Fix -u, change meaning of $USER to be EQ -u etc..

[s-mailx.git] / tty.c

/*@ S-nail - a mail user agent derived from Berkeley Mail.
 *@ TTY interaction.
 *
 * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
 * Copyright (c) 2012 - 2013 Steffen "Daode" Nurpmeso <sdaoden@users.sf.net>.
 */
/*
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */
/* The NCL version is
 *
 * Copyright (c) 2013 Steffen "Daode" Nurpmeso <sdaoden@users.sf.net>.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "nail.h"

#ifdef HAVE_READLINE
# include <readline/history.h>
# include <readline/readline.h>
#elif defined HAVE_EDITLINE
# include <histedit.h>
#elif defined HAVE_LINE_EDITOR
# define __NCL
#endif

/* */
#define _CL_HISTFILE(S) \
do {\
   S = voption("NAIL_HISTFILE");\
   if ((S) != NULL)\
      S = fexpand(S, FEXP_LOCAL);\
} while (0)

/* */
#define _CL_HISTSIZE(V) \
do {\
   char const *__sv = voption("NAIL_HISTSIZE");\
   long __rv;\
   if (__sv == NULL || *__sv == '\0' ||\
         (__rv = strtol(__sv, NULL, 10)) == 0)\
      (V) = HIST_SIZE;\
   else if (__rv < 0)\
      (V) = 0;\
   else\
      (V) = __rv;\
} while (0)

/* */
#define _CL_CHECK_ADDHIST(S,NOACT) \
do {\
   switch (*(S)) {\
   case '\0':\
   case ' ':\
      NOACT;\
      /* FALLTHRU */\
   default:\
      break;\
   }\
} while (0)

/* fexpand() flags for expand-on-tab */
#define _CL_TAB_FEXP_FL (FEXP_FULL | FEXP_SILENT | FEXP_MULTIOK)

/*
 * Because we have multiple identical implementations, change file layout a bit
 * and place the implementations one after the other below the other externals
 */

bool_t
yorn(char const *msg)
{
   char *cp;

   if (! (options & OPT_INTERACTIVE))
      return TRU1;
   do if ((cp = readstr_input(msg, NULL)) == NULL)
      return FAL0;
   while (*cp != 'y' && *cp != 'Y' && *cp != 'n' && *cp != 'N');
   return (*cp == 'y' || *cp == 'Y');
}

char *
getuser(char const *query)
{
   char *user = NULL;

   if (query == NULL)
      query = tr(509, "User: ");

   if (readline_input(LNED_NONE, query, &termios_state.ts_linebuf,
         &termios_state.ts_linesize) >= 0)
      user = termios_state.ts_linebuf;
   termios_state_reset();
   return user;
}

char *
getpassword(char const *query) /* FIXME encaps ttystate signal safe */
{
   struct termios tios;
   char *pass = NULL;

   if (query == NULL)
      query = tr(510, "Password: ");
   fputs(query, stdout);
   fflush(stdout);

   if (options & OPT_TTYIN) {
      tcgetattr(STDIN_FILENO, &termios_state.ts_tios);
      memcpy(&tios, &termios_state.ts_tios, sizeof tios);
      termios_state.ts_needs_reset = TRU1;
      tios.c_iflag &= ~(ISTRIP);
      tios.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);
      tcsetattr(STDIN_FILENO, TCSAFLUSH, &tios);
   }

   if (readline_restart(stdin, &termios_state.ts_linebuf,
         &termios_state.ts_linesize, 0) >= 0)
      pass = termios_state.ts_linebuf;
   termios_state_reset();

   if (options & OPT_TTYIN)
      fputc('\n', stdout);
   return pass;
}

bool_t
getcredentials(char **user, char **pass)
{
   bool_t rv = TRU1;
   char *u = *user, *p = *pass;

   if (u == NULL) {
      if ((u = getuser(NULL)) == NULL)
         rv = FAL0;
      else if (p == NULL)
         u = savestr(u);
      *user = u;
   }

   if (p == NULL) {
      if ((p = getpassword(NULL)) == NULL)
         rv = FAL0;
      *pass = p;
   }
   return rv;
}

/*
 * readline(3)
 */

#ifdef HAVE_READLINE
static sighandler_type  _rl_shup;
static char *           _rl_buf;    /* pre_input() hook: initial line */
static int              _rl_buflen; /* content, and its length */

static int  _rl_pre_input(void);

static int
_rl_pre_input(void)
{
   /* Handle leftover data from \ escaped former line */
   rl_extend_line_buffer(_rl_buflen + 10);
   memcpy(rl_line_buffer, _rl_buf, _rl_buflen + 1);
   rl_point = rl_end = _rl_buflen;
   rl_pre_input_hook = (rl_hook_func_t*)NULL;
   rl_redisplay();
   return 0;
}

void
tty_init(void)
{
   long hs;
   char *v;

   _CL_HISTSIZE(hs);

   rl_readline_name = UNCONST(uagent);
   using_history();
   stifle_history((int)hs);
   rl_read_init_file(NULL);

   /* Because rl_read_init_file() may have introduced yet a different
    * history size limit, simply load and incorporate the history, leave
    * it up to readline(3) to do the rest */
   _CL_HISTFILE(v);
   if (v != NULL)
      read_history(v);
}

void
tty_destroy(void)
{
   char *v;

   _CL_HISTFILE(v);
   if (v != NULL)
      write_history(v);
}

void
tty_signal(int sig)
{
   sigset_t nset, oset;

   switch (sig) {
# ifdef SIGWINCH
   case SIGWINCH:
      break;
# endif
   case SIGHUP:
      /* readline(3) doesn't catch it :( */
      rl_free_line_state();
      rl_cleanup_after_signal();
      safe_signal(SIGHUP, _rl_shup);
      sigemptyset(&nset);
      sigaddset(&nset, sig);
      sigprocmask(SIG_UNBLOCK, &nset, &oset);
      kill(0, sig);
      /* XXX When we come here we'll continue editing, so reestablish
       * XXX cannot happen */
      sigprocmask(SIG_BLOCK, &oset, (sigset_t*)NULL);
      _rl_shup = safe_signal(SIGHUP, &tty_signal);
      rl_reset_after_signal();
      break;
   default:
      break;
   }
}

int
(tty_readline)(char const *prompt, char **linebuf, size_t *linesize, size_t n
   SMALLOC_DEBUG_ARGS)
{
   int nn;
   char *line;

   if (n > 0) {
      _rl_buf = *linebuf;
      _rl_buflen = (int)n;
      rl_pre_input_hook = &_rl_pre_input;
   }

   _rl_shup = safe_signal(SIGHUP, &tty_signal);
   line = readline(prompt);
   safe_signal(SIGHUP, _rl_shup);

   if (line == NULL) {
      nn = -1;
      goto jleave;
   }
   n = strlen(line);

   if (n >= *linesize) {
      *linesize = LINESIZE + n + 1;
      *linebuf = (srealloc)(*linebuf, *linesize SMALLOC_DEBUG_ARGSCALL);
   }
   memcpy(*linebuf, line, n);
   (free)(line);
   (*linebuf)[n] = '\0';
   nn = (int)n;
jleave:
   return nn;
}

void
tty_addhist(char const *s)
{
   _CL_CHECK_ADDHIST(s, goto jleave);
   hold_all_sigs();  /* XXX too heavy */
   add_history(s);   /* XXX yet we jump away! */
   rele_all_sigs();  /* XXX remove jumps */
jleave:
   ;
}
#endif /* HAVE_READLINE */

/*
 * BSD editline(3)
 */

#ifdef HAVE_EDITLINE
static EditLine *    _el_el;     /* editline(3) handle */
static History *     _el_hcom;   /* History handle for commline */
static char const *  _el_prompt; /* Current prompt */

static char const *  _el_getprompt(void);

static char const *
_el_getprompt(void)
{
   return _el_prompt;
}

void
tty_init(void)
{
   HistEvent he;
   long hs;
   char *v;

   _CL_HISTSIZE(hs);

   _el_hcom = history_init();
   history(_el_hcom, &he, H_SETSIZE, (int)hs);
   history(_el_hcom, &he, H_SETUNIQUE, 1);

   _el_el = el_init(uagent, stdin, stdout, stderr);
   el_set(_el_el, EL_SIGNAL, 1);
   el_set(_el_el, EL_TERMINAL, NULL);
   /* Need to set HIST before EDITOR, otherwise it won't work automatic */
   el_set(_el_el, EL_HIST, &history, _el_hcom);
   el_set(_el_el, EL_EDITOR, "emacs");
   el_set(_el_el, EL_PROMPT, &_el_getprompt);
# if 0
   el_set(_el_el, EL_ADDFN, "tab_complete",
      "editline(3) internal completion function", &_el_file_cpl);
   el_set(_el_el, EL_BIND, "^I", "tab_complete", NULL);
# endif
   el_set(_el_el, EL_BIND, "^R", "ed-search-prev-history", NULL);
   el_source(_el_el, NULL); /* Source ~/.editrc */

   /* Because el_source() may have introduced yet a different history size
    * limit, simply load and incorporate the history, leave it up to
    * editline(3) to do the rest */
   _CL_HISTFILE(v);
   if (v != NULL)
      history(_el_hcom, &he, H_LOAD, v);
}

void
tty_destroy(void)
{
   HistEvent he;
   char *v;

   el_end(_el_el);

   _CL_HISTFILE(v);
   if (v != NULL)
      history(_el_hcom, &he, H_SAVE, v);
   history_end(_el_hcom);
}

void
tty_signal(int sig)
{
   switch (sig) {
# ifdef SIGWINCH
   case SIGWINCH:
      el_resize(_el_el);
      break;
# endif
   default:
      break;
   }
}

int
(tty_readline)(char const *prompt, char **linebuf, size_t *linesize, size_t n
   SMALLOC_DEBUG_ARGS)
{
   int nn;
   char const *line;

   _el_prompt = prompt;
   if (n > 0)
      el_push(_el_el, *linebuf);
   line = el_gets(_el_el, &nn);

   if (line == NULL) {
      nn = -1;
      goto jleave;
   }
   assert(nn >= 0);
   n = (size_t)nn;
   if (n > 0 && line[n - 1] == '\n')
      nn = (int)--n;

   if (n >= *linesize) {
      *linesize = LINESIZE + n + 1;
      *linebuf = (srealloc)(*linebuf, *linesize SMALLOC_DEBUG_ARGSCALL);
   }
   memcpy(*linebuf, line, n);
   (*linebuf)[n] = '\0';
jleave:
   return nn;
}

void
tty_addhist(char const *s)
{
   /* Enlarge meaning of unique .. to something that rocks;
    * xxx unfortunately this is expensive to do with editline(3)
    * xxx maybe it would be better to hook the ptfs instead? */
   HistEvent he;
   int i;

   _CL_CHECK_ADDHIST(s, goto jleave);

   hold_all_sigs(); /* XXX too heavy, yet we jump away! */
   if (history(_el_hcom, &he, H_GETUNIQUE) < 0 || he.num == 0)
      goto jadd;

   for (i = history(_el_hcom, &he, H_FIRST); i >= 0;
         i = history(_el_hcom, &he, H_NEXT))
      if (strcmp(he.str, s) == 0) {
         history(_el_hcom, &he, H_DEL, he.num);
         break;
      }
jadd:
   history(_el_hcom, &he, H_ENTER, s);
   rele_all_sigs(); /* XXX remove jumps */
jleave:
   ;
}
#endif /* HAVE_EDITLINE */

/*
 * NCL: our homebrew version (inspired from NetBSD sh(1) / dash(1)s hetio.c).
 *
 * Only used in interactive mode, simply use STDIN_FILENO as point of interest.
 * We do not handle character widths because the terminal must deal with that
 * anyway on the one hand, and also wcwidth(3) doesn't support zero-width
 * characters by definition on the other.  We're addicted.
 *
 * To avoid memory leaks etc. with the current codebase that simply longjmp(3)s
 * we're forced to use the very same buffer--the one that is passed through to
 * us from the outside--to store anything we need, i.e., a `struct cell[]', and
 * convert that on-the-fly back to the plain char* result once we're done.
 * To simplify our live, use savestr() buffers for all other needed memory
 */

/*
 * TODO NCL: don't use that stupid .sint=-1 stuff, but simply block all signals
 * TODO NCL: during handler de-/installation handling.
 */

#ifdef __NCL
union xsighdl {
   sighandler_type   shdl; /* Try avoid races by setting */
   sl_it             sint; /* .sint=-1 when inactive */
};
CTA(sizeof(sl_it) >= sizeof(sighandler_type));

struct xtios {
   struct termios told;
   struct termios tnew;
};

struct cell {
   wchar_t  wc;
   ui_it    count;
   char     cbuf[MB_LEN_MAX * 2];   /* .. plus reset shift sequence */
};

struct hist {
   struct hist *  older;
   struct hist *  younger;
   size_t         len;
   char           dat[VFIELD_SIZE(sizeof(size_t))];
};

struct line {
   size_t         cursor;     /* Current cursor position */
   size_t         topins;     /* Outermost cursor col set */
   union {
      char *         cbuf;    /* *x_buf */
      struct cell *  cells;
   }              line;
   struct str     defc;       /* Current default content */
   struct str     savec;      /* Saved default content */
   struct hist *  hist;       /* History cursor */
   char const *   prompt;
   char const *   nd;         /* Cursor right */
   char **        x_buf;      /* Caller pointers */
   size_t *       x_bufsize;
};

static union xsighdl _ncl_oint;
static union xsighdl _ncl_oquit;
static union xsighdl _ncl_oterm;
static union xsighdl _ncl_ohup;
static union xsighdl _ncl_otstp;
static union xsighdl _ncl_ottin;
static union xsighdl _ncl_ottou;
static struct xtios  _ncl_tios;
static struct hist * _ncl_hist;
static size_t        _ncl_hist_size;
static size_t        _ncl_hist_size_max;
static bool_t        _ncl_hist_load;

static void    _ncl_sigs_up(void);
static void    _ncl_sigs_down(void);

static void    _ncl_term_mode(bool_t raw);

static void    _ncl_check_grow(struct line *l, size_t no SMALLOC_DEBUG_ARGS);
static void    _ncl_bs_eof_dvup(struct cell *cap, size_t i);
static ssize_t _ncl_wboundary(struct line *l, ssize_t dir);
static ssize_t _ncl_cell2dat(struct line *l);
static void    _ncl_cell2save(struct line *l);

static void    _ncl_khome(struct line *l, bool_t dobell);
static void    _ncl_kend(struct line *l);
static void    _ncl_kbs(struct line *l);
static void    _ncl_kkill(struct line *l, bool_t dobell);
static ssize_t _ncl_keof(struct line *l);
static void    _ncl_kleft(struct line *l);
static void    _ncl_kright(struct line *l);
static void    _ncl_krefresh(struct line *l);
static size_t  _ncl_kht(struct line *l);
static size_t  __ncl_khist_shared(struct line *l, struct hist *hp);
static size_t  _ncl_khist(struct line *l, bool_t backwd);
static size_t  _ncl_krhist(struct line *l);
static void    _ncl_kbwddelw(struct line *l);
static void    _ncl_kgow(struct line *l, ssize_t dir);
static void    _ncl_kother(struct line *l, wchar_t wc);
static ssize_t _ncl_readline(char const *prompt, char **buf, size_t *bufsize,
                  size_t len SMALLOC_DEBUG_ARGS);

static void
_ncl_sigs_up(void)
{
   if (_ncl_oint.sint == -1)
      _ncl_oint.shdl = safe_signal(SIGINT, &tty_signal);
   if (_ncl_oquit.sint == -1)
      _ncl_oquit.shdl = safe_signal(SIGQUIT, &tty_signal);
   if (_ncl_oterm.sint == -1)
      _ncl_oterm.shdl = safe_signal(SIGTERM, &tty_signal);
   if (_ncl_ohup.sint == -1)
      _ncl_ohup.shdl = safe_signal(SIGHUP, &tty_signal);
   if (_ncl_otstp.sint == -1)
      _ncl_otstp.shdl = safe_signal(SIGTSTP, &tty_signal);
   if (_ncl_ottin.sint == -1)
      _ncl_ottin.shdl = safe_signal(SIGTTIN, &tty_signal);
   if (_ncl_ottou.sint == -1)
      _ncl_ottou.shdl  = safe_signal(SIGTTOU, &tty_signal);
}

static void
_ncl_sigs_down(void)
{
   /* aaah.. atomic cas would be nice (but isn't it all redundant?) */
   sighandler_type st;

   if (_ncl_ottou.sint != -1) {
      st = _ncl_ottou.shdl, _ncl_ottou.sint = -1;
      safe_signal(SIGTTOU, st);
   }
   if (_ncl_ottin.sint != -1) {
      st = _ncl_ottin.shdl, _ncl_ottin.sint = -1;
      safe_signal(SIGTTIN, st);
   }
   if (_ncl_otstp.sint != -1) {
      st = _ncl_otstp.shdl, _ncl_otstp.sint = -1;
      safe_signal(SIGTSTP, st);
   }
   if (_ncl_ohup.sint != -1) {
      st = _ncl_ohup.shdl, _ncl_ohup.sint = -1;
      safe_signal(SIGHUP, st);
   }
   if (_ncl_oterm.sint != -1) {
      st = _ncl_oterm.shdl, _ncl_oterm.sint = -1;
      safe_signal(SIGTERM, st);
   }
   if (_ncl_oquit.sint != -1) {
      st = _ncl_oquit.shdl, _ncl_oquit.sint = -1;
      safe_signal(SIGQUIT, st);
   }
   if (_ncl_oint.sint != -1) {
      st = _ncl_oint.shdl, _ncl_oint.sint = -1;
      safe_signal(SIGINT, st);
   }
}

static void
_ncl_term_mode(bool_t raw)
{
   struct termios *tiosp = &_ncl_tios.told;

   if (!raw)
      goto jleave;

   /* Always requery the attributes, in case we've been moved from background
    * to foreground or however else in between sessions */
   tcgetattr(STDIN_FILENO, tiosp);
   memcpy(&_ncl_tios.tnew, tiosp, sizeof *tiosp);
   tiosp = &_ncl_tios.tnew;
   tiosp->c_cc[VMIN] = 1;
   tiosp->c_cc[VTIME] = 0;
   tiosp->c_iflag &= ~(ISTRIP);
   tiosp->c_lflag &= ~(ECHO /*| ECHOE | ECHONL */| ICANON | IEXTEN);
jleave:
   tcsetattr(STDIN_FILENO, TCSADRAIN, tiosp);
}

static void
_ncl_check_grow(struct line *l, size_t no SMALLOC_DEBUG_ARGS)
{
   size_t i = (l->topins + no) * sizeof(struct cell) + 2 * sizeof(struct cell);

   if (i > *l->x_bufsize) {
      i <<= 1;
      *l->x_bufsize = i;
      l->line.cbuf =
      *l->x_buf = (srealloc_safe)(*l->x_buf, i SMALLOC_DEBUG_ARGSCALL);
   }
}

static void
_ncl_bs_eof_dvup(struct cell *cap, size_t i)
{
   size_t j;

   if (i > 0)
      memmove(cap, cap + 1, i * sizeof(*cap));

   /* And.. the (rest of the) visual update */
   for (j = 0; j < i; ++j)
      fwrite(cap[j].cbuf, sizeof *cap->cbuf, cap[j].count, stdout);
   fputs(" \b", stdout);
   for (j = 0; j < i; ++j)
      putchar('\b');
}

static ssize_t
_ncl_wboundary(struct line *l, ssize_t dir)
{
   size_t c = l->cursor, t = l->topins;
   ssize_t i;
   struct cell *cap;
   bool_t anynon;

   i = -1;
   if (dir < 0) {
      if (c == 0)
         goto jleave;
   } else if (c == t)
      goto jleave;
   else
      --t, --c; /* Unsigned wrapping may occur (twice), then */

   for (i = 0, cap = l->line.cells, anynon = FAL0;;) {
      wchar_t wc = cap[c + dir].wc;
      if (iswblank(wc) || iswpunct(wc)) {
         if (anynon)
            break;
      } else
         anynon = TRU1;
      ++i;
      c += dir;
      if (dir < 0) {
         if (c == 0)
            break;
      } else if (c == t)
         break;
   }
jleave:
   return i;
}

static ssize_t
_ncl_cell2dat(struct line *l)
{
   size_t len = 0, i;

   if (l->topins > 0)
      for (i = 0; i < l->topins; ++i) {
         struct cell *cap = l->line.cells + i;
         memcpy(l->line.cbuf + len, cap->cbuf, cap->count);
         len += cap->count;
      }
   l->line.cbuf[len] = '\0';
   return (ssize_t)len;
}

static void
_ncl_cell2save(struct line *l)
{
   size_t len, i;
   struct cell *cap;

   l->savec.s = NULL, l->savec.l = 0;
   if (l->topins == 0)
      goto jleave;

   for (cap = l->line.cells, len = i = 0; i < l->topins; ++cap, ++i)
      len += cap->count;

   l->savec.l = len;
   l->savec.s = salloc(len + 1);

   for (cap = l->line.cells, len = i = 0; i < l->topins; ++cap, ++i) {
      memcpy(l->savec.s + len, cap->cbuf, cap->count);
      len += cap->count;
   }
   l->savec.s[len] = '\0';
jleave:
   ;
}

static void
_ncl_khome(struct line *l, bool_t dobell)
{
   size_t c = l->cursor;

   if (c > 0) {
      l->cursor = 0;
      while (c-- != 0)
         putchar('\b');
   } else if (dobell)
      putchar('\a');
}

static void
_ncl_kend(struct line *l)
{
   ssize_t i = (ssize_t)(l->topins - l->cursor);

   if (i > 0) {
      l->cursor = l->topins;
      while (i-- != 0)
         fputs(l->nd, stdout);
   } else
      putchar('\a');
}

static void
_ncl_kbs(struct line *l)
{
   ssize_t c = l->cursor, t = l->topins;

   if (c > 0) {
      putchar('\b');
      l->cursor = --c;
      l->topins = --t;
      t -= c;
      _ncl_bs_eof_dvup(l->line.cells + c, t);
   } else
      putchar('\a');
}

static void
_ncl_kkill(struct line *l, bool_t dobell)
{
   size_t j, c = l->cursor, i = (size_t)(l->topins - c);

   if (i > 0) {
      l->topins = c;
      for (j = i; j != 0; --j)
         putchar(' ');
      for (j = i; j != 0; --j)
         putchar('\b');
   } else if (dobell)
      putchar('\a');
}

static ssize_t
_ncl_keof(struct line *l)
{
   size_t c = l->cursor, t = l->topins;
   ssize_t i = (ssize_t)(t - c);

   if (i > 0) {
      l->topins = --t;
      _ncl_bs_eof_dvup(l->line.cells + c, --i);
   } else if (t == 0 && ! boption("ignoreeof")) {
      fputs("^D", stdout);
      fflush(stdout);
      i = -1;
   } else {
      putchar('\a');
      i = 0;
   }
   return i;
}

static void
_ncl_kleft(struct line *l)
{
   if (l->cursor > 0) {
      --l->cursor;
      putchar('\b');
   } else
      putchar('\a');
}

static void
_ncl_kright(struct line *l)
{
   if (l->cursor < l->topins) {
      ++l->cursor;
      fputs(l->nd, stdout);
   } else
      putchar('\a');
}

static void
_ncl_krefresh(struct line *l)
{
   struct cell *cap;
   size_t i;

   putchar('\r');
   if (*l->prompt)
      fputs(l->prompt, stdout);
   for (cap = l->line.cells, i = l->topins; i > 0; ++cap, --i)
      fwrite(cap->cbuf, sizeof *cap->cbuf, cap->count, stdout);
   for (i = l->topins - l->cursor; i > 0; --i)
      putchar('\b');
}

static size_t
_ncl_kht(struct line *l)
{
   struct str orig, bot, topp, sub, exp;
   struct cell *cword, *ctop, *cx;
   bool_t set_savec = FAL0;
   size_t rv = 0;

   /* We cannot expand an empty line */
   if (l->topins == 0)
      goto jleave;

   /* Get plain line data; if this is the first expansion/xy, update the
    * very original content so that ^G gets the origin back */
   orig = l->savec;
   _ncl_cell2save(l);
   exp = l->savec;
   if (orig.s != NULL)
      l->savec = orig;
   else
      set_savec = TRU1;
   orig = exp;

   cword = l->line.cells;
   ctop = cword + l->cursor;

   /* topp: separate data right of cursor */
   if ((cx = cword + l->topins) != ctop) {
      for (rv = 0; cx > ctop; --cx)
         rv += cx->count;
      topp.l = rv;
      topp.s = orig.s + orig.l - rv;
   } else
      topp.s = NULL, topp.l = 0;

   /* bot, sub: we cannot expand the entire data left of cursor, but only
    * the last "word", so separate them */
   while (cx > cword && ! iswspace(cx[-1].wc))
      --cx;
   for (rv = 0; cword < cx; ++cword)
      rv += cword->count;
   sub =
   bot = orig;
   bot.l = rv;
   sub.s += rv;
   sub.l -= rv;
   sub.l -= topp.l;

   if (sub.l > 0) {
      sub.s = savestrbuf(sub.s, sub.l);
      /* TODO there is a TODO note upon fexpand() with multi-return;
       * TODO if that will change, the if() below can be simplified */
      /* Super-Heavy-Metal: block all sigs, avoid leaks on jump */
      hold_all_sigs();
      exp.s = fexpand(sub.s, _CL_TAB_FEXP_FL);
      rele_all_sigs();

      if (exp.s != NULL && (exp.l = strlen(exp.s)) > 0 &&
            (exp.l != sub.l || strcmp(exp.s, sub.s))) {
         /* TODO cramp expansion length to MAX_INPUT, or 255 if not defined;
          * TODO the problem is that we loose control otherwise; in the best
          * TODO case the user can control via ^A and ^K etc., but be safe;
          * TODO we cannot simply adjust fexpand() because we don't know how
          * TODO that is implemented...  The real solution would be to check
          * TODO wether we fit on a line, and start a pager if not.
          * TODO However, that should be part of a real tab-COMPLETION, then,
          * TODO i.e., don't EXPAND, but SHOW COMPLETIONS, page-wise if needed.
          * TODO And: MAX_INPUT is dynamic: pathconf(2), _SC_MAX_INPUT:
          * TODO Note how hacky this is in respect to excess of final string */
# ifndef MAX_INPUT
#  define MAX_INPUT 255 /* (_POSIX_MAX_INPUT = 255 as of Issue 7 TC1) */
# endif
         if (exp.l >= MAX_INPUT) {
            char const cp[] = "[maximum line size exceeded]";
            exp.s = UNCONST(cp);
            exp.l = sizeof(cp) - 1;
         }
         orig.l = bot.l + exp.l + topp.l;
         orig.s = salloc(orig.l + 1);
         rv = bot.l;
         memcpy(orig.s, bot.s, rv);
         memcpy(orig.s + rv, exp.s, exp.l);
         rv += exp.l;
         memcpy(orig.s + rv, topp.s, topp.l);
         rv += topp.l;
         orig.s[rv] = '\0';

         l->defc = orig;
         _ncl_khome(l, FAL0);
         _ncl_kkill(l, FAL0);
         goto jleave;
      }
   }

   /* If we've provided a default content, but failed to expand, there is
    * nothing we can "revert to": drop that default again */
   if (set_savec)
      l->savec.s = NULL, l->savec.l = 0;
   rv = 0;
jleave:
   return rv;
}

static size_t
__ncl_khist_shared(struct line *l, struct hist *hp)
{
   size_t rv;

   if ((l->hist = hp) != NULL) {
      l->defc.s = savestrbuf(hp->dat, hp->len);
      rv =
      l->defc.l = hp->len;
      if (l->topins > 0) {
         _ncl_khome(l, FAL0);
         _ncl_kkill(l, FAL0);
      }
   } else {
      putchar('\a');
      rv = 0;
   }
   return rv;
}

static size_t
_ncl_khist(struct line *l, bool_t backwd)
{
   struct hist *hp;

   /* If we're not in history mode yet, save line content;
    * also, disallow forward search, then, and, of course, bail unless we
    * do have any history at all */
   if ((hp = l->hist) == NULL) {
      if (! backwd)
         goto jleave;
      if ((hp = _ncl_hist) == NULL)
         goto jleave;
      _ncl_cell2save(l);
      goto jleave;
   }

   hp = backwd ? hp->older : hp->younger;
jleave:
   return __ncl_khist_shared(l, hp);
}

static size_t
_ncl_krhist(struct line *l)
{
   struct str orig_savec;
   struct hist *hp = NULL;

   /* We cannot complete an empty line */
   if (l->topins == 0) {
      /* XXX The upcoming hard reset would restore a set savec buffer,
       * XXX so forcefully reset that.  A cleaner solution would be to
       * XXX reset it whenever a restore is no longer desired */
      l->savec.s = NULL, l->savec.l = 0;
      goto jleave;
   }
   if ((hp = l->hist) == NULL) {
      if ((hp = _ncl_hist) == NULL)
         goto jleave;
      orig_savec.s = NULL;
   } else if ((hp = hp->older) == NULL)
      goto jleave;
   else
      orig_savec = l->savec;

   if (orig_savec.s == NULL)
      _ncl_cell2save(l);
   for (; hp != NULL; hp = hp->older)
      if (is_prefix(l->savec.s, hp->dat))
         break;
   if (orig_savec.s != NULL)
      l->savec = orig_savec;
jleave:
   return __ncl_khist_shared(l, hp);
}

static void
_ncl_kbwddelw(struct line *l)
{
   ssize_t i;
   size_t c = l->cursor, t, j;
   struct cell *cap;

   i = _ncl_wboundary(l, -1);
   if (i <= 0) {
      if (i < 0)
         putchar('\a');
      goto jleave;
   }

   c = l->cursor - i;
   t = l->topins;
   l->topins = t - i;
   l->cursor = c;
   cap = l->line.cells + c;

   if (t != l->cursor) {
      j = t - c + i;
      memmove(cap, cap + i, j * sizeof(*cap));
   }

   for (j = i; j > 0; --j)
      putchar('\b');
   for (j = l->topins - c; j > 0; ++cap, --j)
      fwrite(cap[0].cbuf, sizeof *cap->cbuf, cap[0].count, stdout);
   for (j = i; j > 0; --j)
      putchar(' ');
   for (j = t - c; j > 0; --j)
      putchar('\b');
jleave: ;
}

static void
_ncl_kgow(struct line *l, ssize_t dir)
{
   ssize_t i = _ncl_wboundary(l, dir);
   if (i <= 0) {
      if (i < 0)
         putchar('\a');
      goto jleave;
   }

   if (dir < 0) {
      l->cursor -= i;
      while (i-- > 0)
         putchar('\b');
   } else {
      l->cursor += i;
      while (i-- > 0)
         fputs(l->nd, stdout);
   }
jleave:
   ;
}

static void
_ncl_kother(struct line *l, wchar_t wc)
{
   /* Append if at EOL, insert otherwise;
    * since we may move around character-wise, always use a fresh ps */
   mbstate_t ps;
   struct cell cell, *cap;
   size_t i, c;

   /* First init a cell and see wether we'll really handle this wc */
   cell.wc = wc;
   memset(&ps, 0, sizeof ps);
   i = wcrtomb(cell.cbuf, wc, &ps);
   if (i > MB_LEN_MAX)
      goto jleave;
   cell.count = (ui_it)i;
   if (enc_has_state) {
      i = wcrtomb(cell.cbuf + i, L'\0', &ps);
      if (i == 1)
         ;
      else if (--i < MB_LEN_MAX)
         cell.count += (ui_it)i;
      else
         goto jleave;
   }

   /* Yes, we will!  Place it in the array */
   c = l->cursor++;
   i = l->topins++ - c;
   cap = l->line.cells + c;
   if (i > 0)
      memmove(cap + 1, cap, i * sizeof(cell));
   memcpy(cap, &cell, sizeof cell);

   /* And update visual */
   c = i;
   do
      fwrite(cap->cbuf, sizeof *cap->cbuf, cap->count, stdout);
   while ((++cap, i-- != 0));
   while (c-- != 0)
      putchar('\b');
jleave: ;
}

static ssize_t
_ncl_readline(char const *prompt, char **buf, size_t *bufsize, size_t len
   SMALLOC_DEBUG_ARGS)
{
   /* We want to save code, yet we may have to incorporate a lines'
    * default content and / or default input to switch back to after some
    * history movement; let "len > 0" mean "have to display some data
    * buffer", and only otherwise read(2) it */
   mbstate_t ps[2];
   struct line l;
   char cbuf_base[MB_LEN_MAX * 2], *cbuf, *cbufp;
   wchar_t wc;
   ssize_t rv;

   memset(&l, 0, sizeof l);
   l.line.cbuf = *buf;
   if (len != 0) {
      l.defc.s = savestrbuf(*buf, len);
      l.defc.l = len;
   }
   l.prompt = prompt;
   if ((l.nd = voption("line-editor-cursor-right")) == NULL)
      l.nd = "\033[C";
   l.x_buf = buf;
   l.x_bufsize = bufsize;

   if (*prompt) {
      fputs(prompt, stdout);
      fflush(stdout);
   }
jrestart:
   memset(ps, 0, sizeof ps);
   /* TODO: NCL: we should output the reset sequence when we jrestart:
    * TODO: NCL: if we are using a stateful encoding? !
    * TODO: NCL: in short: this is not yet well understood */
   for (;;) {
      _ncl_check_grow(&l, len SMALLOC_DEBUG_ARGSCALL);

      /* Normal read(2)?  Else buffer-takeover: speed this one up */
      if (len == 0)
         cbufp =
         cbuf = cbuf_base;
      else {
         assert(l.defc.l > 0 && l.defc.s != NULL);
         cbufp =
         cbuf = l.defc.s + (l.defc.l - len);
         cbufp += len;
      }

      /* Read in the next complete multibyte character */
      for (;;) {
         if (len == 0) {
            if ((rv = read(STDIN_FILENO, cbufp, 1)) < 1) {
               if (errno == EINTR) /* xxx #if !SA_RESTART ? */
                  continue;
               goto jleave;
            }
            ++cbufp;
         }

         /* Ach! the ISO C multibyte handling!
          * Encodings with locking shift states cannot really be helped, since
          * it is impossible to only query the shift state, as opposed to the
          * entire shift state + character pair (via ISO C functions) */
         rv = (ssize_t)mbrtowc(&wc, cbuf, (size_t)(cbufp - cbuf), ps + 0);
         if (rv <= 0) {
            /* Any error during take-over can only result in a hard reset;
             * Otherwise, if it's a hard error, or if too many redundant shift
             * sequences overflow our buffer, also perform a hard reset */
            if (len != 0 || rv == -1 ||
                  sizeof cbuf_base == (size_t)(cbufp - cbuf)) {
               l.savec.s = l.defc.s = NULL,
               l.savec.l = l.defc.l = len = 0;
               putchar('\a');
               wc = 'G';
               goto jreset;
            }
            /* Otherwise, due to the way we deal with the buffer, we need to
             * restore the mbstate_t from before this conversion */
            ps[0] = ps[1];
            continue;
         }

         if (len != 0 && (len -= (size_t)rv) == 0)
            l.defc.s = NULL, l.defc.l = 0;
         ps[1] = ps[0];
         break;
      }

      /* Don't interpret control bytes during buffer take-over */
      if (cbuf != cbuf_base)
         goto jprint;
      switch (wc) {
      case 'A' ^ 0x40: /* cursor home */
         _ncl_khome(&l, TRU1);
         break;
      case 'B' ^ 0x40: /* ("history backward") */
         if ((len = _ncl_khist(&l, TRU1)) > 0)
            goto jrestart;
         wc = 'G' ^ 0x40;
         goto jreset;
      /* 'C': interrupt (CTRL-C) */
      case 'D' ^ 0x40: /* delete char forward if any, else EOF */
         if ((rv = _ncl_keof(&l)) < 0)
            goto jleave;
         break;
      case 'E' ^ 0x40: /* end of line */
         _ncl_kend(&l);
         break;
      case 'F' ^ 0x40: /* history forward */
         if (l.hist == NULL)
            goto jbell;
         if ((len = _ncl_khist(&l, FAL0)) > 0)
            goto jrestart;
         wc = 'G' ^ 0x40;
         goto jreset;
      /* 'G' below */
      case 'H' ^ 0x40: /* backspace */
      case '\177':
         _ncl_kbs(&l);
         break;
      case 'I' ^ 0x40: /* horizontal tab */
         if ((len = _ncl_kht(&l)) > 0)
            goto jrestart;
         goto jbell;
      case 'J' ^ 0x40: /* NL (\n) */
         goto jdone;
      case 'G' ^ 0x40: /* full reset */
jreset:
         /* FALLTHRU */
      case 'U' ^ 0x40: /* ^U: ^A + ^K */
         _ncl_khome(&l, FAL0);
         /* FALLTHRU */
      case 'K' ^ 0x40: /* kill from cursor to end of line */
         _ncl_kkill(&l, (wc == ('K' ^ 0x40) || l.topins == 0));
         /* (Handle full reset?) */
         if (wc == ('G' ^ 0x40)) {
            l.hist = NULL;
            if ((len = l.savec.l) != 0) {
               l.defc = l.savec;
               l.savec.s = NULL, l.savec.l = 0;
            } else
               len = l.defc.l;
         }
         fflush(stdout);
         goto jrestart;
      case 'L' ^ 0x40: /* repaint line */
         _ncl_krefresh(&l);
         break;
      /* 'M': CR (\r) */
      /* 'N' */
      case 'O' ^ 0x40: /* cursor left */
         _ncl_kleft(&l);
         break;
      case 'P' ^ 0x40: /* cursor right */
         _ncl_kright(&l);
         break;
      /* 'Q': no code */
      case 'R' ^ 0x40: /* reverse history search */
         if ((len = _ncl_krhist(&l)) > 0)
            goto jrestart;
         wc = 'G' ^ 0x40;
         goto jreset;
      /* 'S': no code */
      /* 'U' above */
      /*case 'V' ^ 0x40: TODO*/ /* forward delete "word" */
      case 'W' ^ 0x40: /* backward delete "word" */
         _ncl_kbwddelw(&l);
         break;
      case 'X' ^ 0x40: /* move cursor forward "word" */
         _ncl_kgow(&l, +1);
         break;
      case 'Y' ^ 0x40: /* move cursor backward "word" */
         _ncl_kgow(&l, -1);
         break;
      /* 'Z': suspend (CTRL-Z) */
      default:
jprint:
         if (iswprint(wc)) {
            _ncl_kother(&l, wc);
            /* Don't clear the history during takeover..
             * ..and also avoid fflush()ing unless we've
             * worked the entire buffer */
            if (len > 0)
               continue;
            if (cbuf == cbuf_base)
               l.hist = NULL;
         } else {
jbell:
            putchar('\a');
         }
         break;
      }
      fflush(stdout);
   }

   /* We have a completed input line, convert the struct cell data to its
    * plain character equivalent */
jdone:
   putchar('\n');
   fflush(stdout);
   len = _ncl_cell2dat(&l);
   rv = (ssize_t)len;
jleave:
   return rv;
}

void
tty_init(void)
{
   long hs;
   char *v, *lbuf;
   FILE *f;
   size_t lsize, cnt, llen;

   _ncl_oint.sint = _ncl_oquit.sint = _ncl_oterm.sint =
   _ncl_ohup.sint = _ncl_otstp.sint = _ncl_ottin.sint =
   _ncl_ottou.sint = -1;

   _CL_HISTSIZE(hs);
   _ncl_hist_size_max = hs;
   if (hs == 0)
      goto jleave;

   _CL_HISTFILE(v);
   if (v == NULL)
      goto jleave;

   hold_all_sigs(); /* XXX too heavy, yet we may jump even here!? */
   f = fopen(v, "r"); /* TODO HISTFILE LOAD: use linebuf pool */
   if (f == NULL)
      goto jdone;

   lbuf = NULL;
   lsize = 0;
   cnt = fsize(f);
   while (fgetline(&lbuf, &lsize, &cnt, &llen, f, FAL0) != NULL) {
      if (llen > 0 && lbuf[llen - 1] == '\n')
         lbuf[--llen] = '\0';
      if (llen == 0 || lbuf[0] == '#') /* xxx comments? noone! */
         continue;
      _ncl_hist_load = TRU1;
      tty_addhist(lbuf);
      _ncl_hist_load = FAL0;
   }
   if (lbuf != NULL)
      free(lbuf);

   fclose(f);
jdone:
   rele_all_sigs(); /* XXX remove jumps */
jleave:
   ;
}

void
tty_destroy(void)
{
   long hs;
   char *v;
   struct hist *hp;
   FILE *f;

   _CL_HISTSIZE(hs);
   if (hs == 0)
      goto jleave;

   _CL_HISTFILE(v);
   if (v == NULL)
      goto jleave;

   if ((hp = _ncl_hist) != NULL)
      while (hp->older != NULL && hs-- != 0)
         hp = hp->older;

   hold_all_sigs(); /* too heavy, yet we may jump even here!? */
   f = fopen(v, "w"); /* TODO temporary + rename?! */
   if (f == NULL)
      goto jdone;
   if (fchmod(fileno(f), S_IRUSR | S_IWUSR) != 0)
      goto jclose;

   for (; hp != NULL; hp = hp->younger) {
      fwrite(hp->dat, sizeof *hp->dat, hp->len, f);
      putc('\n', f);
   }
jclose:
   fclose(f);
jdone:
   rele_all_sigs(); /* XXX remove jumps */
jleave:
   ;
}

void
tty_signal(int sig)
{
   sigset_t nset, oset;

   switch (sig) {
   case SIGWINCH:
      /* We don't deal with SIGWINCH, yet get called from main.c */
      break;
   default:
      _ncl_term_mode(FAL0);
      _ncl_sigs_down();
      sigemptyset(&nset);
      sigaddset(&nset, sig);
      sigprocmask(SIG_UNBLOCK, &nset, &oset);
      kill(0, sig);
      /* When we come here we'll continue editing, so reestablish */
      sigprocmask(SIG_BLOCK, &oset, (sigset_t*)NULL);
      _ncl_sigs_up();
      _ncl_term_mode(TRU1);
      break;
   }
}

int
(tty_readline)(char const *prompt, char **linebuf, size_t *linesize, size_t n
   SMALLOC_DEBUG_ARGS)
{
   ssize_t nn;

   /* Of course we have races here, but they cannot be avoided on POSIX
    * (except by even *more* actions) */
   _ncl_sigs_up();
   _ncl_term_mode(TRU1);
   nn = _ncl_readline(prompt, linebuf, linesize, n SMALLOC_DEBUG_ARGSCALL);
   _ncl_term_mode(FAL0);
   _ncl_sigs_down();

   return (int)nn;
}

void
tty_addhist(char const *s)
{
   /* Super-Heavy-Metal: block all sigs, avoid leaks+ on jump */
   size_t l = strlen(s);
   struct hist *h, *o, *y;

   _CL_CHECK_ADDHIST(s, goto j_leave);

   /* Eliminating duplicates is expensive, but simply inacceptable so
    * during the load of a potentially large history file! */
   if (! _ncl_hist_load)
      for (h = _ncl_hist; h != NULL; h = h->older)
         if (h->len == l && strcmp(h->dat, s) == 0) {
            hold_all_sigs();
            o = h->older;
            y = h->younger;
            if (o != NULL) {
               if ((o->younger = y) == NULL)
                  _ncl_hist = o;
            }
            if (y != NULL)
               y->older = o;
            else
               _ncl_hist = o;
            goto jleave;
         }
   hold_all_sigs();

   if (! _ncl_hist_load && _ncl_hist_size >= _ncl_hist_size_max) {
      (h = _ncl_hist->younger
      )->older = NULL;
      free(_ncl_hist);
      _ncl_hist = h;
   }

   h = smalloc((sizeof(struct hist) - VFIELD_SIZEOF(struct hist, dat)) + l + 1);
   h->len = l;
   memcpy(h->dat, s, l + 1);
jleave:
   if ((h->older = _ncl_hist) != NULL)
      _ncl_hist->younger = h;
   h->younger = NULL;
   _ncl_hist = h;

   rele_all_sigs();
j_leave:
   ;
}
#endif /* __NCL */

/*
 * The really-nothing-at-all implementation
 */

#ifndef HAVE_LINE_EDITOR
void
tty_init(void)
{}

void
tty_destroy(void)
{}

void
tty_signal(int sig)
{
   (void)sig;
}

int
(tty_readline)(char const *prompt, char **linebuf, size_t *linesize, size_t n
   SMALLOC_DEBUG_ARGS)
{
   /*
    * TODO The nothing-at-all tty layer even forces re-entering all the
    * TODO original data when re-editing a field
    */
   bool_t doffl = FAL0;

   if (*prompt != '\0') {
      fputs(prompt, stdout);
      doffl = TRU1;
   }
   if (n > 0) {
      fprintf(stdout, tr(511, "{former content: %.*s} "), (int)n, *linebuf);
      n = 0;
      doffl = TRU1;
   }
   if (doffl)
      fflush(stdout);
   return (readline_restart)(stdin, linebuf, linesize,n SMALLOC_DEBUG_ARGSCALL);
}

void
tty_addhist(char const *s)
{
   (void)s;
}
#endif /* ! HAVE_LINE_EDITOR */

/* vim:set fenc=utf-8:s-it-mode */