birdterm

birdterm.c (59267B)

---

 /* See LICENSE for license details. */
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <pwd.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <signal.h>
 #include <sys/ioctl.h>
 #include <sys/select.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <termios.h>
 #include <unistd.h>
 #include <wchar.h>
 
 #include "birdterm.h"
 #include "win.h"
 
 #if   defined(__linux)
  #include <pty.h>
 #elif defined(__OpenBSD__) || defined(__NetBSD__) || defined(__APPLE__)
  #include <util.h>
 #elif defined(__FreeBSD__) || defined(__DragonFly__)
  #include <libutil.h>
 #endif
 
 /* Arbitrary sizes */
 #define UTF_INVALID   0xFFFD
 #define UTF_SIZ       4
 #define ESC_BUF_SIZ   (128*UTF_SIZ)
 #define ESC_ARG_SIZ   16
 #define STR_BUF_SIZ   ESC_BUF_SIZ
 #define STR_ARG_SIZ   ESC_ARG_SIZ
 #define HISTSIZE      2000
 
 /* macros */
 #define IS_SET(flag)		((term.mode & (flag)) != 0)
 #define ISCONTROLC0(c)		(BETWEEN(c, 0, 0x1f) || (c) == 0x7f)
 #define ISCONTROLC1(c)		(BETWEEN(c, 0x80, 0x9f))
 #define ISCONTROL(c)		(ISCONTROLC0(c) || ISCONTROLC1(c))
 #define ISDELIM(u)		(u && wcschr(worddelimiters, u))
 #define TLINE(y)		((y) < term.scr ? term.hist[((y) + term.histi - \
             term.scr + HISTSIZE + 1) % HISTSIZE] : \
             term.line[(y) - term.scr])
 
 enum term_mode {
 	MODE_WRAP        = 1 << 0,
 	MODE_INSERT      = 1 << 1,
 	MODE_ALTSCREEN   = 1 << 2,
 	MODE_CRLF        = 1 << 3,
 	MODE_ECHO        = 1 << 4,
 	MODE_PRINT       = 1 << 5,
 	MODE_UTF8        = 1 << 6,
 };
 
 enum cursor_movement {
 	CURSOR_SAVE,
 	CURSOR_LOAD
 };
 
 enum cursor_state {
 	CURSOR_DEFAULT  = 0,
 	CURSOR_WRAPNEXT = 1,
 	CURSOR_ORIGIN   = 2
 };
 
 enum charset {
 	CS_GRAPHIC0,
 	CS_GRAPHIC1,
 	CS_UK,
 	CS_USA,
 	CS_MULTI,
 	CS_GER,
 	CS_FIN
 };
 
 enum escape_state {
 	ESC_START      = 1,
 	ESC_CSI        = 2,
 	ESC_STR        = 4,  /* DCS, OSC, PM, APC */
 	ESC_ALTCHARSET = 8,
 	ESC_STR_END    = 16, /* a final string was encountered */
 	ESC_TEST       = 32, /* Enter in test mode */
 	ESC_UTF8       = 64,
 };
 
 typedef struct {
 	Glyph attr; /* current char attributes */
 	int x;
 	int y;
 	char state;
 } TCursor;
 
 typedef struct {
 	int mode;
 	int type;
 	int snap;
 	/*
 	 * Selection variables:
 	 * nb – normalized coordinates of the beginning of the selection
 	 * ne – normalized coordinates of the end of the selection
 	 * ob – original coordinates of the beginning of the selection
 	 * oe – original coordinates of the end of the selection
 	 */
 	struct {
 		int x, y;
 	} nb, ne, ob, oe;
 
 	int alt;
 } Selection;
 
 /* Internal representation of the screen */
 typedef struct {
 	int row;      /* nb row */
 	int col;      /* nb col */
 	Line *line;   /* screen */
 	Line *alt;    /* alternate screen */
 	Line hist[HISTSIZE]; /* history buffer */
 	int histi;    /* history index */
 	int scr;      /* scroll back */
 	int *dirty;   /* dirtyness of lines */
 	TCursor c;    /* cursor */
 	int ocx;      /* old cursor col */
 	int ocy;      /* old cursor row */
 	int top;      /* top    scroll limit */
 	int bot;      /* bottom scroll limit */
 	int mode;     /* terminal mode flags */
 	int esc;      /* escape state flags */
 	char trantbl[4]; /* charset table translation */
 	int charset;  /* current charset */
 	int icharset; /* selected charset for sequence */
 	int *tabs;
 	Rune lastc;   /* last printed char outside of sequence, 0 if control */
 } Term;
 
 /* CSI Escape sequence structs */
 /* ESC '[' [[ [<priv>] <arg> [;]] <mode> [<mode>]] */
 typedef struct {
 	char buf[ESC_BUF_SIZ]; /* raw string */
 	size_t len;            /* raw string length */
 	char priv;
 	int arg[ESC_ARG_SIZ];
 	int narg;              /* nb of args */
 	char mode[2];
 } CSIEscape;
 
 /* STR Escape sequence structs */
 /* ESC type [[ [<priv>] <arg> [;]] <mode>] ESC '\' */
 typedef struct {
 	char type;             /* ESC type ... */
 	char *buf;             /* allocated raw string */
 	size_t siz;            /* allocation size */
 	size_t len;            /* raw string length */
 	char *args[STR_ARG_SIZ];
 	int narg;              /* nb of args */
 } STREscape;
 
 static void execsh(char *, char **);
 static void stty(char **);
 static void sigchld(int);
 static void ttywriteraw(const char *, size_t);
 
 static void csidump(void);
 static void csihandle(void);
 static void csiparse(void);
 static void csireset(void);
 static void osc_color_response(int, int, int);
 static int eschandle(uchar);
 static void strdump(void);
 static void strhandle(void);
 static void strparse(void);
 static void strreset(void);
 
 static void tprinter(char *, size_t);
 static void tdumpsel(void);
 static void tdumpline(int);
 static void tdump(void);
 static void tclearregion(int, int, int, int);
 static void tcursor(int);
 static void tdeletechar(int);
 static void tdeleteline(int);
 static void tinsertblank(int);
 static void tinsertblankline(int);
 static int tlinelen(int);
 static void tmoveto(int, int);
 static void tmoveato(int, int);
 static void tnewline(int);
 static void tputtab(int);
 static void tputc(Rune);
 static void treset(void);
 static void tscrollup(int, int, int);
 static void tscrolldown(int, int, int);
 static void tsetattr(const int *, int);
 static void tsetchar(Rune, const Glyph *, int, int);
 static void tsetdirt(int, int);
 static void tsetscroll(int, int);
 static void tswapscreen(void);
 static void tsetmode(int, int, const int *, int);
 static int twrite(const char *, int, int);
 static void tfulldirt(void);
 static void tcontrolcode(uchar );
 static void tdectest(char );
 static void tdefutf8(char);
 static int32_t tdefcolor(const int *, int *, int);
 static void tdeftran(char);
 static void tstrsequence(uchar);
 
 static void drawregion(int, int, int, int);
 
 static void selnormalize(void);
 static void selscroll(int, int);
 static void selsnap(int *, int *, int);
 
 static size_t utf8decode(const char *, Rune *, size_t);
 static Rune utf8decodebyte(char, size_t *);
 static char utf8encodebyte(Rune, size_t);
 static size_t utf8validate(Rune *, size_t);
 
 static char *base64dec(const char *);
 static char base64dec_getc(const char **);
 
 static ssize_t xwrite(int, const char *, size_t);
 
 /* Globals */
 static Term term;
 static Selection sel;
 static CSIEscape csiescseq;
 static STREscape strescseq;
 static int iofd = 1;
 static int cmdfd;
 static pid_t pid;
 
 static const uchar utfbyte[UTF_SIZ + 1] = {0x80,    0, 0xC0, 0xE0, 0xF0};
 static const uchar utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
 static const Rune utfmin[UTF_SIZ + 1] = {       0,    0,  0x80,  0x800,  0x10000};
 static const Rune utfmax[UTF_SIZ + 1] = {0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
 
 ssize_t
 xwrite(int fd, const char *s, size_t len)
 {
 	size_t aux = len;
 	ssize_t r;
 
 	while (len > 0) {
 		r = write(fd, s, len);
 		if (r < 0)
 			return r;
 		len -= r;
 		s += r;
 	}
 
 	return aux;
 }
 
 void *
 xmalloc(size_t len)
 {
 	void *p;
 
 	if (!(p = malloc(len)))
 		die("malloc: %s\n", strerror(errno));
 
 	return p;
 }
 
 void *
 xrealloc(void *p, size_t len)
 {
 	if ((p = realloc(p, len)) == NULL)
 		die("realloc: %s\n", strerror(errno));
 
 	return p;
 }
 
 char *
 xstrdup(const char *s)
 {
 	char *p;
 
 	if ((p = strdup(s)) == NULL)
 		die("strdup: %s\n", strerror(errno));
 
 	return p;
 }
 
 size_t
 utf8decode(const char *c, Rune *u, size_t clen)
 {
 	size_t i, j, len, type;
 	Rune udecoded;
 
 	*u = UTF_INVALID;
 	if (!clen)
 		return 0;
 	udecoded = utf8decodebyte(c[0], &len);
 	if (!BETWEEN(len, 1, UTF_SIZ))
 		return 1;
 	for (i = 1, j = 1; i < clen && j < len; ++i, ++j) {
 		udecoded = (udecoded << 6) | utf8decodebyte(c[i], &type);
 		if (type != 0)
 			return j;
 	}
 	if (j < len)
 		return 0;
 	*u = udecoded;
 	utf8validate(u, len);
 
 	return len;
 }
 
 Rune
 utf8decodebyte(char c, size_t *i)
 {
 	for (*i = 0; *i < LEN(utfmask); ++(*i))
 		if (((uchar)c & utfmask[*i]) == utfbyte[*i])
 			return (uchar)c & ~utfmask[*i];
 
 	return 0;
 }
 
 size_t
 utf8encode(Rune u, char *c)
 {
 	size_t len, i;
 
 	len = utf8validate(&u, 0);
 	if (len > UTF_SIZ)
 		return 0;
 
 	for (i = len - 1; i != 0; --i) {
 		c[i] = utf8encodebyte(u, 0);
 		u >>= 6;
 	}
 	c[0] = utf8encodebyte(u, len);
 
 	return len;
 }
 
 char
 utf8encodebyte(Rune u, size_t i)
 {
 	return utfbyte[i] | (u & ~utfmask[i]);
 }
 
 size_t
 utf8validate(Rune *u, size_t i)
 {
 	if (!BETWEEN(*u, utfmin[i], utfmax[i]) || BETWEEN(*u, 0xD800, 0xDFFF))
 		*u = UTF_INVALID;
 	for (i = 1; *u > utfmax[i]; ++i)
 		;
 
 	return i;
 }
 
 char
 base64dec_getc(const char **src)
 {
 	while (**src && !isprint((unsigned char)**src))
 		(*src)++;
 	return **src ? *((*src)++) : '=';  /* emulate padding if string ends */
 }
 
 char *
 base64dec(const char *src)
 {
 	size_t in_len = strlen(src);
 	char *result, *dst;
 	static const char base64_digits[256] = {
 		[43] = 62, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
 		0, 0, 0, -1, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
 		13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0,
 		0, 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
 		40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
 	};
 
 	if (in_len % 4)
 		in_len += 4 - (in_len % 4);
 	result = dst = xmalloc(in_len / 4 * 3 + 1);
 	while (*src) {
 		int a = base64_digits[(unsigned char) base64dec_getc(&src)];
 		int b = base64_digits[(unsigned char) base64dec_getc(&src)];
 		int c = base64_digits[(unsigned char) base64dec_getc(&src)];
 		int d = base64_digits[(unsigned char) base64dec_getc(&src)];
 
 		/* invalid input. 'a' can be -1, e.g. if src is "\n" (c-str) */
 		if (a == -1 || b == -1)
 			break;
 
 		*dst++ = (a << 2) | ((b & 0x30) >> 4);
 		if (c == -1)
 			break;
 		*dst++ = ((b & 0x0f) << 4) | ((c & 0x3c) >> 2);
 		if (d == -1)
 			break;
 		*dst++ = ((c & 0x03) << 6) | d;
 	}
 	*dst = '\0';
 	return result;
 }
 
 void
 selinit(void)
 {
 	sel.mode = SEL_IDLE;
 	sel.snap = 0;
 	sel.ob.x = -1;
 }
 
 int
 tlinelen(int y)
 {
 	int i = term.col;
 
 	if (TLINE(y)[i - 1].mode & ATTR_WRAP)
 		return i;
 
 	while (i > 0 && TLINE(y)[i - 1].u == ' ')
 		--i;
 
 	return i;
 }
 
 void
 selstart(int col, int row, int snap)
 {
 	selclear();
 	sel.mode = SEL_EMPTY;
 	sel.type = SEL_REGULAR;
 	sel.alt = IS_SET(MODE_ALTSCREEN);
 	sel.snap = snap;
 	sel.oe.x = sel.ob.x = col;
 	sel.oe.y = sel.ob.y = row;
 	selnormalize();
 
 	if (sel.snap != 0)
 		sel.mode = SEL_READY;
 	tsetdirt(sel.nb.y, sel.ne.y);
 }
 
 void
 selextend(int col, int row, int type, int done)
 {
 	int oldey, oldex, oldsby, oldsey, oldtype;
 
 	if (sel.mode == SEL_IDLE)
 		return;
 	if (done && sel.mode == SEL_EMPTY) {
 		selclear();
 		return;
 	}
 
 	oldey = sel.oe.y;
 	oldex = sel.oe.x;
 	oldsby = sel.nb.y;
 	oldsey = sel.ne.y;
 	oldtype = sel.type;
 
 	sel.oe.x = col;
 	sel.oe.y = row;
 	selnormalize();
 	sel.type = type;
 
 	if (oldey != sel.oe.y || oldex != sel.oe.x || oldtype != sel.type || sel.mode == SEL_EMPTY)
 		tsetdirt(MIN(sel.nb.y, oldsby), MAX(sel.ne.y, oldsey));
 
 	sel.mode = done ? SEL_IDLE : SEL_READY;
 }
 
 void
 selnormalize(void)
 {
 	int i;
 
 	if (sel.type == SEL_REGULAR && sel.ob.y != sel.oe.y) {
 		sel.nb.x = sel.ob.y < sel.oe.y ? sel.ob.x : sel.oe.x;
 		sel.ne.x = sel.ob.y < sel.oe.y ? sel.oe.x : sel.ob.x;
 	} else {
 		sel.nb.x = MIN(sel.ob.x, sel.oe.x);
 		sel.ne.x = MAX(sel.ob.x, sel.oe.x);
 	}
 	sel.nb.y = MIN(sel.ob.y, sel.oe.y);
 	sel.ne.y = MAX(sel.ob.y, sel.oe.y);
 
 	selsnap(&sel.nb.x, &sel.nb.y, -1);
 	selsnap(&sel.ne.x, &sel.ne.y, +1);
 
 	/* expand selection over line breaks */
 	if (sel.type == SEL_RECTANGULAR)
 		return;
 	i = tlinelen(sel.nb.y);
 	if (i < sel.nb.x)
 		sel.nb.x = i;
 	if (tlinelen(sel.ne.y) <= sel.ne.x)
 		sel.ne.x = term.col - 1;
 }
 
 int
 selected(int x, int y)
 {
 	if (sel.mode == SEL_EMPTY || sel.ob.x == -1 ||
 			sel.alt != IS_SET(MODE_ALTSCREEN))
 		return 0;
 
 	if (sel.type == SEL_RECTANGULAR)
 		return BETWEEN(y, sel.nb.y, sel.ne.y)
 		    && BETWEEN(x, sel.nb.x, sel.ne.x);
 
 	return BETWEEN(y, sel.nb.y, sel.ne.y)
 	    && (y != sel.nb.y || x >= sel.nb.x)
 	    && (y != sel.ne.y || x <= sel.ne.x);
 }
 
 void
 selsnap(int *x, int *y, int direction)
 {
 	int newx, newy, xt, yt;
 	int delim, prevdelim;
 	const Glyph *gp, *prevgp;
 
 	switch (sel.snap) {
 	case SNAP_WORD:
 		/*
 		 * Snap around if the word wraps around at the end or
 		 * beginning of a line.
 		 */
 		prevgp = &TLINE(*y)[*x];
 		prevdelim = ISDELIM(prevgp->u);
 		for (;;) {
 			newx = *x + direction;
 			newy = *y;
 			if (!BETWEEN(newx, 0, term.col - 1)) {
 				newy += direction;
 				newx = (newx + term.col) % term.col;
 				if (!BETWEEN(newy, 0, term.row - 1))
 					break;
 
 				if (direction > 0)
 					yt = *y, xt = *x;
 				else
 					yt = newy, xt = newx;
 				if (!(TLINE(yt)[xt].mode & ATTR_WRAP))
 					break;
 			}
 
 			if (newx >= tlinelen(newy))
 				break;
 
 			gp = &TLINE(newy)[newx];
 			delim = ISDELIM(gp->u);
 			if (!(gp->mode & ATTR_WDUMMY) && (delim != prevdelim
 					|| (delim && gp->u != prevgp->u)))
 				break;
 
 			*x = newx;
 			*y = newy;
 			prevgp = gp;
 			prevdelim = delim;
 		}
 		break;
 	case SNAP_LINE:
 		/*
 		 * Snap around if the the previous line or the current one
 		 * has set ATTR_WRAP at its end. Then the whole next or
 		 * previous line will be selected.
 		 */
 		*x = (direction < 0) ? 0 : term.col - 1;
 		if (direction < 0) {
 			for (; *y > 0; *y += direction) {
 				if (!(TLINE(*y-1)[term.col-1].mode
 						& ATTR_WRAP)) {
 					break;
 				}
 			}
 		} else if (direction > 0) {
 			for (; *y < term.row-1; *y += direction) {
 				if (!(TLINE(*y)[term.col-1].mode
 						& ATTR_WRAP)) {
 					break;
 				}
 			}
 		}
 		break;
 	}
 }
 
 char *
 getsel(void)
 {
 	char *str, *ptr;
 	int y, bufsize, lastx, linelen;
 	const Glyph *gp, *last;
 
 	if (sel.ob.x == -1)
 		return NULL;
 
 	bufsize = (term.col+1) * (sel.ne.y-sel.nb.y+1) * UTF_SIZ;
 	ptr = str = xmalloc(bufsize);
 
 	/* append every set & selected glyph to the selection */
 	for (y = sel.nb.y; y <= sel.ne.y; y++) {
 		if ((linelen = tlinelen(y)) == 0) {
 			*ptr++ = '\n';
 			continue;
 		}
 
 		if (sel.type == SEL_RECTANGULAR) {
 			gp = &TLINE(y)[sel.nb.x];
 			lastx = sel.ne.x;
 		} else {
 			gp = &TLINE(y)[sel.nb.y == y ? sel.nb.x : 0];
 			lastx = (sel.ne.y == y) ? sel.ne.x : term.col-1;
 		}
 		last = &TLINE(y)[MIN(lastx, linelen-1)];
 		while (last >= gp && last->u == ' ')
 			--last;
 
 		for ( ; gp <= last; ++gp) {
 			if (gp->mode & ATTR_WDUMMY)
 				continue;
 
 			ptr += utf8encode(gp->u, ptr);
 		}
 
 		/*
 		 * Copy and pasting of line endings is inconsistent
 		 * in the inconsistent terminal and GUI world.
 		 * The best solution seems like to produce '\n' when
 		 * something is copied from st and convert '\n' to
 		 * '\r', when something to be pasted is received by
 		 * st.
 		 * FIXME: Fix the computer world.
 		 */
 		if ((y < sel.ne.y || lastx >= linelen) &&
 		    (!(last->mode & ATTR_WRAP) || sel.type == SEL_RECTANGULAR))
 			*ptr++ = '\n';
 	}
 	*ptr = 0;
 	return str;
 }
 
 void
 selclear(void)
 {
 	if (sel.ob.x == -1)
 		return;
 	sel.mode = SEL_IDLE;
 	sel.ob.x = -1;
 	tsetdirt(sel.nb.y, sel.ne.y);
 }
 
 void
 die(const char *errstr, ...)
 {
 	va_list ap;
 
 	va_start(ap, errstr);
 	vfprintf(stderr, errstr, ap);
 	va_end(ap);
 	exit(1);
 }
 
 void
 execsh(char *cmd, char **args)
 {
 	char *sh, *prog, *arg;
 	const struct passwd *pw;
 
 	errno = 0;
 	if ((pw = getpwuid(getuid())) == NULL) {
 		if (errno)
 			die("getpwuid: %s\n", strerror(errno));
 		else
 			die("who are you?\n");
 	}
 
 	if ((sh = getenv("SHELL")) == NULL)
 		sh = (pw->pw_shell[0]) ? pw->pw_shell : cmd;
 
 	if (args) {
 		prog = args[0];
 		arg = NULL;
 	} else if (scroll) {
 		prog = scroll;
 		arg = utmp ? utmp : sh;
 	} else if (utmp) {
 		prog = utmp;
 		arg = NULL;
 	} else {
 		prog = sh;
 		arg = NULL;
 	}
 	DEFAULT(args, ((char *[]) {prog, arg, NULL}));
 
 	unsetenv("COLUMNS");
 	unsetenv("LINES");
 	unsetenv("TERMCAP");
 	setenv("LOGNAME", pw->pw_name, 1);
 	setenv("USER", pw->pw_name, 1);
 	setenv("SHELL", sh, 1);
 	setenv("HOME", pw->pw_dir, 1);
 	setenv("TERM", termname, 1);
 
 	signal(SIGCHLD, SIG_DFL);
 	signal(SIGHUP, SIG_DFL);
 	signal(SIGINT, SIG_DFL);
 	signal(SIGQUIT, SIG_DFL);
 	signal(SIGTERM, SIG_DFL);
 	signal(SIGALRM, SIG_DFL);
 
 	execvp(prog, args);
 	_exit(1);
 }
 
 void
 sigchld(int a)
 {
 	int stat;
 	pid_t p;
 
 	if ((p = waitpid(pid, &stat, WNOHANG)) < 0)
 		die("waiting for pid %hd failed: %s\n", pid, strerror(errno));
 
 	if (pid != p)
 		return;
 
 	if (WIFEXITED(stat) && WEXITSTATUS(stat))
 		die("child exited with status %d\n", WEXITSTATUS(stat));
 	else if (WIFSIGNALED(stat))
 		die("child terminated due to signal %d\n", WTERMSIG(stat));
 	_exit(0);
 }
 
 void
 stty(char **args)
 {
 	char cmd[_POSIX_ARG_MAX], **p, *q, *s;
 	size_t n, siz;
 
 	if ((n = strlen(stty_args)) > sizeof(cmd)-1)
 		die("incorrect stty parameters\n");
 	memcpy(cmd, stty_args, n);
 	q = cmd + n;
 	siz = sizeof(cmd) - n;
 	for (p = args; p && (s = *p); ++p) {
 		if ((n = strlen(s)) > siz-1)
 			die("stty parameter length too long\n");
 		*q++ = ' ';
 		memcpy(q, s, n);
 		q += n;
 		siz -= n + 1;
 	}
 	*q = '\0';
 	if (system(cmd) != 0)
 		perror("Couldn't call stty");
 }
 
 int
 ttynew(const char *line, char *cmd, const char *out, char **args)
 {
 	int m, s;
 
 	if (out) {
 		term.mode |= MODE_PRINT;
 		iofd = (!strcmp(out, "-")) ?
 			  1 : open(out, O_WRONLY | O_CREAT, 0666);
 		if (iofd < 0) {
 			fprintf(stderr, "Error opening %s:%s\n",
 				out, strerror(errno));
 		}
 	}
 
 	if (line) {
 		if ((cmdfd = open(line, O_RDWR)) < 0)
 			die("open line '%s' failed: %s\n",
 			    line, strerror(errno));
 		dup2(cmdfd, 0);
 		stty(args);
 		return cmdfd;
 	}
 
 	/* seems to work fine on linux, openbsd and freebsd */
 	if (openpty(&m, &s, NULL, NULL, NULL) < 0)
 		die("openpty failed: %s\n", strerror(errno));
 
 	switch (pid = fork()) {
 	case -1:
 		die("fork failed: %s\n", strerror(errno));
 		break;
 	case 0:
 		close(iofd);
 		close(m);
 		setsid(); /* create a new process group */
 		dup2(s, 0);
 		dup2(s, 1);
 		dup2(s, 2);
 		if (ioctl(s, TIOCSCTTY, NULL) < 0)
 			die("ioctl TIOCSCTTY failed: %s\n", strerror(errno));
 		if (s > 2)
 			close(s);
 #ifdef __OpenBSD__
 		if (pledge("stdio getpw proc exec", NULL) == -1)
 			die("pledge\n");
 #endif
 		execsh(cmd, args);
 		break;
 	default:
 #ifdef __OpenBSD__
 		if (pledge("stdio rpath tty proc", NULL) == -1)
 			die("pledge\n");
 #endif
 		close(s);
 		cmdfd = m;
 		signal(SIGCHLD, sigchld);
 		break;
 	}
 	return cmdfd;
 }
 
 size_t
 ttyread(void)
 {
 	static char buf[BUFSIZ];
 	static int buflen = 0;
 	int ret, written;
 
 	/* append read bytes to unprocessed bytes */
 	ret = read(cmdfd, buf+buflen, LEN(buf)-buflen);
 
 	switch (ret) {
 	case 0:
 		exit(0);
 	case -1:
 		die("couldn't read from shell: %s\n", strerror(errno));
 	default:
 		buflen += ret;
 		written = twrite(buf, buflen, 0);
 		buflen -= written;
 		/* keep any incomplete UTF-8 byte sequence for the next call */
 		if (buflen > 0)
 			memmove(buf, buf + written, buflen);
 		return ret;
 	}
 }
 
 void
 ttywrite(const char *s, size_t n, int may_echo)
 {
 	const char *next;
 	Arg arg = (Arg) { .i = term.scr };
 
 	kscrolldown(&arg);
 
 	if (may_echo && IS_SET(MODE_ECHO))
 		twrite(s, n, 1);
 
 	if (!IS_SET(MODE_CRLF)) {
 		ttywriteraw(s, n);
 		return;
 	}
 
 	/* This is similar to how the kernel handles ONLCR for ttys */
 	while (n > 0) {
 		if (*s == '\r') {
 			next = s + 1;
 			ttywriteraw("\r\n", 2);
 		} else {
 			next = memchr(s, '\r', n);
 			DEFAULT(next, s + n);
 			ttywriteraw(s, next - s);
 		}
 		n -= next - s;
 		s = next;
 	}
 }
 
 void
 ttywriteraw(const char *s, size_t n)
 {
 	fd_set wfd, rfd;
 	ssize_t r;
 	size_t lim = 256;
 
 	/*
 	 * Remember that we are using a pty, which might be a modem line.
 	 * Writing too much will clog the line. That's why we are doing this
 	 * dance.
 	 * FIXME: Migrate the world to Plan 9.
 	 */
 	while (n > 0) {
 		FD_ZERO(&wfd);
 		FD_ZERO(&rfd);
 		FD_SET(cmdfd, &wfd);
 		FD_SET(cmdfd, &rfd);
 
 		/* Check if we can write. */
 		if (pselect(cmdfd+1, &rfd, &wfd, NULL, NULL, NULL) < 0) {
 			if (errno == EINTR)
 				continue;
 			die("select failed: %s\n", strerror(errno));
 		}
 		if (FD_ISSET(cmdfd, &wfd)) {
 			/*
 			 * Only write the bytes written by ttywrite() or the
 			 * default of 256. This seems to be a reasonable value
 			 * for a serial line. Bigger values might clog the I/O.
 			 */
 			if ((r = write(cmdfd, s, (n < lim)? n : lim)) < 0)
 				goto write_error;
 			if (r < n) {
 				/*
 				 * We weren't able to write out everything.
 				 * This means the buffer is getting full
 				 * again. Empty it.
 				 */
 				if (n < lim)
 					lim = ttyread();
 				n -= r;
 				s += r;
 			} else {
 				/* All bytes have been written. */
 				break;
 			}
 		}
 		if (FD_ISSET(cmdfd, &rfd))
 			lim = ttyread();
 	}
 	return;
 
 write_error:
 	die("write error on tty: %s\n", strerror(errno));
 }
 
 void
 ttyresize(int tw, int th)
 {
 	struct winsize w;
 
 	w.ws_row = term.row;
 	w.ws_col = term.col;
 	w.ws_xpixel = tw;
 	w.ws_ypixel = th;
 	if (ioctl(cmdfd, TIOCSWINSZ, &w) < 0)
 		fprintf(stderr, "Couldn't set window size: %s\n", strerror(errno));
 }
 
 void
 ttyhangup(void)
 {
 	/* Send SIGHUP to shell */
 	kill(pid, SIGHUP);
 }
 
 int
 tattrset(int attr)
 {
 	int i, j;
 
 	for (i = 0; i < term.row-1; i++) {
 		for (j = 0; j < term.col-1; j++) {
 			if (term.line[i][j].mode & attr)
 				return 1;
 		}
 	}
 
 	return 0;
 }
 
 void
 tsetdirt(int top, int bot)
 {
 	int i;
 
 	LIMIT(top, 0, term.row-1);
 	LIMIT(bot, 0, term.row-1);
 
 	for (i = top; i <= bot; i++)
 		term.dirty[i] = 1;
 }
 
 void
 tsetdirtattr(int attr)
 {
 	int i, j;
 
 	for (i = 0; i < term.row-1; i++) {
 		for (j = 0; j < term.col-1; j++) {
 			if (term.line[i][j].mode & attr) {
 				tsetdirt(i, i);
 				break;
 			}
 		}
 	}
 }
 
 void
 tfulldirt(void)
 {
 	tsetdirt(0, term.row-1);
 }
 
 void
 tcursor(int mode)
 {
 	static TCursor c[2];
 	int alt = IS_SET(MODE_ALTSCREEN);
 
 	if (mode == CURSOR_SAVE) {
 		c[alt] = term.c;
 	} else if (mode == CURSOR_LOAD) {
 		term.c = c[alt];
 		tmoveto(c[alt].x, c[alt].y);
 	}
 }
 
 void
 treset(void)
 {
 	uint i;
 
 	term.c = (TCursor){{
 		.mode = ATTR_NULL,
 		.fg = defaultfg,
 		.bg = defaultbg
 	}, .x = 0, .y = 0, .state = CURSOR_DEFAULT};
 
 	memset(term.tabs, 0, term.col * sizeof(*term.tabs));
 	for (i = tabspaces; i < term.col; i += tabspaces)
 		term.tabs[i] = 1;
 	term.top = 0;
 	term.bot = term.row - 1;
 	term.mode = MODE_WRAP|MODE_UTF8;
 	memset(term.trantbl, CS_USA, sizeof(term.trantbl));
 	term.charset = 0;
 
 	for (i = 0; i < 2; i++) {
 		tmoveto(0, 0);
 		tcursor(CURSOR_SAVE);
 		tclearregion(0, 0, term.col-1, term.row-1);
 		tswapscreen();
 	}
 }
 
 void
 tnew(int col, int row)
 {
 	term = (Term){ .c = { .attr = { .fg = defaultfg, .bg = defaultbg } } };
 	tresize(col, row);
 	treset();
 }
 
 void
 tswapscreen(void)
 {
 	Line *tmp = term.line;
 
 	term.line = term.alt;
 	term.alt = tmp;
 	term.mode ^= MODE_ALTSCREEN;
 	tfulldirt();
 }
 
 void
 kscrolldown(const Arg* a)
 {
 	int n = a->i;
 
 	if (n < 0)
 		n = term.row + n;
 
 	if (n > term.scr)
 		n = term.scr;
 
 	if (term.scr > 0) {
 		term.scr -= n;
 		selscroll(0, -n);
 		tfulldirt();
 	}
 }
 
 void
 kscrollup(const Arg* a)
 {
 	int n = a->i;
 
 	if (n < 0)
 		n = term.row + n;
 
 	if (term.scr <= HISTSIZE-n) {
 		term.scr += n;
 		selscroll(0, n);
 		tfulldirt();
 	}
 }
 
 void
 tscrolldown(int orig, int n, int copyhist)
 {
 	int i;
 	Line temp;
 
 	LIMIT(n, 0, term.bot-orig+1);
 
 	if (copyhist) {
 		term.histi = (term.histi - 1 + HISTSIZE) % HISTSIZE;
 		temp = term.hist[term.histi];
 		term.hist[term.histi] = term.line[term.bot];
 		term.line[term.bot] = temp;
 	}
 
 	tsetdirt(orig, term.bot-n);
 	tclearregion(0, term.bot-n+1, term.col-1, term.bot);
 
 	for (i = term.bot; i >= orig+n; i--) {
 		temp = term.line[i];
 		term.line[i] = term.line[i-n];
 		term.line[i-n] = temp;
 	}
 
 	if (term.scr == 0)
 		selscroll(orig, n);
 }
 
 void
 tscrollup(int orig, int n, int copyhist)
 {
 	int i;
 	Line temp;
 
 	LIMIT(n, 0, term.bot-orig+1);
 
 	if (copyhist) {
 		term.histi = (term.histi + 1) % HISTSIZE;
 		temp = term.hist[term.histi];
 		term.hist[term.histi] = term.line[orig];
 		term.line[orig] = temp;
 	}
 
 	if (term.scr > 0 && term.scr < HISTSIZE)
 		term.scr = MIN(term.scr + n, HISTSIZE-1);
 
 	tclearregion(0, orig, term.col-1, orig+n-1);
 	tsetdirt(orig+n, term.bot);
 
 	for (i = orig; i <= term.bot-n; i++) {
 		temp = term.line[i];
 		term.line[i] = term.line[i+n];
 		term.line[i+n] = temp;
 	}
 
 	if (term.scr == 0)
 		selscroll(orig, -n);
 }
 
 void
 selscroll(int orig, int n)
 {
 	if (sel.ob.x == -1 || sel.alt != IS_SET(MODE_ALTSCREEN))
 		return;
 
 	if (BETWEEN(sel.nb.y, orig, term.bot) != BETWEEN(sel.ne.y, orig, term.bot)) {
 		selclear();
 	} else if (BETWEEN(sel.nb.y, orig, term.bot)) {
 		sel.ob.y += n;
 		sel.oe.y += n;
 		if (sel.ob.y < term.top || sel.ob.y > term.bot ||
 		    sel.oe.y < term.top || sel.oe.y > term.bot) {
 			selclear();
 		} else {
 			selnormalize();
 		}
 	}
 }
 
 void
 tnewline(int first_col)
 {
 	int y = term.c.y;
 
 	if (y == term.bot) {
 		tscrollup(term.top, 1, 1);
 	} else {
 		y++;
 	}
 	tmoveto(first_col ? 0 : term.c.x, y);
 }
 
 void
 csiparse(void)
 {
 	char *p = csiescseq.buf, *np;
 	long int v;
 	int sep = ';'; /* colon or semi-colon, but not both */
 
 	csiescseq.narg = 0;
 	if (*p == '?') {
 		csiescseq.priv = 1;
 		p++;
 	}
 
 	csiescseq.buf[csiescseq.len] = '\0';
 	while (p < csiescseq.buf+csiescseq.len) {
 		np = NULL;
 		v = strtol(p, &np, 10);
 		if (np == p)
 			v = 0;
 		if (v == LONG_MAX || v == LONG_MIN)
 			v = -1;
 		csiescseq.arg[csiescseq.narg++] = v;
 		p = np;
 		if (sep == ';' && *p == ':')
 			sep = ':'; /* allow override to colon once */
 		if (*p != sep || csiescseq.narg == ESC_ARG_SIZ)
 			break;
 		p++;
 	}
 	csiescseq.mode[0] = *p++;
 	csiescseq.mode[1] = (p < csiescseq.buf+csiescseq.len) ? *p : '\0';
 }
 
 /* for absolute user moves, when decom is set */
 void
 tmoveato(int x, int y)
 {
 	tmoveto(x, y + ((term.c.state & CURSOR_ORIGIN) ? term.top: 0));
 }
 
 void
 tmoveto(int x, int y)
 {
 	int miny, maxy;
 
 	if (term.c.state & CURSOR_ORIGIN) {
 		miny = term.top;
 		maxy = term.bot;
 	} else {
 		miny = 0;
 		maxy = term.row - 1;
 	}
 	term.c.state &= ~CURSOR_WRAPNEXT;
 	term.c.x = LIMIT(x, 0, term.col-1);
 	term.c.y = LIMIT(y, miny, maxy);
 }
 
 void
 tsetchar(Rune u, const Glyph *attr, int x, int y)
 {
 	static const char *vt100_0[62] = { /* 0x41 - 0x7e */
 		"↑", "↓", "→", "←", "█", "▚", "☃", /* A - G */
 		0, 0, 0, 0, 0, 0, 0, 0, /* H - O */
 		0, 0, 0, 0, 0, 0, 0, 0, /* P - W */
 		0, 0, 0, 0, 0, 0, 0, " ", /* X - _ */
 		"◆", "▒", "␉", "␌", "␍", "␊", "°", "±", /* ` - g */
 		"␤", "␋", "┘", "┐", "┌", "└", "┼", "⎺", /* h - o */
 		"⎻", "─", "⎼", "⎽", "├", "┤", "┴", "┬", /* p - w */
 		"│", "≤", "≥", "π", "≠", "£", "·", /* x - ~ */
 	};
 
 	/*
 	 * The table is proudly stolen from rxvt.
 	 */
 	if (term.trantbl[term.charset] == CS_GRAPHIC0 &&
 	   BETWEEN(u, 0x41, 0x7e) && vt100_0[u - 0x41])
 		utf8decode(vt100_0[u - 0x41], &u, UTF_SIZ);
 
 	if (term.line[y][x].mode & ATTR_WIDE) {
 		if (x+1 < term.col) {
 			term.line[y][x+1].u = ' ';
 			term.line[y][x+1].mode &= ~ATTR_WDUMMY;
 		}
 	} else if (term.line[y][x].mode & ATTR_WDUMMY) {
 		term.line[y][x-1].u = ' ';
 		term.line[y][x-1].mode &= ~ATTR_WIDE;
 	}
 
 	term.dirty[y] = 1;
 	term.line[y][x] = *attr;
 	term.line[y][x].u = u;
 }
 
 void
 tclearregion(int x1, int y1, int x2, int y2)
 {
 	int x, y, temp;
 	Glyph *gp;
 
 	if (x1 > x2)
 		temp = x1, x1 = x2, x2 = temp;
 	if (y1 > y2)
 		temp = y1, y1 = y2, y2 = temp;
 
 	LIMIT(x1, 0, term.col-1);
 	LIMIT(x2, 0, term.col-1);
 	LIMIT(y1, 0, term.row-1);
 	LIMIT(y2, 0, term.row-1);
 
 	for (y = y1; y <= y2; y++) {
 		term.dirty[y] = 1;
 		for (x = x1; x <= x2; x++) {
 			gp = &term.line[y][x];
 			if (selected(x, y))
 				selclear();
 			gp->fg = term.c.attr.fg;
 			gp->bg = term.c.attr.bg;
 			gp->mode = 0;
 			gp->u = ' ';
 		}
 	}
 }
 
 void
 tdeletechar(int n)
 {
 	int dst, src, size;
 	Glyph *line;
 
 	LIMIT(n, 0, term.col - term.c.x);
 
 	dst = term.c.x;
 	src = term.c.x + n;
 	size = term.col - src;
 	line = term.line[term.c.y];
 
 	memmove(&line[dst], &line[src], size * sizeof(Glyph));
 	tclearregion(term.col-n, term.c.y, term.col-1, term.c.y);
 }
 
 void
 tinsertblank(int n)
 {
 	int dst, src, size;
 	Glyph *line;
 
 	LIMIT(n, 0, term.col - term.c.x);
 
 	dst = term.c.x + n;
 	src = term.c.x;
 	size = term.col - dst;
 	line = term.line[term.c.y];
 
 	memmove(&line[dst], &line[src], size * sizeof(Glyph));
 	tclearregion(src, term.c.y, dst - 1, term.c.y);
 }
 
 void
 tinsertblankline(int n)
 {
 	if (BETWEEN(term.c.y, term.top, term.bot))
 		tscrolldown(term.c.y, n, 0);
 }
 
 void
 tdeleteline(int n)
 {
 	if (BETWEEN(term.c.y, term.top, term.bot))
 		tscrollup(term.c.y, n, 0);
 }
 
 int32_t
 tdefcolor(const int *attr, int *npar, int l)
 {
 	int32_t idx = -1;
 	uint r, g, b;
 
 	switch (attr[*npar + 1]) {
 	case 2: /* direct color in RGB space */
 		if (*npar + 4 >= l) {
 			fprintf(stderr,
 				"erresc(38): Incorrect number of parameters (%d)\n",
 				*npar);
 			break;
 		}
 		r = attr[*npar + 2];
 		g = attr[*npar + 3];
 		b = attr[*npar + 4];
 		*npar += 4;
 		if (!BETWEEN(r, 0, 255) || !BETWEEN(g, 0, 255) || !BETWEEN(b, 0, 255))
 			fprintf(stderr, "erresc: bad rgb color (%u,%u,%u)\n",
 				r, g, b);
 		else
 			idx = TRUECOLOR(r, g, b);
 		break;
 	case 5: /* indexed color */
 		if (*npar + 2 >= l) {
 			fprintf(stderr,
 				"erresc(38): Incorrect number of parameters (%d)\n",
 				*npar);
 			break;
 		}
 		*npar += 2;
 		if (!BETWEEN(attr[*npar], 0, 255))
 			fprintf(stderr, "erresc: bad fgcolor %d\n", attr[*npar]);
 		else
 			idx = attr[*npar];
 		break;
 	case 0: /* implemented defined (only foreground) */
 	case 1: /* transparent */
 	case 3: /* direct color in CMY space */
 	case 4: /* direct color in CMYK space */
 	default:
 		fprintf(stderr,
 		        "erresc(38): gfx attr %d unknown\n", attr[*npar]);
 		break;
 	}
 
 	return idx;
 }
 
 void
 tsetattr(const int *attr, int l)
 {
 	int i;
 	int32_t idx;
 
 	for (i = 0; i < l; i++) {
 		switch (attr[i]) {
 		case 0:
 			term.c.attr.mode &= ~(
 				ATTR_BOLD       |
 				ATTR_FAINT      |
 				ATTR_ITALIC     |
 				ATTR_UNDERLINE  |
 				ATTR_BLINK      |
 				ATTR_REVERSE    |
 				ATTR_INVISIBLE  |
 				ATTR_STRUCK     );
 			term.c.attr.fg = defaultfg;
 			term.c.attr.bg = defaultbg;
 			break;
 		case 1:
 			term.c.attr.mode |= ATTR_BOLD;
 			break;
 		case 2:
 			term.c.attr.mode |= ATTR_FAINT;
 			break;
 		case 3:
 			term.c.attr.mode |= ATTR_ITALIC;
 			break;
 		case 4:
 			term.c.attr.mode |= ATTR_UNDERLINE;
 			break;
 		case 5: /* slow blink */
 			/* FALLTHROUGH */
 		case 6: /* rapid blink */
 			term.c.attr.mode |= ATTR_BLINK;
 			break;
 		case 7:
 			term.c.attr.mode |= ATTR_REVERSE;
 			break;
 		case 8:
 			term.c.attr.mode |= ATTR_INVISIBLE;
 			break;
 		case 9:
 			term.c.attr.mode |= ATTR_STRUCK;
 			break;
 		case 22:
 			term.c.attr.mode &= ~(ATTR_BOLD | ATTR_FAINT);
 			break;
 		case 23:
 			term.c.attr.mode &= ~ATTR_ITALIC;
 			break;
 		case 24:
 			term.c.attr.mode &= ~ATTR_UNDERLINE;
 			break;
 		case 25:
 			term.c.attr.mode &= ~ATTR_BLINK;
 			break;
 		case 27:
 			term.c.attr.mode &= ~ATTR_REVERSE;
 			break;
 		case 28:
 			term.c.attr.mode &= ~ATTR_INVISIBLE;
 			break;
 		case 29:
 			term.c.attr.mode &= ~ATTR_STRUCK;
 			break;
 		case 38:
 			if ((idx = tdefcolor(attr, &i, l)) >= 0)
 				term.c.attr.fg = idx;
 			break;
 		case 39:
 			term.c.attr.fg = defaultfg;
 			break;
 		case 48:
 			if ((idx = tdefcolor(attr, &i, l)) >= 0)
 				term.c.attr.bg = idx;
 			break;
 		case 49:
 			term.c.attr.bg = defaultbg;
 			break;
 		default:
 			if (BETWEEN(attr[i], 30, 37)) {
 				term.c.attr.fg = attr[i] - 30;
 			} else if (BETWEEN(attr[i], 40, 47)) {
 				term.c.attr.bg = attr[i] - 40;
 			} else if (BETWEEN(attr[i], 90, 97)) {
 				term.c.attr.fg = attr[i] - 90 + 8;
 			} else if (BETWEEN(attr[i], 100, 107)) {
 				term.c.attr.bg = attr[i] - 100 + 8;
 			} else {
 				fprintf(stderr,
 					"erresc(default): gfx attr %d unknown\n",
 					attr[i]);
 				csidump();
 			}
 			break;
 		}
 	}
 }
 
 void
 tsetscroll(int t, int b)
 {
 	int temp;
 
 	LIMIT(t, 0, term.row-1);
 	LIMIT(b, 0, term.row-1);
 	if (t > b) {
 		temp = t;
 		t = b;
 		b = temp;
 	}
 	term.top = t;
 	term.bot = b;
 }
 
 void
 tsetmode(int priv, int set, const int *args, int narg)
 {
 	int alt; const int *lim;
 
 	for (lim = args + narg; args < lim; ++args) {
 		if (priv) {
 			switch (*args) {
 			case 1: /* DECCKM -- Cursor key */
 				xsetmode(set, MODE_APPCURSOR);
 				break;
 			case 5: /* DECSCNM -- Reverse video */
 				xsetmode(set, MODE_REVERSE);
 				break;
 			case 6: /* DECOM -- Origin */
 				MODBIT(term.c.state, set, CURSOR_ORIGIN);
 				tmoveato(0, 0);
 				break;
 			case 7: /* DECAWM -- Auto wrap */
 				MODBIT(term.mode, set, MODE_WRAP);
 				break;
 			case 0:  /* Error (IGNORED) */
 			case 2:  /* DECANM -- ANSI/VT52 (IGNORED) */
 			case 3:  /* DECCOLM -- Column  (IGNORED) */
 			case 4:  /* DECSCLM -- Scroll (IGNORED) */
 			case 8:  /* DECARM -- Auto repeat (IGNORED) */
 			case 18: /* DECPFF -- Printer feed (IGNORED) */
 			case 19: /* DECPEX -- Printer extent (IGNORED) */
 			case 42: /* DECNRCM -- National characters (IGNORED) */
 			case 12: /* att610 -- Start blinking cursor (IGNORED) */
 				break;
 			case 25: /* DECTCEM -- Text Cursor Enable Mode */
 				xsetmode(!set, MODE_HIDE);
 				break;
 			case 9:    /* X10 mouse compatibility mode */
 				xsetpointermotion(0);
 				xsetmode(0, MODE_MOUSE);
 				xsetmode(set, MODE_MOUSEX10);
 				break;
 			case 1000: /* 1000: report button press */
 				xsetpointermotion(0);
 				xsetmode(0, MODE_MOUSE);
 				xsetmode(set, MODE_MOUSEBTN);
 				break;
 			case 1002: /* 1002: report motion on button press */
 				xsetpointermotion(0);
 				xsetmode(0, MODE_MOUSE);
 				xsetmode(set, MODE_MOUSEMOTION);
 				break;
 			case 1003: /* 1003: enable all mouse motions */
 				xsetpointermotion(set);
 				xsetmode(0, MODE_MOUSE);
 				xsetmode(set, MODE_MOUSEMANY);
 				break;
 			case 1004: /* 1004: send focus events to tty */
 				xsetmode(set, MODE_FOCUS);
 				break;
 			case 1006: /* 1006: extended reporting mode */
 				xsetmode(set, MODE_MOUSESGR);
 				break;
 			case 1034:
 				xsetmode(set, MODE_8BIT);
 				break;
 			case 1049: /* swap screen & set/restore cursor as xterm */
 				if (!allowaltscreen)
 					break;
 				tcursor((set) ? CURSOR_SAVE : CURSOR_LOAD);
 				/* FALLTHROUGH */
 			case 47: /* swap screen */
 			case 1047:
 				if (!allowaltscreen)
 					break;
 				alt = IS_SET(MODE_ALTSCREEN);
 				if (alt) {
 					tclearregion(0, 0, term.col-1,
 							term.row-1);
 				}
 				if (set ^ alt) /* set is always 1 or 0 */
 					tswapscreen();
 				if (*args != 1049)
 					break;
 				/* FALLTHROUGH */
 			case 1048:
 				tcursor((set) ? CURSOR_SAVE : CURSOR_LOAD);
 				break;
 			case 2004: /* 2004: bracketed paste mode */
 				xsetmode(set, MODE_BRCKTPASTE);
 				break;
 			/* Not implemented mouse modes. See comments there. */
 			case 1001: /* mouse highlight mode; can hang the
 				      terminal by design when implemented. */
 			case 1005: /* UTF-8 mouse mode; will confuse
 				      applications not supporting UTF-8
 				      and luit. */
 			case 1015: /* urxvt mangled mouse mode; incompatible
 				      and can be mistaken for other control
 				      codes. */
 				break;
 			default:
 				fprintf(stderr,
 					"erresc: unknown private set/reset mode %d\n",
 					*args);
 				break;
 			}
 		} else {
 			switch (*args) {
 			case 0:  /* Error (IGNORED) */
 				break;
 			case 2:
 				xsetmode(set, MODE_KBDLOCK);
 				break;
 			case 4:  /* IRM -- Insertion-replacement */
 				MODBIT(term.mode, set, MODE_INSERT);
 				break;
 			case 12: /* SRM -- Send/Receive */
 				MODBIT(term.mode, !set, MODE_ECHO);
 				break;
 			case 20: /* LNM -- Linefeed/new line */
 				MODBIT(term.mode, set, MODE_CRLF);
 				break;
 			default:
 				fprintf(stderr,
 					"erresc: unknown set/reset mode %d\n",
 					*args);
 				break;
 			}
 		}
 	}
 }
 
 void
 csihandle(void)
 {
 	char buf[40];
 	int len;
 
 	switch (csiescseq.mode[0]) {
 	default:
 	unknown:
 		fprintf(stderr, "erresc: unknown csi ");
 		csidump();
 		/* die(""); */
 		break;
 	case '@': /* ICH -- Insert <n> blank char */
 		DEFAULT(csiescseq.arg[0], 1);
 		tinsertblank(csiescseq.arg[0]);
 		break;
 	case 'A': /* CUU -- Cursor <n> Up */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveto(term.c.x, term.c.y-csiescseq.arg[0]);
 		break;
 	case 'B': /* CUD -- Cursor <n> Down */
 	case 'e': /* VPR --Cursor <n> Down */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveto(term.c.x, term.c.y+csiescseq.arg[0]);
 		break;
 	case 'i': /* MC -- Media Copy */
 		switch (csiescseq.arg[0]) {
 		case 0:
 			tdump();
 			break;
 		case 1:
 			tdumpline(term.c.y);
 			break;
 		case 2:
 			tdumpsel();
 			break;
 		case 4:
 			term.mode &= ~MODE_PRINT;
 			break;
 		case 5:
 			term.mode |= MODE_PRINT;
 			break;
 		}
 		break;
 	case 'c': /* DA -- Device Attributes */
 		if (csiescseq.arg[0] == 0)
 			ttywrite(vtiden, strlen(vtiden), 0);
 		break;
 	case 'b': /* REP -- if last char is printable print it <n> more times */
 		LIMIT(csiescseq.arg[0], 1, 65535);
 		if (term.lastc)
 			while (csiescseq.arg[0]-- > 0)
 				tputc(term.lastc);
 		break;
 	case 'C': /* CUF -- Cursor <n> Forward */
 	case 'a': /* HPR -- Cursor <n> Forward */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveto(term.c.x+csiescseq.arg[0], term.c.y);
 		break;
 	case 'D': /* CUB -- Cursor <n> Backward */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveto(term.c.x-csiescseq.arg[0], term.c.y);
 		break;
 	case 'E': /* CNL -- Cursor <n> Down and first col */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveto(0, term.c.y+csiescseq.arg[0]);
 		break;
 	case 'F': /* CPL -- Cursor <n> Up and first col */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveto(0, term.c.y-csiescseq.arg[0]);
 		break;
 	case 'g': /* TBC -- Tabulation clear */
 		switch (csiescseq.arg[0]) {
 		case 0: /* clear current tab stop */
 			term.tabs[term.c.x] = 0;
 			break;
 		case 3: /* clear all the tabs */
 			memset(term.tabs, 0, term.col * sizeof(*term.tabs));
 			break;
 		default:
 			goto unknown;
 		}
 		break;
 	case 'G': /* CHA -- Move to <col> */
 	case '`': /* HPA */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveto(csiescseq.arg[0]-1, term.c.y);
 		break;
 	case 'H': /* CUP -- Move to <row> <col> */
 	case 'f': /* HVP */
 		DEFAULT(csiescseq.arg[0], 1);
 		DEFAULT(csiescseq.arg[1], 1);
 		tmoveato(csiescseq.arg[1]-1, csiescseq.arg[0]-1);
 		break;
 	case 'I': /* CHT -- Cursor Forward Tabulation <n> tab stops */
 		DEFAULT(csiescseq.arg[0], 1);
 		tputtab(csiescseq.arg[0]);
 		break;
 	case 'J': /* ED -- Clear screen */
 		switch (csiescseq.arg[0]) {
 		case 0: /* below */
 			tclearregion(term.c.x, term.c.y, term.col-1, term.c.y);
 			if (term.c.y < term.row-1) {
 				tclearregion(0, term.c.y+1, term.col-1,
 						term.row-1);
 			}
 			break;
 		case 1: /* above */
 			if (term.c.y > 0)
 				tclearregion(0, 0, term.col-1, term.c.y-1);
 			tclearregion(0, term.c.y, term.c.x, term.c.y);
 			break;
 		case 2: /* all */
 			tclearregion(0, 0, term.col-1, term.row-1);
 			break;
 		default:
 			goto unknown;
 		}
 		break;
 	case 'K': /* EL -- Clear line */
 		switch (csiescseq.arg[0]) {
 		case 0: /* right */
 			tclearregion(term.c.x, term.c.y, term.col-1,
 					term.c.y);
 			break;
 		case 1: /* left */
 			tclearregion(0, term.c.y, term.c.x, term.c.y);
 			break;
 		case 2: /* all */
 			tclearregion(0, term.c.y, term.col-1, term.c.y);
 			break;
 		}
 		break;
 	case 'S': /* SU -- Scroll <n> line up */
 		if (csiescseq.priv) break;
 		DEFAULT(csiescseq.arg[0], 1);
 		tscrollup(term.top, csiescseq.arg[0], 0);
 		break;
 	case 'T': /* SD -- Scroll <n> line down */
 		DEFAULT(csiescseq.arg[0], 1);
 		tscrolldown(term.top, csiescseq.arg[0], 0);
 		break;
 	case 'L': /* IL -- Insert <n> blank lines */
 		DEFAULT(csiescseq.arg[0], 1);
 		tinsertblankline(csiescseq.arg[0]);
 		break;
 	case 'l': /* RM -- Reset Mode */
 		tsetmode(csiescseq.priv, 0, csiescseq.arg, csiescseq.narg);
 		break;
 	case 'M': /* DL -- Delete <n> lines */
 		DEFAULT(csiescseq.arg[0], 1);
 		tdeleteline(csiescseq.arg[0]);
 		break;
 	case 'X': /* ECH -- Erase <n> char */
 		DEFAULT(csiescseq.arg[0], 1);
 		tclearregion(term.c.x, term.c.y,
 				term.c.x + csiescseq.arg[0] - 1, term.c.y);
 		break;
 	case 'P': /* DCH -- Delete <n> char */
 		DEFAULT(csiescseq.arg[0], 1);
 		tdeletechar(csiescseq.arg[0]);
 		break;
 	case 'Z': /* CBT -- Cursor Backward Tabulation <n> tab stops */
 		DEFAULT(csiescseq.arg[0], 1);
 		tputtab(-csiescseq.arg[0]);
 		break;
 	case 'd': /* VPA -- Move to <row> */
 		DEFAULT(csiescseq.arg[0], 1);
 		tmoveato(term.c.x, csiescseq.arg[0]-1);
 		break;
 	case 'h': /* SM -- Set terminal mode */
 		tsetmode(csiescseq.priv, 1, csiescseq.arg, csiescseq.narg);
 		break;
 	case 'm': /* SGR -- Terminal attribute (color) */
 		tsetattr(csiescseq.arg, csiescseq.narg);
 		break;
 	case 'n': /* DSR -- Device Status Report */
 		switch (csiescseq.arg[0]) {
 		case 5: /* Status Report "OK" `0n` */
 			ttywrite("\033[0n", sizeof("\033[0n") - 1, 0);
 			break;
 		case 6: /* Report Cursor Position (CPR) "<row>;<column>R" */
 			len = snprintf(buf, sizeof(buf), "\033[%i;%iR",
 			               term.c.y+1, term.c.x+1);
 			ttywrite(buf, len, 0);
 			break;
 		default:
 			goto unknown;
 		}
 		break;
 	case 'r': /* DECSTBM -- Set Scrolling Region */
 		if (csiescseq.priv) {
 			goto unknown;
 		} else {
 			DEFAULT(csiescseq.arg[0], 1);
 			DEFAULT(csiescseq.arg[1], term.row);
 			tsetscroll(csiescseq.arg[0]-1, csiescseq.arg[1]-1);
 			tmoveato(0, 0);
 		}
 		break;
 	case 's': /* DECSC -- Save cursor position (ANSI.SYS) */
 		tcursor(CURSOR_SAVE);
 		break;
 	case 'u': /* DECRC -- Restore cursor position (ANSI.SYS) */
 		if (csiescseq.priv) {
 			goto unknown;
 		} else {
 			tcursor(CURSOR_LOAD);
 		}
 		break;
 	case ' ':
 		switch (csiescseq.mode[1]) {
 		case 'q': /* DECSCUSR -- Set Cursor Style */
 			if (xsetcursor(csiescseq.arg[0]))
 				goto unknown;
 			break;
 		default:
 			goto unknown;
 		}
 		break;
 	}
 }
 
 void
 csidump(void)
 {
 	size_t i;
 	uint c;
 
 	fprintf(stderr, "ESC[");
 	for (i = 0; i < csiescseq.len; i++) {
 		c = csiescseq.buf[i] & 0xff;
 		if (isprint(c)) {
 			putc(c, stderr);
 		} else if (c == '\n') {
 			fprintf(stderr, "(\\n)");
 		} else if (c == '\r') {
 			fprintf(stderr, "(\\r)");
 		} else if (c == 0x1b) {
 			fprintf(stderr, "(\\e)");
 		} else {
 			fprintf(stderr, "(%02x)", c);
 		}
 	}
 	putc('\n', stderr);
 }
 
 void
 csireset(void)
 {
 	memset(&csiescseq, 0, sizeof(csiescseq));
 }
 
 void
 osc_color_response(int num, int index, int is_osc4)
 {
 	int n;
 	char buf[32];
 	unsigned char r, g, b;
 
 	if (xgetcolor(is_osc4 ? num : index, &r, &g, &b)) {
 		fprintf(stderr, "erresc: failed to fetch %s color %d\n",
 		        is_osc4 ? "osc4" : "osc",
 		        is_osc4 ? num : index);
 		return;
 	}
 
 	n = snprintf(buf, sizeof buf, "\033]%s%d;rgb:%02x%02x/%02x%02x/%02x%02x\007",
 	             is_osc4 ? "4;" : "", num, r, r, g, g, b, b);
 	if (n < 0 || n >= sizeof(buf)) {
 		fprintf(stderr, "error: %s while printing %s response\n",
 		        n < 0 ? "snprintf failed" : "truncation occurred",
 		        is_osc4 ? "osc4" : "osc");
 	} else {
 		ttywrite(buf, n, 1);
 	}
 }
 
 void
 strhandle(void)
 {
 	char *p = NULL, *dec;
 	int j, narg, par;
 	const struct { int idx; char *str; } osc_table[] = {
 		{ defaultfg, "foreground" },
 		{ defaultbg, "background" },
 		{ defaultcs, "cursor" }
 	};
 
 	term.esc &= ~(ESC_STR_END|ESC_STR);
 	strparse();
 	par = (narg = strescseq.narg) ? atoi(strescseq.args[0]) : 0;
 
 	switch (strescseq.type) {
 	case ']': /* OSC -- Operating System Command */
 		switch (par) {
 		case 0:
 			if (narg > 1) {
 				xsettitle(strescseq.args[1]);
 				xseticontitle(strescseq.args[1]);
 			}
 			return;
 		case 1:
 			if (narg > 1)
 				xseticontitle(strescseq.args[1]);
 			return;
 		case 2:
 			if (narg > 1)
 				xsettitle(strescseq.args[1]);
 			return;
 		case 52:
 			if (narg > 2 && allowwindowops) {
 				dec = base64dec(strescseq.args[2]);
 				if (dec) {
 					xsetsel(dec);
 					xclipcopy();
 				} else {
 					fprintf(stderr, "erresc: invalid base64\n");
 				}
 			}
 			return;
 		case 10:
 		case 11:
 		case 12:
 			if (narg < 2)
 				break;
 			p = strescseq.args[1];
 			if ((j = par - 10) < 0 || j >= LEN(osc_table))
 				break; /* shouldn't be possible */
 
 			if (!strcmp(p, "?")) {
 				osc_color_response(par, osc_table[j].idx, 0);
 			} else if (xsetcolorname(osc_table[j].idx, p)) {
 				fprintf(stderr, "erresc: invalid %s color: %s\n",
 				        osc_table[j].str, p);
 			} else {
 				tfulldirt();
 			}
 			return;
 		case 4: /* color set */
 			if (narg < 3)
 				break;
 			p = strescseq.args[2];
 			/* FALLTHROUGH */
 		case 104: /* color reset */
 			j = (narg > 1) ? atoi(strescseq.args[1]) : -1;
 
 			if (p && !strcmp(p, "?")) {
 				osc_color_response(j, 0, 1);
 			} else if (xsetcolorname(j, p)) {
 				if (par == 104 && narg <= 1) {
 					xloadcols();
 					return; /* color reset without parameter */
 				}
 				fprintf(stderr, "erresc: invalid color j=%d, p=%s\n",
 				        j, p ? p : "(null)");
 			} else {
 				/*
 				 * TODO if defaultbg color is changed, borders
 				 * are dirty
 				 */
 				tfulldirt();
 			}
 			return;
 		}
 		break;
 	case 'k': /* old title set compatibility */
 		xsettitle(strescseq.args[0]);
 		return;
 	case 'P': /* DCS -- Device Control String */
 	case '_': /* APC -- Application Program Command */
 	case '^': /* PM -- Privacy Message */
 		return;
 	}
 
 	fprintf(stderr, "erresc: unknown str ");
 	strdump();
 }
 
 void
 strparse(void)
 {
 	int c;
 	char *p = strescseq.buf;
 
 	strescseq.narg = 0;
 	strescseq.buf[strescseq.len] = '\0';
 
 	if (*p == '\0')
 		return;
 
 	while (strescseq.narg < STR_ARG_SIZ) {
 		strescseq.args[strescseq.narg++] = p;
 		while ((c = *p) != ';' && c != '\0')
 			++p;
 		if (c == '\0')
 			return;
 		*p++ = '\0';
 	}
 }
 
 void
 strdump(void)
 {
 	size_t i;
 	uint c;
 
 	fprintf(stderr, "ESC%c", strescseq.type);
 	for (i = 0; i < strescseq.len; i++) {
 		c = strescseq.buf[i] & 0xff;
 		if (c == '\0') {
 			putc('\n', stderr);
 			return;
 		} else if (isprint(c)) {
 			putc(c, stderr);
 		} else if (c == '\n') {
 			fprintf(stderr, "(\\n)");
 		} else if (c == '\r') {
 			fprintf(stderr, "(\\r)");
 		} else if (c == 0x1b) {
 			fprintf(stderr, "(\\e)");
 		} else {
 			fprintf(stderr, "(%02x)", c);
 		}
 	}
 	fprintf(stderr, "ESC\\\n");
 }
 
 void
 strreset(void)
 {
 	strescseq = (STREscape){
 		.buf = xrealloc(strescseq.buf, STR_BUF_SIZ),
 		.siz = STR_BUF_SIZ,
 	};
 }
 
 void
 sendbreak(const Arg *arg)
 {
 	if (tcsendbreak(cmdfd, 0))
 		perror("Error sending break");
 }
 
 void
 tprinter(char *s, size_t len)
 {
 	if (iofd != -1 && xwrite(iofd, s, len) < 0) {
 		perror("Error writing to output file");
 		close(iofd);
 		iofd = -1;
 	}
 }
 
 void
 toggleprinter(const Arg *arg)
 {
 	term.mode ^= MODE_PRINT;
 }
 
 void
 printscreen(const Arg *arg)
 {
 	tdump();
 }
 
 void
 printsel(const Arg *arg)
 {
 	tdumpsel();
 }
 
 void
 tdumpsel(void)
 {
 	char *ptr;
 
 	if ((ptr = getsel())) {
 		tprinter(ptr, strlen(ptr));
 		free(ptr);
 	}
 }
 
 void
 tdumpline(int n)
 {
 	char buf[UTF_SIZ];
 	const Glyph *bp, *end;
 
 	bp = &term.line[n][0];
 	end = &bp[MIN(tlinelen(n), term.col) - 1];
 	if (bp != end || bp->u != ' ') {
 		for ( ; bp <= end; ++bp)
 			tprinter(buf, utf8encode(bp->u, buf));
 	}
 	tprinter("\n", 1);
 }
 
 void
 tdump(void)
 {
 	int i;
 
 	for (i = 0; i < term.row; ++i)
 		tdumpline(i);
 }
 
 void
 tputtab(int n)
 {
 	uint x = term.c.x;
 
 	if (n > 0) {
 		while (x < term.col && n--)
 			for (++x; x < term.col && !term.tabs[x]; ++x)
 				/* nothing */ ;
 	} else if (n < 0) {
 		while (x > 0 && n++)
 			for (--x; x > 0 && !term.tabs[x]; --x)
 				/* nothing */ ;
 	}
 	term.c.x = LIMIT(x, 0, term.col-1);
 }
 
 void
 tdefutf8(char ascii)
 {
 	if (ascii == 'G')
 		term.mode |= MODE_UTF8;
 	else if (ascii == '@')
 		term.mode &= ~MODE_UTF8;
 }
 
 void
 tdeftran(char ascii)
 {
 	static char cs[] = "0B";
 	static int vcs[] = {CS_GRAPHIC0, CS_USA};
 	char *p;
 
 	if ((p = strchr(cs, ascii)) == NULL) {
 		fprintf(stderr, "esc unhandled charset: ESC ( %c\n", ascii);
 	} else {
 		term.trantbl[term.icharset] = vcs[p - cs];
 	}
 }
 
 void
 tdectest(char c)
 {
 	int x, y;
 
 	if (c == '8') { /* DEC screen alignment test. */
 		for (x = 0; x < term.col; ++x) {
 			for (y = 0; y < term.row; ++y)
 				tsetchar('E', &term.c.attr, x, y);
 		}
 	}
 }
 
 void
 tstrsequence(uchar c)
 {
 	switch (c) {
 	case 0x90:   /* DCS -- Device Control String */
 		c = 'P';
 		break;
 	case 0x9f:   /* APC -- Application Program Command */
 		c = '_';
 		break;
 	case 0x9e:   /* PM -- Privacy Message */
 		c = '^';
 		break;
 	case 0x9d:   /* OSC -- Operating System Command */
 		c = ']';
 		break;
 	}
 	strreset();
 	strescseq.type = c;
 	term.esc |= ESC_STR;
 }
 
 void
 tcontrolcode(uchar ascii)
 {
 	switch (ascii) {
 	case '\t':   /* HT */
 		tputtab(1);
 		return;
 	case '\b':   /* BS */
 		tmoveto(term.c.x-1, term.c.y);
 		return;
 	case '\r':   /* CR */
 		tmoveto(0, term.c.y);
 		return;
 	case '\f':   /* LF */
 	case '\v':   /* VT */
 	case '\n':   /* LF */
 		/* go to first col if the mode is set */
 		tnewline(IS_SET(MODE_CRLF));
 		return;
 	case '\a':   /* BEL */
 		if (term.esc & ESC_STR_END) {
 			/* backwards compatibility to xterm */
 			strhandle();
 		} else {
 			xbell();
 		}
 		break;
 	case '\033': /* ESC */
 		csireset();
 		term.esc &= ~(ESC_CSI|ESC_ALTCHARSET|ESC_TEST);
 		term.esc |= ESC_START;
 		return;
 	case '\016': /* SO (LS1 -- Locking shift 1) */
 	case '\017': /* SI (LS0 -- Locking shift 0) */
 		term.charset = 1 - (ascii - '\016');
 		return;
 	case '\032': /* SUB */
 		tsetchar('?', &term.c.attr, term.c.x, term.c.y);
 		/* FALLTHROUGH */
 	case '\030': /* CAN */
 		csireset();
 		break;
 	case '\005': /* ENQ (IGNORED) */
 	case '\000': /* NUL (IGNORED) */
 	case '\021': /* XON (IGNORED) */
 	case '\023': /* XOFF (IGNORED) */
 	case 0177:   /* DEL (IGNORED) */
 		return;
 	case 0x80:   /* TODO: PAD */
 	case 0x81:   /* TODO: HOP */
 	case 0x82:   /* TODO: BPH */
 	case 0x83:   /* TODO: NBH */
 	case 0x84:   /* TODO: IND */
 		break;
 	case 0x85:   /* NEL -- Next line */
 		tnewline(1); /* always go to first col */
 		break;
 	case 0x86:   /* TODO: SSA */
 	case 0x87:   /* TODO: ESA */
 		break;
 	case 0x88:   /* HTS -- Horizontal tab stop */
 		term.tabs[term.c.x] = 1;
 		break;
 	case 0x89:   /* TODO: HTJ */
 	case 0x8a:   /* TODO: VTS */
 	case 0x8b:   /* TODO: PLD */
 	case 0x8c:   /* TODO: PLU */
 	case 0x8d:   /* TODO: RI */
 	case 0x8e:   /* TODO: SS2 */
 	case 0x8f:   /* TODO: SS3 */
 	case 0x91:   /* TODO: PU1 */
 	case 0x92:   /* TODO: PU2 */
 	case 0x93:   /* TODO: STS */
 	case 0x94:   /* TODO: CCH */
 	case 0x95:   /* TODO: MW */
 	case 0x96:   /* TODO: SPA */
 	case 0x97:   /* TODO: EPA */
 	case 0x98:   /* TODO: SOS */
 	case 0x99:   /* TODO: SGCI */
 		break;
 	case 0x9a:   /* DECID -- Identify Terminal */
 		ttywrite(vtiden, strlen(vtiden), 0);
 		break;
 	case 0x9b:   /* TODO: CSI */
 	case 0x9c:   /* TODO: ST */
 		break;
 	case 0x90:   /* DCS -- Device Control String */
 	case 0x9d:   /* OSC -- Operating System Command */
 	case 0x9e:   /* PM -- Privacy Message */
 	case 0x9f:   /* APC -- Application Program Command */
 		tstrsequence(ascii);
 		return;
 	}
 	/* only CAN, SUB, \a and C1 chars interrupt a sequence */
 	term.esc &= ~(ESC_STR_END|ESC_STR);
 }
 
 /*
  * returns 1 when the sequence is finished and it hasn't to read
  * more characters for this sequence, otherwise 0
  */
 int
 eschandle(uchar ascii)
 {
 	switch (ascii) {
 	case '[':
 		term.esc |= ESC_CSI;
 		return 0;
 	case '#':
 		term.esc |= ESC_TEST;
 		return 0;
 	case '%':
 		term.esc |= ESC_UTF8;
 		return 0;
 	case 'P': /* DCS -- Device Control String */
 	case '_': /* APC -- Application Program Command */
 	case '^': /* PM -- Privacy Message */
 	case ']': /* OSC -- Operating System Command */
 	case 'k': /* old title set compatibility */
 		tstrsequence(ascii);
 		return 0;
 	case 'n': /* LS2 -- Locking shift 2 */
 	case 'o': /* LS3 -- Locking shift 3 */
 		term.charset = 2 + (ascii - 'n');
 		break;
 	case '(': /* GZD4 -- set primary charset G0 */
 	case ')': /* G1D4 -- set secondary charset G1 */
 	case '*': /* G2D4 -- set tertiary charset G2 */
 	case '+': /* G3D4 -- set quaternary charset G3 */
 		term.icharset = ascii - '(';
 		term.esc |= ESC_ALTCHARSET;
 		return 0;
 	case 'D': /* IND -- Linefeed */
 		if (term.c.y == term.bot) {
 			tscrollup(term.top, 1, 1);
 		} else {
 			tmoveto(term.c.x, term.c.y+1);
 		}
 		break;
 	case 'E': /* NEL -- Next line */
 		tnewline(1); /* always go to first col */
 		break;
 	case 'H': /* HTS -- Horizontal tab stop */
 		term.tabs[term.c.x] = 1;
 		break;
 	case 'M': /* RI -- Reverse index */
 		if (term.c.y == term.top) {
 			tscrolldown(term.top, 1, 1);
 		} else {
 			tmoveto(term.c.x, term.c.y-1);
 		}
 		break;
 	case 'Z': /* DECID -- Identify Terminal */
 		ttywrite(vtiden, strlen(vtiden), 0);
 		break;
 	case 'c': /* RIS -- Reset to initial state */
 		treset();
 		resettitle();
 		xloadcols();
 		xsetmode(0, MODE_HIDE);
 		break;
 	case '=': /* DECPAM -- Application keypad */
 		xsetmode(1, MODE_APPKEYPAD);
 		break;
 	case '>': /* DECPNM -- Normal keypad */
 		xsetmode(0, MODE_APPKEYPAD);
 		break;
 	case '7': /* DECSC -- Save Cursor */
 		tcursor(CURSOR_SAVE);
 		break;
 	case '8': /* DECRC -- Restore Cursor */
 		tcursor(CURSOR_LOAD);
 		break;
 	case '\\': /* ST -- String Terminator */
 		if (term.esc & ESC_STR_END)
 			strhandle();
 		break;
 	default:
 		fprintf(stderr, "erresc: unknown sequence ESC 0x%02X '%c'\n",
 			(uchar) ascii, isprint(ascii)? ascii:'.');
 		break;
 	}
 	return 1;
 }
 
 void
 tputc(Rune u)
 {
 	char c[UTF_SIZ];
 	int control;
 	int width, len;
 	Glyph *gp;
 
 	control = ISCONTROL(u);
 	if (u < 127 || !IS_SET(MODE_UTF8)) {
 		c[0] = u;
 		width = len = 1;
 	} else {
 		len = utf8encode(u, c);
 		if (!control && (width = wcwidth(u)) == -1)
 			width = 1;
 	}
 
 	if (IS_SET(MODE_PRINT))
 		tprinter(c, len);
 
 	/*
 	 * STR sequence must be checked before anything else
 	 * because it uses all following characters until it
 	 * receives a ESC, a SUB, a ST or any other C1 control
 	 * character.
 	 */
 	if (term.esc & ESC_STR) {
 		if (u == '\a' || u == 030 || u == 032 || u == 033 ||
 		   ISCONTROLC1(u)) {
 			term.esc &= ~(ESC_START|ESC_STR);
 			term.esc |= ESC_STR_END;
 			goto check_control_code;
 		}
 
 		if (strescseq.len+len >= strescseq.siz) {
 			/*
 			 * Here is a bug in terminals. If the user never sends
 			 * some code to stop the str or esc command, then st
 			 * will stop responding. But this is better than
 			 * silently failing with unknown characters. At least
 			 * then users will report back.
 			 *
 			 * In the case users ever get fixed, here is the code:
 			 */
 			/*
 			 * term.esc = 0;
 			 * strhandle();
 			 */
 			if (strescseq.siz > (SIZE_MAX - UTF_SIZ) / 2)
 				return;
 			strescseq.siz *= 2;
 			strescseq.buf = xrealloc(strescseq.buf, strescseq.siz);
 		}
 
 		memmove(&strescseq.buf[strescseq.len], c, len);
 		strescseq.len += len;
 		return;
 	}
 
 check_control_code:
 	/*
 	 * Actions of control codes must be performed as soon they arrive
 	 * because they can be embedded inside a control sequence, and
 	 * they must not cause conflicts with sequences.
 	 */
 	if (control) {
 		/* in UTF-8 mode ignore handling C1 control characters */
 		if (IS_SET(MODE_UTF8) && ISCONTROLC1(u))
 			return;
 		tcontrolcode(u);
 		/*
 		 * control codes are not shown ever
 		 */
 		if (!term.esc)
 			term.lastc = 0;
 		return;
 	} else if (term.esc & ESC_START) {
 		if (term.esc & ESC_CSI) {
 			csiescseq.buf[csiescseq.len++] = u;
 			if (BETWEEN(u, 0x40, 0x7E)
 					|| csiescseq.len >= \
 					sizeof(csiescseq.buf)-1) {
 				term.esc = 0;
 				csiparse();
 				csihandle();
 			}
 			return;
 		} else if (term.esc & ESC_UTF8) {
 			tdefutf8(u);
 		} else if (term.esc & ESC_ALTCHARSET) {
 			tdeftran(u);
 		} else if (term.esc & ESC_TEST) {
 			tdectest(u);
 		} else {
 			if (!eschandle(u))
 				return;
 			/* sequence already finished */
 		}
 		term.esc = 0;
 		/*
 		 * All characters which form part of a sequence are not
 		 * printed
 		 */
 		return;
 	}
 	if (selected(term.c.x, term.c.y))
 		selclear();
 
 	gp = &term.line[term.c.y][term.c.x];
 	if (IS_SET(MODE_WRAP) && (term.c.state & CURSOR_WRAPNEXT)) {
 		gp->mode |= ATTR_WRAP;
 		tnewline(1);
 		gp = &term.line[term.c.y][term.c.x];
 	}
 
 	if (IS_SET(MODE_INSERT) && term.c.x+width < term.col) {
 		memmove(gp+width, gp, (term.col - term.c.x - width) * sizeof(Glyph));
 		gp->mode &= ~ATTR_WIDE;
 	}
 
 	if (term.c.x+width > term.col) {
 		if (IS_SET(MODE_WRAP))
 			tnewline(1);
 		else
 			tmoveto(term.col - width, term.c.y);
 		gp = &term.line[term.c.y][term.c.x];
 	}
 
 	tsetchar(u, &term.c.attr, term.c.x, term.c.y);
 	term.lastc = u;
 
 	if (width == 2) {
 		gp->mode |= ATTR_WIDE;
 		if (term.c.x+1 < term.col) {
 			if (gp[1].mode == ATTR_WIDE && term.c.x+2 < term.col) {
 				gp[2].u = ' ';
 				gp[2].mode &= ~ATTR_WDUMMY;
 			}
 			gp[1].u = '\0';
 			gp[1].mode = ATTR_WDUMMY;
 		}
 	}
 	if (term.c.x+width < term.col) {
 		tmoveto(term.c.x+width, term.c.y);
 	} else {
 		term.c.state |= CURSOR_WRAPNEXT;
 	}
 }
 
 int
 twrite(const char *buf, int buflen, int show_ctrl)
 {
 	int charsize;
 	Rune u;
 	int n;
 
 	for (n = 0; n < buflen; n += charsize) {
 		if (IS_SET(MODE_UTF8)) {
 			/* process a complete utf8 char */
 			charsize = utf8decode(buf + n, &u, buflen - n);
 			if (charsize == 0)
 				break;
 		} else {
 			u = buf[n] & 0xFF;
 			charsize = 1;
 		}
 		if (show_ctrl && ISCONTROL(u)) {
 			if (u & 0x80) {
 				u &= 0x7f;
 				tputc('^');
 				tputc('[');
 			} else if (u != '\n' && u != '\r' && u != '\t') {
 				u ^= 0x40;
 				tputc('^');
 			}
 		}
 		tputc(u);
 	}
 	return n;
 }
 
 void
 tresize(int col, int row)
 {
 	int i, j;
 	int minrow = MIN(row, term.row);
 	int mincol = MIN(col, term.col);
 	int *bp;
 	TCursor c;
 
 	if (col < 1 || row < 1) {
 		fprintf(stderr,
 		        "tresize: error resizing to %dx%d\n", col, row);
 		return;
 	}
 
 	/*
 	 * slide screen to keep cursor where we expect it -
 	 * tscrollup would work here, but we can optimize to
 	 * memmove because we're freeing the earlier lines
 	 */
 	for (i = 0; i <= term.c.y - row; i++) {
 		free(term.line[i]);
 		free(term.alt[i]);
 	}
 	/* ensure that both src and dst are not NULL */
 	if (i > 0) {
 		memmove(term.line, term.line + i, row * sizeof(Line));
 		memmove(term.alt, term.alt + i, row * sizeof(Line));
 	}
 	for (i += row; i < term.row; i++) {
 		free(term.line[i]);
 		free(term.alt[i]);
 	}
 
 	/* resize to new height */
 	term.line = xrealloc(term.line, row * sizeof(Line));
 	term.alt  = xrealloc(term.alt,  row * sizeof(Line));
 	term.dirty = xrealloc(term.dirty, row * sizeof(*term.dirty));
 	term.tabs = xrealloc(term.tabs, col * sizeof(*term.tabs));
 
 	for (i = 0; i < HISTSIZE; i++) {
 		term.hist[i] = xrealloc(term.hist[i], col * sizeof(Glyph));
 		for (j = mincol; j < col; j++) {
 			term.hist[i][j] = term.c.attr;
 			term.hist[i][j].u = ' ';
 		}
 	}
 
 	/* resize each row to new width, zero-pad if needed */
 	for (i = 0; i < minrow; i++) {
 		term.line[i] = xrealloc(term.line[i], col * sizeof(Glyph));
 		term.alt[i]  = xrealloc(term.alt[i],  col * sizeof(Glyph));
 	}
 
 	/* allocate any new rows */
 	for (/* i = minrow */; i < row; i++) {
 		term.line[i] = xmalloc(col * sizeof(Glyph));
 		term.alt[i] = xmalloc(col * sizeof(Glyph));
 	}
 	if (col > term.col) {
 		bp = term.tabs + term.col;
 
 		memset(bp, 0, sizeof(*term.tabs) * (col - term.col));
 		while (--bp > term.tabs && !*bp)
 			/* nothing */ ;
 		for (bp += tabspaces; bp < term.tabs + col; bp += tabspaces)
 			*bp = 1;
 	}
 	/* update terminal size */
 	term.col = col;
 	term.row = row;
 	/* reset scrolling region */
 	tsetscroll(0, row-1);
 	/* make use of the LIMIT in tmoveto */
 	tmoveto(term.c.x, term.c.y);
 	/* Clearing both screens (it makes dirty all lines) */
 	c = term.c;
 	for (i = 0; i < 2; i++) {
 		if (mincol < col && 0 < minrow) {
 			tclearregion(mincol, 0, col - 1, minrow - 1);
 		}
 		if (0 < col && minrow < row) {
 			tclearregion(0, minrow, col - 1, row - 1);
 		}
 		tswapscreen();
 		tcursor(CURSOR_LOAD);
 	}
 	term.c = c;
 }
 
 void
 resettitle(void)
 {
 	xsettitle(NULL);
 }
 
 void
 drawregion(int x1, int y1, int x2, int y2)
 {
 	int y;
 
 	for (y = y1; y < y2; y++) {
 		if (!term.dirty[y])
 			continue;
 
 		term.dirty[y] = 0;
 		xdrawline(TLINE(y), x1, y, x2);
 	}
 }
 
 void
 draw(void)
 {
 	int cx = term.c.x, ocx = term.ocx, ocy = term.ocy;
 
 	if (!xstartdraw())
 		return;
 
 	/* adjust cursor position */
 	LIMIT(term.ocx, 0, term.col-1);
 	LIMIT(term.ocy, 0, term.row-1);
 	if (term.line[term.ocy][term.ocx].mode & ATTR_WDUMMY)
 		term.ocx--;
 	if (term.line[term.c.y][cx].mode & ATTR_WDUMMY)
 		cx--;
 
 	drawregion(0, 0, term.col, term.row);
 	if (term.scr == 0)
 		xdrawcursor(cx, term.c.y, term.line[term.c.y][cx],
 				term.ocx, term.ocy, term.line[term.ocy][term.ocx]);
 	term.ocx = cx;
 	term.ocy = term.c.y;
 	xfinishdraw();
 	if (ocx != term.ocx || ocy != term.ocy)
 		xximspot(term.ocx, term.ocy);
 }
 
 void
 redraw(void)
 {
 	tfulldirt();
 	draw();
 }