st.c

/* See LICENSE for license details. */
#include "st.h"
#include <stddef.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>
#include <wchar.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

#define UTF_INVALID 0xFFFD
#define UTF_SIZ 4
#define ESC_BUF_SIZ (128 * UTF_SIZ)
#define ESC_ARG_SIZ 16
#define STR_BUF_SIZ ESC_BUF_SIZ
#define STR_ARG_SIZ ESC_ARG_SIZ
#define HISTSIZE 2000

/* macros */
#define IS_SET(flag) ((term.mode & (flag)) != 0)
#define NUMMAXLEN(x) ((int)(sizeof(x) * 2.56 + 0.5) + 1)
#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))
#define TLINE(y)                                                                         \
    ((y) < term.scr ? term.hist[((y) + term.histi - term.scr + HISTSIZE + 1) % HISTSIZE] \
                    : term.line[(y)-term.scr])

#define TLINE_HIST(y) \
    ((y) <= HISTSIZE - term.row + 2 ? term.hist[(y)] : term.line[(y - HISTSIZE + term.row - 3)])

/* constants */
#define ISO14755CMD "dmenu -w \"$WINDOWID\" -p codepoint: </dev/null"

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 */
    int maxcol;
    Line *line;          /* screen */
    Line *alt;           /* alternate screen */
    Line hist[HISTSIZE]; /* history buffer */
    int histi;           /* history index */
    int scr;             /* scroll back */
    int *dirty;          /* dirtyness of lines */
    TCursor c;           /* cursor */
    int ocx;             /* old cursor col */
    int ocy;             /* old cursor row */
    int top;             /* top    scroll limit */
    int bot;             /* bottom scroll limit */
    int mode;            /* terminal mode flags */
    int esc;             /* escape state flags */
    char trantbl[4];     /* charset table translation */
    int charset;         /* current charset */
    int icharset;        /* selected charset for sequence */
    int *tabs;
    struct timespec last_ximspot_update;
} Term;

/* CSI Escape sequence structs */
/* ESC '[' [[ [<priv>] <arg> [;]] <mode> [<mode>]] */
typedef struct {
    char buf[ESC_BUF_SIZ]; /* raw string */
    int 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[STR_BUF_SIZ]; /* raw string */
    int len;               /* raw string length */
    char *args[STR_ARG_SIZ];
    int narg; /* nb of args */
} STREscape;

static void execsh(char *, char **);
static char *getcwd_by_pid(pid_t pid);
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, int);
static void tscrolldown(int, 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 tsetcolor(int, int, int, uint32_t, uint32_t);
static char *findlastany(char *, const char **, size_t);

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)++);
}

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)];

        *dst++ = (a << 2) | ((b & 0x30) >> 4);
        if (c == -1) break;
        *dst++ = ((b & 0x0f) << 4) | ((c & 0x3c) >> 2);
        if (d == -1) break;
        *dst++ = ((c & 0x03) << 6) | d;
    }
    *dst = '\0';
    return result;
}

void selinit(void) {
    sel.mode = SEL_IDLE;
    sel.snap = 0;
    sel.ob.x = -1;
}

int tlinelen(int y) {
    int i = term.col;

    if (TLINE(y)[i - 1].mode & ATTR_WRAP) return i;

    while (i > 0 && TLINE(y)[i - 1].u == ' ') --i;

    return i;
}

int tlinehistlen(int y) {
    int i = term.col;

    if (TLINE_HIST(y)[i - 1].mode & ATTR_WRAP) return i;

    while (i > 0 && TLINE_HIST(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 = &TLINE(*y)[*x];
            prevdelim = ISDELIM(prevgp->u);
            for (;;) {
                newx = *x + direction;
                newy = *y;
                if (!BETWEEN(newx, 0, term.col - 1)) {
                    newy += direction;
                    newx = (newx + term.col) % term.col;
                    if (!BETWEEN(newy, 0, term.row - 1)) break;

                    if (direction > 0)
                        yt = *y, xt = *x;
                    else
                        yt = newy, xt = newx;
                    if (!(TLINE(yt)[xt].mode & ATTR_WRAP)) break;
                }

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

                gp = &TLINE(newy)[newx];
                delim = ISDELIM(gp->u);
                if (!(gp->mode & ATTR_WDUMMY) &&
                    (delim != prevdelim || (delim && gp->u != prevgp->u)))
                    break;

                *x = newx;
                *y = newy;
                prevgp = gp;
                prevdelim = delim;
            }
            break;
        case SNAP_LINE:
            /*
             * Snap around if the the previous line or the current one
             * has set ATTR_WRAP at its end. Then the whole next or
             * previous line will be selected.
             */
            *x = (direction < 0) ? 0 : term.col - 1;
            if (direction < 0) {
                for (; *y > 0; *y += direction) {
                    if (!(TLINE(*y - 1)[term.col - 1].mode & ATTR_WRAP)) {
                        break;
                    }
                }
            } else if (direction > 0) {
                for (; *y < term.row - 1; *y += direction) {
                    if (!(TLINE(*y)[term.col - 1].mode & ATTR_WRAP)) {
                        break;
                    }
                }
            }
            break;
    }
}

char *getsel(void) {
    char *str, *ptr;
    int y, bufsize, lastx, linelen;
    Glyph *gp, *last;

    if (sel.ob.x == -1) return NULL;

    bufsize = (term.col + 1) * (sel.ne.y - sel.nb.y + 1) * UTF_SIZ;
    ptr = str = xmalloc(bufsize);

    /* append every set & selected glyph to the selection */
    for (y = sel.nb.y; y <= sel.ne.y; y++) {
        if ((linelen = tlinelen(y)) == 0) {
            *ptr++ = '\n';
            continue;
        }

        if (sel.type == SEL_RECTANGULAR) {
            gp = &TLINE(y)[sel.nb.x];
            lastx = sel.ne.x;
        } else {
            gp = &TLINE(y)[sel.nb.y == y ? sel.nb.x : 0];
            lastx = (sel.ne.y == y) ? sel.ne.x : term.col - 1;
        }
        last = &TLINE(y)[MIN(lastx, linelen - 1)];
        while (last >= gp && last->u == ' ') --last;

        for (; gp <= last; ++gp) {
            if (gp->mode & ATTR_WDUMMY) continue;

            ptr += utf8encode(gp->u, ptr);
        }

        /*
         * Copy and pasting of line endings is inconsistent
         * in the inconsistent terminal and GUI world.
         * The best solution seems like to produce '\n' when
         * something is copied from st and convert '\n' to
         * '\r', when something to be pasted is received by
         * st.
         * FIXME: Fix the computer world.
         */
        if ((y < sel.ne.y || lastx >= linelen) && !(last->mode & ATTR_WRAP)) *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;
    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];
    else if (utmp)
        prog = utmp;
    else
        prog = sh;
    DEFAULT(args, ((char *[]){prog, 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;
    Arg arg = (Arg){.i = term.scr};

    kscrolldown(&arg);

    if (may_echo && IS_SET(MODE_ECHO)) twrite(s, n, 1);

    if (!IS_SET(MODE_CRLF)) {
        ttywriteraw(s, n);
        return;
    }

    /* This is similar to how the kernel handles ONLCR for ttys */
    while (n > 0) {
        if (*s == '\r') {
            next = s + 1;
            ttywriteraw("\r\n", 2);
        } else {
            next = memchr(s, '\r', n);
            DEFAULT(next, s + n);
            ttywriteraw(s, next - s);
        }
        n -= next - s;
        s = next;
    }
}

void ttywriteraw(const char *s, size_t n) {
    fd_set wfd, rfd;
    ssize_t r;
    size_t lim = 256;

    /*
     * Remember that we are using a pty, which might be a modem line.
     * Writing too much will clog the line. That's why we are doing this
     * dance.
     * FIXME: Migrate the world to Plan 9.
     */
    while (n > 0) {
        FD_ZERO(&wfd);
        FD_ZERO(&rfd);
        FD_SET(cmdfd, &wfd);
        FD_SET(cmdfd, &rfd);

        /* Check if we can write. */
        if (pselect(cmdfd + 1, &rfd, &wfd, NULL, NULL, NULL) < 0) {
            if (errno == EINTR) continue;
            die("select failed: %s\n", strerror(errno));
        }
        if (FD_ISSET(cmdfd, &wfd)) {
            /*
             * Only write the bytes written by ttywrite() or the
             * default of 256. This seems to be a reasonable value
             * for a serial line. Bigger values might clog the I/O.
             */
            if ((r = write(cmdfd, s, (n < lim) ? n : lim)) < 0) goto write_error;
            if (r < n) {
                /*
                 * We weren't able to write out everything.
                 * This means the buffer is getting full
                 * again. Empty it.
                 */
                if (n < lim) lim = ttyread();
                n -= r;
                s += r;
            } else {
                /* All bytes have been written. */
                break;
            }
        }
        if (FD_ISSET(cmdfd, &rfd)) lim = ttyread();
    }
    return;

write_error:
    die("write error on tty: %s\n", strerror(errno));
}

void ttyresize(int tw, int th) {
    struct winsize w;

    w.ws_row = term.row;
    w.ws_col = term.col;
    w.ws_xpixel = tw;
    w.ws_ypixel = th;
    if (ioctl(cmdfd, TIOCSWINSZ, &w) < 0)
        fprintf(stderr, "Couldn't set window size: %s\n", strerror(errno));
}

void ttyhangup() {
    /* 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}}};
    clock_gettime(CLOCK_MONOTONIC, &term.last_ximspot_update);
    tresize(col, row);
    treset();
}

int tisaltscr(void) { return IS_SET(MODE_ALTSCREEN); }

void tswapscreen(void) {
    Line *tmp = term.line;

    term.line = term.alt;
    term.alt = tmp;
    term.mode ^= MODE_ALTSCREEN;
    tfulldirt();
}

void newterm(const Arg *a) {
    switch (fork()) {
        case -1:
            die("fork failed: %s\n", strerror(errno));
            break;
        case 0:
            chdir(getcwd_by_pid(pid));
            execlp("st", "./st", NULL);
            break;
    }
}

static char *getcwd_by_pid(pid_t pid) {
    char buf[32];
    snprintf(buf, sizeof buf, "/proc/%d/cwd", pid);
    return realpath(buf, NULL);
}

void kscrolldown(const Arg *a) {
    int n = a->i;

    if (n < 0) n = term.row + n;

    if (n > term.scr) n = term.scr;

    if (term.scr > 0) {
        term.scr -= n;
        selscroll(0, -n);
        tfulldirt();
    }
}

void kscrollup(const Arg *a) {
    int n = a->i;

    if (n < 0) n = term.row + n;

    if (term.scr <= HISTSIZE - n) {
        term.scr += n;
        selscroll(0, n);
        tfulldirt();
    }
}

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

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

    if (copyhist) {
        term.histi = (term.histi - 1 + HISTSIZE) % HISTSIZE;
        temp = term.hist[term.histi];
        term.hist[term.histi] = term.line[term.bot];
        term.line[term.bot] = temp;
    }

    tsetdirt(orig, term.bot - n);
    tclearregion(0, term.bot - n + 1, term.col - 1, term.bot);

    for (i = term.bot; i >= orig + n; i--) {
        temp = term.line[i];
        term.line[i] = term.line[i - n];
        term.line[i - n] = temp;
    }

    selscroll(orig, n);
}

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

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

    if (copyhist) {
        term.histi = (term.histi + 1) % HISTSIZE;
        temp = term.hist[term.histi];
        term.hist[term.histi] = term.line[orig];
        term.line[orig] = temp;
    }

    if (term.scr > 0 && term.scr < HISTSIZE) term.scr = MIN(term.scr + n, HISTSIZE - 1);

    tclearregion(0, orig, term.col - 1, orig + n - 1);
    tsetdirt(orig + n, term.bot);

    for (i = orig; i <= term.bot - n; i++) {
        temp = term.line[i];
        term.line[i] = term.line[i + n];
        term.line[i + n] = temp;
    }

    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, 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;

    if (isboxdraw(u)) term.line[y][x].mode |= ATTR_BOXDRAW;
}

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.maxcol - 1);
    LIMIT(x2, 0, term.maxcol - 1);
    LIMIT(y1, 0, term.row - 1);
    LIMIT(y2, 0, term.row - 1);

    for (y = y1; y <= y2; y++) {
        term.dirty[y] = 1;
        for (x = x1; x <= x2; x++) {
            gp = &term.line[y][x];
            if (selected(x, y)) selclear();
            gp->fg = term.c.attr.fg;
            gp->bg = term.c.attr.bg;
            gp->mode = 0;
            gp->u = ' ';
        }
    }
}

void tdeletechar(int n) {
    int dst, src, size;
    Glyph *line;

    LIMIT(n, 0, term.col - term.c.x);

    dst = term.c.x;
    src = term.c.x + n;
    size = term.col - src;
    line = term.line[term.c.y];

    memmove(&line[dst], &line[src], size * sizeof(Glyph));
    tclearregion(term.col - n, term.c.y, term.col - 1, term.c.y);
}

void tinsertblank(int n) {
    int dst, src, size;
    Glyph *line;

    LIMIT(n, 0, term.col - term.c.x);

    dst = term.c.x + n;
    src = term.c.x;
    size = term.col - dst;
    line = term.line[term.c.y];

    memmove(&line[dst], &line[src], size * sizeof(Glyph));
    tclearregion(src, term.c.y, dst - 1, term.c.y);
}

void tinsertblankline(int n) {
    if (BETWEEN(term.c.y, term.top, term.bot)) tscrolldown(term.c.y, n, 0);
}

void tdeleteline(int n) {
    if (BETWEEN(term.c.y, term.top, term.bot)) tscrollup(term.c.y, n, 0);
}

int32_t tdefcolor(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], 0);
            break;
        case 'T': /* SD -- Scroll <n> line down */
            DEFAULT(csiescseq.arg[0], 1);
            tscrolldown(term.top, csiescseq.arg[0], 0);
            break;
        case 'L': /* IL -- Insert <n> blank lines */
            DEFAULT(csiescseq.arg[0], 1);
            tinsertblankline(csiescseq.arg[0]);
            break;
        case 'l': /* RM -- Reset Mode */
            tsetmode(csiescseq.priv, 0, csiescseq.arg, csiescseq.narg);
            break;
        case 'M': /* DL -- Delete <n> lines */
            DEFAULT(csiescseq.arg[0], 1);
            tdeleteline(csiescseq.arg[0]);
            break;
        case 'X': /* ECH -- Erase <n> char */
            DEFAULT(csiescseq.arg[0], 1);
            tclearregion(term.c.x, term.c.y, term.c.x + csiescseq.arg[0] - 1, term.c.y);
            break;
        case 'P': /* DCH -- Delete <n> char */
            DEFAULT(csiescseq.arg[0], 1);
            tdeletechar(csiescseq.arg[0]);
            break;
        case 'Z': /* CBT -- Cursor Backward Tabulation <n> tab stops */
            DEFAULT(csiescseq.arg[0], 1);
            tputtab(-csiescseq.arg[0]);
            break;
        case 'd': /* VPA -- Move to <row> */
            DEFAULT(csiescseq.arg[0], 1);
            tmoveato(term.c.x, csiescseq.arg[0] - 1);
            break;
        case 'h': /* SM -- Set terminal mode */
            tsetmode(csiescseq.priv, 1, csiescseq.arg, csiescseq.narg);
            break;
        case 'm': /* SGR -- Terminal attribute (color) */
            tsetattr(csiescseq.arg, csiescseq.narg);
            break;
        case 'n': /* DSR – Device Status Report (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) {
    int 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 */
                case 10: /* foreground set */
                case 11: /* background set */
                case 12: /* cursor color */
                    if ((par == 4 && narg < 3) || narg < 2) break;
                    p = strescseq.args[((par == 4) ? 2 : 1)];
                    /* FALLTHROUGH */
                case 104: /* color reset, here p = NULL */
                    if (par == 10)
                        j = defaultfg;
                    else if (par == 11)
                        j = defaultbg;
                    else if (par == 12)
                        j = defaultcs;
                    else
                        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
                         */
                        if (j == defaultbg) xclearwin();
                        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) {
    int 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) { memset(&strescseq, 0, sizeof(strescseq)); }

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 externalpipe(const Arg *arg) {
    int to[2];
    char buf[UTF_SIZ];
    void (*oldsigpipe)(int);
    Glyph *bp, *end;
    int lastpos, n, newline;

    if (pipe(to) == -1) return;

    switch (fork()) {
        case -1:
            close(to[0]);
            close(to[1]);
            return;
        case 0:
            dup2(to[0], STDIN_FILENO);
            close(to[0]);
            close(to[1]);
            execvp(((char **)arg->v)[0], (char **)arg->v);
            fprintf(stderr, "st: execvp %s\n", ((char **)arg->v)[0]);
            perror("failed");
            exit(0);
    }

    close(to[0]);
    /* ignore sigpipe for now, in case child exists early */
    oldsigpipe = signal(SIGPIPE, SIG_IGN);
    newline = 0;
    /* modify externalpipe patch to pipe history too      */
    for (n = 0; n <= HISTSIZE + 2; n++) {
        bp = TLINE_HIST(n);
        lastpos = MIN(tlinehistlen(n) + 1, term.col) - 1;
        if (lastpos < 0) break;
        if (lastpos == 0) continue;
        end = &bp[lastpos + 1];
        for (; bp < end; ++bp)
            if (xwrite(to[1], buf, utf8encode(bp->u, buf)) < 0) break;
        if ((newline = TLINE_HIST(n)[lastpos].mode & ATTR_WRAP)) continue;
        if (xwrite(to[1], "\n", 1) < 0) break;
        newline = 0;
    }
    if (newline) (void)xwrite(to[1], "\n", 1);
    close(to[1]);
    /* restore */
    signal(SIGPIPE, oldsigpipe);
}

void iso14755(const Arg *arg) {
    FILE *p;
    char *us, *e, codepoint[9], uc[UTF_SIZ];
    unsigned long utf32;

    if (!(p = popen(ISO14755CMD, "r"))) return;

    us = fgets(codepoint, sizeof(codepoint), p);
    pclose(p);

    if (!us || *us == '\0' || *us == '-' || strlen(us) > 7) return;
    if ((utf32 = strtoul(us, &e, 16)) == ULONG_MAX || (*e != '\n' && *e != '\0')) return;

    ttywrite(uc, utf8encode(utf32, uc), 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, 1);
            } else {
                tmoveto(term.c.x, term.c.y + 1);
            }
            break;
        case 'E':        /* NEL -- Next line */
            tnewline(1); /* always go to first col */
            break;
        case 'H': /* HTS -- Horizontal tab stop */
            term.tabs[term.c.x] = 1;
            break;
        case 'M': /* RI -- Reverse index */
            if (term.c.y == term.top) {
                tscrolldown(term.top, 1, 1);
            } else {
                tmoveto(term.c.x, term.c.y - 1);
            }
            break;
        case 'Z': /* DECID -- Identify Terminal */
            ttywrite(vtiden, strlen(vtiden), 0);
            break;
        case 'c': /* RIS -- Reset to initial state */
            treset();
            resettitle();
            xloadcols();
            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 >= sizeof(strescseq.buf) - 1) {
            /*
             * 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();
             */
            return;
        }

        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, j;
    int tmp;
    int minrow, mincol;
    int *bp;
    TCursor c;

    tmp = col;
    if (!term.maxcol) term.maxcol = term.col;
    col = MAX(col, term.maxcol);
    minrow = MIN(row, term.row);
    mincol = MIN(col, term.maxcol);

    if (col < 1 || row < 1) {
        fprintf(stderr, "tresize: error resizing to %dx%d\n", col, row);
        return;
    }

    /*
     * slide screen to keep cursor where we expect it -
     * tscrollup would work here, but we can optimize to
     * memmove because we're freeing the earlier lines
     */
    for (i = 0; i <= term.c.y - row; i++) {
        free(term.line[i]);
        free(term.alt[i]);
    }
    /* ensure that both src and dst are not NULL */
    if (i > 0) {
        memmove(term.line, term.line + i, row * sizeof(Line));
        memmove(term.alt, term.alt + i, row * sizeof(Line));
    }
    for (i += row; i < term.row; i++) {
        free(term.line[i]);
        free(term.alt[i]);
    }

    /* resize to new height */
    term.line = xrealloc(term.line, row * sizeof(Line));
    term.alt = xrealloc(term.alt, row * sizeof(Line));
    term.dirty = xrealloc(term.dirty, row * sizeof(*term.dirty));
    term.tabs = xrealloc(term.tabs, col * sizeof(*term.tabs));

    for (i = 0; i < HISTSIZE; i++) {
        term.hist[i] = xrealloc(term.hist[i], col * sizeof(Glyph));
        for (j = mincol; j < col; j++) {
            term.hist[i][j] = term.c.attr;
            term.hist[i][j].u = ' ';
        }
    }

    /* resize each row to new width, zero-pad if needed */
    for (i = 0; i < minrow; i++) {
        term.line[i] = xrealloc(term.line[i], col * sizeof(Glyph));
        term.alt[i] = xrealloc(term.alt[i], col * sizeof(Glyph));
    }

    /* allocate any new rows */
    for (/* i = minrow */; i < row; i++) {
        term.line[i] = xmalloc(col * sizeof(Glyph));
        term.alt[i] = xmalloc(col * sizeof(Glyph));
    }

    if (col > term.maxcol) {
        bp = term.tabs + term.maxcol;
        memset(bp, 0, sizeof(*term.tabs) * (col - term.maxcol));
        while (--bp > term.tabs && !*bp) /* nothing */;
        for (bp += tabspaces; bp < term.tabs + col; bp += tabspaces) *bp = 1;
    }
    /* update terminal size */
    term.col = tmp;
    term.maxcol = col;
    term.row = row;
    /* reset scrolling region */
    tsetscroll(0, row - 1);
    /* make use of the LIMIT in tmoveto */
    tmoveto(term.c.x, term.c.y);
    /* Clearing both screens (it makes dirty all lines) */
    c = term.c;
    for (i = 0; i < 2; i++) {
        if (mincol < col && 0 < minrow) {
            tclearregion(mincol, 0, col - 1, minrow - 1);
        }
        if (0 < col && minrow < row) {
            tclearregion(0, minrow, col - 1, row - 1);
        }
        tswapscreen();
        tcursor(CURSOR_LOAD);
    }
    term.c = c;
}

void resettitle(void) { xsettitle(NULL); }

void drawregion(int x1, int y1, int x2, int y2) {
    int y;
    for (y = y1; y < y2; y++) {
        if (!term.dirty[y]) continue;

        term.dirty[y] = 0;
        xdrawline(TLINE(y), x1, y, x2);
    }
}

void draw(void) {
    int cx = term.c.x;

    if (!xstartdraw()) return;

    /* adjust cursor position */
    LIMIT(term.ocx, 0, term.col - 1);
    LIMIT(term.ocy, 0, term.row - 1);
    if (term.line[term.ocy][term.ocx].mode & ATTR_WDUMMY) term.ocx--;
    if (term.line[term.c.y][cx].mode & ATTR_WDUMMY) cx--;

    drawregion(0, 0, term.col, term.row);
    if (term.scr == 0)
        xdrawcursor(cx, term.c.y, term.line[term.c.y][cx], term.ocx, term.ocy,
                    term.line[term.ocy][term.ocx], term.line[term.ocy], term.col);
    term.ocx = cx, term.ocy = term.c.y;
    xfinishdraw();

    struct timespec now;
    clock_gettime(CLOCK_MONOTONIC, &now);
    if (ximspot_update_interval &&
        TIMEDIFF(now, term.last_ximspot_update) > ximspot_update_interval) {
        xximspot(term.ocx, term.ocy);
        term.last_ximspot_update = now;
    }
}

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

void tsetcolor(int row, int start, int end, uint32_t fg, uint32_t bg) {
    int i = start;
    for (; i < end; ++i) {
        term.line[row][i].fg = fg;
        term.line[row][i].bg = bg;
    }
}

char *findlastany(char *str, const char **find, size_t len) {
    char *found = NULL;
    int i = 0;
    for (found = str + strlen(str) - 1; found >= str; --found) {
        for (i = 0; i < len; i++) {
            if (strncmp(found, find[i], strlen(find[i])) == 0) {
                return found;
            }
        }
    }

    return NULL;
}

/*
** Select and copy the previous url on screen (do nothing if there's no url).
**
** FIXME: doesn't handle urls that span multiple lines; will need to add support
**        for multiline "getsel()" first
*/
void copyurl(const Arg *arg) {
    /* () and [] can appear in urls, but excluding them here will reduce false
     * positives when figuring out where a given url ends.
     */
    static char URLCHARS[] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz"
        "0123456789-._~:/?#@!$&'*+,;=%";

    static const char *URLSTRINGS[] = {"http://", "https://"};

    /* remove highlighting from previous selection if any */
    if (sel.ob.x >= 0 && sel.oe.x >= 0)
        tsetcolor(sel.nb.y, sel.ob.x, sel.oe.x + 1, defaultfg, defaultbg);

    int i = 0, row = 0, /* row of current URL */
        col = 0,        /* column of current URL start */
        startrow = 0,   /* row of last occurrence */
        colend = 0,     /* column of last occurrence */
        passes = 0;     /* how many rows have been scanned */

    char *linestr = calloc(sizeof(char), term.col + 1); /* assume ascii */
    char *c = NULL, *match = NULL;

    row = (sel.ob.x >= 0 && sel.nb.y > 0) ? sel.nb.y : term.bot;
    LIMIT(row, term.top, term.bot);
    startrow = row;

    colend = (sel.ob.x >= 0 && sel.nb.y > 0) ? sel.nb.x : term.col;
    LIMIT(colend, 0, term.col);

    /*
    ** Scan from (term.bot,term.col) to (0,0) and find
    ** next occurrance of a URL
    */
    while (passes != term.bot + 2) {
        /* Read in each column of every row until
        ** we hit previous occurrence of URL
        */
        for (col = 0, i = 0; col < colend; ++col, ++i) {
            /* assume ascii */
            if (term.line[row][col].u > 127) continue;
            linestr[i] = term.line[row][col].u;
        }
        linestr[term.col] = '\0';

        if ((match = findlastany(linestr, URLSTRINGS, sizeof(URLSTRINGS) / sizeof(URLSTRINGS[0]))))
            break;

        if (--row < term.top) row = term.bot;

        colend = term.col;
        passes++;
    };

    if (match) {
        /* must happen before trim */
        selclear();
        sel.ob.x = strlen(linestr) - strlen(match);

        /* trim the rest of the line from the url match */
        for (c = match; *c != '\0'; ++c)
            if (!strchr(URLCHARS, *c)) {
                *c = '\0';
                break;
            }

        /* highlight selection by inverting terminal colors */
        tsetcolor(row, sel.ob.x, sel.ob.x + strlen(match), defaultbg, defaultfg);

        /* select and copy */
        sel.mode = 1;
        sel.type = SEL_REGULAR;
        sel.oe.x = sel.ob.x + strlen(match) - 1;
        sel.ob.y = sel.oe.y = row;
        selnormalize();
        tsetdirt(sel.nb.y, sel.ne.y);
        xsetsel(getsel());
        xclipcopy();
    }

    free(linestr);
}