linenoise.c revision 192a28831520dee50410a17953d87280d0fd8996 
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
84static char *unsupported_term[] = {"dumb","cons25",NULL};
85
86static struct termios orig_termios; /* in order to restore at exit */
87static int rawmode = 0; /* for atexit() function to check if restore is needed*/
88static int atexit_registered = 0; /* register atexit just 1 time */
89static int history_max_len = 100;
90static int history_len = 0;
91char **history = NULL;
92
93static void linenoiseAtExit(void);
94int linenoiseHistoryAdd(const char *line);
95
96static 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
106static 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
116static 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 */
142    if (tcsetattr(fd,TCSADRAIN,&raw) < 0) goto fatal;
143    rawmode = 1;
144    return 0;
145
146fatal:
147    errno = ENOTTY;
148    return -1;
149}
150
151static void disableRawMode(int fd) {
152    /* Don't even check the return value as it's too late. */
153    if (rawmode && tcsetattr(fd,TCSADRAIN,&orig_termios) != -1)
154        rawmode = 0;
155}
156
157/* At exit we'll try to fix the terminal to the initial conditions. */
158static void linenoiseAtExit(void) {
159    disableRawMode(STDIN_FILENO);
160    freeHistory();
161}
162
163static int getColumns(void) {
164    struct winsize ws;
165
166    if (ioctl(1, TIOCGWINSZ, &ws) == -1) return 4096;
167    if (ws.ws_col == 0) {
168        return 4096;
169    }
170    return ws.ws_col;
171}
172
173static int effectiveLen(const char* prompt) {
174    int col = 0;
175    char c;
176    // TODO: Handle escape sequences.
177    while ( (c = *prompt++) != 0 ) {
178        if (c == '\n') {
179            col = 0;
180        } else {
181            col++;
182        }
183    }
184    return col;
185}
186
187static void refreshLine(int fd, const char *prompt, char *buf, size_t len, size_t pos, size_t cols) {
188    char seq[64];
189    size_t plen = effectiveLen(prompt);
190
191    while((plen+pos) >= cols) {
192        buf++;
193        len--;
194        pos--;
195    }
196    while (plen+len > cols) {
197        len--;
198    }
199
200    /* Cursor to left edge */
201    snprintf(seq,64,"\x1b[0G");
202    if (write(fd,seq,strlen(seq)) == -1) return;
203    /* Write the prompt and the current buffer content */
204    if (write(fd,prompt,strlen(prompt)) == -1) return;
205    if (write(fd,buf,len) == -1) return;
206    /* Erase to right */
207    snprintf(seq,64,"\x1b[0K");
208    if (write(fd,seq,strlen(seq)) == -1) return;
209    /* Move cursor to original position. */
210    snprintf(seq,64,"\x1b[0G\x1b[%dC", (int)(pos+plen));
211    if (write(fd,seq,strlen(seq)) == -1) return;
212}
213
214static int linenoisePrompt(int fd, char *buf, size_t buflen, const char *prompt) {
215    size_t plen = strlen(prompt);
216    size_t pos = 0;
217    size_t len = 0;
218    size_t cols = getColumns();
219    int history_index = 0;
220
221    buf[0] = '\0';
222    buflen--; /* Make sure there is always space for the nulterm */
223
224    /* The latest history entry is always our current buffer, that
225     * initially is just an empty string. */
226    linenoiseHistoryAdd("");
227
228    if (write(fd,prompt,plen) == -1) return -1;
229    while(1) {
230        char c;
231        int nread;
232        char seq[2];
233
234        nread = read(fd,&c,1);
235        if (nread <= 0) return len;
236        switch(c) {
237        case 10:    /* line feed. */
238        case 13:    /* enter */
239            history_len--;
240            return len;
241        case 4:     /* ctrl-d */
242            history_len--;
243            return (len == 0) ? -1 : (int)len;
244        case 3:     /* ctrl-c */
245            errno = EAGAIN;
246            return -1;
247        case 127:   /* backspace */
248        case 8:     /* ctrl-h */
249            if (pos > 0 && len > 0) {
250                memmove(buf+pos-1,buf+pos,len-pos);
251                pos--;
252                len--;
253                buf[len] = '\0';
254                refreshLine(fd,prompt,buf,len,pos,cols);
255            }
256            break;
257        case 20:    /* ctrl-t */
258            if (pos > 0 && pos < len) {
259                int aux = buf[pos-1];
260                buf[pos-1] = buf[pos];
261                buf[pos] = aux;
262                if (pos != len-1) pos++;
263                refreshLine(fd,prompt,buf,len,pos,cols);
264            }
265            break;
266        case 2:     /* ctrl-b */
267            goto left_arrow;
268        case 6:     /* ctrl-f */
269            goto right_arrow;
270        case 16:    /* ctrl-p */
271            seq[1] = 65;
272            goto up_down_arrow;
273        case 14:    /* ctrl-n */
274            seq[1] = 66;
275            goto up_down_arrow;
276            break;
277        case 27:    /* escape sequence */
278            if (read(fd,seq,2) == -1) break;
279            if (seq[0] == 91 && seq[1] == 68) {
280left_arrow:
281                /* left arrow */
282                if (pos > 0) {
283                    pos--;
284                    refreshLine(fd,prompt,buf,len,pos,cols);
285                }
286            } else if (seq[0] == 91 && seq[1] == 67) {
287right_arrow:
288                /* right arrow */
289                if (pos != len) {
290                    pos++;
291                    refreshLine(fd,prompt,buf,len,pos,cols);
292                }
293            } else if (seq[0] == 91 && (seq[1] == 65 || seq[1] == 66)) {
294up_down_arrow:
295                /* up and down arrow: history */
296                if (history_len > 1) {
297                    /* Update the current history entry before to
298                     * overwrite it with tne next one. */
299                    free(history[history_len-1-history_index]);
300                    history[history_len-1-history_index] = strdup(buf);
301                    /* Show the new entry */
302                    history_index += (seq[1] == 65) ? 1 : -1;
303                    if (history_index < 0) {
304                        history_index = 0;
305                        break;
306                    } else if (history_index >= history_len) {
307                        history_index = history_len-1;
308                        break;
309                    }
310                    strncpy(buf,history[history_len-1-history_index],buflen);
311                    buf[buflen] = '\0';
312                    len = pos = strlen(buf);
313                    refreshLine(fd,prompt,buf,len,pos,cols);
314                }
315            }
316            break;
317        default:
318            if (len < buflen) {
319                if (len == pos) {
320                    buf[pos] = c;
321                    pos++;
322                    len++;
323                    buf[len] = '\0';
324                    if (plen+len < cols) {
325                        /* Avoid a full update of the line in the
326                         * trivial case. */
327                        if (write(fd,&c,1) == -1) return -1;
328                    } else {
329                        refreshLine(fd,prompt,buf,len,pos,cols);
330                    }
331                } else {
332                    memmove(buf+pos+1,buf+pos,len-pos);
333                    buf[pos] = c;
334                    len++;
335                    pos++;
336                    buf[len] = '\0';
337                    refreshLine(fd,prompt,buf,len,pos,cols);
338                }
339            }
340            break;
341        case 21: /* Ctrl+u, delete the whole line. */
342            buf[0] = '\0';
343            pos = len = 0;
344            refreshLine(fd,prompt,buf,len,pos,cols);
345            break;
346        case 11: /* Ctrl+k, delete from current to end of line. */
347            buf[pos] = '\0';
348            len = pos;
349            refreshLine(fd,prompt,buf,len,pos,cols);
350            break;
351        case 1: /* Ctrl+a, go to the start of the line */
352            pos = 0;
353            refreshLine(fd,prompt,buf,len,pos,cols);
354            break;
355        case 5: /* ctrl+e, go to the end of the line */
356            pos = len;
357            refreshLine(fd,prompt,buf,len,pos,cols);
358            break;
359        }
360    }
361    return len;
362}
363
364static int linenoiseRaw(char *buf, size_t buflen, const char *prompt) {
365    int fd = STDIN_FILENO;
366    int count;
367
368    if (buflen == 0) {
369        errno = EINVAL;
370        return -1;
371    }
372    if (!isatty(STDIN_FILENO)) {
373        if (fgets(buf, buflen, stdin) == NULL) return -1;
374        count = strlen(buf);
375        if (count && buf[count-1] == '\n') {
376            count--;
377            buf[count] = '\0';
378        }
379    } else {
380        if (enableRawMode(fd) == -1) return -1;
381        count = linenoisePrompt(fd, buf, buflen, prompt);
382        disableRawMode(fd);
383    }
384    return count;
385}
386
387char *linenoise(const char *prompt) {
388    char buf[LINENOISE_MAX_LINE];
389    int count;
390
391    if (isUnsupportedTerm()) {
392        size_t len;
393
394        printf("%s",prompt);
395        fflush(stdout);
396        if (fgets(buf,LINENOISE_MAX_LINE,stdin) == NULL) return NULL;
397        len = strlen(buf);
398        while(len && (buf[len-1] == '\n' || buf[len-1] == '\r')) {
399            len--;
400            buf[len] = '\0';
401        }
402        return strdup(buf);
403    } else {
404        count = linenoiseRaw(buf,LINENOISE_MAX_LINE,prompt);
405        if (count == -1) return NULL;
406        return strdup(buf);
407    }
408}
409
410/* Using a circular buffer is smarter, but a bit more complex to handle. */
411int linenoiseHistoryAdd(const char *line) {
412    char *linecopy;
413
414    if (history_max_len == 0) return 0;
415    if (history == 0) {
416        history = malloc(sizeof(char*)*history_max_len);
417        if (history == NULL) return 0;
418        memset(history,0,(sizeof(char*)*history_max_len));
419    }
420    linecopy = strdup(line);
421    if (!linecopy) return 0;
422    if (history_len == history_max_len) {
423        memmove(history,history+1,sizeof(char*)*(history_max_len-1));
424        history_len--;
425    }
426    history[history_len] = linecopy;
427    history_len++;
428    return 1;
429}
430
431int linenoiseHistorySetMaxLen(int len) {
432    char **new;
433
434    if (len < 1) return 0;
435    if (history) {
436        int tocopy = history_len;
437
438        new = malloc(sizeof(char*)*len);
439        if (new == NULL) return 0;
440        if (len < tocopy) tocopy = len;
441        memcpy(new,history+(history_max_len-tocopy), sizeof(char*)*tocopy);
442        free(history);
443        history = new;
444    }
445    history_max_len = len;
446    if (history_len > history_max_len)
447        history_len = history_max_len;
448    return 1;
449}
450