Unexpected interrupt event");
+		break;
+	case E_QUIT:
+		msgq(sp, M_ERR, "280|Unexpected quit event");
+		break;
+	case E_REPAINT:
+		msgq(sp, M_ERR, "281|Unexpected repaint event");
+		break;
+	case E_STRING:
+		msgq(sp, M_ERR, "285|Unexpected string event");
+		break;
+	case E_TIMEOUT:
+		msgq(sp, M_ERR, "286|Unexpected timeout event");
+		break;
+	case E_WRITE:
+		msgq(sp, M_ERR, "287|Unexpected write event");
+		break;
+	case E_WRITEQUIT:
+		msgq(sp, M_ERR, "288|Unexpected write-and-quit event");
+		break;
+
+	/*
+	 * Theoretically, none of these can occur, as they're handled at the
+	 * top editor level.
+	 */
+	case E_ERR:
+	case E_SIGHUP:
+	case E_SIGTERM:
+	default:
+		abort();
+	}
+
+	/* Free any allocated memory. */
+	if (evp->e_asp != NULL)
+		free(evp->e_asp);
+}
+
+/*
+ * v_event_flush --
+ *	Flush any flagged keys, returning if any keys were flushed.
+ *
+ * PUBLIC: int v_event_flush __P((SCR *, u_int));
+ */
+int
+v_event_flush(sp, flags)
+	SCR *sp;
+	u_int flags;
+{
+	GS *gp;
+	int rval;
+
+	for (rval = 0, gp = sp->gp; gp->i_cnt != 0 &&
+	    F_ISSET(&gp->i_event[gp->i_next].e_ch, flags); rval = 1)
+		QREM(1);
+	return (rval);
+}
+
+/*
+ * v_event_grow --
+ *	Grow the terminal queue.
+ */
+static int
+v_event_grow(sp, add)
+	SCR *sp;
+	int add;
+{
+	GS *gp;
+	size_t new_nelem, olen;
+
+	gp = sp->gp;
+	new_nelem = gp->i_nelem + add;
+	olen = gp->i_nelem * sizeof(gp->i_event[0]);
+	BINC_RET(sp, gp->i_event, olen, new_nelem * sizeof(gp->i_event[0]));
+	gp->i_nelem = olen / sizeof(gp->i_event[0]);
+	return (0);
+}
+
+/*
+ * v_key_cmp --
+ *	Compare two keys for sorting.
+ */
+static int
+v_key_cmp(ap, bp)
+	const void *ap, *bp;
+{
+	return (((KEYLIST *)ap)->ch - ((KEYLIST *)bp)->ch);
+}