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 <termios.h>
  73 #include <unistd.h>
  74 #include <stdlib.h>
  75 #include <stdio.h>
  76 #include <errno.h>
  77 #include <string.h>
  78 #include <stdlib.h>
  79 #include <sys/types.h>
  80 #include <sys/ioctl.h>
  81 #include <unistd.h>
  82
  83 #define LINENOISE_MAX_LINE 4096
  84
  85 static struct termios orig_termios; /* in order to restore at exit */
  86 static int rawmode = 0; /* for atexit() function to check if restore is needed*/
  87 static int atexit_registered = 0; /* register atexit just 1 time */
  88 static int history_max_len = 100;
  89 static int history_len = 0;
  90 char **history = NULL;
  91
  92 static void linenoiseAtExit(void);
  93 int linenoiseHistoryAdd(char *line);
  94
  95 static void freeHistory(void) {
  96     if (history) {
  97         int j;
  98
  99         for (j = 0; j < history_len; j++)
 100             free(history[j]);
 101         free(history);
 102     }
 103 }
 104
 105 static int enableRawMode(int fd) {
 106     struct termios raw;
 107
 108     if (!isatty(STDIN_FILENO)) goto fatal;
 109     if (!atexit_registered) {
 110         atexit(linenoiseAtExit);
 111         atexit_registered = 1;
 112     }
 113     if (tcgetattr(fd,&orig_termios) == -1) goto fatal;
 114
 115     raw = orig_termios;  /* modify the original mode */
 116     /* input modes: no break, no CR to NL, no parity check, no strip char,
 117      * no start/stop output control. */
 118     raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
 119     /* output modes - disable post processing */
 120     raw.c_oflag &= ~(OPOST);
 121     /* control modes - set 8 bit chars */
 122     raw.c_cflag |= (CS8);
 123     /* local modes - choing off, canonical off, no extended functions,
 124      * no signal chars (^Z,^C) */
 125     raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
 126     /* control chars - set return condition: min number of bytes and timer.
 127      * We want read to return every single byte, without timeout. */
 128     raw.c_cc[VMIN] = 1; raw.c_cc[VTIME] = 0; /* 1 byte, no timer */
 129
 130     /* put terminal in raw mode after flushing */
 131     if (tcsetattr(fd,TCSAFLUSH,&raw) < 0) goto fatal;
 132     rawmode = 1;
 133     return 0;
 134
 135 fatal:
 136     errno = ENOTTY;
 137     return -1;
 138 }
 139
 140 static void disableRawMode(int fd) {
 141     /* Don't even check the return value as it's too late. */
 142     if (rawmode && tcsetattr(fd,TCSAFLUSH,&orig_termios) != -1)
 143         rawmode = 0;
 144 }
 145
 146 /* At exit we'll try to fix the terminal to the initial conditions. */
 147 static void linenoiseAtExit(void) {
 148     disableRawMode(STDIN_FILENO);
 149     freeHistory();
 150 }
 151
 152 static int getColumns(void) {
 153     struct winsize ws;
 154
 155     if (ioctl(1, TIOCGWINSZ, &ws) == -1) return 80;
 156     return ws.ws_col;
 157 }
 158
 159 static void refreshLine(int fd, const char *prompt, char *buf, size_t len, size_t pos, size_t cols) {
 160     char seq[64];
 161     size_t plen = strlen(prompt);
 162
 163     while((plen+pos) >= cols) {
 164         buf++;
 165         len--;
 166         pos--;
 167     }
 168     while (plen+len > cols) {
 169         len--;
 170     }
 171
 172     /* Cursor to left edge */
 173     snprintf(seq,64,"\x1b[0G");
 174     if (write(fd,seq,strlen(seq)) == -1) return;
 175     /* Write the prompt and the current buffer content */
 176     if (write(fd,prompt,strlen(prompt)) == -1) return;
 177     if (write(fd,buf,len) == -1) return;
 178     /* Erase to right */
 179     snprintf(seq,64,"\x1b[0K");
 180     if (write(fd,seq,strlen(seq)) == -1) return;
 181     /* Move cursor to original position. */
 182     snprintf(seq,64,"\x1b[0G\x1b[%dC", (int)(pos+plen));
 183     if (write(fd,seq,strlen(seq)) == -1) return;
 184 }
 185
 186 static int linenoisePrompt(int fd, char *buf, size_t buflen, const char *prompt) {
 187     size_t plen = strlen(prompt);
 188     size_t pos = 0;
 189     size_t len = 0;
 190     size_t cols = getColumns();
 191     int history_index = 0;
 192
 193     buf[0] = '\0';
 194     buflen--; /* Make sure there is always space for the nulterm */
 195
 196     /* The latest history entry is always our current buffer, that
 197      * initially is just an empty string. */
 198     linenoiseHistoryAdd("");
 199
 200     if (write(fd,prompt,plen) == -1) return -1;
 201     while(1) {
 202         char c;
 203         int nread;
 204         char seq[2];
 205
 206         nread = read(fd,&c,1);
 207         if (nread <= 0) return len;
 208         switch(c) {
 209         case 13:    /* enter */
 210             history_len--;
 211             return len;
 212         case 4:     /* ctrl-d */
 213             history_len--;
 214             return (len == 0) ? -1 : (int)len;
 215         case 3:     /* ctrl-c */
 216             errno = EAGAIN;
 217             return -1;
 218         case 127:   /* backspace */
 219         case 8:     /* ctrl-h */
 220             if (pos > 0 && len > 0) {
 221                 memmove(buf+pos-1,buf+pos,len-pos);
 222                 pos--;
 223                 len--;
 224                 buf[len] = '\0';
 225                 refreshLine(fd,prompt,buf,len,pos,cols);
 226             }
 227             break;
 228         case 20:    /* ctrl-t */
 229             if (pos > 0 && pos < len) {
 230                 int aux = buf[pos-1];
 231                 buf[pos-1] = buf[pos];
 232                 buf[pos] = aux;
 233                 if (pos != len-1) pos++;
 234                 refreshLine(fd,prompt,buf,len,pos,cols);
 235             }
 236             break;
 237         case 2:     /* ctrl-b */
 238             goto left_arrow;
 239         case 6:     /* ctrl-f */
 240             goto right_arrow;
 241         case 16:    /* ctrl-p */
 242             seq[1] = 65;
 243             goto up_down_arrow;
 244         case 14:    /* ctrl-n */
 245             seq[1] = 66;
 246             goto up_down_arrow;
 247             break;
 248         case 27:    /* escape sequence */
 249             if (read(fd,seq,2) == -1) break;
 250             if (seq[0] == 91 && seq[1] == 68) {
 251 left_arrow:
 252                 /* left arrow */
 253                 if (pos > 0) {
 254                     pos--;
 255                     refreshLine(fd,prompt,buf,len,pos,cols);
 256                 }
 257             } else if (seq[0] == 91 && seq[1] == 67) {
 258 right_arrow:
 259                 /* right arrow */
 260                 if (pos != len) {
 261                     pos++;
 262                     refreshLine(fd,prompt,buf,len,pos,cols);
 263                 }
 264             } else if (seq[0] == 91 && (seq[1] == 65 || seq[1] == 66)) {
 265 up_down_arrow:
 266                 /* up and down arrow: history */
 267                 if (history_len > 1) {
 268                     /* Update the current history entry before to
 269                      * overwrite it with tne next one. */
 270                     free(history[history_len-1-history_index]);
 271                     history[history_len-1-history_index] = strdup(buf);
 272                     /* Show the new entry */
 273                     history_index += (seq[1] == 65) ? 1 : -1;
 274                     if (history_index < 0) {
 275                         history_index = 0;
 276                         break;
 277                     } else if (history_index >= history_len) {
 278                         history_index = history_len-1;
 279                         break;
 280                     }
 281                     strncpy(buf,history[history_len-1-history_index],buflen);
 282                     buf[buflen] = '\0';
 283                     len = pos = strlen(buf);
 284                     refreshLine(fd,prompt,buf,len,pos,cols);
 285                 }
 286             }
 287             break;
 288         default:
 289             if (len < buflen) {
 290                 if (len == pos) {
 291                     buf[pos] = c;
 292                     pos++;
 293                     len++;
 294                     buf[len] = '\0';
 295                     if (plen+len < cols) {
 296                         /* Avoid a full update of the line in the
 297                          * trivial case. */
 298                         if (write(fd,&c,1) == -1) return -1;
 299                     } else {
 300                         refreshLine(fd,prompt,buf,len,pos,cols);
 301                     }
 302                 } else {
 303                     memmove(buf+pos+1,buf+pos,len-pos);
 304                     buf[pos] = c;
 305                     len++;
 306                     pos++;
 307                     buf[len] = '\0';
 308                     refreshLine(fd,prompt,buf,len,pos,cols);
 309                 }
 310             }
 311             break;
 312         case 21: /* Ctrl+u, delete the whole line. */
 313             buf[0] = '\0';
 314             pos = len = 0;
 315             refreshLine(fd,prompt,buf,len,pos,cols);
 316             break;
 317         case 11: /* Ctrl+k, delete from current to end of line. */
 318             buf[pos] = '\0';
 319             len = pos;
 320             refreshLine(fd,prompt,buf,len,pos,cols);
 321             break;
 322         case 1: /* Ctrl+a, go to the start of the line */
 323             pos = 0;
 324             refreshLine(fd,prompt,buf,len,pos,cols);
 325             break;
 326         case 5: /* ctrl+e, go to the end of the line */
 327             pos = len;
 328             refreshLine(fd,prompt,buf,len,pos,cols);
 329             break;
 330         }
 331     }
 332     return len;
 333 }
 334
 335 static int linenoiseRaw(char *buf, size_t buflen, const char *prompt) {
 336     int fd = STDIN_FILENO;
 337     int count;
 338
 339     if (buflen == 0) {
 340         errno = EINVAL;
 341         return -1;
 342     }
 343     if (enableRawMode(fd) == -1) return -1;
 344     count = linenoisePrompt(fd, buf, buflen, prompt);
 345     disableRawMode(fd);
 346     printf("\n");
 347     return count;
 348 }
 349
 350 char *linenoise(const char *prompt) {
 351     char buf[LINENOISE_MAX_LINE];
 352     int count;
 353
 354     count = linenoiseRaw(buf,LINENOISE_MAX_LINE,prompt);
 355     if (count == -1) return NULL;
 356     return strdup(buf);
 357 }
 358
 359 /* Using a circular buffer is smarter, but a bit more complex to handle. */
 360 int linenoiseHistoryAdd(char *line) {
 361     if (history_max_len == 0) return 0;
 362     if (history == 0) {
 363         history = malloc(sizeof(char*)*history_max_len);
 364         if (history == NULL) return 0;
 365         memset(history,0,(sizeof(char*)*history_max_len));
 366     }
 367     line = strdup(line);
 368     if (!line) return 0;
 369     if (history_len == history_max_len) {
 370         memmove(history,history+1,sizeof(char*)*(history_max_len-1));
 371         history_len--;
 372     }
 373     history[history_len] = line;
 374     history_len++;
 375     return 1;
 376 }
 377
 378 int linenoiseHistorySetMaxLen(int len) {
 379     char **new;
 380
 381     if (len < 1) return 0;
 382     if (history) {
 383         int tocopy = history_len;
 384
 385         new = malloc(sizeof(char*)*len);
 386         if (new == NULL) return 0;
 387         if (len < tocopy) tocopy = len;
 388         memcpy(new,history+(history_max_len-tocopy), sizeof(char*)*tocopy);
 389         free(history);
 390         history = new;
 391     }
 392     history_max_len = len;
 393     if (history_len > history_max_len)
 394         history_len = history_max_len;
 395     return 1;
 396 }