linenoise.c

   1 /* linenoise.c -- guerrilla line editing library against the idea that a
   2  * line editing lib needs to be 20,000 lines of C code.
   3  *
   4  * You can find the latest source code at:
   5  *
   6  *   http://github.com/antirez/linenoise
   7  *
   8  * Does a number of crazy assumptions that happen to be true in 99.9999% of
   9  * the 2010 UNIX computers around.
  10  *
  11  * Copyright (c) 2010, Salvatore Sanfilippo <antirez at gmail dot com>
  12  * All rights reserved.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are met:
  16  *
  17  *   * Redistributions of source code must retain the above copyright notice,
  18  *     this list of conditions and the following disclaimer.
  19  *   * Redistributions in binary form must reproduce the above copyright
  20  *     notice, this list of conditions and the following disclaimer in the
  21  *     documentation and/or other materials provided with the distribution.
  22  *   * Neither the name of Redis nor the names of its contributors may be used
  23  *     to endorse or promote products derived from this software without
  24  *     specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  27  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  30  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  36  * POSSIBILITY OF SUCH DAMAGE.
  37  *
  38  * References:
  39  * - http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
  40  * - http://www.3waylabs.com/nw/WWW/products/wizcon/vt220.html
  41  *
  42  * Todo list:
  43  * - Switch to gets() if $TERM is something we can't support.
  44  * - Filter bogus Ctrl+<char> combinations.
  45  * - Win32 support
  46  *
  47  * Bloat:
  48  * - Completion?
  49  * - History search like Ctrl+r in readline?
  50  *
  51  * List of escape sequences used by this program, we do everything just
  52  * with three sequences. In order to be so cheap we may have some
  53  * flickering effect with some slow terminal, but the lesser sequences
  54  * the more compatible.
  55  *
  56  * CHA (Cursor Horizontal Absolute)
  57  *    Sequence: ESC [ n G
  58  *    Effect: moves cursor to column n
  59  *
  60  * EL (Erase Line)
  61  *    Sequence: ESC [ n K
  62  *    Effect: if n is 0 or missing, clear from cursor to end of line
  63  *    Effect: if n is 1, clear from beginning of line to cursor
  64  *    Effect: if n is 2, clear entire line
  65  *
  66  * CUF (CUrsor Forward)
  67  *    Sequence: ESC [ n C
  68  *    Effect: moves cursor forward of n chars
  69  *
  70  */
  71
  72 #include "fmacros.h"
  73 #include <termios.h>
  74 #include <unistd.h>
  75 #include <stdlib.h>
  76 #include <stdio.h>
  77 #include <errno.h>
  78 #include <string.h>
  79 #include <stdlib.h>
  80 #include <sys/types.h>
  81 #include <sys/ioctl.h>
  82 #include <unistd.h>
  83
  84 #define LINENOISE_MAX_LINE 4096
  85
  86 static struct termios orig_termios; /* in order to restore at exit */
  87 static int rawmode = 0; /* for atexit() function to check if restore is needed*/
  88 static int atexit_registered = 0; /* register atexit just 1 time */
  89 static int history_max_len = 100;
  90 static int history_len = 0;
  91 char **history = NULL;
  92
  93 static void linenoiseAtExit(void);
  94 int linenoiseHistoryAdd(char *line);
  95
  96 static void freeHistory(void) {
  97     if (history) {
  98         int j;
  99
 100         for (j = 0; j < history_len; j++)
 101             free(history[j]);
 102         free(history);
 103     }
 104 }
 105
 106 static int enableRawMode(int fd) {
 107     struct termios raw;
 108
 109     if (!isatty(STDIN_FILENO)) goto fatal;
 110     if (!atexit_registered) {
 111         atexit(linenoiseAtExit);
 112         atexit_registered = 1;
 113     }
 114     if (tcgetattr(fd,&orig_termios) == -1) goto fatal;
 115
 116     raw = orig_termios;  /* modify the original mode */
 117     /* input modes: no break, no CR to NL, no parity check, no strip char,
 118      * no start/stop output control. */
 119     raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
 120     /* output modes - disable post processing */
 121     raw.c_oflag &= ~(OPOST);
 122     /* control modes - set 8 bit chars */
 123     raw.c_cflag |= (CS8);
 124     /* local modes - choing off, canonical off, no extended functions,
 125      * no signal chars (^Z,^C) */
 126     raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
 127     /* control chars - set return condition: min number of bytes and timer.
 128      * We want read to return every single byte, without timeout. */
 129     raw.c_cc[VMIN] = 1; raw.c_cc[VTIME] = 0; /* 1 byte, no timer */
 130
 131     /* put terminal in raw mode after flushing */
 132     if (tcsetattr(fd,TCSAFLUSH,&raw) < 0) goto fatal;
 133     rawmode = 1;
 134     return 0;
 135
 136 fatal:
 137     errno = ENOTTY;
 138     return -1;
 139 }
 140
 141 static void disableRawMode(int fd) {
 142     /* Don't even check the return value as it's too late. */
 143     if (rawmode && tcsetattr(fd,TCSAFLUSH,&orig_termios) != -1)
 144         rawmode = 0;
 145 }
 146
 147 /* At exit we'll try to fix the terminal to the initial conditions. */
 148 static void linenoiseAtExit(void) {
 149     disableRawMode(STDIN_FILENO);
 150     freeHistory();
 151 }
 152
 153 static int getColumns(void) {
 154     struct winsize ws;
 155
 156     if (ioctl(1, TIOCGWINSZ, &ws) == -1) return 80;
 157     return ws.ws_col;
 158 }
 159
 160 static void refreshLine(int fd, const char *prompt, char *buf, size_t len, size_t pos, size_t cols) {
 161     char seq[64];
 162     size_t plen = strlen(prompt);
 163
 164     while((plen+pos) >= cols) {
 165         buf++;
 166         len--;
 167         pos--;
 168     }
 169     while (plen+len > cols) {
 170         len--;
 171     }
 172
 173     /* Cursor to left edge */
 174     snprintf(seq,64,"\x1b[0G");
 175     if (write(fd,seq,strlen(seq)) == -1) return;
 176     /* Write the prompt and the current buffer content */
 177     if (write(fd,prompt,strlen(prompt)) == -1) return;
 178     if (write(fd,buf,len) == -1) return;
 179     /* Erase to right */
 180     snprintf(seq,64,"\x1b[0K");
 181     if (write(fd,seq,strlen(seq)) == -1) return;
 182     /* Move cursor to original position. */
 183     snprintf(seq,64,"\x1b[0G\x1b[%dC", (int)(pos+plen));
 184     if (write(fd,seq,strlen(seq)) == -1) return;
 185 }
 186
 187 static int linenoisePrompt(int fd, char *buf, size_t buflen, const char *prompt) {
 188     size_t plen = strlen(prompt);
 189     size_t pos = 0;
 190     size_t len = 0;
 191     size_t cols = getColumns();
 192     int history_index = 0;
 193
 194     buf[0] = '\0';
 195     buflen--; /* Make sure there is always space for the nulterm */
 196
 197     /* The latest history entry is always our current buffer, that
 198      * initially is just an empty string. */
 199     linenoiseHistoryAdd("");
 200
 201     if (write(fd,prompt,plen) == -1) return -1;
 202     while(1) {
 203         char c;
 204         int nread;
 205         char seq[2];
 206
 207         nread = read(fd,&c,1);
 208         if (nread <= 0) return len;
 209         switch(c) {
 210         case 13:    /* enter */
 211             history_len--;
 212             return len;
 213         case 4:     /* ctrl-d */
 214             history_len--;
 215             return (len == 0) ? -1 : (int)len;
 216         case 3:     /* ctrl-c */
 217             errno = EAGAIN;
 218             return -1;
 219         case 127:   /* backspace */
 220         case 8:     /* ctrl-h */
 221             if (pos > 0 && len > 0) {
 222                 memmove(buf+pos-1,buf+pos,len-pos);
 223                 pos--;
 224                 len--;
 225                 buf[len] = '\0';
 226                 refreshLine(fd,prompt,buf,len,pos,cols);
 227             }
 228             break;
 229         case 20:    /* ctrl-t */
 230             if (pos > 0 && pos < len) {
 231                 int aux = buf[pos-1];
 232                 buf[pos-1] = buf[pos];
 233                 buf[pos] = aux;
 234                 if (pos != len-1) pos++;
 235                 refreshLine(fd,prompt,buf,len,pos,cols);
 236             }
 237             break;
 238         case 2:     /* ctrl-b */
 239             goto left_arrow;
 240         case 6:     /* ctrl-f */
 241             goto right_arrow;
 242         case 16:    /* ctrl-p */
 243             seq[1] = 65;
 244             goto up_down_arrow;
 245         case 14:    /* ctrl-n */
 246             seq[1] = 66;
 247             goto up_down_arrow;
 248             break;
 249         case 27:    /* escape sequence */
 250             if (read(fd,seq,2) == -1) break;
 251             if (seq[0] == 91 && seq[1] == 68) {
 252 left_arrow:
 253                 /* left arrow */
 254                 if (pos > 0) {
 255                     pos--;
 256                     refreshLine(fd,prompt,buf,len,pos,cols);
 257                 }
 258             } else if (seq[0] == 91 && seq[1] == 67) {
 259 right_arrow:
 260                 /* right arrow */
 261                 if (pos != len) {
 262                     pos++;
 263                     refreshLine(fd,prompt,buf,len,pos,cols);
 264                 }
 265             } else if (seq[0] == 91 && (seq[1] == 65 || seq[1] == 66)) {
 266 up_down_arrow:
 267                 /* up and down arrow: history */
 268                 if (history_len > 1) {
 269                     /* Update the current history entry before to
 270                      * overwrite it with tne next one. */
 271                     free(history[history_len-1-history_index]);
 272                     history[history_len-1-history_index] = strdup(buf);
 273                     /* Show the new entry */
 274                     history_index += (seq[1] == 65) ? 1 : -1;
 275                     if (history_index < 0) {
 276                         history_index = 0;
 277                         break;
 278                     } else if (history_index >= history_len) {
 279                         history_index = history_len-1;
 280                         break;
 281                     }
 282                     strncpy(buf,history[history_len-1-history_index],buflen);
 283                     buf[buflen] = '\0';
 284                     len = pos = strlen(buf);
 285                     refreshLine(fd,prompt,buf,len,pos,cols);
 286                 }
 287             }
 288             break;
 289         default:
 290             if (len < buflen) {
 291                 if (len == pos) {
 292                     buf[pos] = c;
 293                     pos++;
 294                     len++;
 295                     buf[len] = '\0';
 296                     if (plen+len < cols) {
 297                         /* Avoid a full update of the line in the
 298                          * trivial case. */
 299                         if (write(fd,&c,1) == -1) return -1;
 300                     } else {
 301                         refreshLine(fd,prompt,buf,len,pos,cols);
 302                     }
 303                 } else {
 304                     memmove(buf+pos+1,buf+pos,len-pos);
 305                     buf[pos] = c;
 306                     len++;
 307                     pos++;
 308                     buf[len] = '\0';
 309                     refreshLine(fd,prompt,buf,len,pos,cols);
 310                 }
 311             }
 312             break;
 313         case 21: /* Ctrl+u, delete the whole line. */
 314             buf[0] = '\0';
 315             pos = len = 0;
 316             refreshLine(fd,prompt,buf,len,pos,cols);
 317             break;
 318         case 11: /* Ctrl+k, delete from current to end of line. */
 319             buf[pos] = '\0';
 320             len = pos;
 321             refreshLine(fd,prompt,buf,len,pos,cols);
 322             break;
 323         case 1: /* Ctrl+a, go to the start of the line */
 324             pos = 0;
 325             refreshLine(fd,prompt,buf,len,pos,cols);
 326             break;
 327         case 5: /* ctrl+e, go to the end of the line */
 328             pos = len;
 329             refreshLine(fd,prompt,buf,len,pos,cols);
 330             break;
 331         }
 332     }
 333     return len;
 334 }
 335
 336 static int linenoiseRaw(char *buf, size_t buflen, const char *prompt) {
 337     int fd = STDIN_FILENO;
 338     int count;
 339
 340     if (buflen == 0) {
 341         errno = EINVAL;
 342         return -1;
 343     }
 344     if (enableRawMode(fd) == -1) return -1;
 345     count = linenoisePrompt(fd, buf, buflen, prompt);
 346     disableRawMode(fd);
 347     printf("\n");
 348     return count;
 349 }
 350
 351 char *linenoise(const char *prompt) {
 352     char buf[LINENOISE_MAX_LINE];
 353     int count;
 354
 355     count = linenoiseRaw(buf,LINENOISE_MAX_LINE,prompt);
 356     if (count == -1) return NULL;
 357     return strdup(buf);
 358 }
 359
 360 /* Using a circular buffer is smarter, but a bit more complex to handle. */
 361 int linenoiseHistoryAdd(char *line) {
 362     if (history_max_len == 0) return 0;
 363     if (history == 0) {
 364         history = malloc(sizeof(char*)*history_max_len);
 365         if (history == NULL) return 0;
 366         memset(history,0,(sizeof(char*)*history_max_len));
 367     }
 368     line = strdup(line);
 369     if (!line) return 0;
 370     if (history_len == history_max_len) {
 371         memmove(history,history+1,sizeof(char*)*(history_max_len-1));
 372         history_len--;
 373     }
 374     history[history_len] = line;
 375     history_len++;
 376     return 1;
 377 }
 378
 379 int linenoiseHistorySetMaxLen(int len) {
 380     char **new;
 381
 382     if (len < 1) return 0;
 383     if (history) {
 384         int tocopy = history_len;
 385
 386         new = malloc(sizeof(char*)*len);
 387         if (new == NULL) return 0;
 388         if (len < tocopy) tocopy = len;
 389         memcpy(new,history+(history_max_len-tocopy), sizeof(char*)*tocopy);
 390         free(history);
 391         history = new;
 392     }
 393     history_max_len = len;
 394     if (history_len > history_max_len)
 395         history_len = history_max_len;
 396     return 1;
 397 }