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 <strings.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 <regex.h>
#include <wctype.h>
#include <time.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 NUMMAXLEN(x)    ((int)(sizeof(x) * 2.56 + 0.5) + 1)
#define ISCONTROLC0(c)    (BETWEEN(c, 0, 0x1f) || (c) == 0x7f)
#define ISCONTROLC1(c)    (BETWEEN(c, 0x80, 0x9f))
#define ISCONTROL(c)    (ISCONTROLC0(c) || ISCONTROLC1(c))
#define ISDELIM(u)      ((iswspace(u) || iswpunct(u)) && wcschr(worddelimiters, u) != NULL)

/* constants */
#define ISO14755CMD   "dmenu -bw 2 -w %lu -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,
};

enum cursor_movement {
  CURSOR_SAVE,
  CURSOR_LOAD
};

enum cursor_state {
  CURSOR_DEFAULT  = 0,
  CURSOR_WRAPNEXT = 1,
  CURSOR_ORIGIN   = 2
};

enum charset {
  CS_GRAPHIC0,
  CS_GRAPHIC1,
  CS_UK,
  CS_USA,
  CS_MULTI,
  CS_GER,
  CS_FIN
};

enum escape_state {
  ESC_START      = 1,
  ESC_CSI        = 2,
  ESC_STR        = 4,  /* DCS, OSC, PM, APC */
  ESC_ALTCHARSET = 8,
  ESC_STR_END    = 16, /* a final string was encountered */
  ESC_TEST       = 32, /* Enter in test mode */
  ESC_UTF8       = 64,
};

typedef struct {
  Glyph attr; /* current char attributes */
  int x;
  int y;
  char state;
} TCursor;

typedef struct {
  int mode;
  int type;
  int snap;
  /*
   * Selection variables:
   * nb – normalized coordinates of the beginning of the selection
   * ne – normalized coordinates of the end of the selection
   * ob – original coordinates of the beginning of the selection
   * oe – original coordinates of the end of the selection
   */
  struct {
    int x, y;
  } nb, ne, ob, oe;

  int alt;
} Selection;

/* Internal representation of the screen */
typedef struct {
  int row;      /* nb row */
  int col;      /* nb col */
  Line *line;   /* screen */
  Line *alt;    /* alternate screen */
  Line *hist;   /* history buffer */
  int histi;    /* history index */
  int scr;      /* scroll back */
  int *dirty;   /* dirtyness of lines */
  TCursor c;    /* cursor */
  int ocx;      /* old cursor col */
  int ocy;      /* old cursor row */
  int top;      /* top    scroll limit */
  int bot;      /* bottom scroll limit */
  int mode;     /* terminal mode flags */
  int esc;      /* escape state flags */
  char trantbl[4]; /* charset table translation */
  int charset;  /* current charset */
  int icharset; /* selected charset for sequence */
  int *tabs;
  Rune lastc;   /* last printed char outside of sequence, 0 if control */
} Term;

/* CSI Escape sequence structs */
/* ESC '[' [[ [<priv>] <arg> [;]] <mode> [<mode>]] */
typedef struct {
  char buf[ESC_BUF_SIZ]; /* raw string */
  size_t len;               /* raw string length */
  char priv;
  int arg[ESC_ARG_SIZ];
  int narg;              /* nb of args */
  char mode[2];
} CSIEscape;

/* STR Escape sequence structs */
/* ESC type [[ [<priv>] <arg> [;]] <mode>] ESC '\' */
typedef struct {
  char type;             /* ESC type ... */
  char *buf; /* raw string */
  size_t siz; /* allocation size */
  size_t len;               /* raw string length */
  char *args[STR_ARG_SIZ];
  int narg;              /* nb of args */
} STREscape;

static void execsh(char *, char **);
static void stty(char **);
static void sigchld(int);
static void ttywriteraw(const char *, size_t);

static void csidump(void);
static void csihandle(void);
static void csiparse(void);
static void csireset(void);
static void osc_color_response(int, int, int);
static int eschandle(uchar);
static void strdump(void);
static void strhandle(void);
static void strparse(void);
static void strreset(void);

static void tprinter(char *, size_t);
static void tdumpsel(void);
static void tdumpline(int);
static void tdump(void);
static void tclearregion(int, int, int, int);
static void tcursor(int);
static void tdeletechar(int);
static void tdeleteline(int);
static void tinsertblank(int);
static void tinsertblankline(int);
static int tlinelen(int);
static void tmoveto(int, int);
static void tmoveato(int, int);
static void tnewline(int);
static void tputtab(int);
static void tputc(Rune);
static void treset(void);
static void tscrollup(int, int, int);
static void tscrolldown(int, int, int);
static void tsetattr(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 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};

static int su = 0;
struct timespec sutv;

static void
tsync_begin()
{
  clock_gettime(CLOCK_MONOTONIC, &sutv);
  su = 1;
}

static void
tsync_end()
{
  su = 0;
}

int
tinsync(uint timeout)
{
  struct timespec now;
  if (su && !clock_gettime(CLOCK_MONOTONIC, &now)
         && TIMEDIFF(now, sutv) >= timeout)
    su = 0;
  return su;
}

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;
}

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

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

  static const char base64_digits[256] = {
    [43] = 62, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
    0, 0, 0, -1, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
    13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0,
    0, 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
    40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
  };

  if (in_len % 4)
    in_len += 4 - (in_len % 4);
  result = dst = (char *)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
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;
  }
}

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

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

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

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

  return i;
}

void
selstart(int col, int row, int snap)
{
  selclear();
  sel.mode = SEL_EMPTY;
  sel.type = SEL_REGULAR;
  sel.alt = IS_SET(MODE_ALTSCREEN);
  sel.snap = snap;
  sel.oe.x = sel.ob.x = col;
  sel.oe.y = sel.ob.y = row;
  selnormalize();

  if (sel.snap != 0)
    sel.mode = SEL_READY;
  tsetdirt(sel.nb.y, sel.ne.y);
}

void
selextend(int col, int row, int type, int done)
{
  int oldey, oldex, oldsby, oldsey, oldtype;

  if (sel.mode == SEL_IDLE)
    return;

  if (done && sel.mode == SEL_EMPTY) {
    selclear();
    return;
  }

  oldey = sel.oe.y;
  oldex = sel.oe.x;
  oldsby = sel.nb.y;
  oldsey = sel.ne.y;
  oldtype = sel.type;

  sel.oe.x = col;
  sel.oe.y = row;
  selnormalize();
  sel.type = type;

  if (oldey != sel.oe.y || oldex != sel.oe.x || oldtype != sel.type || sel.mode == SEL_EMPTY)
    tsetdirt(MIN(sel.nb.y, oldsby), MAX(sel.ne.y, oldsey));

  sel.mode = done ? SEL_IDLE : SEL_READY;
}

void
selnormalize(void)
{
  int i;

  if (sel.type == SEL_REGULAR && sel.ob.y != sel.oe.y) {
    sel.nb.x = sel.ob.y < sel.oe.y ? sel.ob.x : sel.oe.x;
    sel.ne.x = sel.ob.y < sel.oe.y ? sel.oe.x : sel.ob.x;
  } else {
    sel.nb.x = MIN(sel.ob.x, sel.oe.x);
    sel.ne.x = MAX(sel.ob.x, sel.oe.x);
  }
  sel.nb.y = MIN(sel.ob.y, sel.oe.y);
  sel.ne.y = MAX(sel.ob.y, sel.oe.y);

  selsnap(&sel.nb.x, &sel.nb.y, -1);
  selsnap(&sel.ne.x, &sel.ne.y, +1);

  /* expand selection over line breaks */
  if (sel.type == SEL_RECTANGULAR)
    return;
  i = tlinelen(sel.nb.y);
  if (i < sel.nb.x)
    sel.nb.x = i;
  if (tlinelen(sel.ne.y) <= sel.ne.x)
    sel.ne.x = term.col - 1;
}

int
selected(int x, int y)
{
  if (sel.mode == SEL_EMPTY || sel.ob.x == -1 ||
      sel.alt != IS_SET(MODE_ALTSCREEN))
    return 0;

  if (sel.type == SEL_RECTANGULAR)
    return BETWEEN(y, sel.nb.y, sel.ne.y)
        && BETWEEN(x, sel.nb.x, sel.ne.x);

  return BETWEEN(y, sel.nb.y, sel.ne.y)
      && (y != sel.nb.y || x >= sel.nb.x)
      && (y != sel.ne.y || x <= sel.ne.x);
}

void
selsnap(int *x, int *y, int direction)
{
  int newx, newy, xt, yt;
  int delim, prevdelim;
  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) || sel.type == SEL_RECTANGULAR))
      *ptr++ = '\n';
  }
  *ptr = 0;
  return str;
}

void
selclear(void)
{
  if (sel.ob.x == -1)
    return;
  sel.mode = SEL_IDLE;
  sel.ob.x = -1;
  tsetdirt(sel.nb.y, sel.ne.y);
}

void
die(const char *errstr, ...)
{
  va_list ap;

  va_start(ap, errstr);
  vfprintf(stderr, errstr, ap);
  va_end(ap);
  exit(1);
}

void
execsh(char *cmd, char **args)
{
  char *sh, *prog, *arg;
  const struct passwd *pw;

  errno = 0;
  if ((pw = getpwuid(getuid())) == NULL) {
    if (errno)
      die("getpwuid: %s\n", strerror(errno));
    else
      die("who are you?\n");
  }

  if ((sh = getenv("SHELL")) == NULL)
    sh = (pw->pw_shell[0]) ? pw->pw_shell : cmd;

  if (args) {
    prog = args[0];
    arg = NULL;
  } else if (scroll) {
    prog = scroll;
    arg = scroll ? utmp : sh;
  } else if (utmp) {
    prog = utmp;
    arg = NULL;
  } else {
    prog = sh;
    arg = NULL;
  }

  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);
    close(m);
    setsid(); /* create a new process group */
    dup2(s, 0);
    dup2(s, 1);
    dup2(s, 2);
    if (ioctl(s, TIOCSCTTY, NULL) < 0)
      die("ioctl TIOCSCTTY failed: %s\n", strerror(errno));
    if (s > 2)
      close(s);
#ifdef __OpenBSD__
    if (pledge("stdio getpw proc exec ps rpath wpath tty", NULL) == -1)
      die("Failed to execute pledge() system call.\n");
#endif
    execsh(cmd, args);
    break;
  default:
#ifdef __OpenBSD__
    if (pledge("stdio getpw proc exec ps rpath wpath tty", NULL) == -1)
      die("Failed to execute pledge() system call\n");
#endif
    close(s);
    cmdfd = m;
    signal(SIGCHLD, sigchld);
    break;
  }
  return cmdfd;
}

static int twrite_aborted = 0;
int ttyread_pending() { return twrite_aborted; }

size_t
ttyread(void)
{
  static char buf[BUFSIZ];
  static int buflen = 0;
  int written;
  int ret;

  /* append read bytes to unprocessed bytes */
  ret = twrite_aborted ? 1 : read(cmdfd, buf+buflen, LEN(buf)-buflen);

  switch (ret) {
  case 0:
    fputs("Found EOF in input\n", stderr);
    exit(0);
  case -1:
    die("couldn't read from shell: %s\n", strerror(errno));
  default:
    buflen += twrite_aborted ? 0 : 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);
  }

  if (term.scr > 0 && (unsigned int)term.scr < (histsize - 1))
    term.scr++;

  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)
{
  tsync_end();
  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 < (unsigned int)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 } } };

  /* allocate history buffer */
  term.hist = (Line*)xrealloc(term.hist, (histsize+1) * sizeof(Line));
  bzero(term.hist, ((histsize+1) * sizeof(Line)));

  tresize(col, row);
  treset();
}

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

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

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

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

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

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

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

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

  if ((term.histi - term.scr - n) > 0  && (unsigned int)term.scr <= (histsize-n)) {
    term.scr += n;
    selscroll(0, n);
    tfulldirt();
  }
}

void
histfree(void) {
  if (term.hist)
    free(term.hist);
}

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;
  }

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

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

  selscroll(orig, -n);
}

void
selscroll(int orig, int n)
{
  if (sel.ob.x == -1 || sel.alt != IS_SET(MODE_ALTSCREEN))
    return;

  if (BETWEEN(sel.nb.y, orig, term.bot) != BETWEEN(sel.ne.y, orig, term.bot)) {
    selclear();
  } else if (BETWEEN(sel.nb.y, orig, term.bot)) {
    sel.ob.y += n;
    sel.oe.y += n;
    if (sel.ob.y < term.top || sel.ob.y > term.bot ||
        sel.oe.y < term.top || sel.oe.y > term.bot) {
      selclear();
    } else {
      selnormalize();
    }
  }
}

void
tnewline(int first_col)
{
  int y = term.c.y;

  if (y == term.bot) {
    tscrollup(term.top, 1, 1);
  } else {
    y++;
  }
  tmoveto(first_col ? 0 : term.c.x, y);
}

void
csiparse(void)
{
  char *p = csiescseq.buf, *np;
  long int v;
  int sep = ';'; /* colon or semi-colon, but not both*/

  csiescseq.narg = 0;
  if (*p == '?') {
    csiescseq.priv = 1;
    p++;
  }

  csiescseq.buf[csiescseq.len] = '\0';
  while (p < csiescseq.buf+csiescseq.len) {
    np = NULL;
    v = strtol(p, &np, 10);
    if (np == p)
      v = 0;
    if (v == LONG_MAX || v == LONG_MIN)
      v = -1;
    csiescseq.arg[csiescseq.narg++] = v;
    p = np;
    if (sep == ';' && *p == ':')
      sep = ':'; /* allow override to colon once */
    if (*p != sep || csiescseq.narg == ESC_ARG_SIZ)
      break;
    p++;
  }
  csiescseq.mode[0] = *p++;
  csiescseq.mode[1] = (p < csiescseq.buf+csiescseq.len) ? *p : '\0';
}

/* for absolute user moves, when decom is set */
void
tmoveato(int x, int y)
{
  tmoveto(x, y + ((term.c.state & CURSOR_ORIGIN) ? term.top: 0));
}

void
tmoveto(int x, int y)
{
  int miny, maxy;

  if (term.c.state & CURSOR_ORIGIN) {
    miny = term.top;
    maxy = term.bot;
  } else {
    miny = 0;
    maxy = term.row - 1;
  }
  term.c.state &= ~CURSOR_WRAPNEXT;
  term.c.x = LIMIT(x, 0, term.col-1);
  term.c.y = LIMIT(y, miny, maxy);
}

void
tsetchar(Rune u, 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.col-1);
  LIMIT(x2, 0, term.col-1);
  LIMIT(y1, 0, term.row-1);
  LIMIT(y2, 0, term.row-1);

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

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

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

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

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

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

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

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

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

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

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

int32_t
tdefcolor(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 'b': /* REP -- if last char is printable print it <n> more times */
    LIMIT(csiescseq.arg[0], 1, 65535);
    if (term.lastc)
      while (csiescseq.arg[0]-- > 0)
        tputc(term.lastc);
    break;
  case 'C': /* CUF -- Cursor <n> Forward */
  case 'a': /* HPR -- Cursor <n> Forward */
    DEFAULT(csiescseq.arg[0], 1);
    tmoveto(term.c.x+csiescseq.arg[0], term.c.y);
    break;
  case 'D': /* CUB -- Cursor <n> Backward */
    DEFAULT(csiescseq.arg[0], 1);
    tmoveto(term.c.x-csiescseq.arg[0], term.c.y);
    break;
  case 'E': /* CNL -- Cursor <n> Down and first col */
    DEFAULT(csiescseq.arg[0], 1);
    tmoveto(0, term.c.y+csiescseq.arg[0]);
    break;
  case 'F': /* CPL -- Cursor <n> Up and first col */
    DEFAULT(csiescseq.arg[0], 1);
    tmoveto(0, term.c.y-csiescseq.arg[0]);
    break;
  case 'g': /* TBC -- Tabulation clear */
    switch (csiescseq.arg[0]) {
    case 0: /* clear current tab stop */
      term.tabs[term.c.x] = 0;
      break;
    case 3: /* clear all the tabs */
      memset(term.tabs, 0, term.col * sizeof(*term.tabs));
      break;
    default:
      goto unknown;
    }
    break;
  case 'G': /* CHA -- Move to <col> */
  case '`': /* HPA */
    DEFAULT(csiescseq.arg[0], 1);
    tmoveto(csiescseq.arg[0]-1, term.c.y);
    break;
  case 'H': /* CUP -- Move to <row> <col> */
  case 'f': /* HVP */
    DEFAULT(csiescseq.arg[0], 1);
    DEFAULT(csiescseq.arg[1], 1);
    tmoveato(csiescseq.arg[1]-1, csiescseq.arg[0]-1);
    break;
  case 'I': /* CHT -- Cursor Forward Tabulation <n> tab stops */
    DEFAULT(csiescseq.arg[0], 1);
    tputtab(csiescseq.arg[0]);
    break;
  case 'J': /* ED -- Clear screen */
    switch (csiescseq.arg[0]) {
    case 0: /* below */
      tclearregion(term.c.x, term.c.y, term.col-1, term.c.y);
      if (term.c.y < term.row-1) {
        tclearregion(0, term.c.y+1, term.col-1,
            term.row-1);
      }
      break;
    case 1: /* above */
      if (term.c.y > 1)
        tclearregion(0, 0, term.col-1, term.c.y-1);
      tclearregion(0, term.c.y, term.c.x, term.c.y);
      break;
    case 2: /* all */
      tclearregion(0, 0, term.col-1, term.row-1);
      break;
    default:
      goto unknown;
    }
    break;
  case 'K': /* EL -- Clear line */
    switch (csiescseq.arg[0]) {
    case 0: /* right */
      tclearregion(term.c.x, term.c.y, term.col-1,
          term.c.y);
      break;
    case 1: /* left */
      tclearregion(0, term.c.y, term.c.x, term.c.y);
      break;
    case 2: /* all */
      tclearregion(0, term.c.y, term.col-1, term.c.y);
      break;
    }
    break;
  case 'S': /* SU -- Scroll <n> line up */
    if (csiescseq.priv) break;
    DEFAULT(csiescseq.arg[0], 1);
    tscrollup(term.top, csiescseq.arg[0], 0);
    break;
  case 'T': /* SD -- Scroll <n> line down */
    DEFAULT(csiescseq.arg[0], 1);
    tscrolldown(term.top, csiescseq.arg[0], 0);
    break;
  case 't': /* title stack operations */
    switch (csiescseq.arg[0]) {
    case 22: /* pust current title on stack */
      switch (csiescseq.arg[1]) {
      case 0:
      case 1:
      case 2:
        xpushtitle();
        break;
      default:
        goto unknown;
      }
      break;
    case 23: /* pop last title from stack */
      switch (csiescseq.arg[1]) {
      case 0:
      case 1:
      case 2:
        xsettitle(NULL, 1);
        break;
      default:
        goto unknown;
      }
      break;
    default:
      goto unknown;
    }
  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) */
    switch (csiescseq.arg[0]) {
      case 5: // Status report "OK" '0n'
        ttywrite("\033[0n", sizeof("\033[0n") - 1, 0);
        break;
      case 6: // Report Cursor Position (CPR) '<row>;<col>R'
        len = snprintf(buf, sizeof(buf),"\033[%i;%iR",
            term.c.y+1, term.c.x+1);
        ttywrite(buf, len, 0);
        break;
      default:
        goto unknown;
    }
    break;
  case 'r': /* DECSTBM -- Set Scrolling Region */
    if (csiescseq.priv) {
      goto unknown;
    } else {
      DEFAULT(csiescseq.arg[0], 1);
      DEFAULT(csiescseq.arg[1], term.row);
      tsetscroll(csiescseq.arg[0]-1, csiescseq.arg[1]-1);
      tmoveato(0, 0);
    }
    break;
  case 's': /* DECSC -- Save cursor position (ANSI.SYS) */
    tcursor(CURSOR_SAVE);
    break;
  case 'u': /* DECRC -- Restore cursor position (ANSI.SYS) */
    tcursor(CURSOR_LOAD);
    break;
  case ' ':
    switch (csiescseq.mode[1]) {
    case 'q': /* DECSCUSR -- Set Cursor Style */
      if (xsetcursor(csiescseq.arg[0]))
        goto unknown;
      break;
    default:
      goto unknown;
    }
    break;
  }
}

void
csidump(void)
{
  size_t i;
  uint c;

  fprintf(stderr, "ESC[");
  for (i = 0; i < csiescseq.len; i++) {
    c = csiescseq.buf[i] & 0xff;
    if (isprint(c)) {
      putc(c, stderr);
    } else if (c == '\n') {
      fprintf(stderr, "(\\n)");
    } else if (c == '\r') {
      fprintf(stderr, "(\\r)");
    } else if (c == 0x1b) {
      fprintf(stderr, "(\\e)");
    } else {
      fprintf(stderr, "(%02x)", c);
    }
  }
  putc('\n', stderr);
}

void
csireset(void)
{
  memset(&csiescseq, 0, sizeof(csiescseq));
}

void
osc_color_response(int num, int index, int is_osc4)
{
  int n;
  char buf[32];
  unsigned char r, g, b;

  if (xgetcolor(is_osc4 ? num: index, &r, &g, &b)) {
    fprintf(stderr, "erresc: failed to fetch %s color %d\n", is_osc4 ? "osc4": "osc", is_osc4 ? num : index);
    return;
  }

  n = snprintf(buf, sizeof buf, "\033]%s%d;rgb:%02x%02x/%02x%02x/%02x%02x\007",
         is_osc4 ? "4": "", num, r, r, g, g, b, b);

  if (n < 0 || n >= sizeof(buf)) {
    fprintf(stderr, "error: %s while printing %s response\n",
        n<0 ? "snprintf failed" : "truncation occurred",
        is_osc4 ? "osc4": "osc");
  } else {
    ttywrite(buf, n, 1);
  }
}

void
strhandle(void)
{
  char *p = NULL;
  int j, narg, par;

  const struct { int idx; char *str; } osc_table[] = {
    { defaultfg, "foreground" },
    { defaultbg, "background" },
    { defaultcs, "cursor" }
  };

  term.esc &= ~(ESC_STR_END|ESC_STR);
  strparse();
  par = (narg = strescseq.narg) ? atoi(strescseq.args[0]) : 0;

  switch (strescseq.type) {
  case ']': /* OSC -- Operating System Command */
    switch (par) {
    case 0:
      if (narg > 1) {
        xsettitle(strescseq.args[1], 0);
        xseticontitle(strescseq.args[1]);
      }
      return;
    case 1:
      if (narg > 1)
        xseticontitle(strescseq.args[1]);
      return;
    case 2:
      if (narg > 1)
        xsettitle(strescseq.args[1], 0);
      return;
    case 52:
      if (narg > 2 && allowwindowops) {
        char *dec;

        dec = base64dec(strescseq.args[2]);
        if (dec) {
          xsetsel(dec);
          xclipcopy();
        } else {
          fprintf(stderr, "erresc: invalid base64\n");
        }
      }
      return;
   case 10:
   case 11:
   case 12:
     if (narg < 2)
       break;

     p = strescseq.args[1];

     if ((j = par - 10) < 0 || j >= LEN(osc_table))
       break; // should not be possible

     if (!strcmp(p, "?")) {
       osc_color_response(par, osc_table[j].idx, 0);
     } else if (xsetcolorname(osc_table[j].idx, p)) {
       fprintf(stderr, "erresc: invalid %s color: %s\n", osc_table[j].str, p);
     } else {
       tfulldirt();
     }
     return;
    case 4: /* color set */
      if (narg < 3)
        break;
      p = strescseq.args[2];
      /* FALLTHROUGH */
    case 104: /* color reset */
      j = (narg > 1) ? atoi(strescseq.args[1]) : -1;

     if ( p && !strcmp(p, "?")) {
       osc_color_response(j, 0, 1);
     } else if (xsetcolorname(j, p)) {
        if (par == 104 && narg <= 1) {
          xloadcols();
          return; /* color reset without parameter */
        }
        fprintf(stderr, "erresc: invalid color j=%d, p=%s\n",
                j, p ? p : "(null)");
      } else {
        /*
         * TODO if defaultbg color is changed, borders
         * are dirty
         */
        tfulldirt();
      }
      return;
    }
    break;
  case 'k': /* old title set compatibility */
    xsettitle(strescseq.args[0], 0);
    return;
  case 'P': /* DCS -- Device Control String */
    /* https://gitlab.com/gnachman/iterm2/-/wikis/synchronized-updates-spec */
    if (strstr(strescseq.buf, "=1s") == strescseq.buf)
      tsync_begin(), term.mode &= ~ESC_STR;  /* BSU */
    else if (strstr(strescseq.buf, "=2s") == strescseq.buf)
      tsync_end(), term.mode &= ~ESC_STR;  /* ESU */
    return;
  case '_': /* APC -- Application Program Command */
  case '^': /* PM -- Privacy Message */
    return;
  }

  if (debug) { 
    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)
{
  memset(&strescseq, 0, sizeof(strescseq));
  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
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(shell, (char *const []) {
        shell,
        "-c",
        (char *)arg->v,
        0
      });

      fprintf(stderr, "st: execvp %s ", ((char **)arg->v)[0]);
      perror("failed");
      exit(0);
  }

  close(to[0]);

  /* ignore sigpipe for now, in case child exits early */
  oldsigpipe = signal(SIGPIPE, SIG_IGN);
  newline = 0;
  for (n = 0; n < term.row; n++) {
    bp = term.line[n];
    lastpos = MIN(tlinelen(n) + 1, term.col) - 1;
    if (lastpos < 0)
      break;
    end = &bp[lastpos + 1];
    for (; bp < end; ++bp)
      if (xwrite(to[1], buf, utf8encode(bp->u, buf)) < 0)
        break;
    if ((newline = term.line[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
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
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';
    break;
  case 0x9f:   /* APC -- Application Program Command */
    c = '_';
    break;
  case 0x9e:   /* PM -- Privacy Message */
    c = '^';
    break;
  case 0x9d:   /* OSC -- Operating System Command */
    c = ']';
    break;
  }
  strreset();
  strescseq.type = c;
  term.esc |= ESC_STR;
}

void
tcontrolcode(uchar ascii)
{
  switch (ascii) {
  case '\t':   /* HT */
    tputtab(1);
    return;
  case '\b':   /* BS */
    tmoveto(term.c.x-1, term.c.y);
    return;
  case '\r':   /* CR */
    tmoveto(0, term.c.y);
    return;
  case '\f':   /* LF */
  case '\v':   /* VT */
  case '\n':   /* LF */
    /* go to first col if the mode is set */
    tnewline(IS_SET(MODE_CRLF));
    return;
  case '\a':   /* BEL */
    if (term.esc & ESC_STR_END) {
      /* backwards compatibility to xterm */
      strhandle();
    } else {
      xbell();
    }
    break;
  case '\033': /* ESC */
    csireset();
    term.esc &= ~(ESC_CSI|ESC_ALTCHARSET|ESC_TEST);
    term.esc |= ESC_START;
    return;
  case '\016': /* SO (LS1 -- Locking shift 1) */
  case '\017': /* SI (LS0 -- Locking shift 0) */
    term.charset = 1 - (ascii - '\016');
    return;
  case '\032': /* SUB */
    tsetchar('?', &term.c.attr, term.c.x, term.c.y);
    /* FALLTHROUGH */
  case '\030': /* CAN */
    csireset();
    break;
  case '\005': /* ENQ (IGNORED) */
  case '\000': /* NUL (IGNORED) */
  case '\021': /* XON (IGNORED) */
  case '\023': /* XOFF (IGNORED) */
  case 0177:   /* DEL (IGNORED) */
    return;
  case 0x80:   /* TODO: PAD */
  case 0x81:   /* TODO: HOP */
  case 0x82:   /* TODO: BPH */
  case 0x83:   /* TODO: NBH */
  case 0x84:   /* TODO: IND */
    break;
  case 0x85:   /* NEL -- Next line */
    tnewline(1); /* always go to first col */
    break;
  case 0x86:   /* TODO: SSA */
  case 0x87:   /* TODO: ESA */
    break;
  case 0x88:   /* HTS -- Horizontal tab stop */
    term.tabs[term.c.x] = 1;
    break;
  case 0x89:   /* TODO: HTJ */
  case 0x8a:   /* TODO: VTS */
  case 0x8b:   /* TODO: PLD */
  case 0x8c:   /* TODO: PLU */
  case 0x8d:   /* TODO: RI */
  case 0x8e:   /* TODO: SS2 */
  case 0x8f:   /* TODO: SS3 */
  case 0x91:   /* TODO: PU1 */
  case 0x92:   /* TODO: PU2 */
  case 0x93:   /* TODO: STS */
  case 0x94:   /* TODO: CCH */
  case 0x95:   /* TODO: MW */
  case 0x96:   /* TODO: SPA */
  case 0x97:   /* TODO: EPA */
  case 0x98:   /* TODO: SOS */
  case 0x99:   /* TODO: SGCI */
    break;
  case 0x9a:   /* DECID -- Identify Terminal */
    ttywrite(vtiden, strlen(vtiden), 0);
    break;
  case 0x9b:   /* TODO: CSI */
  case 0x9c:   /* TODO: ST */
    break;
  case 0x90:   /* DCS -- Device Control String */
  case 0x9d:   /* OSC -- Operating System Command */
  case 0x9e:   /* PM -- Privacy Message */
  case 0x9f:   /* APC -- Application Program Command */
    tstrsequence(ascii);
    return;
  }
  /* only CAN, SUB, \a and C1 chars interrupt a sequence */
  term.esc &= ~(ESC_STR_END|ESC_STR);
}

/*
 * returns 1 when the sequence is finished and it hasn't to read
 * more characters for this sequence, otherwise 0
 */
int
eschandle(uchar ascii)
{
  switch (ascii) {
  case '[':
    term.esc |= ESC_CSI;
    return 0;
  case '#':
    term.esc |= ESC_TEST;
    return 0;
  case '%':
    term.esc |= ESC_UTF8;
    return 0;
  case 'P': /* DCS -- Device Control String */
  case '_': /* APC -- Application Program Command */
  case '^': /* PM -- Privacy Message */
  case ']': /* OSC -- Operating System Command */
  case 'k': /* old title set compatibility */
    tstrsequence(ascii);
    return 0;
  case 'n': /* LS2 -- Locking shift 2 */
  case 'o': /* LS3 -- Locking shift 3 */
    term.charset = 2 + (ascii - 'n');
    break;
  case '(': /* GZD4 -- set primary charset G0 */
  case ')': /* G1D4 -- set secondary charset G1 */
  case '*': /* G2D4 -- set tertiary charset G2 */
  case '+': /* G3D4 -- set quaternary charset G3 */
    term.icharset = ascii - '(';
    term.esc |= ESC_ALTCHARSET;
    return 0;
  case 'D': /* IND -- Linefeed */
    if (term.c.y == term.bot) {
      tscrollup(term.top, 1, 1);
    } else {
      tmoveto(term.c.x, term.c.y+1);
    }
    break;
  case 'E': /* NEL -- Next line */
    tnewline(1); /* always go to first col */
    break;
  case 'H': /* HTS -- Horizontal tab stop */
    term.tabs[term.c.x] = 1;
    break;
  case 'M': /* RI -- Reverse index */
    if (term.c.y == term.top) {
      tscrolldown(term.top, 1, 1);
    } else {
      tmoveto(term.c.x, term.c.y-1);
    }
    break;
  case 'Z': /* DECID -- Identify Terminal */
    ttywrite(vtiden, strlen(vtiden), 0);
    break;
  case 'c': /* RIS -- Reset to inital state */
    treset();
    xfreetitlestack();
    resettitle();
    xloadcols();
    xsetmode(0, MODE_HIDE);
    break;
  case '=': /* DECPAM -- Application keypad */
    xsetmode(1, MODE_APPKEYPAD);
    break;
  case '>': /* DECPNM -- Normal keypad */
    xsetmode(0, MODE_APPKEYPAD);
    break;
  case '7': /* DECSC -- Save Cursor */
    tcursor(CURSOR_SAVE);
    break;
  case '8': /* DECRC -- Restore Cursor */
    tcursor(CURSOR_LOAD);
    break;
  case '\\': /* ST -- String Terminator */
    if (term.esc & ESC_STR_END)
      strhandle();
    break;
  default:
    fprintf(stderr, "erresc: unknown sequence ESC 0x%02X '%c'\n",
      (uchar) ascii, isprint(ascii)? ascii:'.');
    break;
  }
  return 1;
}

void
tputc(Rune u)
{
  char c[UTF_SIZ];
  int control;
  int width, len;
  Glyph *gp;

  control = ISCONTROL(u);
  if (u < 127 || !IS_SET(MODE_UTF8)) {
    c[0] = u;
    width = len = 1;
  } else {
    len = utf8encode(u, c);
    if (!control && (width = wcwidth(u)) == -1) {
      width = 1;
    }
  }

  if (IS_SET(MODE_PRINT))
    tprinter(c, len);

  /*
   * STR sequence must be checked before anything else
   * because it uses all following characters until it
   * receives a ESC, a SUB, a ST or any other C1 control
   * character.
   */
  if (term.esc & ESC_STR) {
    if (u == '\a' || u == 030 || u == 032 || u == 033 ||
       ISCONTROLC1(u)) {
      term.esc &= ~(ESC_START|ESC_STR);
      term.esc |= ESC_STR_END;
      goto check_control_code;
    }

    if (strescseq.len+len >= strescseq.siz) {
      /*
       * Here is a bug in terminals. If the user never sends
       * some code to stop the str or esc command, then st
       * will stop responding. But this is better than
       * silently failing with unknown characters. At least
       * then users will report back.
       *
       * In the case users ever get fixed, here is the code:
       */
      /*
       * term.esc = 0;
       * strhandle();
       */
      if (strescseq.siz > (SIZE_MAX - UTF_SIZ) / 2) return;
      // resize buffer
      strescseq.siz *= 2;
      strescseq.buf = xrealloc(strescseq.buf, strescseq.siz);
    }

    memmove(&strescseq.buf[strescseq.len], c, len);
    strescseq.len += len;
    return;
  }

check_control_code:
  /*
   * Actions of control codes must be performed as soon they arrive
   * because they can be embedded inside a control sequence, and
   * they must not cause conflicts with sequences.
   */
  if (control) {
    // in UTF-8 mode ignore handling C1 control characters
    if (IS_SET(MODE_UTF8) && ISCONTROLC1(u))
      return;
    tcontrolcode(u);
    /*
     * control codes are not shown ever
     */
    if (!term.esc)
      term.lastc = 0;
    return;
  } else if (term.esc & ESC_START) {
    if (term.esc & ESC_CSI) {
      csiescseq.buf[csiescseq.len++] = u;
      if (BETWEEN(u, 0x40, 0x7E)
          || csiescseq.len >= \
          sizeof(csiescseq.buf)-1) {
        term.esc = 0;
        csiparse();
        csihandle();
      }
      return;
    } else if (term.esc & ESC_UTF8) {
      tdefutf8(u);
    } else if (term.esc & ESC_ALTCHARSET) {
      tdeftran(u);
    } else if (term.esc & ESC_TEST) {
      tdectest(u);
    } else {
      if (!eschandle(u))
        return;
      /* sequence already finished */
    }
    term.esc = 0;
    /*
     * All characters which form part of a sequence are not
     * printed
     */
    return;
  }
  if (selected(term.c.x, term.c.y))
    selclear();

  gp = &term.line[term.c.y][term.c.x];
  if (IS_SET(MODE_WRAP) && (term.c.state & CURSOR_WRAPNEXT)) {
    gp->mode |= ATTR_WRAP;
    tnewline(1);
    gp = &term.line[term.c.y][term.c.x];
  }

  if (IS_SET(MODE_INSERT) && term.c.x+width < term.col) {
    memmove(gp+width, gp, (term.col - term.c.x - width) * sizeof(Glyph));
    gp->mode &= ~ATTR_WIDE;
  }

  if (term.c.x+width > term.col) {
    if (IS_SET(MODE_WRAP)) {
      tnewline(1);
    } else {
      tmoveto(term.col - width, term.c.y);
    }
    gp = &term.line[term.c.y][term.c.x];
  }

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

  if (width == 2) {
    gp->mode |= ATTR_WIDE;
    if (term.c.x+1 < term.col) {
      if (gp[1].mode == ATTR_WIDE && term.c.x+2 < term.col) {
        gp[2].u = ' ';
        gp[2].mode &= ~ATTR_WDUMMY;
      }
      gp[1].u = '\0';
      gp[1].mode = ATTR_WDUMMY;
    }
  }
  if (term.c.x+width < term.col) {
    tmoveto(term.c.x+width, term.c.y);
  } else {
    term.c.state |= CURSOR_WRAPNEXT;
  }
}

int
twrite(const char *buf, int buflen, int show_ctrl)
{
  int charsize;
  Rune u;
  int n;

  int su0 = su;
  twrite_aborted = 0;

  for (n = 0; n < buflen; n += charsize) {
    if (IS_SET(MODE_UTF8)) {
      /* process a complete utf8 char */
      charsize = utf8decode(buf + n, &u, buflen - n);
      if (charsize == 0)
        break;
    } else {
      u = buf[n] & 0xFF;
      charsize = 1;
    }
    if (su0 && !su) {
      twrite_aborted = 1;
      break;  // ESU - allow rendering before a new BSU
    }
    if (show_ctrl && ISCONTROL(u)) {
      if (u & 0x80) {
        u &= 0x7f;
        tputc('^');
        tputc('[');
      } else if (u != '\n' && u != '\r' && u != '\t') {
        u ^= 0x40;
        tputc('^');
      }
    }
    tputc(u);
  }
  return n;
}

void
tresize(int col, int row)
{
  int i, j;
  int minrow = MIN(row, term.row);
  int mincol = MIN(col, term.col);
  int *bp;
  TCursor c;

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

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

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

  /* resize each row to new width, zero-pad if needed */
  for (i=0; i < histsize; i++) {
    /* allocate line */
    term.hist[i] = xrealloc(term.hist[i], col * sizeof(Glyph));
    /* initialize line contents */
    for (j=mincol; j<col; j++) {
      term.hist[i][j] = term.c.attr;
      term.hist[i][j].u = ' ';
    }
  }

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

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

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

void
resettitle(void)
{
  xsettitle(NULL, 0);
}

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;
  int ocx = term.ocx, ocy = term.ocy;

  if (!xstartdraw())
    return;

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

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

  // update xim cursor only if position is actually changed
  if (ocx != term.ocx || ocy != term.ocy)
    xximspot(term.ocx, term.ocy);
}

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