Add support for scroll(1)

[st.git] / st.c

/* 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 "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) == '\177')
#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,
        MODE_SIXEL       = 1 << 7,
};

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,  /* 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,
        ESC_DCS        =128,
};

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;
} 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 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(int *, int);
static void tsetchar(Rune, Glyph *, int, int);
static void tsetdirt(int, int);
static void tsetscroll(int, int);
static void tswapscreen(void);
static void tsetmode(int, int, 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(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 uchar utfbyte[UTF_SIZ + 1] = {0x80,    0, 0xC0, 0xE0, 0xF0};
static uchar utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
static Rune utfmin[UTF_SIZ + 1] = {       0,    0,  0x80,  0x800,  0x10000};
static 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(char *s)
{
        if ((s = strdup(s)) == NULL)
                die("strdup: %s\n", strerror(errno));

        return s;
}

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;
}

static const char base64_digits[] = {
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 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, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

char
base64dec_getc(const char **src)
{
        while (**src && !isprint(**src)) (*src)++;
        return **src ? *((*src)++) : '=';  /* emulate padding if string ends */
}

char *
base64dec(const char *src)
{
        size_t in_len = strlen(src);
        char *result, *dst;

        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;
        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;
        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))
                        *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 || utmp) {
                prog = scroll ? scroll : utmp;
                arg = scroll ? utmp : 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(char *line, char *cmd, 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);
                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));
                close(s);
                close(m);
#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 written;
        int ret;

        /* append read bytes to unprocessed bytes */
        if ((ret = read(cmdfd, buf+buflen, LEN(buf)-buflen)) < 0)
                die("couldn't read from shell: %s\n", strerror(errno));
        buflen += ret;

        written = twrite(buf, buflen, 0);
        buflen -= written;
        /* keep any uncomplete utf8 char 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()
{
        /* 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)
                return;

        if (BETWEEN(sel.ob.y, orig, term.bot) || BETWEEN(sel.oe.y, orig, term.bot)) {
                if ((sel.ob.y += n) > term.bot || (sel.oe.y += n) < term.top) {
                        selclear();
                        return;
                }
                if (sel.type == SEL_RECTANGULAR) {
                        if (sel.ob.y < term.top)
                                sel.ob.y = term.top;
                        if (sel.oe.y > term.bot)
                                sel.oe.y = term.bot;
                } else {
                        if (sel.ob.y < term.top) {
                                sel.ob.y = term.top;
                                sel.ob.x = 0;
                        }
                        if (sel.oe.y > term.bot) {
                                sel.oe.y = term.bot;
                                sel.oe.x = term.col;
                        }
                }
                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, Glyph *attr, int x, int y)
{
        static 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(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(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, int *args, int narg)
{
        int alt, *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 '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 */
                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 (cursor position) */
                if (csiescseq.arg[0] == 6) {
                        len = snprintf(buf, sizeof(buf),"\033[%i;%iR",
                                        term.c.y+1, term.c.x+1);
                        ttywrite(buf, len, 0);
                }
                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
strhandle(void)
{
        char *p = NULL, *dec;
        int j, narg, par;

        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:
                case 1:
                case 2:
                        if (narg > 1)
                                xsettitle(strescseq.args[1]);
                        return;
                case 52:
                        if (narg > 2) {
                                dec = base64dec(strescseq.args[2]);
                                if (dec) {
                                        xsetsel(dec);
                                        xclipcopy();
                                } else {
                                        fprintf(stderr, "erresc: invalid base64\n");
                                }
                        }
                        return;
                case 4: /* color set */
                        if (narg < 3)
                                break;
                        p = strescseq.args[2];
                        /* FALLTHROUGH */
                case 104: /* color reset, here p = NULL */
                        j = (narg > 1) ? atoi(strescseq.args[1]) : -1;
                        if (xsetcolorname(j, p)) {
                                if (par == 104 && narg <= 1)
                                        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
                                 */
                                redraw();
                        }
                        return;
                }
                break;
        case 'k': /* old title set compatibility */
                xsettitle(strescseq.args[0]);
                return;
        case 'P': /* DCS -- Device Control String */
                term.mode |= ESC_DCS;
        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];
        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)
{
        strreset();

        switch (c) {
        case 0x90:   /* DCS -- Device Control String */
                c = 'P';
                term.esc |= ESC_DCS;
                break;
        case 0x9f:   /* APC -- Application Program Command */
                c = '_';
                break;
        case 0x9e:   /* PM -- Privacy Message */
                c = '^';
                break;
        case 0x9d:   /* OSC -- Operating System Command */
                c = ']';
                break;
        }
        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);
        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();
                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 (!IS_SET(MODE_UTF8) && !IS_SET(MODE_SIXEL)) {
                c[0] = u;
                width = len = 1;
        } else {
                len = utf8encode(u, c);
                if (!control && (width = wcwidth(u)) == -1) {
                        memcpy(c, "\357\277\275", 4); /* UTF_INVALID */
                        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|ESC_DCS);
                        if (IS_SET(MODE_SIXEL)) {
                                /* TODO: render sixel */;
                                term.mode &= ~MODE_SIXEL;
                                return;
                        }
                        term.esc |= ESC_STR_END;
                        goto check_control_code;
                }

                if (IS_SET(MODE_SIXEL)) {
                        /* TODO: implement sixel mode */
                        return;
                }
                if (term.esc&ESC_DCS && strescseq.len == 0 && u == 'q')
                        term.mode |= MODE_SIXEL;

                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) {
                tcontrolcode(u);
                /*
                 * control codes are not shown ever
                 */
                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 (sel.ob.x != -1 && BETWEEN(term.c.y, sel.ob.y, sel.oe.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));

        if (term.c.x+width > term.col) {
                tnewline(1);
                gp = &term.line[term.c.y][term.c.x];
        }

        tsetchar(u, &term.c.attr, term.c.x, term.c.y);

        if (width == 2) {
                gp->mode |= ATTR_WIDE;
                if (term.c.x+1 < term.col) {
                        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) && !IS_SET(MODE_SIXEL)) {
                        /* 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;

        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();
        xximspot(term.ocx, term.ocy);
}

void
redraw(void)
{
        tfulldirt();
        draw();
}