// Pipe Watch ("pw")
// Copyright 2022-2023 Kaz Kylheku <kaz@kylheku.com>
//
// BSD-2 License
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
//    this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <ctype.h>
#include <string.h>
#include <limits.h>
#include <stdarg.h>
#include <math.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/poll.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <regex.h>
#ifdef _DARWIN_C_SOURCE
#include "macpoll.h"
#endif

#define ctrl(ch) ((ch) & 0x1f)
#define BS 8
#define TAB 9
#define CR 13
#define ESC 27
#define DEL 127

#define min(a, b) ((a) < (b) ? (a) : (b))
#define max(a, b) ((a) > (b) ? (a) : (b))

#define twocc(ch1, ch2) (((int) (ch1)) << 8 | (ch2))

#ifdef __GNUC__
#define printf_attr(fmtpos, vargpos) __attribute__ ((format (printf, \
                                                             fmtpos, vargpos)))
#else
#define printf_attr(fmtpos, vargpos)
#endif

#define cmdsize 256
#define maxgrep 64
#define maxtrig 100
#define snhistsize 20
#define workmax 4096

enum status_flags {
  stat_dirty =    0x0001, // display needs refresh
  stat_eof =      0x0002, // end of data reached
  stat_susp =     0x0004, // display refresh suspended
  stat_htmode =   0x0008, // head trigger mode
  stat_ttmode =   0x0010, // tail trigger mode
  stat_trgrd =    0x0020, // triggered flag
  stat_grep =     0x0040, // grep mode
  stat_force =    0x0080, // force refresh even if clean
  stat_lino =     0x0100, // render line numbers
  stat_bkgnd =    0x0200, // running in the background
  stat_hlite =    0x0400, // running in the background
  stat_oneshot =  0x0800, // running in the background
  stat_diff =     0x1000, // highlight differences
  stat_save =     stat_susp | stat_lino | stat_hlite | stat_diff
};

enum dstr_flags {
  dstr_cmark    = 0x0001, // committed trigger mark
  dstr_tmark    = 0x0002, // tentative trigger mark
};

typedef enum execode {
  exec_ok, exec_msg, exec_failed
} execode;

typedef struct pwstate {
  char **circbuf;
  int nlines, maxlines;
  int hpos;
  int vsplit1, vsplit2, vs2pos;
  int hist, prevhist;
  int columns;
  int tstop;
  unsigned stat;
  int sncount, tcount;
  char *curcmd, *savedcmd;
  size_t editpos;
  char cmdbuf[cmdsize];
} pwstate;

typedef struct grep {
  char *pat;
  regex_t rx;
  int inv;
  int flags;
  int err;
  void (*dtor)(char *);
} grep;

typedef struct dstr {
  int refs;
  size_t len;
  int flags;
  char str[];
} dstr;

#define dstr_of(str) ((dstr *) ((str) - sizeof (dstr)))

static char *pw_name;
static int poll_interval = 1000;
static int long_interval = 10000;
static int regex_flags = 0;

static char **snapshot[snhistsize];
static int snaplines[snhistsize];

static grep grepstack[maxgrep];
static int ngrep;

static grep *triglist[maxtrig];
static int sncount;
static int tfreq;

static char **cmdhist;
static int ncmdhist;

static char **pathist;
static int npathist;

volatile sig_atomic_t winch;

static void panic(const char *fmt, ...)
{
  va_list vl;
  va_start (vl, fmt);
  fprintf(stderr, "%s: ", pw_name);
  vfprintf(stderr, fmt, vl);
  abort();
}

printf_attr(1, 2)
static void error(const char *fmt, ...)
{
  va_list vl;
  va_start (vl, fmt);
  fprintf(stderr, "%s: ", pw_name);
  vfprintf(stderr, fmt, vl);
}

static char *dsref(char *str)
{
  dstr *ds = dstr_of(str);
  ds->refs++;
  return str;
}

static void dsdrop(char *str)
{
  if (str) {
    dstr *ds = dstr_of(str);
    assert (ds->refs > 0);
    if (!--ds->refs)
      free(ds);
  }
}

static size_t dslen(const char *str)
{
  if (str) {
    const dstr *ds = dstr_of(str);
    return ds->len;
  }
  return 0;
}

static char *dsgrow(char *str, size_t len)
{
  dstr *ds = str ? dstr_of(str) : 0;
  int flags = str ? ds->flags : 0;
  size_t size = sizeof *ds + len + 1;

  assert (ds == 0 || ds->refs == 1);

  if (size < len)
    panic("string size overflow");
  ds = realloc(ds, size);
  if (ds == 0)
    panic("out of memory");

  ds->refs = 1;
  ds->flags = flags;
  ds->len = len;
  ds->str[len] = 0;

  return ds->str;
}

static char *dsensure(char *str)
{
  if (str)
    return str;
  return dsgrow(0, 0);
}

static char *dsdup(const char *str)
{
  size_t len = strlen(str);
  char *copy = dsgrow(0, len);
  memcpy(copy, str, len);
  return copy;
}

printf_attr(1, 2)
static char *dsdupf(char *fmt, ...)
{
  size_t len = 256, needed;
  char *out = dsgrow(0, len);

  for (;;) {
    va_list vl;
    va_start (vl, fmt);
    needed = vsnprintf(out, len + 1, fmt, vl);
    va_end (vl);
    if (needed <= len)
      break;
    len = needed;
  }

  return dsgrow(out, needed);
}

static char *addch(char *line, int ch)
{
  size_t len = line ? dslen(line) : 0;

  if (len + 1 > len) {
    char *nline = dsgrow(line, len + 1);

    if (nline == 0)
      panic("out of memory");

    nline[len] = ch;
    return nline;
  }

  panic("line overflow");
  abort();
}

static char *addchesc(char *line, int tstop, int ch)
{
  switch (ch) {
  case DEL:
    line = addch(line, '^');
    line = addch(line, '?');
    break;
  case TAB:
    for (size_t len = dslen(line); line = addch(line, ' '), ++len % tstop != 0;)
      /* empty */;
    break;
  default:
    if (ch < 32) {
      line = addch(line, '^');
      line = addch(line, ch + 64);
      break;
    }
    line = addch(line, ch);
    break;
  }

  return line;
}

static char *getln(FILE *stream)
{
  for (char *line = 0;;) {
    int ch = getc(stream);
    if (ch == EOF)
      return line;
    if (ch == '\n')
      return dsensure(line);
    line = addch(line, ch);
  }
}

static void usage(void)
{
  fprintf(stderr,
          "\nThis is pw version %s.\n\n"
          "Usage: <command> | %s [options]\n\n"
          "-i realnum      poll interval (s)\n"
          "-l realnum      long update interval (s)\n"
          "-n integer      display size (# of lines)\n"
          "-d              do not quit on end-of-input\n"
          "-q integer      Require this many repetitions of q to quit\n"
          "-E              treat regular expressions as extended\n"
          "-B              treat regular expressions as basic (default)\n"
          "-g [!]pattern   add pattern to grep stack; ! inverts\n"
          "-m integer      specify maximum line length\n"
          "-p values       set display parameters\n"
          "-e command      execute : /  ? command\n"
          "-f file         execute : /  ? commands from file\n\n"
          "<command> represents an arbitrary command that generates the\n"
          "output to be monitored by %s.\n\n"
          "Standard input must be redirected; it cannot be the same device\n"
          "as the controlling tty (/dev/tty) of the terminal session.\n\n"
          "For a full description, see the manual page.\n\n",
          CONFIG_PW_VER, pw_name, pw_name);
  exit(EXIT_FAILURE);
}

static int grinit(grep *gr, char *pat, int inv, void (*dtor)(char *))

{
  gr->pat = pat;
  gr->inv = inv;
  gr->dtor = dtor;
  gr->flags = regex_flags;
  return (gr->err = regcomp(&gr->rx, pat, regex_flags | REG_NOSUB)) != 0;
}

static void grclean(grep *gr)
{
  if (gr->err == 0)
    regfree(&gr->rx);
  if (gr->dtor)
    gr->dtor(gr->pat);
  memset(gr, 0, sizeof *gr);
}

static int grerr(grep *gr)
{
  return gr->err;
}

static size_t grerrstr(grep *gr, char *buf, size_t size)
{
  return regerror(gr->err, &gr->rx, buf, size);
}

static grep *grnew(char *pat, int inv, void (*dtor)(char *))
{
  grep *gr = calloc(sizeof *gr, 1);
  if (gr == 0)
    panic("out of memory");
  (void) grinit(gr, pat, inv, dtor);
  return gr;
}

static void grfree(grep *gr)
{
  if (gr != 0)  {
    grclean(gr);
    free(gr);
  }
}

static int grexec(grep *gr, const char *line)
{
  int match = regexec(&gr->rx, line, 0, NULL, 0) == 0;
  return match != gr->inv;
}

static void clrline(unsigned stat)
{
  if ((stat & stat_bkgnd) == 0)
    printf("\r\033[J");
}

static void clreol(int nl)
{
  printf("\033[K");
  if (nl)
    putchar('\n');
}

static void hlon(int *phlite)
{
  if (!*phlite) {
    printf("\033[7m");
    *phlite = 1;
  }
}

static void hloff(int *phlite)
{
  if (*phlite) {
    printf("\033[m");
    *phlite = 0;
  }
}

#define with_hl(on, keep, hlite, expr)                                        \
  do {                                                                        \
    if (on)                                                                   \
       hlon(&hlite);                                                          \
    expr;                                                                     \
    if (!keep)                                                                \
       hloff(&hlite);                                                         \
  } while (0)

#define with_hlonoff(onoff, hlite, expr)                                      \
  do {                                                                        \
    (onoff ? hlon : hloff)(&hlite);                                           \
    expr;                                                                     \
  } while(0)

static int diff(const char *line, const char *dline, int dlen, int i)
{
  return i >= dlen || line[i] != dline[i];
}

static void drawline(pwstate *pw, const char *line, int lineno, char *dline)
{
  const dstr *ds = dstr_of(line);
  int olen = (int) ds->len, len = olen, pos = 0;
  int dlen = dslen(dline);
  int columns = pw->columns;
  int vsplit1 = pw->vsplit1;
  int vsplit2 = pw->vsplit2;
  int vs2pos = pw->vs2pos;
  int endmark = 0;
  int hlpanel = (pw->stat & stat_hlite) != 0;
  int hlineno = hlpanel && (ds->flags & dstr_cmark);
  int hldiff = (pw->stat & stat_diff) != 0 && dline != 0;
  int hlite = 0;

  if (lineno >= 0)
    with_hl (hlineno, 0, hlite, columns -= printf("%3d ", lineno));

  if (vsplit1 > 0) {
    if (len <= vsplit1) {
      if (!vsplit2) {
        if (!hldiff)
          fputs(line, stdout);
        else
          for (int i = 0; i < len; i++)
            with_hlonoff (diff(line, dline, dlen, i), hlite, putchar(line[i]));
        columns -= len;
      } else {
        int spaces = vsplit1 - len;
        if (!hldiff)
          fputs(line, stdout);
        else
          for (int i = 0; i < len; i++)
            with_hlonoff (diff(line, dline, dlen, i), hlite, putchar(line[i]));
        if (spaces)
          hloff(&hlite);
        for (int i = 0; i < spaces; i++)
          putchar(' ');
        columns -= vsplit1;
      }
      pos += len;
      len = 0;
    } else {
      if (!hldiff)
        for (int i = 0; i < vsplit1; i++)
          putchar(line[i]);
      else
        for (int i = 0; i < vsplit1; i++)
          with_hlonoff (diff(line, dline, dlen, i), hlite, putchar(line[i]));
      len -= vsplit1;
      pos += vsplit1;
      columns -= vsplit1;
      endmark = 1;
    }
  }

  if (vsplit2 > 0) {
    int width = vsplit2;
    int i = 0;

    if (vsplit1 || vs2pos) {
      with_hl (hlpanel, hldiff, hlite, putchar('|'));
      i++;
    }

    if (vs2pos < olen) {
      int nchar = min(olen - vs2pos, width);
      if (!hldiff)
        for (; i < nchar; i++)
          putchar(line[vs2pos + i]);
      else
        for (; i < nchar; i++)
          with_hlonoff (diff(line, dline, dlen, vs2pos + i), hlite,
                        putchar(line[vs2pos + i]));
      endmark = 1;
    }

    if (len > vsplit2 + pw->hpos) {
      if (i < width)
        hloff(&hlite);
      for (; i < width; i++)
        putchar(' ');

      columns -= vsplit2;
      pos += vsplit2;
      len -= vsplit2;
      endmark = 1;
    } else {
      pos += len;
      len = 0;
      endmark = (i == width);
    }
  }

  if (pw->hpos < len) {
    if (pw->hpos || vsplit1 || vsplit2) {
      pos += pw->hpos + 1;
      len -= pw->hpos + 1;
      with_hl (hlpanel, hldiff, hlite, putchar('>'));
      columns--;
    }

    if (len < columns) {
      if (!hldiff)
        fputs(line + pos, stdout);
      else
        for (; pos < olen; pos++)
          with_hlonoff (diff(line, dline, dlen, pos), hlite,
                        putchar(line[pos]));
      clreol(1);
    } else {
      if (!hldiff)
        for (int i = 0; i < columns - 1; i++)
          putchar(line[pos + i]);
      else
        for (int i = 0; i < columns - 1; i++)
          with_hlonoff (diff(line, dline, dlen, pos + i), hlite,
                        putchar(line[pos + i]));
      with_hl (hlpanel, hldiff, hlite, putchar('<'));
      putchar('\n');
    }
  } else {
    if (endmark)
      with_hl (hlpanel, hldiff, hlite, putchar('>'));
    clreol(1);
  }

  hloff(&hlite);
}

static void drawstatus(pwstate *pw)
{
  char status[cmdsize] = "", *ptr = status;
  size_t lim = sizeof status;

  if ((pw->stat & stat_bkgnd))
    return;

  if (pw->columns - 1 < (int) lim)
    lim = pw->columns - 1;

  char *end = ptr + lim;

  if (pw->curcmd) {
    snprintf(status, lim, "%s", pw->curcmd);
  } else if (pw->hist > 0 ||
             (pw->stat & (stat_eof | stat_susp | stat_htmode | stat_ttmode |
                          stat_grep)))
  {
    if (pw->hist > 0)
      ptr += snprintf(ptr, end - ptr, "HIST%u ", pw->hist);

    if ((pw->stat & stat_eof))
      ptr += snprintf(ptr, end - ptr, "EOF ");

    if ((pw->stat & stat_grep)) {
      ptr += snprintf(ptr, end - ptr, "GREP (");
      for (int i = 0; i < ngrep; i++) {
        grep *gr = &grepstack[i];
        ptr += snprintf(ptr, end - ptr, "%s%s%c ",
                        gr->inv ? "!" : "", gr->pat,
                        (i < ngrep - 1) ? ',' : ')');
      }
    }

    if ((pw->stat & (stat_htmode | stat_ttmode))) {
      ptr += snprintf(ptr, end - ptr, "TRIG%c (",
                      (pw->stat & stat_htmode) ? '/' : '?');
      for (int i = 0, first = 1; i < maxtrig; i++) {
        grep *gr = triglist[i];
        if (gr) {
          if (!first)
            ptr += snprintf(ptr, end - ptr, ", ");
          if (i > 0)
            ptr += snprintf(ptr, end - ptr, "[%d]", i + 1);
          ptr += snprintf(ptr, end - ptr, "%s%s", gr->inv ? "!" : "", gr->pat);
          first = 0;
        }
      }
      ptr += snprintf(ptr, end - ptr, ") ");
    }

    if ((pw->stat & stat_susp))
      ptr += snprintf(ptr, end - ptr, "SUSPENDED ");
  }

  fputs(status, stdout);
  clreol(0);
  if (pw->curcmd) {
    if (pw->curcmd[pw->editpos] != 0) {
      putchar('\r');
      if (pw->editpos > 0)
        printf("\033[%dC", (int) pw->editpos);
    }
  }
  fflush(stdout);
}

static void freebuf(char **buf, size_t size)
{
  if (buf != 0)
    for (size_t i = 0; i < size; i++)
      dsdrop(buf[i]);
}

static void redraw(pwstate *pw)
{
  int updln = 0;

  if ((pw->stat & (stat_dirty | stat_susp)) == stat_dirty &&
      (pw->stat & (stat_htmode | stat_trgrd)) != stat_htmode &&
      (pw->stat & (stat_ttmode | stat_trgrd)) != stat_ttmode)
  {
    if (snapshot[snhistsize - 1]) {
      freebuf(snapshot[snhistsize - 1], snaplines[snhistsize - 1]);
      free(snapshot[snhistsize - 1]);
    }
    memmove(snapshot + 1, snapshot, sizeof *snapshot * (snhistsize - 1));
    memmove(snaplines + 1, snaplines, sizeof *snaplines * (snhistsize - 1));
    snapshot[0] = calloc(sizeof *snapshot[0], pw->nlines);
    snaplines[0] = pw->nlines;
    updln = 1;
    for (int i = 0; i < pw->nlines; i++)
      snapshot[0][i] = dsref(pw->circbuf[i]);
    if ((pw->stat & stat_oneshot))
      pw->stat |= stat_susp;
    pw->stat &= ~(stat_dirty | stat_trgrd | stat_oneshot);
    updln = 1;
    if (pw->prevhist == 0 && pw->hist == 0)
      pw->prevhist = 1;
  } else if ((pw->stat & stat_force)) {
    pw->stat &= ~stat_force;
    updln = 1;
  }

  if ((pw->stat & stat_bkgnd))
    return;

  if (updln && snaplines[pw->hist] > 0) {
    printf("\r\033[%dA", snaplines[pw->hist]);
    if ((pw->stat & stat_lino) == 0) {
      for (int i = 0; i < snaplines[pw->hist]; i++)
        drawline(pw, snapshot[pw->hist][i], -1, snapshot[pw->prevhist][i]);
    } else {
      int start = 1, step = 1;
      if (pw->stat & stat_htmode) {
        start = snaplines[pw->hist];
        step = -1;
      }
      for (int i = 0, l = start; i < snaplines[pw->hist]; i++, l += step)
        drawline(pw, snapshot[pw->hist][i], l, snapshot[pw->prevhist][i]);
    }
  } else {
    clrline(pw->stat);
  }

  drawstatus(pw);
}

static int getznn(const char *str, char **err)
{
  char *endp;
  long val = strtol(str, &endp, 10);

  if (endp == str) {
    *err = dsdup("number expected");
    return -1;
  }
  if (val < 0) {
    *err = dsdup("non-negative value required");
    return -1;
  }

  if (val >= INT_MAX) {
    *err = dsdup("unreasonably large value");
    return -1;
  }

  return val;
}

static int getzp(const char *str, char **err)
{
  int val = getznn(str, err);

  if (val <= 0) {
    *err = dsdup("positive value required");
    return -1;
  }

  return val;
}

static int getms(const char *str, char **err)
{
  errno = 0;
  char *endp;
  double sec = strtod(str, &endp);

  if (endp == str) {
    *err = dsdup("number expected");
    return -1;
  }

  if ((sec == 0 || sec == HUGE_VAL) && errno != 0) {
    *err = dsdup("unreasonable real value");
    return -1;
  }

  if (sec < 0) {
    *err = dsdup("positive value required");
    return -1;
  }

  double msec = sec * 1000;

  if (msec > (double) INT_MAX) {
    *err = dsdupf("maximum interval is %f", INT_MAX / 1000.0);
    return -1;
  }

  return msec;
}

static int decodeparms(pwstate *pw, char *parms,
                       char *resbuf, size_t size)
{
  char *err;
  char *hpos = strtok(parms, ", \t");
  char *lpane = strtok(0, ", \t");
  char *rpane = strtok(0, ", \t");
  char *vs2pos = strtok(0, ", \t");
  char *flags = strtok(0, ", \t");
  char *tstop = strtok(0, ", \t");

  pw->hpos = pw->vsplit1 = pw->vsplit2 = pw->vs2pos = 0;
  pw->stat &= ~stat_save;

  if (hpos && (pw->hpos = getznn(hpos, &err)) < 0) {
    snprintf(resbuf, size, "bad horizontal scroll offset %s: %s\n", hpos, err);
    return 0;
  }

  if (lpane && (pw->vsplit1 = getznn(lpane, &err)) < 0) {
    snprintf(resbuf, size, "bad left pane width %s: %s\n", lpane, err);
    return 0;
  }

  if (rpane && (pw->vsplit2 = getznn(rpane, &err)) < 0) {
    snprintf(resbuf, size, "bad right pane width %s: %s\n", rpane, err);
    return 0;
  }

  if (vs2pos && (pw->vs2pos = getznn(vs2pos, &err)) < 0) {
    snprintf(resbuf, size, "bad right pane view offset %s: %s\n", vs2pos, err);
    return 0;
  }

  if (flags) {
    int stat = getznn(flags, &err);
    if (stat < 0) {
      snprintf(resbuf, size, "bad flags %s: %s\n", flags, err);
      return 0;
    }
    pw->stat |= (stat & stat_save);
  }

  if (tstop && ((pw->tstop = getznn(tstop, &err)) < 0 || pw->tstop > 16)) {
    snprintf(resbuf, size, "bad tab stop size%s: %s\n", tstop, err);
    if (pw->tstop == 0)
      pw->tstop = 8;
    return 0;
  }

  return 1;
}

static execode execute(pwstate *pw, char *cmd, char *resbuf,
                       size_t size, int count)
{
  execode res = exec_failed;
  char cmdbuf[16];
  int cmdlen = 0;
  int ntok = sscanf(cmd + 1, "%15[a-zA-Z]%n", cmdbuf, &cmdlen);
  char *arg = cmd + 1 + cmdlen;

  if (*arg == ' ')
    arg++;

  if (cmd[0] == ':' && ntok == 1 && cmdlen == 1) switch (cmd[1]) {
  case 'w': case 'a':
    if (arg[0] == 0) {
      snprintf(resbuf, size, "file name required!");
      break;
    } else {
      FILE *f = fopen(arg, cmd[1] == 'w' ? "w" : "a");

      if (!f) {
        snprintf(resbuf, size, "unable to open file");
        break;
      }

      res = exec_msg;

      for (int i = 0; res == exec_msg && i < snaplines[pw->hist]; i++)
        if (fprintf(f, "%s\n", snapshot[pw->hist][i]) < 0) {
          snprintf(resbuf, size, "write error!");
          res = exec_failed;
          break;
        }

      fclose(f);
      if (res == exec_msg)
        snprintf(resbuf, size, "saved!");
    }
    break;
  case '!':
    if (arg[0] == 0) {
      snprintf(resbuf, size, "command required!");
      break;
    } else {
      FILE *p = popen(arg, "w");

      if (!p) {
        snprintf(resbuf, size, "unable to open command");
        break;
      }

      res = exec_msg;

      for (int i = 0; i < snaplines[pw->hist] && res == exec_msg; i++)
        if (fprintf(p, "%s\n", snapshot[pw->hist][i]) < 0) {
          snprintf(resbuf, size, "write error!");
          res = exec_failed;
          break;
        }

      pclose(p);
      if (res == exec_msg)
        snprintf(resbuf, size, "piped!");
    }
    break;
  case 'g':
  case 'v':
    {
      grep *gr = &grepstack[ngrep];

      if (arg[0] == 0) {
        snprintf(resbuf, size, "pattern required!");
        break;
      }

      if (ngrep >= maxgrep) {
        snprintf(resbuf, size, "too many greps");
        break;
      }

      if ((grinit(gr, dsdup(arg), cmd[1] == 'v', dsdrop)) != 0) {
        grerrstr(gr, resbuf, size);
        grclean(gr);
        break;
      }

      if (ngrep++ == 0)
        pw->stat |= stat_grep;

      res = exec_ok;
    }
    break;
  case 'r':
    while (ngrep > 0) {
      grclean(&grepstack[--ngrep]);
      if (cmd[2] != '!')
        break;
    }
    if (ngrep == 0)
      pw->stat &= ~stat_grep;
    res = exec_ok;
    break;
  case 'i': case 'l':
    {
      char *err = 0;
      int interval = getms(arg, &err);

      if (interval < 0) {
        snprintf(resbuf, size, "%s", err);
        break;
      }

      if (cmd[1] == 'i')
        poll_interval = interval;
      else
        long_interval = interval;

      dsdrop(err);
      res = exec_ok;
    }
    break;
  case 'E':
    regex_flags = REG_EXTENDED;
    res = exec_ok;
    break;
  case 'B':
    regex_flags = 0;
    res = exec_ok;
    break;
  case 'c':
    if (arg[0] == 0) {
      pw->sncount = 0;
    } else  {
      char *err = 0;
      int val = getznn(arg, &err);
      if (val < 0) {
        snprintf(resbuf, size, "bad trigger count: %s", err);
        break;
      }
      sncount = val;
      dsdrop(err);
      res = exec_ok;
    }
    break;
  case 'f':
    if (arg[0] == 0) {
      snprintf(resbuf, size, "frequency argument required!");
      break;
    }
    {
      char *err = 0;
      int val = getznn(arg, &err);
      if (val < 0) {
        snprintf(resbuf, size, "bad trigger freq: %s", err);
        break;
      }
      tfreq = val;
      dsdrop(err);
      res = exec_ok;
    }
    break;
  case 'p':
    {
      if (decodeparms(pw, arg, resbuf, size)) {
        pw->stat |= stat_force;
        res = exec_ok;
      }
    }
    break;
  default:
    goto badcmd;
  } else if (cmd[0] == ':' && ntok == 1) switch (twocc(cmd[1], cmd[2])) {
  case twocc('s', 'a'):
    {
      int rflg = 0;
      FILE *f;

      if (arg[0] == 0) {
        snprintf(resbuf, size, "file name required!");
        break;
      }

      if ((f = fopen(arg, "w")) == 0) {
        snprintf(resbuf, size, "unable to open %s", arg);
        break;
      }

      fprintf(f, ":p%d,%d,%d,%d,%d,%d\n", pw->hpos, pw->vsplit1, pw->vsplit2,
              pw->vs2pos, (int) pw->stat & stat_save, pw->tstop);

      if (tfreq)
        fprintf(f, ":f%d\n", tfreq);
      if (sncount)
        fprintf(f, ":c%d\n", sncount);

      for (int i = 0; i < ngrep; i++) {
        grep *gr = &grepstack[i];
        if (gr->flags != rflg) {
          rflg = gr->flags;
          fputs(((gr->flags & REG_EXTENDED)) ? ":E\n" : ":B\n", f);
        }
        fputs(gr->inv ? ":v " : ":g ", f);
        fputs(gr->pat, f);
        putc('\n', f);
      }

      if ((pw->stat & (stat_htmode | stat_ttmode))) {
        int tch = ((pw->stat & stat_htmode)) ? '/' : '?';
        for (int i = 0; i < maxtrig; i++) {
          grep *gr = triglist[i];
          if (gr != 0) {
            if (gr->flags != rflg) {
              rflg = gr->flags;
              fputs(((gr->flags & REG_EXTENDED)) ? ":E\n" : ":B\n", f);
            }
            if (gr->inv)
              fprintf(f, "%d%c!%s\n", i + 1, tch, gr->pat);
            else if (gr->pat[0] == '!')
              fprintf(f, "%d%c\\!%s\n", i + 1, tch, gr->pat);
            else
              fprintf(f, "%d%c%s\n", i + 1, tch, gr->pat);
          }
        }
      }

      if (ferror(f)) {
        snprintf(resbuf, size, "write error!");
      } else {
        snprintf(resbuf, size, "config saved!");
        res = exec_msg;
      }

      fclose(f);
    }
    break;
  default:
    goto badcmd;
  } else if (cmd[0] == '?' || cmd[0] == '/') {
    int trig = count > 0 ? count - 1 : count;

    if (trig < pw->maxlines && trig < maxtrig)
    {
      const char *rx = cmd + 1;
      int inv = 0;
      grep *gr = 0;

      if (strncmp(rx, "\\!", 2) == 0) {
        rx++;
      } else if (rx[0] == '!') {
        rx++;
        inv = 1;
      }

      char *pat = dsdup(rx);

      if (*pat && (gr = grnew(dsref(pat), inv, dsdrop),
                   grerr(gr) != 0))
      {
        grerrstr(gr, resbuf, size);
        grfree(gr);
      } else {
        if ((cmd[0] == '/' && (pw->stat & stat_ttmode)) ||
            (cmd[0] == '?' && (pw->stat & stat_htmode)))
        {
          for (int i = 0; i < maxtrig; i++) {
            grfree(triglist[i]);
            triglist[i] = 0;
          }
        }

        grfree(triglist[trig]);
        triglist[trig] = gr;
        res = exec_ok;
      }
      dsdrop(pat);
    } else {
      snprintf(resbuf, size, "trigger position out of range");
      res = exec_failed;
    }

    if (res == exec_ok) {
      pw->stat &= ~(stat_htmode | stat_ttmode);
      for (int i = 0; i < maxtrig; i++) {
        if (triglist[i]) {
          pw->stat |= (cmd[0] == '/'
                       ? stat_htmode : stat_ttmode);
          break;
        }
      }
    }
  } else if (cmd[1] == 0) {
    res = exec_ok;
  } else {
badcmd:
    snprintf(resbuf, size, "unrecognized command");
  }

  return res;
}

static execode batchexe(pwstate *pw, char *cmd, char *resbuf, size_t size)
{
  size_t ndigits = strspn(cmd, "0123456789");
  int count = 0;

  if (ndigits > 3) {
    snprintf(resbuf, size, "command count out of 0-999 range");
    return exec_failed;
  } else if (ndigits) {
    (void) sscanf(cmd, "%3d", &count);
    cmd += ndigits;
  }
  switch (cmd[0]) {
  case ':': case '?': case '/':
    return execute(pw, cmd, resbuf, size, count);
  }
  snprintf(resbuf, size, "missing command prefix [:/?]");
  return exec_failed;
}

static void ttyset(int fd, struct termios *tty)
{
  if (tcsetattr(fd, TCSANOW, tty) < 0)
    panic("unable to set TTY parameters");
}

static void ttyget(int fd, struct termios *tty)
{
  if (tcgetattr(fd, tty) < 0)
    panic("unable to get TTY parameters");
}

#ifdef SIGWINCH
static void sigwinch(int sig)
{
  (void) sig;
  winch = 1;
}
#endif

static char **resizebuf(char **buf, size_t nlfrom, size_t nlto)
{
  if (nlfrom > nlto) {
    for (size_t i = nlto; i < nlfrom; i++)
      dsdrop(buf[i]);
  } else if (nlfrom < nlto) {
    if ((buf = realloc(buf, sizeof *buf * nlto)) == 0)
      panic("out of memory");
    memset(buf + nlfrom, 0, (nlto - nlfrom) * sizeof *buf);
  }
  return buf;
}

int isbkgnd(int ttyfd)
{
  pid_t grp = getpgrp();
  pid_t fgrp = tcgetpgrp(ttyfd);
  return (grp != fgrp);
}

int ismytty(int ttyfd)
{
  pid_t fgrp = tcgetpgrp(ttyfd);
  return fgrp != -1;
}

void clipsplits(pwstate *pw)
{
  int columns = pw->columns;

  if ((pw->stat & stat_lino))
    columns -= 4;

  if (columns < 8 || (int) pw->vsplit1 > columns - 2) {
    pw->vsplit2 = 0;
    pw->vsplit1 = columns - 2;
  } else if ((int) (pw->vsplit1 + pw->vsplit2) >= columns - 2) {
    pw->vsplit2 = columns - 2 - pw->vsplit1;
  }
}

int main(int argc, char **argv)
{
  struct pwstate pw = { .columns = 80, .maxlines = 15, .tstop = 8 };
  char *line = 0;
  FILE *tty = fopen("/dev/tty", "r+");
  int maxed = 0;
  size_t maxlen = 2047;
  int opt;
  int ifd = fileno(stdin);
  int ofd = fileno(stdout);
  int ttyfd = tty ? fileno(tty) : -1;
  struct termios tty_saved, tty_new;
  struct winsize ws = { 0 };
  enum kbd_state {
    kbd_cmd, kbd_esc, kbd_bkt, kbd_exit,
    kbd_lcmd, kbd_result
  };
  int auto_quit = 1;
  int quit_count = 1, quit_cntdwn = quit_count;
  int exit_status = EXIT_FAILURE;
  FILE *out = NULL;
#ifdef SIGWINCH
  static struct sigaction sa;
#endif

  pw_name = argv[0] ? argv[0] : "pw";

  if (ifd < 0)
    panic("unable to obtain input file descriptor\n");

  if (ttyfd < 0)
    panic("unable to open /dev/tty\n");

  {
    pid_t igrp = tcgetpgrp(ifd);
    pid_t tgrp = tcgetpgrp(ttyfd);

    if (igrp == tgrp) {
      error("standard input cannot be the TTY used for display\n");
      usage();
    }
  }

  if (!isatty(ofd) || !ismytty(ttyfd)) {
    int dup_ofd = dup(ofd);
    dup2(ttyfd, ofd);
    out = fdopen(dup_ofd, "w");
  }

  while ((opt = getopt(argc, argv, "n:i:l:dEBg:q:m:p:e:f:")) != -1) {
    switch (opt) {
    case 'n':
      {
        char *err;
        if ((pw.maxlines = getzp(optarg, &err)) < 0) {
          error("-%c option: %s\n", opt, err);
          return EXIT_FAILURE;
        }
      }
      break;
    case 'i': case 'l':
      {
        char *err;
        int interval = getms(optarg, &err);

        if (interval < 0) {
          error("-%c option: %s\n", opt, err);
          return EXIT_FAILURE;
        }

        if (opt == 'i')
          poll_interval = interval;
        else
          long_interval = interval;
      }
      break;
    case 'd':
      auto_quit = 0;
      break;
    case 'q':
      {
        char *err;
        if ((quit_cntdwn = quit_count = getzp(optarg, &err)) < 0) {
          error("-%c option: %s\n", opt, err);
          return EXIT_FAILURE;
        }
        break;
      }
    case 'E':
      regex_flags = REG_EXTENDED;
      break;
    case 'B':
      regex_flags = 0;
      break;
    case 'g':
      {
        grep *gr = &grepstack[ngrep];
        char *pat = optarg;
        int inv = 0;

        if (ngrep >= maxgrep) {
          error("too many patterns specified with -g\n");
          return EXIT_FAILURE;
        }

        if (*pat == '!') {
          inv = 1;
          pat++;
        } else if (strncmp(pat, "\\!", 2) == 0) {
          pat++;
        }

        if ((grinit(gr, dsdup(pat), inv, dsdrop)) != 0) {
          char grmsg[cmdsize];
          grerrstr(gr, grmsg, sizeof grmsg);
          error("-%c option: bad pattern %s: %s\n", opt, pat, grmsg);
          return EXIT_FAILURE;
        }

        ngrep++;
        pw.stat |= stat_grep;
      }
      break;
    case 'm':
      {
        char *err;
        int val = getzp(optarg, &err);
        if (val < 0) {
          error("-%c option: bad value %s: %s\n", opt, optarg, err);
          return EXIT_FAILURE;
        }

        if ((int) (size_t) val != val)
          val = -1;
        maxlen = max(72, val);
      }
      break;
    case 'p':
      {
        int ok = decodeparms(&pw, optarg, pw.cmdbuf, cmdsize);
        if (!ok) {
          error("-%c option: %s\n", opt, pw.cmdbuf);
          return EXIT_FAILURE;
        }
      }
      break;
    case 'e':
      {
        if (batchexe(&pw, optarg, pw.cmdbuf, cmdsize) == exec_failed) {
          error("-%c option: %s: %s\n", opt, optarg, pw.cmdbuf);
          return EXIT_FAILURE;
        }
      }
      break;
    case 'f':
      {
        FILE *f = fopen(optarg, "r");
        long lino = 1;
        int errors = 0;
        char *line;
        if (f == 0) {
          error("-%c option: unable to open %s\n", opt, optarg);
          return EXIT_FAILURE;
        }
        for (; (line = getln(f)) != 0; lino++) {
          if (line[0] == '#')
            continue;
          if (batchexe(&pw, line, pw.cmdbuf, cmdsize) == exec_failed) {
            error("%s:%ld: %s\n", optarg, lino, pw.cmdbuf);
            errors = 1;
          }
          dsdrop(line);
        }
        fclose(f);
        if (errors) {
          return EXIT_FAILURE;
          dsdrop(line);
        }
      }
      break;
    default:
      usage();
    }
  }

  if (pw.maxlines <= 0 || pw.maxlines > 1000) {
    error("%d is an unreasonable number of lines to display\n", pw.maxlines);
    return EXIT_FAILURE;
  }

  if ((pw.circbuf = calloc(sizeof *pw.circbuf, pw.maxlines)) == 0)
    panic("out of memory");
  if ((snapshot[0] = calloc(sizeof *snapshot[0], pw.maxlines)) == 0)
    panic("out of memory");

  if (ioctl(ttyfd, TIOCGWINSZ, &ws) == 0 && ws.ws_row != 0) {
    if (pw.maxlines >= ws.ws_row) {
      pw.maxlines = ws.ws_row - 1;
      maxed = 1;
    }
    pw.columns = ws.ws_col;
  }

  clipsplits(&pw);

  ttyget(ttyfd, &tty_saved);

  tty_new = tty_saved;

  tty_new.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP |
                       INLCR | IGNCR | ICRNL);
  tty_new.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);

  tty_new.c_cc[VMIN] = 1;
  tty_new.c_cc[VTIME] = 0;

  setvbuf(tty, NULL, _IONBF, 0);

  if (fcntl(ifd, F_SETFL, O_NONBLOCK) < 0)
    panic("unable to set stdin nonblocking");

  if (!isbkgnd(ttyfd))
    ttyset(ttyfd, &tty_new);
  else
    pw.stat = stat_bkgnd;

#ifdef SIGWINCH
  sa.sa_handler = sigwinch;
  sigaction(SIGWINCH, &sa, NULL);
#endif

  for (int kbd_state = kbd_cmd, kbd_prev = kbd_cmd, lasttime = -1,
           workbout = workmax, work = workbout, histpos = 0,
           cmdcount = INT_MAX, prevcmd = 0, prevcount = 0;
       kbd_state != kbd_exit ;)
  {
    int force = 0, nfds = 2, pollms = poll_interval;
    struct pollfd pe[2] = {
      { .fd = ttyfd, .events = POLLIN | POLLHUP | POLLERR },
      { .fd = ifd, .events = POLLIN | POLLHUP | POLLERR },
    };

    if ((pw.stat & stat_eof) == 0) {
      int ch;
      while ((ch = getchar()) != EOF && ch != '\n' && dslen(line) < maxlen) {
        line = addchesc(line, pw.tstop, ch);
        if (out)
          putc(ch, out);
      }
      if (ch == EOF) {
        if (out)
          fflush(out);
        if (feof(stdin) || (errno != EAGAIN && errno != EWOULDBLOCK)) {
          nfds = 1;
          if (!ferror(stdin))
            exit_status = 0;
          if (auto_quit) {
            if ((pw.stat & stat_bkgnd) == 0)
              clrline(pw.stat);
            break;
          }
          pw.stat |= stat_eof;
          clrline(pw.stat);
          drawstatus(&pw);
          if (out)
            fflush(out);
        }
        clearerr(stdin);
      } else if (ch == '\n') {
        if (out)
          putc(ch, out);
        nfds = 1;
        line = dsensure(line);
        if ((pw.stat & stat_grep)) {
          int i;
          for (i = 0; i < ngrep; i++)
            if (!grexec(&grepstack[i], line))
              break;
          if (i < ngrep) {
            dsdrop(line);
            line = 0;
          }
        }
        if (line) {
          if (pw.nlines == pw.maxlines) {
            int trig = 0;
            dsdrop(pw.circbuf[0]);
            memmove(pw.circbuf, pw.circbuf + 1,
                    (pw.nlines - 1) * sizeof *pw.circbuf);
            pw.circbuf[pw.nlines - 1] = line;
            pw.stat |= stat_dirty;
            if ((pw.stat & (stat_ttmode | stat_susp)) == stat_ttmode) {
              int lim = min(maxtrig, pw.nlines);
              int match = 1;
              for (int i = 0; i < lim; i++) {
                grep *gr = triglist[i];
                if (gr) {
                  if (!grexec(gr, pw.circbuf[i])) {
                    match = 0;
                    break;
                  }
                  dstr_of(pw.circbuf[i])->flags |= dstr_tmark;
                }
              }
              trig = match;
            } else if ((pw.stat & (stat_htmode | stat_susp)) == stat_htmode) {
              int match = 1;
              for (int j = pw.nlines - 1, i = 0; j >= 0 && i < maxtrig;
                   j--, i++)
              {
                grep *gr = triglist[i];
                if (gr) {
                  if (!grexec(gr, pw.circbuf[j])) {
                    match = 0;
                    break;
                  }
                  dstr_of(pw.circbuf[j])->flags |= dstr_tmark;
                }
              }
              trig = match;
            }

            if (trig) {
              trig = 0;
              if (tfreq == 0 || ++pw.tcount >= tfreq) {
                pw.tcount = 0;
                if (sncount == 0 || ++pw.sncount < sncount) {
                  pw.stat |= stat_trgrd;
                  trig = 1;
                } else if (sncount) {
                  pw.stat |= stat_trgrd | stat_oneshot;
                  pw.sncount = 0;
                  trig = 1;
                }
              }
            }

            for (int i = 0; i < pw.nlines; i++) {
              dstr *ds = dstr_of(pw.circbuf[i]);
              int flags = ds->flags;
              int addflag = trig ? dstr_cmark : 0;
              if ((flags & dstr_tmark) != 0) {
                flags |= addflag;
                flags &= ~dstr_tmark;
                ds->flags = flags;
              }
            }
          } else {
            pw.circbuf[pw.nlines++] = line;
            if ((pw.stat & (stat_susp | stat_bkgnd)) == 0) {
              snapshot[0] = resizebuf(snapshot[0], snaplines[0],
                                      snaplines[0] + 1);
              snapshot[0][snaplines[0]++] = dsref(line);
              clrline(pw.stat);
              drawline(&pw, line, (pw.stat & stat_lino) ? 0: -1, 0);
              drawstatus(&pw);
            }
          }
          line = 0;
        }
      }
    } else {
      nfds = 1;
    }

    if (winch) {
      winch = 0;
      if (ioctl(ttyfd, TIOCGWINSZ, &ws) == 0) {
        int oldmax = pw.maxlines;
        if (maxed || pw.maxlines >= ws.ws_row - 1) {
          maxed = 1;
          pw.maxlines = ws.ws_row - 1;
        }
        if (maxed) {
          pw.prevhist = pw.hist = 0;
          pw.circbuf = resizebuf(pw.circbuf, oldmax, pw.maxlines);
          snapshot[0] = resizebuf(snapshot[0], oldmax, pw.maxlines);
          if (pw.nlines > pw.maxlines)
            pw.nlines = pw.maxlines;
          if (snaplines[0] > pw.maxlines)
            snaplines[0] = pw.maxlines;
          for (int i = 1; i < snhistsize; i++) {
            freebuf(snapshot[i], snaplines[i]);
            free(snapshot[i]);
            snapshot[i] = 0;
          }
        }

        pw.columns = ws.ws_col;

        clipsplits(&pw);
      }
      pw.stat |= stat_force;
      force = 1;
    }

    if ((pw.stat & stat_eof))
      pollms = -1;
    else if (nfds < 2)
      pollms = 0;

    if ((pw.stat & (stat_trgrd | stat_susp)) == stat_trgrd)
      force = 1;

    if (pollms == 0 && !force && work-- > 0)
      continue;

    work = workbout;

    if ((pw.stat & stat_bkgnd)) {
      if (!isbkgnd(ttyfd)) {
        pw.stat &= ~stat_bkgnd;
        ttyset(ttyfd, &tty_new);
        for (int i = 0; i < pw.nlines; i++)
          puts("");
        pw.stat |= stat_force;
        redraw(&pw);
      } else {
        if ((pw.stat & stat_eof)) {
          sleep(1);
          continue;
        } else {
          pe[0].events = 0;
        }
      }
    }

    if ((pw.stat & stat_susp) == 0) {
      if (!force) {
        struct timeval tv;
        int now;

        gettimeofday(&tv, NULL);
        now = tv.tv_sec % 1000000 * 1000 + tv.tv_usec / 1000;
        if (lasttime == -1 ||
            (now + 1000000000 - lasttime) % 1000000000 > long_interval)
        {
          if ((pw.stat & stat_dirty) && pw.nlines == pw.maxlines)
            force = 1;
          lasttime = now;
        }
      }

      if (force)
        redraw(&pw);
    }

    if (poll(pe, nfds, pollms) <= 0) {
      if (pollms) {
        if ((pw.stat & stat_dirty) && pw.nlines == pw.maxlines)
          redraw(&pw);
        if (kbd_state == kbd_esc) {
          kbd_state = kbd_cmd;
          pw.curcmd = 0;
          clrline(pw.stat);
          drawstatus(&pw);
        }
      }
      if (workbout < workmax)
        work = workbout += workbout / 4;
    } else {
      if ((pe[0].revents)) {
        int ch = getc(tty);

        if (workbout > 16)
          work = workbout /= 2;

        if (ch == ctrl('z')) {
          ttyset(ttyfd, &tty_saved);
          pw.stat |= stat_bkgnd;
          kill(0, SIGTSTP);
          continue;
        }

      fakecmd:
        switch (kbd_state) {
        case kbd_result:
          kbd_state = kbd_cmd;
          pw.stat |= stat_force;
          pw.curcmd = 0;
          if (ch == CR)  // Prevent accidental resume of suspended mode.
            break;
          // fallthrough
        case kbd_cmd:
          if (ch != 'q' && ch != 3)
            quit_cntdwn = quit_count;
          switch (ch) {
          case 'q': case 3:
            if (--quit_cntdwn == 0) {
              kbd_state = kbd_exit;
            } else {
              pw.editpos = sprintf(pw.cmdbuf, "%d more to quit", quit_cntdwn);
              pw.curcmd = pw.cmdbuf;
              kbd_state = kbd_result;
            }
            break;
          case 'h':
            if (cmdcount == INT_MAX)
              cmdcount = 8;
            if (pw.hpos >= cmdcount)
              pw.hpos -= cmdcount;
            else
              pw.hpos = 0;
            pw.stat |= stat_force;
            break;
          case 'l':
            if (cmdcount == INT_MAX)
              cmdcount = 8;
            if ((size_t) pw.hpos < maxlen)
              pw.hpos += cmdcount;
            pw.stat |= stat_force;
            break;
          case '>':
            if (cmdcount == INT_MAX)
              cmdcount = 1;
            pw.vsplit1 += cmdcount;
            clipsplits(&pw);
            pw.stat |= stat_force;
            break;
          case '<':
            if (cmdcount == INT_MAX)
              cmdcount = 1;
            pw.vsplit1 = max(0, pw.vsplit1 - cmdcount);
            pw.stat |= stat_force;
            break;
          case ']':
            if (cmdcount == INT_MAX)
              cmdcount = 1;
            if (pw.vsplit2 == 0)
              pw.vs2pos = pw.hpos + pw.vsplit1;
            pw.vsplit2 += cmdcount;
            clipsplits(&pw);
            pw.stat |= stat_force;
            break;
          case '[':
            if (cmdcount == INT_MAX)
              cmdcount = 1;
            pw.vsplit2 = max(0, pw.vsplit2 - cmdcount);
            pw.stat |= stat_force;
            break;
          case '}':
            if (cmdcount == INT_MAX)
              cmdcount = 1;
            pw.vs2pos = min((int) maxlen, pw.vs2pos + cmdcount);
            pw.stat |= stat_force;
            break;
          case '{':
            if (cmdcount == INT_MAX)
              cmdcount = 1;
            pw.vs2pos = max(0, pw.vs2pos - cmdcount);
            pw.stat |= stat_force;
            break;
          case ctrl('i'):
            pw.stat ^= stat_hlite;
            pw.stat |= stat_force;
            break;
          case ctrl('d'):
            pw.stat ^= stat_diff;
            pw.stat |= stat_force;
            break;
          case 'j':
            if (pw.hist > 0) {
              pw.prevhist = pw.hist--;
              pw.stat |= stat_force;
            }
            break;
          case 'k':
            if (pw.hist < snhistsize - 1 && snapshot[pw.hist + 1]) {
              pw.prevhist = pw.hist++;
              pw.stat |= stat_force;
            }
            break;
          case ' ':
            if ((pw.stat & stat_eof) == 0)
              pw.stat |= stat_susp;
            break;
          case 't':
            if (cmdcount < 1 || cmdcount > 16)
              cmdcount = 8;
            pw.tstop = cmdcount;
            pw.stat |= stat_force;
            break;
          case CR:
            pw.stat &= ~stat_susp;
            break;
          case ESC:
            kbd_prev = kbd_state;
            kbd_state = kbd_esc;
            break;
          case ':': case '/': case '?':
            kbd_state = kbd_lcmd;
            histpos = 0;
            pw.editpos = 1;
            pw.cmdbuf[0] = ch;
            pw.cmdbuf[1] = 0;
            pw.curcmd = pw.cmdbuf;
            break;
          case 'a': case 'd':
            if ((pw.stat & (stat_htmode | stat_ttmode))) {
              int step = ((((pw.stat & stat_htmode) && ch == 'a') ||
                           ((pw.stat & stat_ttmode) && ch == 'd'))
                          ? -1 : 1);

              if (cmdcount == INT_MAX)
                cmdcount = 1;

              if (step < 0) {
                for (; cmdcount && !triglist[0]; cmdcount --) {
                  memmove(triglist, triglist + 1,
                          (maxtrig - 1) * sizeof *triglist);
                  triglist[maxtrig - 1] = 0;
                }
              } else if (pw.nlines <= maxtrig) {
                for (; (cmdcount &&
                        !triglist[pw.nlines - 1] &&
                        !triglist[maxtrig - 1]);
                     cmdcount --)
                {
                  memmove(triglist + 1, triglist,
                          (maxtrig - 1) * sizeof *triglist);
                  triglist[0] = 0;
                }
              }
            }
            break;
          case '+':
            if (pw.hist > 0 || (ws.ws_row && pw.maxlines >= ws.ws_row - 1)) {
              break;
            } else {
              int count = (cmdcount == INT_MAX) ? 1 : cmdcount;
              int oldmax = pw.maxlines;

              pw.maxlines += count;

              if (pw.maxlines >= ws.ws_row - 1) {
                maxed = 1;
                pw.maxlines = ws.ws_row - 1;
              }

              pw.circbuf = resizebuf(pw.circbuf, oldmax, pw.maxlines);
              snapshot[0] = resizebuf(snapshot[0], oldmax, pw.maxlines);

              for (int i = 1; i < snhistsize; i++) {
                freebuf(snapshot[i], snaplines[i]);
                free(snapshot[i]);
                snapshot[i] = 0;
              }

              pw.prevhist = 0;
            }
            break;
          case '#':
            pw.stat ^= stat_lino;
            if ((pw.stat & stat_lino))
              clipsplits(&pw);
            // fallthrough
          case ctrl('l'):
            pw.stat |= stat_force;
            break;
          case ctrl('g'):
            pw.editpos = snprintf(pw.cmdbuf, sizeof pw.cmdbuf,
                                  "-p %d,%d,%d,%d,%d",
                                  pw.hpos, pw.vsplit1, pw.vsplit2, pw.vs2pos,
                                  (int) pw.stat & stat_save);
            pw.curcmd = pw.cmdbuf;
            kbd_state = kbd_result;
            break;
          case '.':
            if (prevcmd) {
              ch = prevcmd;
              cmdcount = prevcount;
              goto fakecmd;
            }
            break;
          case '0':
            if (cmdcount == INT_MAX) {
              pw.hpos = 0;
              pw.stat |= stat_force;
              break;
            }
            // fallthrough
          default:
            if (isdigit(ch)) {
              if (cmdcount == INT_MAX)
                cmdcount = 0;
              cmdcount = (cmdcount * 10 + (ch - '0')) % 1000;
              break;
            }
            ch = 0;
            break;
          }
          if (!isdigit(ch)) {
            if (ch && ch != '.') {
              prevcmd = ch;
              prevcount = cmdcount;
            }
            if (kbd_state == kbd_cmd)
              cmdcount = INT_MAX;
          }
          break;
        case kbd_esc:
          if (ch == '[') {
            kbd_state = kbd_bkt;
            break;
          }
          kbd_state = kbd_cmd;
          pw.curcmd = 0;
          break;
        case kbd_bkt:
          kbd_state = kbd_prev;
          if (kbd_prev == kbd_cmd) switch (ch) {
          case 'D':
            ch = 'h';
            goto fakecmd;
          case 'C':
            ch = 'l';
            goto fakecmd;
          case 'H':
            ch = '0';
            goto fakecmd;
          case 'A':
            ch = 'k';
            goto fakecmd;
          case 'B':
            ch = 'j';
            goto fakecmd;
          }
          switch (ch) {
          case 'A':
            ch = ctrl('p');
            goto fakecmd;
          case 'B':
            ch = ctrl('n');
            goto fakecmd;
          case 'D':
            ch = ctrl('b');
            goto fakecmd;
          case 'C':
            ch = ctrl('f');
            goto fakecmd;
          }
          break;
        case kbd_lcmd:
          switch (ch) {
          case ESC:
            kbd_prev = kbd_state;
            kbd_state = kbd_esc;
            break;
          case CR: case ctrl('c'):
            if (ch == CR) {
              int count = (cmdcount == INT_MAX) ? 0 : cmdcount;
              if (pw.cmdbuf[1]) {
                int iscolon = pw.cmdbuf[0] == ':';
                int *pnhist = (iscolon ? &ncmdhist : &npathist);
                int nhist = *pnhist;
                char ***hist = (iscolon ? &cmdhist : &pathist);

                if (nhist == 0 || strcmp(pw.cmdbuf, (*hist)[0]) != 0) {
                  if ((*hist = resizebuf(*hist, nhist, nhist + 1)) == 0)
                    panic("out of memory");
                  memmove(*hist + 1, *hist, sizeof **hist * nhist);
                  *pnhist = nhist + 1;
                  (*hist)[0] = dsdup(pw.cmdbuf);
                }
              }

              if (execute(&pw, pw.cmdbuf, pw.cmdbuf,
                          cmdsize, count) != exec_ok)
              {
                pw.editpos = strlen(pw.cmdbuf);
                kbd_state = kbd_result;
                cmdcount = INT_MAX;
                break;
              }
            }

            kbd_state = kbd_cmd;
            pw.curcmd = 0;
            cmdcount = INT_MAX;
            prevcmd = 0;
            break;
          case ctrl('b'):
            if (pw.editpos > 1)
              pw.editpos--;
            break;
          case ctrl('f'):
            if (pw.cmdbuf[pw.editpos] != 0)
              pw.editpos++;
            break;
          case ctrl('k'):
            pw.cmdbuf[pw.editpos] = 0;
            break;
          case ctrl('a'):
            pw.editpos = 1;
            break;
          case ctrl('e'):
            pw.editpos = strlen(pw.cmdbuf);
            break;
          case BS: case DEL:
            {
              size_t len = strlen(pw.cmdbuf);
              if (pw.editpos > 1 || (pw.editpos == 1 && len == 1)) {
                pw.editpos--;
                memmove(pw.cmdbuf + pw.editpos, pw.cmdbuf + pw.editpos + 1,
                        len - pw.editpos);
              }

              if (len == 1) {
                kbd_state = kbd_cmd;
                pw.curcmd = 0;
                // cmdcount deliberately not reset to INT_MAX
              }
            }
            break;
          case ctrl('d'):
            {
              size_t len = strlen(pw.cmdbuf);
              if (pw.editpos < len)
                memmove(pw.cmdbuf + pw.editpos, pw.cmdbuf + pw.editpos + 1,
                        len - pw.editpos + 1);
            }
            break;
          case ctrl('u'):
            memmove(pw.cmdbuf + 1, pw.cmdbuf + pw.editpos,
                    strlen(pw.cmdbuf + pw.editpos) + 1);
            pw.editpos = 1;
            break;
          case ctrl('w'):
            {
              size_t npos = pw.editpos;
              while (npos > 1 && isspace((unsigned char) pw.cmdbuf[npos - 1]))
                npos--;
              while (npos > 1 && !isspace((unsigned char) pw.cmdbuf[npos - 1]))
                npos--;
              memmove(pw.cmdbuf + npos, pw.cmdbuf + pw.editpos,
                      strlen(pw.cmdbuf + pw.editpos) + 1);
              pw.editpos = npos;
            }
            break;
          case ctrl('p'):
          case ctrl('n'):
            {
              int iscolon = pw.cmdbuf[0] == ':';
              int nhist = (iscolon ? ncmdhist : npathist);
              char ***hist = (iscolon ? &cmdhist : &pathist);

              if (ch == ctrl('p')) {
                if (histpos == 0) {
                  dsdrop(pw.savedcmd);
                  pw.savedcmd = dsdup(pw.cmdbuf);
                } else {
                  dsdrop((*hist)[histpos-1]);
                  (*hist)[histpos-1] = dsdup(pw.cmdbuf);
                }
                if (histpos < nhist) {
                  char *cmd = (*hist)[histpos++];
                  strcpy(pw.cmdbuf, cmd);
                  pw.editpos = strlen(cmd);
                }
              } else {
                if (histpos >= 1) {
                  dsdrop((*hist)[histpos-1]);
                  (*hist)[histpos-1] = dsdup(pw.cmdbuf);
                }
                if (histpos > 1) {
                  char *cmd = (*hist)[--histpos - 1];
                  strcpy(pw.cmdbuf, cmd);
                  pw.editpos = strlen(cmd);
                } else if (histpos == 1) {
                  --histpos;
                  strcpy(pw.cmdbuf, pw.savedcmd);
                  dsdrop(pw.savedcmd);
                  pw.savedcmd = 0;
                }
              }
            }
            break;
          default:
            if (isprint(ch))
            {
              size_t len = strlen(pw.cmdbuf);
              if (len < sizeof pw.cmdbuf - 1 && (int) len < pw.columns - 1) {
                memmove(pw.cmdbuf + pw.editpos + 1, pw.cmdbuf + pw.editpos,
                        len - pw.editpos + 1);
                pw.cmdbuf[pw.editpos++] = ch;
              }
            }
            break;
          }
          break;
        case kbd_exit:
          break;
        }

        if ((pw.stat & (stat_dirty | stat_force))) {
          redraw(&pw);
        } else switch (kbd_state) {
        case kbd_lcmd: case kbd_result: case kbd_cmd:
          clrline(pw.stat);
          drawstatus(&pw);
        }
      } else {
        if (workbout < workmax)
          work = workbout += workbout / 4;
      }
    }
  }

  if ((pw.stat & stat_bkgnd) == 0) {
    clrline(pw.stat);
    ttyset(ttyfd, &tty_saved);
  }

  if (out)
    fclose(out);

#if CONFIG_DEBUG_LEAKS
  freebuf(pw.circbuf, pw.maxlines);
  free(pw.circbuf);
  for (int i = 0; i < snhistsize; i++) {
    freebuf(snapshot[i], snaplines[i]);
    free(snapshot[i]);
  }
  for (int i = 0; i < ngrep; i++)
    grclean(&grepstack[i]);
  for (int i = 0; i < maxtrig; i++) {
    if (triglist[i])
      grclean(triglist[i]);
  }
  freebuf(cmdhist, ncmdhist);
  freebuf(pathist, npathist);
  fclose(tty);
#endif

  return exit_status;
}