/* See license terms in x.c */

#ifndef _XOPEN_SOURCE
#define _XOPEN_SOURCE 600
#endif

#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 "st.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

/* 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))

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 */
    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);
static void tscrolldown(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 (term.line[y][i - 1].mode & ATTR_WRAP)
    {
        return i;
    }

    while (i > 0 && term.line[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 = &term.line[*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 (!(term.line[yt][xt].mode & ATTR_WRAP))
                {
                    break;
                }
            }

            if (newx >= tlinelen(newy))
            {
                break;
            }

            gp = &term.line[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 (!(term.line[*y - 1][term.col - 1].mode
                      & ATTR_WRAP))
                {
                    break;
                }
            }
        }
        else if (direction > 0)
        {
            for (; *y < term.row - 1; *y += direction)
            {
                if (!(term.line[*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 = &term.line[y][sel.nb.x];
            lastx = sel.ne.x;
        }
        else
        {
            gp = &term.line[y][sel.nb.y == y ? sel.nb.x : 0];
            lastx = (sel.ne.y == y) ? sel.ne.x : term.col - 1;
        }
        last = &term.line[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;

    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
tscrolldown(int orig, int n)
{
    int i;
    Line temp;

    LIMIT(n, 0, term.bot - orig + 1);

    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;
    }

    selscroll(orig, n);
}

void
tscrollup(int orig, int n)
{
    int i;
    Line temp;

    LIMIT(n, 0, term.bot - orig + 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;
    }

    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);
    }
    else
    {
        y++;
    }
    tmoveto(first_col ? 0 : term.c.x, y);
}

void
csiparse(void)
{
    char* p = csiescseq.buf, * np;
    long int v;

    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 (*p != ';' || 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);
    }
}

void
tdeleteline(int n)
{
    if (BETWEEN(term.c.y, term.top, term.bot))
    {
        tscrollup(term.c.y, n);
    }
}

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 > 1)
            {
                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]);
        break;
    case 'T': /* SD -- Scroll <n> line down */
        DEFAULT(csiescseq.arg[0], 1);
        tscrolldown(term.top, csiescseq.arg[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) */
        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);
        }
        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);
        }
        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 = 0, 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;
    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));

    /* 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(term.line[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);
    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();
}
