ush

linenoise.c (39251B)

---

 /* 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
 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 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 oldpos;      /* Previous refresh cursor 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 */
 	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->oldpos,plen,rows,rpos, \
             (int)l->maxrows,old_rows); \
         } \
         fprintf(lndebug_fp, ", " __VA_ARGS__); \
         fflush(lndebug_fp); \
     } while (0)
 #else
 #define lndebug(fmt, ...)
 #endif
 
 /* ======================= Low level terminal handling ====================== */
 
 /* 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,TCSAFLUSH,&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,TCSAFLUSH,&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) {
     linenoiseCompletions lc = { 0, NULL };
     int nread, nwritten;
     char 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 = read(ls->ifd,&c,1);
             if (nread <= 0) {
                 freeCompletions(&lc);
                 return -1;
             }
 
             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 c; /* Return last read character */
 }
 
 /* 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 plen) {
     char seq[64];
     if (hintsCallback && plen+l->len < l->cols) {
         int color = -1, bold = 0;
         char *hint = hintsCallback(l->buf,&color,&bold);
         if (hint) {
             int hintlen = strlen(hint);
             int hintmaxlen = l->cols-(plen+l->len);
             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);
         }
     }
 }
 
 /* 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 plen = 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((plen+pos) >= l->cols) {
         buf++;
         len--;
         pos--;
     }
     while (plen+len > l->cols) {
         len--;
     }
 
     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));
     abAppend(&ab,buf,len);
     /* Show hits if any. */
     refreshShowHints(&ab,l,plen);
     /* 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)(pos+plen));
     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];
     int plen = strlen(l->prompt);
     int rows = (plen+l->len+l->cols-1)/l->cols; /* rows used by current buf. */
     int rpos = (plen+l->oldpos+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));
     abAppend(&ab,l->buf,l->len);
 
     /* Show hits if any. */
     refreshShowHints(&ab,l,plen);
 
     /* 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 &&
         (l->pos+plen) % 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 = (plen+l->pos+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 = (plen+(int)l->pos) % (int)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->oldpos = l->pos;
 
     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, char c) {
     if (l->len < l->buflen) {
         if (l->len == l->pos) {
             l->buf[l->pos] = c;
             l->pos++;
             l->len++;
             l->buf[l->len] = '\0';
             if ((!mlmode && l->plen+l->len < l->cols && !hintsCallback)) {
                 /* Avoid a full update of the line in the
                  * trivial case. */
                 if (write(l->ofd,&c,1) == -1) return -1;
             } else {
                 refreshLine(l);
             }
         } else {
             memmove(l->buf+l->pos+1,l->buf+l->pos,l->len-l->pos);
             l->buf[l->pos] = c;
             l->len++;
             l->pos++;
             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--;
         refreshLine(l);
     }
 }
 
 /* Move cursor on the right. */
 void linenoiseEditMoveRight(struct linenoiseState *l) {
     if (l->pos != l->len) {
         l->pos++;
         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) {
         memmove(l->buf+l->pos,l->buf+l->pos+1,l->len-l->pos-1);
         l->len--;
         l->buf[l->len] = '\0';
         refreshLine(l);
     }
 }
 
 /* Backspace implementation. */
 void linenoiseEditBackspace(struct linenoiseState *l) {
     if (l->pos > 0 && l->len > 0) {
         memmove(l->buf+l->pos-1,l->buf+l->pos,l->len-l->pos);
         l->pos--;
         l->len--;
         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.oldpos = 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) {
         char c;
         int nread;
         char seq[3];
 
         nread = read(l.ifd,&c,1);
         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) {
             c = completeLine(&l);
             /* Return on errors */
             if (c < 0) return l.len;
             /* Read next character when 0 */
             if (c == 0) continue;
         }
 
         switch(c) {
         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 */
             errno = EAGAIN;
             return -1;
         case BACKSPACE:   /* backspace */
         case 8:     /* ctrl-h */
             linenoiseEditBackspace(&l);
             break;
         case CTRL_D:     /* ctrl-d, remove char at right of cursor, or if the
                             line is empty, act as end-of-file. */
             if (l.len > 0) {
                 linenoiseEditDelete(&l);
             } else {
                 history_len--;
                 free(history[history_len]);
                 return -1;
             }
             break;
         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,c)) 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(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;
 }