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 static char *unsupported_term[] = {"dumb","cons25",NULL};
  86
  87 static struct termios orig_termios; /* in order to restore at exit */
  88 static int rawmode = 0; /* for atexit() function to check if restore is needed*/
  89 static int atexit_registered = 0; /* register atexit just 1 time */
  90 static int history_max_len = 100;
  91 static int history_len = 0;
  92 char **history = NULL;
  93
  94 static void linenoiseAtExit(void);
  95 int linenoiseHistoryAdd(const char *line);
  96
  97 static int isUnsupportedTerm(void) {
  98     char *term = getenv("TERM");
  99     int j;
 100
 101     if (term == NULL) return 0;
 102     for (j = 0; unsupported_term[j]; j++)
 103         if (!strcasecmp(term,unsupported_term[j])) return 1;
 104     return 0;
 105 }
 106
 107 static void freeHistory(void) {
 108     if (history) {
 109         int j;
 110
 111         for (j = 0; j < history_len; j++)
 112             free(history[j]);
 113         free(history);
 114     }
 115 }
 116
 117 static int enableRawMode(int fd) {
 118     struct termios raw;
 119
 120     if (!isatty(STDIN_FILENO)) goto fatal;
 121     if (!atexit_registered) {
 122         atexit(linenoiseAtExit);
 123         atexit_registered = 1;
 124     }
 125     if (tcgetattr(fd,&orig_termios) == -1) goto fatal;
 126
 127     raw = orig_termios;  /* modify the original mode */
 128     /* input modes: no break, no CR to NL, no parity check, no strip char,
 129      * no start/stop output control. */
 130     raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
 131     /* output modes - disable post processing */
 132     raw.c_oflag &= ~(OPOST);
 133     /* control modes - set 8 bit chars */
 134     raw.c_cflag |= (CS8);
 135     /* local modes - choing off, canonical off, no extended functions,
 136      * no signal chars (^Z,^C) */
 137     raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
 138     /* control chars - set return condition: min number of bytes and timer.
 139      * We want read to return every single byte, without timeout. */
 140     raw.c_cc[VMIN] = 1; raw.c_cc[VTIME] = 0; /* 1 byte, no timer */
 141
 142     /* put terminal in raw mode after flushing */
 143     if (tcsetattr(fd,TCSAFLUSH,&raw) < 0) goto fatal;
 144     rawmode = 1;
 145     return 0;
 146
 147 fatal:
 148     errno = ENOTTY;
 149     return -1;
 150 }
 151
 152 static void disableRawMode(int fd) {
 153     /* Don't even check the return value as it's too late. */
 154     if (rawmode && tcsetattr(fd,TCSAFLUSH,&orig_termios) != -1)
 155         rawmode = 0;
 156 }
 157
 158 /* At exit we'll try to fix the terminal to the initial conditions. */
 159 static void linenoiseAtExit(void) {
 160     disableRawMode(STDIN_FILENO);
 161     freeHistory();
 162 }
 163
 164 static int getColumns(void) {
 165     struct winsize ws;
 166
 167     if (ioctl(1, TIOCGWINSZ, &ws) == -1) return 80;
 168     return ws.ws_col;
 169 }
 170
 171 static void refreshLine(int fd, const char *prompt, char *buf, size_t len, size_t pos, size_t cols) {
 172     char seq[64];
 173     size_t plen = strlen(prompt);
 174
 175     while((plen+pos) >= cols) {
 176         buf++;
 177         len--;
 178         pos--;
 179     }
 180     while (plen+len > cols) {
 181         len--;
 182     }
 183
 184     /* Cursor to left edge */
 185     snprintf(seq,64,"\x1b[0G");
 186     if (write(fd,seq,strlen(seq)) == -1) return;
 187     /* Write the prompt and the current buffer content */
 188     if (write(fd,prompt,strlen(prompt)) == -1) return;
 189     if (write(fd,buf,len) == -1) return;
 190     /* Erase to right */
 191     snprintf(seq,64,"\x1b[0K");
 192     if (write(fd,seq,strlen(seq)) == -1) return;
 193     /* Move cursor to original position. */
 194     snprintf(seq,64,"\x1b[0G\x1b[%dC", (int)(pos+plen));
 195     if (write(fd,seq,strlen(seq)) == -1) return;
 196 }
 197
 198 static int linenoisePrompt(int fd, char *buf, size_t buflen, const char *prompt) {
 199     size_t plen = strlen(prompt);
 200     size_t pos = 0;
 201     size_t len = 0;
 202     size_t cols = getColumns();
 203     int history_index = 0;
 204
 205     buf[0] = '\0';
 206     buflen--; /* Make sure there is always space for the nulterm */
 207
 208     /* The latest history entry is always our current buffer, that
 209      * initially is just an empty string. */
 210     linenoiseHistoryAdd("");
 211
 212     if (write(fd,prompt,plen) == -1) return -1;
 213     while(1) {
 214         char c;
 215         int nread;
 216         char seq[2];
 217
 218         nread = read(fd,&c,1);
 219         if (nread <= 0) return len;
 220         switch(c) {
 221         case 13:    /* enter */
 222             history_len--;
 223             return len;
 224         case 4:     /* ctrl-d */
 225             history_len--;
 226             return (len == 0) ? -1 : (int)len;
 227         case 3:     /* ctrl-c */
 228             errno = EAGAIN;
 229             return -1;
 230         case 127:   /* backspace */
 231         case 8:     /* ctrl-h */
 232             if (pos > 0 && len > 0) {
 233                 memmove(buf+pos-1,buf+pos,len-pos);
 234                 pos--;
 235                 len--;
 236                 buf[len] = '\0';
 237                 refreshLine(fd,prompt,buf,len,pos,cols);
 238             }
 239             break;
 240         case 20:    /* ctrl-t */
 241             if (pos > 0 && pos < len) {
 242                 int aux = buf[pos-1];
 243                 buf[pos-1] = buf[pos];
 244                 buf[pos] = aux;
 245                 if (pos != len-1) pos++;
 246                 refreshLine(fd,prompt,buf,len,pos,cols);
 247             }
 248             break;
 249         case 2:     /* ctrl-b */
 250             goto left_arrow;
 251         case 6:     /* ctrl-f */
 252             goto right_arrow;
 253         case 16:    /* ctrl-p */
 254             seq[1] = 65;
 255             goto up_down_arrow;
 256         case 14:    /* ctrl-n */
 257             seq[1] = 66;
 258             goto up_down_arrow;
 259             break;
 260         case 27:    /* escape sequence */
 261             if (read(fd,seq,2) == -1) break;
 262             if (seq[0] == 91 && seq[1] == 68) {
 263 left_arrow:
 264                 /* left arrow */
 265                 if (pos > 0) {
 266                     pos--;
 267                     refreshLine(fd,prompt,buf,len,pos,cols);
 268                 }
 269             } else if (seq[0] == 91 && seq[1] == 67) {
 270 right_arrow:
 271                 /* right arrow */
 272                 if (pos != len) {
 273                     pos++;
 274                     refreshLine(fd,prompt,buf,len,pos,cols);
 275                 }
 276             } else if (seq[0] == 91 && (seq[1] == 65 || seq[1] == 66)) {
 277 up_down_arrow:
 278                 /* up and down arrow: history */
 279                 if (history_len > 1) {
 280                     /* Update the current history entry before to
 281                      * overwrite it with tne next one. */
 282                     free(history[history_len-1-history_index]);
 283                     history[history_len-1-history_index] = strdup(buf);
 284                     /* Show the new entry */
 285                     history_index += (seq[1] == 65) ? 1 : -1;
 286                     if (history_index < 0) {
 287                         history_index = 0;
 288                         break;
 289                     } else if (history_index >= history_len) {
 290                         history_index = history_len-1;
 291                         break;
 292                     }
 293                     strncpy(buf,history[history_len-1-history_index],buflen);
 294                     buf[buflen] = '\0';
 295                     len = pos = strlen(buf);
 296                     refreshLine(fd,prompt,buf,len,pos,cols);
 297                 }
 298             }
 299             break;
 300         default:
 301             if (len < buflen) {
 302                 if (len == pos) {
 303                     buf[pos] = c;
 304                     pos++;
 305                     len++;
 306                     buf[len] = '\0';
 307                     if (plen+len < cols) {
 308                         /* Avoid a full update of the line in the
 309                          * trivial case. */
 310                         if (write(fd,&c,1) == -1) return -1;
 311                     } else {
 312                         refreshLine(fd,prompt,buf,len,pos,cols);
 313                     }
 314                 } else {
 315                     memmove(buf+pos+1,buf+pos,len-pos);
 316                     buf[pos] = c;
 317                     len++;
 318                     pos++;
 319                     buf[len] = '\0';
 320                     refreshLine(fd,prompt,buf,len,pos,cols);
 321                 }
 322             }
 323             break;
 324         case 21: /* Ctrl+u, delete the whole line. */
 325             buf[0] = '\0';
 326             pos = len = 0;
 327             refreshLine(fd,prompt,buf,len,pos,cols);
 328             break;
 329         case 11: /* Ctrl+k, delete from current to end of line. */
 330             buf[pos] = '\0';
 331             len = pos;
 332             refreshLine(fd,prompt,buf,len,pos,cols);
 333             break;
 334         case 1: /* Ctrl+a, go to the start of the line */
 335             pos = 0;
 336             refreshLine(fd,prompt,buf,len,pos,cols);
 337             break;
 338         case 5: /* ctrl+e, go to the end of the line */
 339             pos = len;
 340             refreshLine(fd,prompt,buf,len,pos,cols);
 341             break;
 342         }
 343     }
 344     return len;
 345 }
 346
 347 static int linenoiseRaw(char *buf, size_t buflen, const char *prompt) {
 348     int fd = STDIN_FILENO;
 349     int count;
 350
 351     if (buflen == 0) {
 352         errno = EINVAL;
 353         return -1;
 354     }
 355     if (!isatty(STDIN_FILENO)) {
 356         if (fgets(buf, buflen, stdin) == NULL) return -1;
 357         count = strlen(buf);
 358         if (count && buf[count-1] == '\n') {
 359             count--;
 360             buf[count] = '\0';
 361         }
 362     } else {
 363         if (enableRawMode(fd) == -1) return -1;
 364         count = linenoisePrompt(fd, buf, buflen, prompt);
 365         disableRawMode(fd);
 366         printf("\n");
 367     }
 368     return count;
 369 }
 370
 371 char *linenoise(const char *prompt) {
 372     char buf[LINENOISE_MAX_LINE];
 373     int count;
 374
 375     if (isUnsupportedTerm()) {
 376         size_t len;
 377
 378         printf("%s",prompt);
 379         fflush(stdout);
 380         if (fgets(buf,LINENOISE_MAX_LINE,stdin) == NULL) return NULL;
 381         len = strlen(buf);
 382         while(len && (buf[len-1] == '\n' || buf[len-1] == '\r')) {
 383             len--;
 384             buf[len] = '\0';
 385         }
 386         return strdup(buf);
 387     } else {
 388         count = linenoiseRaw(buf,LINENOISE_MAX_LINE,prompt);
 389         if (count == -1) return NULL;
 390         return strdup(buf);
 391     }
 392 }
 393
 394 /* Using a circular buffer is smarter, but a bit more complex to handle. */
 395 int linenoiseHistoryAdd(const char *line) {
 396     char *linecopy;
 397
 398     if (history_max_len == 0) return 0;
 399     if (history == 0) {
 400         history = malloc(sizeof(char*)*history_max_len);
 401         if (history == NULL) return 0;
 402         memset(history,0,(sizeof(char*)*history_max_len));
 403     }
 404     linecopy = strdup(line);
 405     if (!linecopy) return 0;
 406     if (history_len == history_max_len) {
 407         memmove(history,history+1,sizeof(char*)*(history_max_len-1));
 408         history_len--;
 409     }
 410     history[history_len] = linecopy;
 411     history_len++;
 412     return 1;
 413 }
 414
 415 int linenoiseHistorySetMaxLen(int len) {
 416     char **new;
 417
 418     if (len < 1) return 0;
 419     if (history) {
 420         int tocopy = history_len;
 421
 422         new = malloc(sizeof(char*)*len);
 423         if (new == NULL) return 0;
 424         if (len < tocopy) tocopy = len;
 425         memcpy(new,history+(history_max_len-tocopy), sizeof(char*)*tocopy);
 426         free(history);
 427         history = new;
 428     }
 429     history_max_len = len;
 430     if (history_len > history_max_len)
 431         history_len = history_max_len;
 432     return 1;
 433 }