linenoise.c

/* linenoise.c -- guerrilla line editing library against the idea that a
 * line editing lib needs to be 20,000 lines of C code.
 *
 * You can find the latest source code at:
 *
 *   http://github.com/antirez/linenoise
 *
 * Does a number of crazy assumptions that happen to be true in 99.9999% of
 * the 2010 UNIX computers around.
 *
 * ------------------------------------------------------------------------
 *
 * Copyright (c) 2010-2016, Salvatore Sanfilippo <antirez at gmail dot com>
 * Copyright (c) 2010-2013, Pieter Noordhuis <pcnoordhuis at gmail dot com>
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *  *  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *  *  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.
 *
 * ------------------------------------------------------------------------
 *
 * References:
 * - http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
 * - http://www.3waylabs.com/nw/WWW/products/wizcon/vt220.html
 *
 * Todo list:
 * - Filter bogus Ctrl+<char> combinations.
 * - Win32 support
 *
 * Bloat:
 * - History search like Ctrl+r in readline?
 *
 * List of escape sequences used by this program, we do everything just
 * with three sequences. In order to be so cheap we may have some
 * flickering effect with some slow terminal, but the lesser sequences
 * the more compatible.
 *
 * EL (Erase Line)
 *    Sequence: ESC [ n K
 *    Effect: if n is 0 or missing, clear from cursor to end of line
 *    Effect: if n is 1, clear from beginning of line to cursor
 *    Effect: if n is 2, clear entire line
 *
 * CUF (CUrsor Forward)
 *    Sequence: ESC [ n C
 *    Effect: moves cursor forward n chars
 *
 * CUB (CUrsor Backward)
 *    Sequence: ESC [ n D
 *    Effect: moves cursor backward n chars
 *
 * The following is used to get the terminal width if getting
 * the width with the TIOCGWINSZ ioctl fails
 *
 * DSR (Device Status Report)
 *    Sequence: ESC [ 6 n
 *    Effect: reports the current cusor position as ESC [ n ; m R
 *            where n is the row and m is the column
 *
 * When multi line mode is enabled, we also use an additional escape
 * sequence. However multi line editing is disabled by default.
 *
 * CUU (Cursor Up)
 *    Sequence: ESC [ n A
 *    Effect: moves cursor up of n chars.
 *
 * CUD (Cursor Down)
 *    Sequence: ESC [ n B
 *    Effect: moves cursor down of n chars.
 *
 * When linenoiseClearScreen() is called, two additional escape sequences
 * are used in order to clear the screen and position the cursor at home
 * position.
 *
 * CUP (Cursor position)
 *    Sequence: ESC [ H
 *    Effect: moves the cursor to upper left corner
 *
 * ED (Erase display)
 *    Sequence: ESC [ 2 J
 *    Effect: clear the whole screen
 *
 */

#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include "linenoise.h"

#define LINENOISE_DEFAULT_HISTORY_MAX_LEN 100
#define LINENOISE_MAX_LINE 4096
#define UNUSED(x) (void)(x)
static char *unsupported_term[] = {"dumb","cons25","emacs",NULL};
static linenoiseCompletionCallback *completionCallback = NULL;
static linenoiseHintsCallback *hintsCallback = NULL;
static linenoiseFreeHintsCallback *freeHintsCallback = NULL;

static struct termios orig_termios; /* In order to restore at exit.*/
static int maskmode = 0; /* Show "***" instead of input. For passwords. */
static int rawmode = 0; /* For atexit() function to check if restore is needed*/
static int mlmode = 0;  /* Multi line mode. Default is single line. */
static int atexit_registered = 0; /* Register atexit just 1 time. */
static int history_max_len = LINENOISE_DEFAULT_HISTORY_MAX_LEN;
static int history_len = 0;
static char **history = NULL;

/* The linenoiseState structure represents the state during line editing.
 * We pass this state to functions implementing specific editing
 * functionalities. */
struct linenoiseState {
  int ifd;            /* Terminal stdin file descriptor. */
  int ofd;            /* Terminal stdout file descriptor. */
  char *buf;          /* Edited line buffer. */
  size_t buflen;      /* Edited line buffer size. */
  const char *prompt; /* Prompt to display. */
  size_t plen;        /* Prompt length. */
  size_t pos;         /* Current cursor position. */
  size_t oldcolpos;   /* Previous refresh cursor column position. */
  size_t len;         /* Current edited line length. */
  size_t cols;        /* Number of columns in terminal. */
  size_t maxrows;     /* Maximum num of rows used so far (multiline mode) */
  int history_index;  /* The history index we are currently editing. */
};

enum KEY_ACTION{
  KEY_NULL = 0,	    /* NULL */
  CTRL_A = 1,         /* Ctrl+a */
  CTRL_B = 2,         /* Ctrl-b */
  CTRL_C = 3,         /* Ctrl-c */
  CTRL_D = 4,         /* Ctrl-d */
  CTRL_E = 5,         /* Ctrl-e */
  CTRL_F = 6,         /* Ctrl-f */
  CTRL_H = 8,         /* Ctrl-h */
  TAB = 9,            /* Tab */
  LINE_FEED = 10,            /* Line feed */
  CTRL_K = 11,        /* Ctrl+k */
  CTRL_L = 12,        /* Ctrl+l */
  ENTER = 13,         /* Enter */
  CTRL_N = 14,        /* Ctrl-n */
  CTRL_P = 16,        /* Ctrl-p */
  CTRL_T = 20,        /* Ctrl-t */
  CTRL_U = 21,        /* Ctrl+u */
  CTRL_W = 23,        /* Ctrl+w */
  ESC = 27,           /* Escape */
  BACKSPACE =  127    /* Backspace */
};

static void linenoiseAtExit(void);
int linenoiseHistoryAdd(const char *line);
static void refreshLine(struct linenoiseState *l);

/* Debugging macro. */
#if 0
FILE *lndebug_fp = NULL;
#define lndebug(...) \
do { \
if (lndebug_fp == NULL) { \
lndebug_fp = fopen("/tmp/lndebug.txt","a"); \
fprintf(lndebug_fp, \
"[%d %d %d] p: %d, rows: %d, rpos: %d, max: %d, oldmax: %d\n", \
(int)l->len,(int)l->pos,(int)l->oldcolpos,plen,rows,rpos, \
(int)l->maxrows,old_rows); \
} \
fprintf(lndebug_fp, ", " __VA_ARGS__); \
fflush(lndebug_fp); \
} while (0)
#else
#define lndebug(fmt, ...)
#endif

/* ========================== Encoding functions ============================= */

/* Get byte length and column length of the previous character */
static size_t defaultPrevCharLen(const char *buf, size_t buf_len, size_t pos, size_t *col_len) {
  UNUSED(buf); UNUSED(buf_len); UNUSED(pos);
  if (col_len != NULL) *col_len = 1;
  return 1;
}

/* Get byte length and column length of the next character */
static size_t defaultNextCharLen(const char *buf, size_t buf_len, size_t pos, size_t *col_len) {
  UNUSED(buf); UNUSED(buf_len); UNUSED(pos);
  if (col_len != NULL) *col_len = 1;
  return 1;
}

/* Read bytes of the next character */
static size_t defaultReadCode(int fd, char *buf, size_t buf_len, int* c) {
  if (buf_len < 1) return -1;
  int nread = read(fd,&buf[0],1);
  if (nread == 1) *c = buf[0];
  return nread;
}

/* Set default encoding functions */
static linenoisePrevCharLen *prevCharLen = defaultPrevCharLen;
static linenoiseNextCharLen *nextCharLen = defaultNextCharLen;
static linenoiseReadCode *readCode = defaultReadCode;

/* Set used defined encoding functions */
void linenoiseSetEncodingFunctions(
    linenoisePrevCharLen *prevCharLenFunc,
    linenoiseNextCharLen *nextCharLenFunc,
    linenoiseReadCode *readCodeFunc) {
  prevCharLen = prevCharLenFunc;
  nextCharLen = nextCharLenFunc;
  readCode = readCodeFunc;
}

/* Get column length from begining of buffer to current byte position */
static size_t columnPos(const char *buf, size_t buf_len, size_t pos) {
  size_t ret = 0;
  size_t off = 0;
  while (off < pos) {
    size_t col_len;
    size_t len = nextCharLen(buf,buf_len,off,&col_len);
    off += len;
    ret += col_len;
  }
  return ret;
}

/* Get column length from begining of buffer to current byte position for multiline mode*/
static size_t columnPosForMultiLine(const char *buf, size_t buf_len, size_t pos, size_t cols, size_t ini_pos) {
  size_t ret = 0;
  size_t colwid = ini_pos;

  size_t off = 0;
  while (off < buf_len) {
    size_t col_len;
    size_t len = nextCharLen(buf,buf_len,off,&col_len);

    int dif = (int)(colwid + col_len) - (int)cols;
    if (dif > 0) {
      ret += dif;
      colwid = col_len;
    } else if (dif == 0) {
      colwid = 0;
    } else {
      colwid += col_len;
    }

    if (off >= pos) break;
    off += len;
    ret += col_len;
  }

  return ret;
}

/* ======================= Low level terminal handling ====================== */

/* Enable "mask mode". When it is enabled, instead of the input that
 * the user is typing, the terminal will just display a corresponding
 * number of asterisks, like "****". This is useful for passwords and other
 * secrets that should not be displayed. */
void linenoiseMaskModeEnable(void) {
  maskmode = 1;
}

/* Disable mask mode. */
void linenoiseMaskModeDisable(void) {
  maskmode = 0;
}

/* Set if to use or not the multi line mode. */
void linenoiseSetMultiLine(int ml) {
  mlmode = ml;
}

/* Return true if the terminal name is in the list of terminals we know are
 * not able to understand basic escape sequences. */
static int isUnsupportedTerm(void) {
  char *term = getenv("TERM");
  int j;

  if (term == NULL) return 0;
  for (j = 0; unsupported_term[j]; j++)
    if (!strcasecmp(term,unsupported_term[j])) return 1;
    return 0;
}

/* Raw mode: 1960 magic shit. */
static int enableRawMode(int fd) {
  struct termios raw;

  if (!isatty(STDIN_FILENO)) goto fatal;
  if (!atexit_registered) {
    atexit(linenoiseAtExit);
    atexit_registered = 1;
  }
  if (tcgetattr(fd,&orig_termios) == -1) goto fatal;

  raw = orig_termios;  /* modify the original mode */
  /* input modes: no break, no CR to NL, no parity check, no strip char,
   * no start/stop output control. */
  raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
  /* output modes - disable post processing */
  raw.c_oflag &= ~(OPOST);
  /* control modes - set 8 bit chars */
  raw.c_cflag |= (CS8);
  /* local modes - choing off, canonical off, no extended functions,
   * no signal chars (^Z,^C) */
  raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
  /* control chars - set return condition: min number of bytes and timer.
   * We want read to return every single byte, without timeout. */
  raw.c_cc[VMIN] = 1; raw.c_cc[VTIME] = 0; /* 1 byte, no timer */

  /* put terminal in raw mode after flushing */
  if (tcsetattr(fd,TCSADRAIN,&raw) < 0) goto fatal;
  rawmode = 1;
  return 0;

  fatal:
  errno = ENOTTY;
  return -1;
}

static void disableRawMode(int fd) {
  /* Don't even check the return value as it's too late. */
  if (rawmode && tcsetattr(fd,TCSADRAIN,&orig_termios) != -1)
    rawmode = 0;
}

/* Use the ESC [6n escape sequence to query the horizontal cursor position
 * and return it. On error -1 is returned, on success the position of the
 * cursor. */
static int getCursorPosition(int ifd, int ofd) {
  char buf[32];
  int cols, rows;
  unsigned int i = 0;

  /* Report cursor location */
  if (write(ofd, "\x1b[6n", 4) != 4) return -1;

  /* Read the response: ESC [ rows ; cols R */
  while (i < sizeof(buf)-1) {
    if (read(ifd,buf+i,1) != 1) break;
    if (buf[i] == 'R') break;
    i++;
  }
  buf[i] = '\0';

  /* Parse it. */
  if (buf[0] != ESC || buf[1] != '[') return -1;
  if (sscanf(buf+2,"%d;%d",&rows,&cols) != 2) return -1;
  return cols;
}

/* Try to get the number of columns in the current terminal, or assume 80
 * if it fails. */
static int getColumns(int ifd, int ofd) {
  struct winsize ws;

  if (ioctl(1, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
    /* ioctl() failed. Try to query the terminal itself. */
    int start, cols;

    /* Get the initial position so we can restore it later. */
    start = getCursorPosition(ifd,ofd);
    if (start == -1) goto failed;

    /* Go to right margin and get position. */
    if (write(ofd,"\x1b[999C",6) != 6) goto failed;
    cols = getCursorPosition(ifd,ofd);
    if (cols == -1) goto failed;

    /* Restore position. */
    if (cols > start) {
      char seq[32];
      snprintf(seq,32,"\x1b[%dD",cols-start);
      if (write(ofd,seq,strlen(seq)) == -1) {
        /* Can't recover... */
      }
    }
    return cols;
  } else {
    return ws.ws_col;
  }

  failed:
  return 80;
}

/* Clear the screen. Used to handle ctrl+l */
void linenoiseClearScreen(void) {
  if (write(STDOUT_FILENO,"\x1b[H\x1b[2J",7) <= 0) {
    /* nothing to do, just to avoid warning. */
  }
}

/* Beep, used for completion when there is nothing to complete or when all
 * the choices were already shown. */
static void linenoiseBeep(void) {
  fprintf(stderr, "\x7");
  fflush(stderr);
}

/* ============================== Completion ================================ */

/* Free a list of completion option populated by linenoiseAddCompletion(). */
static void freeCompletions(linenoiseCompletions *lc) {
  size_t i;
  for (i = 0; i < lc->len; i++)
    free(lc->cvec[i]);
  if (lc->cvec != NULL)
    free(lc->cvec);
}

/* This is an helper function for linenoiseEdit() and is called when the
 * user types the <tab> key in order to complete the string currently in the
 * input.
 *
 * The state of the editing is encapsulated into the pointed linenoiseState
 * structure as described in the structure definition. */
static int completeLine(struct linenoiseState *ls, char *cbuf, size_t cbuf_len, int *c) {
  linenoiseCompletions lc = { 0, NULL };
  int nread = 0, nwritten;
  *c = 0;

  completionCallback(ls->buf,&lc);
  if (lc.len == 0) {
    linenoiseBeep();
  } else {
    size_t stop = 0, i = 0;

    while(!stop) {
      /* Show completion or original buffer */
      if (i < lc.len) {
        struct linenoiseState saved = *ls;

        ls->len = ls->pos = strlen(lc.cvec[i]);
        ls->buf = lc.cvec[i];
        refreshLine(ls);
        ls->len = saved.len;
        ls->pos = saved.pos;
        ls->buf = saved.buf;
      } else {
        refreshLine(ls);
      }

      nread = readCode(ls->ifd,cbuf,cbuf_len,c);
      if (nread <= 0) {
        freeCompletions(&lc);
        *c = -1;
        return nread;
      }

      switch(*c) {
        case 9: /* tab */
        i = (i+1) % (lc.len+1);
        if (i == lc.len) linenoiseBeep();
        break;
        case 27: /* escape */
        /* Re-show original buffer */
        if (i < lc.len) refreshLine(ls);
        stop = 1;
        break;
        default:
          /* Update buffer and return */
          if (i < lc.len) {
            nwritten = snprintf(ls->buf,ls->buflen,"%s",lc.cvec[i]);
            ls->len = ls->pos = nwritten;
          }
          stop = 1;
          break;
      }
    }
  }

  freeCompletions(&lc);
  return nread;
}

/* Register a callback function to be called for tab-completion. */
void linenoiseSetCompletionCallback(linenoiseCompletionCallback *fn) {
  completionCallback = fn;
}

/* Register a hits function to be called to show hits to the user at the
 * right of the prompt. */
void linenoiseSetHintsCallback(linenoiseHintsCallback *fn) {
  hintsCallback = fn;
}

/* Register a function to free the hints returned by the hints callback
 * registered with linenoiseSetHintsCallback(). */
void linenoiseSetFreeHintsCallback(linenoiseFreeHintsCallback *fn) {
  freeHintsCallback = fn;
}

/* This function is used by the callback function registered by the user
 * in order to add completion options given the input string when the
 * user typed <tab>. See the example.c source code for a very easy to
 * understand example. */
void linenoiseAddCompletion(linenoiseCompletions *lc, const char *str) {
  size_t len = strlen(str);
  char *copy, **cvec;

  copy = malloc(len+1);
  if (copy == NULL) return;
  memcpy(copy,str,len+1);
  cvec = realloc(lc->cvec,sizeof(char*)*(lc->len+1));
  if (cvec == NULL) {
    free(copy);
    return;
  }
  lc->cvec = cvec;
  lc->cvec[lc->len++] = copy;
}

/* =========================== Line editing ================================= */

/* We define a very simple "append buffer" structure, that is an heap
 * allocated string where we can append to. This is useful in order to
 * write all the escape sequences in a buffer and flush them to the standard
 * output in a single call, to avoid flickering effects. */
struct abuf {
  char *b;
  int len;
};

static void abInit(struct abuf *ab) {
  ab->b = NULL;
  ab->len = 0;
}

static void abAppend(struct abuf *ab, const char *s, int len) {
  char *new = realloc(ab->b,ab->len+len);

  if (new == NULL) return;
  memcpy(new+ab->len,s,len);
  ab->b = new;
  ab->len += len;
}

static void abFree(struct abuf *ab) {
  free(ab->b);
}

/* Helper of refreshSingleLine() and refreshMultiLine() to show hints
 * to the right of the prompt. */
void refreshShowHints(struct abuf *ab, struct linenoiseState *l, int pcollen) {
  char seq[64];
  size_t collen = pcollen+columnPos(l->buf,l->len,l->len);
  if (hintsCallback && collen < l->cols) {
    int color = -1, bold = 0;
    char *hint = hintsCallback(l->buf,&color,&bold);
    if (hint) {
      int hintlen = strlen(hint);
      int hintmaxlen = l->cols-collen;
      if (hintlen > hintmaxlen) hintlen = hintmaxlen;
      if (bold == 1 && color == -1) color = 37;
      if (color != -1 || bold != 0)
        snprintf(seq,64,"\033[%d;%d;49m",bold,color);
      else
        seq[0] = '\0';
      abAppend(ab,seq,strlen(seq));
      abAppend(ab,hint,hintlen);
      if (color != -1 || bold != 0)
        abAppend(ab,"\033[0m",4);
      /* Call the function to free the hint returned. */
      if (freeHintsCallback) freeHintsCallback(hint);
    }
  }
}

/* Check if text is an ANSI escape sequence
 */
static int isAnsiEscape(const char *buf, size_t buf_len, size_t* len) {
  if (buf_len > 2 && !memcmp("\033[", buf, 2)) {
    size_t off = 2;
    while (off < buf_len) {
      switch (buf[off++]) {
        case 'A': case 'B': case 'C': case 'D': case 'E':
          case 'F': case 'G': case 'H': case 'J': case 'K':
            case 'S': case 'T': case 'f': case 'm':
              *len = off;
              return 1;
      }
    }
  }
  return 0;
}

/* Get column length of prompt text
 */
static size_t promptTextColumnLen(const char *prompt, size_t plen) {
  char buf[LINENOISE_MAX_LINE];
  size_t buf_len = 0;
  size_t off = 0;
  while (off < plen) {
    size_t len;
    if (isAnsiEscape(prompt + off, plen - off, &len)) {
      off += len;
      continue;
    }
    buf[buf_len++] = prompt[off++];
  }
  return columnPos(buf,buf_len,buf_len);
}

/* Single line low level line refresh.
 *
 * Rewrite the currently edited line accordingly to the buffer content,
 * cursor position, and number of columns of the terminal. */
static void refreshSingleLine(struct linenoiseState *l) {
  char seq[64];
  size_t pcollen = promptTextColumnLen(l->prompt,strlen(l->prompt));
  int fd = l->ofd;
  char *buf = l->buf;
  size_t len = l->len;
  size_t pos = l->pos;
  struct abuf ab;

  while((pcollen+columnPos(buf,len,pos)) >= l->cols) {
    int chlen = nextCharLen(buf,len,0,NULL);
    buf += chlen;
    len -= chlen;
    pos -= chlen;
  }
  while (pcollen+columnPos(buf,len,len) > l->cols) {
    len -= prevCharLen(buf,len,len,NULL);
  }

  abInit(&ab);
  /* Cursor to left edge */
  snprintf(seq,64,"\r");
  abAppend(&ab,seq,strlen(seq));
  /* Write the prompt and the current buffer content */
  abAppend(&ab,l->prompt,strlen(l->prompt));
  if (maskmode == 1) {
    while (len--) abAppend(&ab,"*",1);
  } else {
    abAppend(&ab,buf,len);
  }
  /* Show hits if any. */
  refreshShowHints(&ab,l,pcollen);
  /* Erase to right */
  snprintf(seq,64,"\x1b[0K");
  abAppend(&ab,seq,strlen(seq));
  /* Move cursor to original position. */
  snprintf(seq,64,"\r\x1b[%dC", (int)(columnPos(buf,len,pos)+pcollen));
  abAppend(&ab,seq,strlen(seq));
  if (write(fd,ab.b,ab.len) == -1) {} /* Can't recover from write error. */
  abFree(&ab);
}

/* Multi line low level line refresh.
 *
 * Rewrite the currently edited line accordingly to the buffer content,
 * cursor position, and number of columns of the terminal. */
static void refreshMultiLine(struct linenoiseState *l) {
  char seq[64];
  size_t pcollen = promptTextColumnLen(l->prompt,strlen(l->prompt));
  int colpos = columnPosForMultiLine(l->buf, l->len, l->len, l->cols, pcollen);
  int colpos2; /* cursor column position. */
  int rows = (pcollen+colpos+l->cols-1)/l->cols; /* rows used by current buf. */
  int rpos = (pcollen+l->oldcolpos+l->cols)/l->cols; /* cursor relative row. */
  int rpos2; /* rpos after refresh. */
  int col; /* colum position, zero-based. */
  int old_rows = l->maxrows;
  int fd = l->ofd, j;
  struct abuf ab;

  /* Update maxrows if needed. */
  if (rows > (int)l->maxrows) l->maxrows = rows;

  /* First step: clear all the lines used before. To do so start by
   * going to the last row. */
  abInit(&ab);
  if (old_rows-rpos > 0) {
    lndebug("go down %d", old_rows-rpos);
    snprintf(seq,64,"\x1b[%dB", old_rows-rpos);
    abAppend(&ab,seq,strlen(seq));
  }

  /* Now for every row clear it, go up. */
  for (j = 0; j < old_rows-1; j++) {
    lndebug("clear+up");
    snprintf(seq,64,"\r\x1b[0K\x1b[1A");
    abAppend(&ab,seq,strlen(seq));
  }

  /* Clean the top line. */
  lndebug("clear");
  snprintf(seq,64,"\r\x1b[0K");
  abAppend(&ab,seq,strlen(seq));

  /* Write the prompt and the current buffer content */
  abAppend(&ab,l->prompt,strlen(l->prompt));
  if (maskmode == 1) {
    unsigned int i;
    for (i = 0; i < l->len; i++) abAppend(&ab,"*",1);
  } else {
    abAppend(&ab,l->buf,l->len);
  }

  /* Show hits if any. */
  refreshShowHints(&ab,l,pcollen);

  /* Get column length to cursor position */
  colpos2 = columnPosForMultiLine(l->buf,l->len,l->pos,l->cols,pcollen);

  /* If we are at the very end of the screen with our prompt, we need to
   * emit a newline and move the prompt to the first column. */
  if (l->pos &&
  l->pos == l->len &&
  (colpos2+pcollen) % l->cols == 0)
  {
    lndebug("<newline>");
    abAppend(&ab,"\n",1);
    snprintf(seq,64,"\r");
    abAppend(&ab,seq,strlen(seq));
    rows++;
    if (rows > (int)l->maxrows) l->maxrows = rows;
  }

  /* Move cursor to right position. */
  rpos2 = (pcollen+colpos2+l->cols)/l->cols; /* current cursor relative row. */
  lndebug("rpos2 %d", rpos2);

  /* Go up till we reach the expected positon. */
  if (rows-rpos2 > 0) {
    lndebug("go-up %d", rows-rpos2);
    snprintf(seq,64,"\x1b[%dA", rows-rpos2);
    abAppend(&ab,seq,strlen(seq));
  }

  /* Set column. */
  col = (pcollen + colpos2) % l->cols;
  lndebug("set col %d", 1+col);
  if (col)
    snprintf(seq,64,"\r\x1b[%dC", col);
  else
    snprintf(seq,64,"\r");
  abAppend(&ab,seq,strlen(seq));

  lndebug("\n");
  l->oldcolpos = colpos2;

  if (write(fd,ab.b,ab.len) == -1) {} /* Can't recover from write error. */
  abFree(&ab);
}

/* Calls the two low level functions refreshSingleLine() or
 * refreshMultiLine() according to the selected mode. */
static void refreshLine(struct linenoiseState *l) {
  if (mlmode)
    refreshMultiLine(l);
  else
    refreshSingleLine(l);
}

/* Insert the character 'c' at cursor current position.
 *
 * On error writing to the terminal -1 is returned, otherwise 0. */
int linenoiseEditInsert(struct linenoiseState *l, const char *cbuf, int clen) {
  if (l->len+clen <= l->buflen) {
    if (l->len == l->pos) {
      memcpy(&l->buf[l->pos],cbuf,clen);
      l->pos+=clen;
      l->len+=clen;;
      l->buf[l->len] = '\0';
      if ((!mlmode && promptTextColumnLen(l->prompt,l->plen)+columnPos(l->buf,l->len,l->len) < l->cols && !hintsCallback)) {
        /* Avoid a full update of the line in the
         * trivial case. */
        if (maskmode == 1) {
          static const char d = '*';
          if (write(l->ofd,&d,1) == -1) return -1;
        } else {
          if (write(l->ofd,cbuf,clen) == -1) return -1;
        }
      } else {
        refreshLine(l);
      }
    } else {
      memmove(l->buf+l->pos+clen,l->buf+l->pos,l->len-l->pos);
      memcpy(&l->buf[l->pos],cbuf,clen);
      l->pos+=clen;
      l->len+=clen;
      l->buf[l->len] = '\0';
      refreshLine(l);
    }
  }
  return 0;
}

/* Move cursor on the left. */
void linenoiseEditMoveLeft(struct linenoiseState *l) {
  if (l->pos > 0) {
    l->pos -= prevCharLen(l->buf,l->len,l->pos,NULL);
    refreshLine(l);
  }
}

/* Move cursor on the right. */
void linenoiseEditMoveRight(struct linenoiseState *l) {
  if (l->pos != l->len) {
    l->pos += nextCharLen(l->buf,l->len,l->pos,NULL);
    refreshLine(l);
  }
}

/* Move cursor to the start of the line. */
void linenoiseEditMoveHome(struct linenoiseState *l) {
  if (l->pos != 0) {
    l->pos = 0;
    refreshLine(l);
  }
}

/* Move cursor to the end of the line. */
void linenoiseEditMoveEnd(struct linenoiseState *l) {
  if (l->pos != l->len) {
    l->pos = l->len;
    refreshLine(l);
  }
}

/* Substitute the currently edited line with the next or previous history
 * entry as specified by 'dir'. */
#define LINENOISE_HISTORY_NEXT 0
#define LINENOISE_HISTORY_PREV 1
void linenoiseEditHistoryNext(struct linenoiseState *l, int dir) {
  if (history_len > 1) {
    /* Update the current history entry before to
     * overwrite it with the next one. */
    free(history[history_len - 1 - l->history_index]);
    history[history_len - 1 - l->history_index] = strdup(l->buf);
    /* Show the new entry */
    l->history_index += (dir == LINENOISE_HISTORY_PREV) ? 1 : -1;
    if (l->history_index < 0) {
      l->history_index = 0;
      return;
    } else if (l->history_index >= history_len) {
      l->history_index = history_len-1;
      return;
    }
    strncpy(l->buf,history[history_len - 1 - l->history_index],l->buflen);
    l->buf[l->buflen-1] = '\0';
    l->len = l->pos = strlen(l->buf);
    refreshLine(l);
  }
}

/* Delete the character at the right of the cursor without altering the cursor
 * position. Basically this is what happens with the "Delete" keyboard key. */
void linenoiseEditDelete(struct linenoiseState *l) {
  if (l->len > 0 && l->pos < l->len) {
    int chlen = nextCharLen(l->buf,l->len,l->pos,NULL);
    memmove(l->buf+l->pos,l->buf+l->pos+chlen,l->len-l->pos-chlen);
    l->len-=chlen;
    l->buf[l->len] = '\0';
    refreshLine(l);
  }
}

/* Backspace implementation. */
void linenoiseEditBackspace(struct linenoiseState *l) {
  if (l->pos > 0 && l->len > 0) {
    int chlen = prevCharLen(l->buf,l->len,l->pos,NULL);
    memmove(l->buf+l->pos-chlen,l->buf+l->pos,l->len-l->pos);
    l->pos-=chlen;
    l->len-=chlen;
    l->buf[l->len] = '\0';
    refreshLine(l);
  }
}

/* Delete the previosu word, maintaining the cursor at the start of the
 * current word. */
void linenoiseEditDeletePrevWord(struct linenoiseState *l) {
  size_t old_pos = l->pos;
  size_t diff;

  while (l->pos > 0 && l->buf[l->pos-1] == ' ')
    l->pos--;
  while (l->pos > 0 && l->buf[l->pos-1] != ' ')
    l->pos--;
  diff = old_pos - l->pos;
  memmove(l->buf+l->pos,l->buf+old_pos,l->len-old_pos+1);
  l->len -= diff;
  refreshLine(l);
}

/* This function is the core of the line editing capability of linenoise.
 * It expects 'fd' to be already in "raw mode" so that every key pressed
 * will be returned ASAP to read().
 *
 * The resulting string is put into 'buf' when the user type enter, or
 * when ctrl+d is typed.
 *
 * The function returns the length of the current buffer. */
static int linenoiseEdit(int stdin_fd, int stdout_fd, char *buf, size_t buflen, const char *prompt)
{
  struct linenoiseState l;

  /* Populate the linenoise state that we pass to functions implementing
   * specific editing functionalities. */
  l.ifd = stdin_fd;
  l.ofd = stdout_fd;
  l.buf = buf;
  l.buflen = buflen;
  l.prompt = prompt;
  l.plen = strlen(prompt);
  l.oldcolpos = l.pos = 0;
  l.len = 0;
  l.cols = getColumns(stdin_fd, stdout_fd);
  l.maxrows = 0;
  l.history_index = 0;

  /* Buffer starts empty. */
  l.buf[0] = '\0';
  l.buflen--; /* Make sure there is always space for the nulterm */

  /* The latest history entry is always our current buffer, that
   * initially is just an empty string. */
  linenoiseHistoryAdd("");

  if (write(l.ofd,prompt,l.plen) == -1) return -1;
  while(1) {
    int c;
    char cbuf[32]; // large enough for any encoding?
    int nread;
    char seq[3];

    nread = readCode(l.ifd,cbuf,sizeof(cbuf),&c);
    if (nread <= 0) return l.len;

    /* Only autocomplete when the callback is set. It returns < 0 when
     * there was an error reading from fd. Otherwise it will return the
     * character that should be handled next. */
    if (c == 9 && completionCallback != NULL) {
      nread = completeLine(&l,cbuf,sizeof(cbuf),&c);
      /* Return on errors */
      if (c < 0) return l.len;
      /* Read next character when 0 */
      if (c == 0) continue;
    }

    switch(c) {
      case LINE_FEED:
      case ENTER:    /* enter */
      history_len--;
      free(history[history_len]);
      if (mlmode) linenoiseEditMoveEnd(&l);
      if (hintsCallback) {
        /* Force a refresh without hints to leave the previous
         * line as the user typed it after a newline. */
        linenoiseHintsCallback *hc = hintsCallback;
        hintsCallback = NULL;
        refreshLine(&l);
        hintsCallback = hc;
      }
      return (int)l.len;
      case CTRL_C:     /* ctrl-c, clear line */
      buf[0] = '\0';
      l.pos = l.len = 0;
      refreshLine(&l);
      break;
      case BACKSPACE:   /* backspace */
      case 8:     /* ctrl-h */
      linenoiseEditBackspace(&l);
      break;
      case CTRL_D:     /* ctrl-d, act as end-of-file. */
      history_len--;
      free(history[history_len]);
      return -1;
      case CTRL_T:    /* ctrl-t, swaps current character with previous. */
      if (l.pos > 0 && l.pos < l.len) {
        int aux = buf[l.pos-1];
        buf[l.pos-1] = buf[l.pos];
        buf[l.pos] = aux;
        if (l.pos != l.len-1) l.pos++;
        refreshLine(&l);
      }
      break;
      case CTRL_B:     /* ctrl-b */
      linenoiseEditMoveLeft(&l);
      break;
      case CTRL_F:     /* ctrl-f */
      linenoiseEditMoveRight(&l);
      break;
      case CTRL_P:    /* ctrl-p */
      linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_PREV);
      break;
      case CTRL_N:    /* ctrl-n */
      linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_NEXT);
      break;
      case ESC:    /* escape sequence */
      /* Read the next two bytes representing the escape sequence.
       * Use two calls to handle slow terminals returning the two
       * chars at different times. */
      if (read(l.ifd,seq,1) == -1) break;
      if (read(l.ifd,seq+1,1) == -1) break;

      /* ESC [ sequences. */
      if (seq[0] == '[') {
        if (seq[1] >= '0' && seq[1] <= '9') {
          /* Extended escape, read additional byte. */
          if (read(l.ifd,seq+2,1) == -1) break;
          if (seq[2] == '~') {
            switch(seq[1]) {
              case '3': /* Delete key. */
              linenoiseEditDelete(&l);
              break;
            }
          }
        } else {
          switch(seq[1]) {
            case 'A': /* Up */
            linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_PREV);
            break;
            case 'B': /* Down */
            linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_NEXT);
            break;
            case 'C': /* Right */
            linenoiseEditMoveRight(&l);
            break;
            case 'D': /* Left */
            linenoiseEditMoveLeft(&l);
            break;
            case 'H': /* Home */
            linenoiseEditMoveHome(&l);
            break;
            case 'F': /* End*/
            linenoiseEditMoveEnd(&l);
            break;
          }
        }
      }

      /* ESC O sequences. */
      else if (seq[0] == 'O') {
        switch(seq[1]) {
          case 'H': /* Home */
          linenoiseEditMoveHome(&l);
          break;
          case 'F': /* End*/
          linenoiseEditMoveEnd(&l);
          break;
        }
      }
      break;
      default:
        if (linenoiseEditInsert(&l,cbuf,nread)) return -1;
        break;
        case CTRL_U: /* Ctrl+u, delete the whole line. */
        buf[0] = '\0';
        l.pos = l.len = 0;
        refreshLine(&l);
        break;
        case CTRL_K: /* Ctrl+k, delete from current to end of line. */
        buf[l.pos] = '\0';
        l.len = l.pos;
        refreshLine(&l);
        break;
        case CTRL_A: /* Ctrl+a, go to the start of the line */
        linenoiseEditMoveHome(&l);
        break;
        case CTRL_E: /* ctrl+e, go to the end of the line */
        linenoiseEditMoveEnd(&l);
        break;
        case CTRL_L: /* ctrl+l, clear screen */
        linenoiseClearScreen();
        refreshLine(&l);
        break;
        case CTRL_W: /* ctrl+w, delete previous word */
        linenoiseEditDeletePrevWord(&l);
        break;
    }
  }
  return l.len;
}

/* This special mode is used by linenoise in order to print scan codes
 * on screen for debugging / development purposes. It is implemented
 * by the linenoise_example program using the --keycodes option. */
void linenoisePrintKeyCodes(void) {
  char quit[4];

  printf("Linenoise key codes debugging mode.\n"
         "Press keys to see scan codes. Type 'quit' at any time to exit.\n");
  if (enableRawMode(STDIN_FILENO) == -1) return;
  memset(quit,' ',4);
  while(1) {
    char c;
    int nread;

    nread = read(STDIN_FILENO,&c,1);
    if (nread <= 0) continue;
    memmove(quit,quit+1,sizeof(quit)-1); /* shift string to left. */
    quit[sizeof(quit)-1] = c; /* Insert current char on the right. */
    if (memcmp(quit,"quit",sizeof(quit)) == 0) break;

    printf("'%c' %02x (%d) (type quit to exit)\n",
           isprint((int)c) ? c : '?', (int)c, (int)c);
    printf("\r"); /* Go left edge manually, we are in raw mode. */
    fflush(stdout);
  }
  disableRawMode(STDIN_FILENO);
}

/* This function calls the line editing function linenoiseEdit() using
 * the STDIN file descriptor set in raw mode. */
static int linenoiseRaw(char *buf, size_t buflen, const char *prompt) {
  int count;

  if (buflen == 0) {
    errno = EINVAL;
    return -1;
  }

  if (enableRawMode(STDIN_FILENO) == -1) return -1;
  count = linenoiseEdit(STDIN_FILENO, STDOUT_FILENO, buf, buflen, prompt);
  disableRawMode(STDIN_FILENO);
  printf("\n");
  return count;
}

/* This function is called when linenoise() is called with the standard
 * input file descriptor not attached to a TTY. So for example when the
 * program using linenoise is called in pipe or with a file redirected
 * to its standard input. In this case, we want to be able to return the
 * line regardless of its length (by default we are limited to 4k). */
static char *linenoiseNoTTY(void) {
  char *line = NULL;
  size_t len = 0, maxlen = 0;

  while(1) {
    if (len == maxlen) {
      if (maxlen == 0) maxlen = 16;
      maxlen *= 2;
      char *oldval = line;
      line = realloc(line,maxlen);
      if (line == NULL) {
        if (oldval) free(oldval);
        return NULL;
      }
    }
    int c = fgetc(stdin);
    if (c == EOF || c == '\n') {
      if (c == EOF && len == 0) {
        free(line);
        return NULL;
      } else {
        line[len] = '\0';
        return line;
      }
    } else {
      line[len] = c;
      len++;
    }
  }
}

/* The high level function that is the main API of the linenoise library.
 * This function checks if the terminal has basic capabilities, just checking
 * for a blacklist of stupid terminals, and later either calls the line
 * editing function or uses dummy fgets() so that you will be able to type
 * something even in the most desperate of the conditions. */
char *linenoise(const char *prompt) {
  char buf[LINENOISE_MAX_LINE];
  int count;

  if (!isatty(STDIN_FILENO)) {
    /* Not a tty: read from file / pipe. In this mode we don't want any
     * limit to the line size, so we call a function to handle that. */
    return linenoiseNoTTY();
  } else if (isUnsupportedTerm()) {
    size_t len;

    printf("%s",prompt);
    fflush(stdout);
    if (fgets(buf,LINENOISE_MAX_LINE,stdin) == NULL) return NULL;
    len = strlen(buf);
    while(len && (buf[len-1] == '\n' || buf[len-1] == '\r')) {
      len--;
      buf[len] = '\0';
    }
    return strdup(buf);
  } else {
    count = linenoiseRaw(buf,LINENOISE_MAX_LINE,prompt);
    if (count == -1) return NULL;
    return strdup(buf);
  }
}

/* This is just a wrapper the user may want to call in order to make sure
 * the linenoise returned buffer is freed with the same allocator it was
 * created with. Useful when the main program is using an alternative
 * allocator. */
void linenoiseFree(void *ptr) {
  free(ptr);
}

/* ================================ History ================================= */

/* Free the history, but does not reset it. Only used when we have to
 * exit() to avoid memory leaks are reported by valgrind & co. */
static void freeHistory(void) {
  if (history) {
    int j;

    for (j = 0; j < history_len; j++)
      free(history[j]);
    free(history);
  }
}

/* At exit we'll try to fix the terminal to the initial conditions. */
static void linenoiseAtExit(void) {
  disableRawMode(STDIN_FILENO);
  freeHistory();
}

/* This is the API call to add a new entry in the linenoise history.
 * It uses a fixed array of char pointers that are shifted (memmoved)
 * when the history max length is reached in order to remove the older
 * entry and make room for the new one, so it is not exactly suitable for huge
 * histories, but will work well for a few hundred of entries.
 *
 * Using a circular buffer is smarter, but a bit more complex to handle. */
int linenoiseHistoryAdd(const char *line) {
  char *linecopy;

  if (history_max_len == 0) return 0;

  /* Initialization on first call. */
  if (history == NULL) {
    history = malloc(sizeof(char*)*history_max_len);
    if (history == NULL) return 0;
    memset(history,0,(sizeof(char*)*history_max_len));
  }

  /* Don't add duplicated lines. */
  if (history_len && !strcmp(history[history_len-1], line)) return 0;

  /* Add an heap allocated copy of the line in the history.
   * If we reached the max length, remove the older line. */
  linecopy = strdup(line);
  if (!linecopy) return 0;
  if (history_len == history_max_len) {
    free(history[0]);
    memmove(history,history+1,sizeof(char*)*(history_max_len-1));
    history_len--;
  }
  history[history_len] = linecopy;
  history_len++;
  return 1;
}

/* Set the maximum length for the history. This function can be called even
 * if there is already some history, the function will make sure to retain
 * just the latest 'len' elements if the new history length value is smaller
 * than the amount of items already inside the history. */
int linenoiseHistorySetMaxLen(int len) {
  char **new;

  if (len < 1) return 0;
  if (history) {
    int tocopy = history_len;

    new = malloc(sizeof(char*)*len);
    if (new == NULL) return 0;

    /* If we can't copy everything, free the elements we'll not use. */
    if (len < tocopy) {
      int j;

      for (j = 0; j < tocopy-len; j++) free(history[j]);
      tocopy = len;
    }
    memset(new,0,sizeof(char*)*len);
    memcpy(new,history+(history_len-tocopy), sizeof(char*)*tocopy);
    free(history);
    history = new;
  }
  history_max_len = len;
  if (history_len > history_max_len)
    history_len = history_max_len;
  return 1;
}

/* Save the history in the specified file. On success 0 is returned
 * otherwise -1 is returned. */
int linenoiseHistorySave(const char *filename) {
  mode_t old_umask = umask(S_IXUSR|S_IRWXG|S_IRWXO);
  FILE *fp;
  int j;

  fp = fopen(filename,"w");
  umask(old_umask);
  if (fp == NULL) return -1;
  chmod(filename,S_IRUSR|S_IWUSR);
  for (j = 0; j < history_len; j++)
    fprintf(fp,"%s\n",history[j]);
  fclose(fp);
  return 0;
}

/* Load the history from the specified file. If the file does not exist
 * zero is returned and no operation is performed.
 *
 * If the file exists and the operation succeeded 0 is returned, otherwise
 * on error -1 is returned. */
int linenoiseHistoryLoad(const char *filename) {
  FILE *fp = fopen(filename,"r");
  char buf[LINENOISE_MAX_LINE];

  if (fp == NULL) return -1;

  while (fgets(buf,LINENOISE_MAX_LINE,fp) != NULL) {
    char *p;

    p = strchr(buf,'\r');
    if (!p) p = strchr(buf,'\n');
    if (p) *p = '\0';
    linenoiseHistoryAdd(buf);
  }
  fclose(fp);
  return 0;
}