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 static char *unsupported_term[] = {"dumb","cons25",NULL};
  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(const char *line);
  95
  96 static int isUnsupportedTerm(void) {
  97     char *term = getenv("TERM");
  98     int j;
  99
 100     if (term == NULL) return 0;
 101     for (j = 0; unsupported_term[j]; j++)
 102         if (!strcasecmp(term,unsupported_term[j])) return 1;
 103     return 0;
 104 }
 105
 106 static void freeHistory(void) {
 107     if (history) {
 108         int j;
 109
 110         for (j = 0; j < history_len; j++)
 111             free(history[j]);
 112         free(history);
 113     }
 114 }
 115
 116 static int enableRawMode(int fd) {
 117     struct termios raw;
 118
 119     if (!isatty(STDIN_FILENO)) goto fatal;
 120     if (!atexit_registered) {
 121         atexit(linenoiseAtExit);
 122         atexit_registered = 1;
 123     }
 124     if (tcgetattr(fd,&orig_termios) == -1) goto fatal;
 125
 126     raw = orig_termios;  /* modify the original mode */
 127     /* input modes: no break, no CR to NL, no parity check, no strip char,
 128      * no start/stop output control. */
 129     raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
 130     /* output modes - disable post processing */
 131     raw.c_oflag &= ~(OPOST);
 132     /* control modes - set 8 bit chars */
 133     raw.c_cflag |= (CS8);
 134     /* local modes - choing off, canonical off, no extended functions,
 135      * no signal chars (^Z,^C) */
 136     raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
 137     /* control chars - set return condition: min number of bytes and timer.
 138      * We want read to return every single byte, without timeout. */
 139     raw.c_cc[VMIN] = 1; raw.c_cc[VTIME] = 0; /* 1 byte, no timer */
 140
 141     /* put terminal in raw mode after flushing */
 142     if (tcsetattr(fd,TCSAFLUSH,&raw) < 0) goto fatal;
 143     rawmode = 1;
 144     return 0;
 145
 146 fatal:
 147     errno = ENOTTY;
 148     return -1;
 149 }
 150
 151 static void disableRawMode(int fd) {
 152     /* Don't even check the return value as it's too late. */
 153     if (rawmode && tcsetattr(fd,TCSAFLUSH,&orig_termios) != -1)
 154         rawmode = 0;
 155 }
 156
 157 /* At exit we'll try to fix the terminal to the initial conditions. */
 158 static void linenoiseAtExit(void) {
 159     disableRawMode(STDIN_FILENO);
 160     freeHistory();
 161 }
 162
 163 static int getColumns(void) {
 164     struct winsize ws;
 165
 166     if (ioctl(1, TIOCGWINSZ, &ws) == -1) return 80;
 167     return ws.ws_col;
 168 }
 169
 170 static void refreshLine(int fd, const char *prompt, char *buf, size_t len, size_t pos, size_t cols) {
 171     char seq[64];
 172     size_t plen = strlen(prompt);
 173
 174     while((plen+pos) >= cols) {
 175         buf++;
 176         len--;
 177         pos--;
 178     }
 179     while (plen+len > cols) {
 180         len--;
 181     }
 182
 183     /* Cursor to left edge */
 184     snprintf(seq,64,"\x1b[0G");
 185     if (write(fd,seq,strlen(seq)) == -1) return;
 186     /* Write the prompt and the current buffer content */
 187     if (write(fd,prompt,strlen(prompt)) == -1) return;
 188     if (write(fd,buf,len) == -1) return;
 189     /* Erase to right */
 190     snprintf(seq,64,"\x1b[0K");
 191     if (write(fd,seq,strlen(seq)) == -1) return;
 192     /* Move cursor to original position. */
 193     snprintf(seq,64,"\x1b[0G\x1b[%dC", (int)(pos+plen));
 194     if (write(fd,seq,strlen(seq)) == -1) return;
 195 }
 196
 197 static int linenoisePrompt(int fd, char *buf, size_t buflen, const char *prompt) {
 198     size_t plen = strlen(prompt);
 199     size_t pos = 0;
 200     size_t len = 0;
 201     size_t cols = getColumns();
 202     int history_index = 0;
 203
 204     buf[0] = '\0';
 205     buflen--; /* Make sure there is always space for the nulterm */
 206
 207     /* The latest history entry is always our current buffer, that
 208      * initially is just an empty string. */
 209     linenoiseHistoryAdd("");
 210
 211     if (write(fd,prompt,plen) == -1) return -1;
 212     while(1) {
 213         char c;
 214         int nread;
 215         char seq[2];
 216
 217         nread = read(fd,&c,1);
 218         if (nread <= 0) return len;
 219         switch(c) {
 220         case 13:    /* enter */
 221             history_len--;
 222             return len;
 223         case 4:     /* ctrl-d */
 224             history_len--;
 225             return (len == 0) ? -1 : (int)len;
 226         case 3:     /* ctrl-c */
 227             errno = EAGAIN;
 228             return -1;
 229         case 127:   /* backspace */
 230         case 8:     /* ctrl-h */
 231             if (pos > 0 && len > 0) {
 232                 memmove(buf+pos-1,buf+pos,len-pos);
 233                 pos--;
 234                 len--;
 235                 buf[len] = '\0';
 236                 refreshLine(fd,prompt,buf,len,pos,cols);
 237             }
 238             break;
 239         case 20:    /* ctrl-t */
 240             if (pos > 0 && pos < len) {
 241                 int aux = buf[pos-1];
 242                 buf[pos-1] = buf[pos];
 243                 buf[pos] = aux;
 244                 if (pos != len-1) pos++;
 245                 refreshLine(fd,prompt,buf,len,pos,cols);
 246             }
 247             break;
 248         case 2:     /* ctrl-b */
 249             goto left_arrow;
 250         case 6:     /* ctrl-f */
 251             goto right_arrow;
 252         case 16:    /* ctrl-p */
 253             seq[1] = 65;
 254             goto up_down_arrow;
 255         case 14:    /* ctrl-n */
 256             seq[1] = 66;
 257             goto up_down_arrow;
 258             break;
 259         case 27:    /* escape sequence */
 260             if (read(fd,seq,2) == -1) break;
 261             if (seq[0] == 91 && seq[1] == 68) {
 262 left_arrow:
 263                 /* left arrow */
 264                 if (pos > 0) {
 265                     pos--;
 266                     refreshLine(fd,prompt,buf,len,pos,cols);
 267                 }
 268             } else if (seq[0] == 91 && seq[1] == 67) {
 269 right_arrow:
 270                 /* right arrow */
 271                 if (pos != len) {
 272                     pos++;
 273                     refreshLine(fd,prompt,buf,len,pos,cols);
 274                 }
 275             } else if (seq[0] == 91 && (seq[1] == 65 || seq[1] == 66)) {
 276 up_down_arrow:
 277                 /* up and down arrow: history */
 278                 if (history_len > 1) {
 279                     /* Update the current history entry before to
 280                      * overwrite it with tne next one. */
 281                     free(history[history_len-1-history_index]);
 282                     history[history_len-1-history_index] = strdup(buf);
 283                     /* Show the new entry */
 284                     history_index += (seq[1] == 65) ? 1 : -1;
 285                     if (history_index < 0) {
 286                         history_index = 0;
 287                         break;
 288                     } else if (history_index >= history_len) {
 289                         history_index = history_len-1;
 290                         break;
 291                     }
 292                     strncpy(buf,history[history_len-1-history_index],buflen);
 293                     buf[buflen] = '\0';
 294                     len = pos = strlen(buf);
 295                     refreshLine(fd,prompt,buf,len,pos,cols);
 296                 }
 297             }
 298             break;
 299         default:
 300             if (len < buflen) {
 301                 if (len == pos) {
 302                     buf[pos] = c;
 303                     pos++;
 304                     len++;
 305                     buf[len] = '\0';
 306                     if (plen+len < cols) {
 307                         /* Avoid a full update of the line in the
 308                          * trivial case. */
 309                         if (write(fd,&c,1) == -1) return -1;
 310                     } else {
 311                         refreshLine(fd,prompt,buf,len,pos,cols);
 312                     }
 313                 } else {
 314                     memmove(buf+pos+1,buf+pos,len-pos);
 315                     buf[pos] = c;
 316                     len++;
 317                     pos++;
 318                     buf[len] = '\0';
 319                     refreshLine(fd,prompt,buf,len,pos,cols);
 320                 }
 321             }
 322             break;
 323         case 21: /* Ctrl+u, delete the whole line. */
 324             buf[0] = '\0';
 325             pos = len = 0;
 326             refreshLine(fd,prompt,buf,len,pos,cols);
 327             break;
 328         case 11: /* Ctrl+k, delete from current to end of line. */
 329             buf[pos] = '\0';
 330             len = pos;
 331             refreshLine(fd,prompt,buf,len,pos,cols);
 332             break;
 333         case 1: /* Ctrl+a, go to the start of the line */
 334             pos = 0;
 335             refreshLine(fd,prompt,buf,len,pos,cols);
 336             break;
 337         case 5: /* ctrl+e, go to the end of the line */
 338             pos = len;
 339             refreshLine(fd,prompt,buf,len,pos,cols);
 340             break;
 341         }
 342     }
 343     return len;
 344 }
 345
 346 static int linenoiseRaw(char *buf, size_t buflen, const char *prompt) {
 347     int fd = STDIN_FILENO;
 348     int count;
 349
 350     if (buflen == 0) {
 351         errno = EINVAL;
 352         return -1;
 353     }
 354     if (!isatty(STDIN_FILENO)) {
 355         if (fgets(buf, buflen, stdin) == NULL) return -1;
 356         count = strlen(buf);
 357         if (count && buf[count-1] == '\n') {
 358             count--;
 359             buf[count] = '\0';
 360         }
 361     } else {
 362         if (enableRawMode(fd) == -1) return -1;
 363         count = linenoisePrompt(fd, buf, buflen, prompt);
 364         disableRawMode(fd);
 365         printf("\n");
 366     }
 367     return count;
 368 }
 369
 370 char *linenoise(const char *prompt) {
 371     char buf[LINENOISE_MAX_LINE];
 372     int count;
 373
 374     if (isUnsupportedTerm()) {
 375         size_t len;
 376
 377         printf("%s",prompt);
 378         fflush(stdout);
 379         if (fgets(buf,LINENOISE_MAX_LINE,stdin) == NULL) return NULL;
 380         len = strlen(buf);
 381         while(len && (buf[len-1] == '\n' || buf[len-1] == '\r')) {
 382             len--;
 383             buf[len] = '\0';
 384         }
 385         return strdup(buf);
 386     } else {
 387         count = linenoiseRaw(buf,LINENOISE_MAX_LINE,prompt);
 388         if (count == -1) return NULL;
 389         return strdup(buf);
 390     }
 391 }
 392
 393 /* Using a circular buffer is smarter, but a bit more complex to handle. */
 394 int linenoiseHistoryAdd(const char *line) {
 395     char *linecopy;
 396
 397     if (history_max_len == 0) return 0;
 398     if (history == 0) {
 399         history = malloc(sizeof(char*)*history_max_len);
 400         if (history == NULL) return 0;
 401         memset(history,0,(sizeof(char*)*history_max_len));
 402     }
 403     linecopy = strdup(line);
 404     if (!linecopy) return 0;
 405     if (history_len == history_max_len) {
 406         memmove(history,history+1,sizeof(char*)*(history_max_len-1));
 407         history_len--;
 408     }
 409     history[history_len] = linecopy;
 410     history_len++;
 411     return 1;
 412 }
 413
 414 int linenoiseHistorySetMaxLen(int len) {
 415     char **new;
 416
 417     if (len < 1) return 0;
 418     if (history) {
 419         int tocopy = history_len;
 420
 421         new = malloc(sizeof(char*)*len);
 422         if (new == NULL) return 0;
 423         if (len < tocopy) tocopy = len;
 424         memcpy(new,history+(history_max_len-tocopy), sizeof(char*)*tocopy);
 425         free(history);
 426         history = new;
 427     }
 428     history_max_len = len;
 429     if (history_len > history_max_len)
 430         history_len = history_max_len;
 431     return 1;
 432 }