xref: /freebsd/bin/sh/input.c (revision 287472b39c7985d968be84ea145c3e75a3e6b875) 
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Kenneth Almquist.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 #if 0
35 static char sccsid[] = "@(#)input.c	8.3 (Berkeley) 6/9/95";
36 #endif
37 #endif /* not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include <stdio.h>	/* defines BUFSIZ */
42 #include <fcntl.h>
43 #include <errno.h>
44 #include <unistd.h>
45 #include <stdlib.h>
46 #include <string.h>
47 
48 /*
49  * This file implements the input routines used by the parser.
50  */
51 
52 #include "shell.h"
53 #include "redir.h"
54 #include "syntax.h"
55 #include "input.h"
56 #include "output.h"
57 #include "options.h"
58 #include "memalloc.h"
59 #include "error.h"
60 #include "alias.h"
61 #include "parser.h"
62 #include "myhistedit.h"
63 #include "trap.h"
64 
65 #define EOF_NLEFT -99		/* value of parsenleft when EOF pushed back */
66 
67 struct strpush {
68 	struct strpush *prev;	/* preceding string on stack */
69 	const char *prevstring;
70 	int prevnleft;
71 	int prevlleft;
72 	struct alias *ap;	/* if push was associated with an alias */
73 };
74 
75 /*
76  * The parsefile structure pointed to by the global variable parsefile
77  * contains information about the current file being read.
78  */
79 
80 struct parsefile {
81 	struct parsefile *prev;	/* preceding file on stack */
82 	int linno;		/* current line */
83 	int fd;			/* file descriptor (or -1 if string) */
84 	int nleft;		/* number of chars left in this line */
85 	int lleft;		/* number of lines left in this buffer */
86 	const char *nextc;	/* next char in buffer */
87 	char *buf;		/* input buffer */
88 	struct strpush *strpush; /* for pushing strings at this level */
89 	struct strpush basestrpush; /* so pushing one is fast */
90 };
91 
92 
93 int plinno = 1;			/* input line number */
94 int parsenleft;			/* copy of parsefile->nleft */
95 static int parselleft;		/* copy of parsefile->lleft */
96 const char *parsenextc;		/* copy of parsefile->nextc */
97 static char basebuf[BUFSIZ + 1];/* buffer for top level input file */
98 static struct parsefile basepf = {	/* top level input file */
99 	.nextc = basebuf,
100 	.buf = basebuf
101 };
102 static struct parsefile *parsefile = &basepf;	/* current input file */
103 int whichprompt;		/* 1 == PS1, 2 == PS2 */
104 
105 EditLine *el;			/* cookie for editline package */
106 
107 static void pushfile(void);
108 static int preadfd(void);
109 static void popstring(void);
110 
111 void
112 resetinput(void)
113 {
114 	popallfiles();
115 	parselleft = parsenleft = 0;	/* clear input buffer */
116 }
117 
118 
119 /*
120  * Read a line from the script.
121  */
122 
123 char *
124 pfgets(char *line, int len)
125 {
126 	char *p = line;
127 	int nleft = len;
128 	int c;
129 
130 	while (--nleft > 0) {
131 		c = pgetc_macro();
132 		if (c == PEOF) {
133 			if (p == line)
134 				return NULL;
135 			break;
136 		}
137 		*p++ = c;
138 		if (c == '\n')
139 			break;
140 	}
141 	*p = '\0';
142 	return line;
143 }
144 
145 
146 
147 /*
148  * Read a character from the script, returning PEOF on end of file.
149  * Nul characters in the input are silently discarded.
150  */
151 
152 int
153 pgetc(void)
154 {
155 	return pgetc_macro();
156 }
157 
158 
159 static int
160 preadfd(void)
161 {
162 	int nr;
163 	parsenextc = parsefile->buf;
164 
165 #ifndef NO_HISTORY
166 	if (el != NULL && gotwinch) {
167 		gotwinch = 0;
168 		el_resize(el);
169 	}
170 #endif
171 retry:
172 #ifndef NO_HISTORY
173 	if (parsefile->fd == 0 && el) {
174 		static const char *rl_cp;
175 		static int el_len;
176 
177 		if (rl_cp == NULL)
178 			rl_cp = el_gets(el, &el_len);
179 		if (rl_cp == NULL)
180 			nr = el_len == 0 ? 0 : -1;
181 		else {
182 			nr = el_len;
183 			if (nr > BUFSIZ)
184 				nr = BUFSIZ;
185 			memcpy(parsefile->buf, rl_cp, nr);
186 			if (nr != el_len) {
187 				el_len -= nr;
188 				rl_cp += nr;
189 			} else
190 				rl_cp = NULL;
191 		}
192 	} else
193 #endif
194 		nr = read(parsefile->fd, parsefile->buf, BUFSIZ);
195 
196 	if (nr <= 0) {
197                 if (nr < 0) {
198                         if (errno == EINTR)
199                                 goto retry;
200                         if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
201                                 int flags = fcntl(0, F_GETFL, 0);
202                                 if (flags >= 0 && flags & O_NONBLOCK) {
203                                         flags &=~ O_NONBLOCK;
204                                         if (fcntl(0, F_SETFL, flags) >= 0) {
205 						out2fmt_flush("sh: turning off NDELAY mode\n");
206                                                 goto retry;
207                                         }
208                                 }
209                         }
210                 }
211                 nr = -1;
212 	}
213 	return nr;
214 }
215 
216 /*
217  * Refill the input buffer and return the next input character:
218  *
219  * 1) If a string was pushed back on the input, pop it;
220  * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
221  *    from a string so we can't refill the buffer, return EOF.
222  * 3) If there is more in this buffer, use it else call read to fill it.
223  * 4) Process input up to the next newline, deleting nul characters.
224  */
225 
226 int
227 preadbuffer(void)
228 {
229 	char *p, *q;
230 	int more;
231 	int something;
232 	char savec;
233 
234 	if (parsefile->strpush) {
235 		popstring();
236 		if (--parsenleft >= 0)
237 			return (*parsenextc++);
238 	}
239 	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
240 		return PEOF;
241 	flushout(&output);
242 	flushout(&errout);
243 
244 again:
245 	if (parselleft <= 0) {
246 		if ((parselleft = preadfd()) == -1) {
247 			parselleft = parsenleft = EOF_NLEFT;
248 			return PEOF;
249 		}
250 	}
251 
252 	q = p = parsefile->buf + (parsenextc - parsefile->buf);
253 
254 	/* delete nul characters */
255 	something = 0;
256 	for (more = 1; more;) {
257 		switch (*p) {
258 		case '\0':
259 			p++;	/* Skip nul */
260 			goto check;
261 
262 		case '\t':
263 		case ' ':
264 			break;
265 
266 		case '\n':
267 			parsenleft = q - parsenextc;
268 			more = 0; /* Stop processing here */
269 			break;
270 
271 		default:
272 			something = 1;
273 			break;
274 		}
275 
276 		*q++ = *p++;
277 check:
278 		if (--parselleft <= 0) {
279 			parsenleft = q - parsenextc - 1;
280 			if (parsenleft < 0)
281 				goto again;
282 			*q = '\0';
283 			more = 0;
284 		}
285 	}
286 
287 	savec = *q;
288 	*q = '\0';
289 
290 #ifndef NO_HISTORY
291 	if (parsefile->fd == 0 && hist && something) {
292 		HistEvent he;
293 		INTOFF;
294 		history(hist, &he, whichprompt == 1 ? H_ENTER : H_ADD,
295 		    parsenextc);
296 		INTON;
297 	}
298 #endif
299 
300 	if (vflag) {
301 		out2str(parsenextc);
302 		flushout(out2);
303 	}
304 
305 	*q = savec;
306 
307 	return *parsenextc++;
308 }
309 
310 /*
311  * Returns if we are certain we are at EOF. Does not cause any more input
312  * to be read from the outside world.
313  */
314 
315 int
316 preadateof(void)
317 {
318 	if (parsenleft > 0)
319 		return 0;
320 	if (parsefile->strpush)
321 		return 0;
322 	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
323 		return 1;
324 	return 0;
325 }
326 
327 /*
328  * Undo the last call to pgetc.  Only one character may be pushed back.
329  * PEOF may be pushed back.
330  */
331 
332 void
333 pungetc(void)
334 {
335 	parsenleft++;
336 	parsenextc--;
337 }
338 
339 /*
340  * Push a string back onto the input at this current parsefile level.
341  * We handle aliases this way.
342  */
343 void
344 pushstring(char *s, int len, struct alias *ap)
345 {
346 	struct strpush *sp;
347 
348 	INTOFF;
349 /*out2fmt_flush("*** calling pushstring: %s, %d\n", s, len);*/
350 	if (parsefile->strpush) {
351 		sp = ckmalloc(sizeof (struct strpush));
352 		sp->prev = parsefile->strpush;
353 		parsefile->strpush = sp;
354 	} else
355 		sp = parsefile->strpush = &(parsefile->basestrpush);
356 	sp->prevstring = parsenextc;
357 	sp->prevnleft = parsenleft;
358 	sp->prevlleft = parselleft;
359 	sp->ap = ap;
360 	if (ap)
361 		ap->flag |= ALIASINUSE;
362 	parsenextc = s;
363 	parsenleft = len;
364 	INTON;
365 }
366 
367 static void
368 popstring(void)
369 {
370 	struct strpush *sp = parsefile->strpush;
371 
372 	INTOFF;
373 	parsenextc = sp->prevstring;
374 	parsenleft = sp->prevnleft;
375 	parselleft = sp->prevlleft;
376 /*out2fmt_flush("*** calling popstring: restoring to '%s'\n", parsenextc);*/
377 	if (sp->ap)
378 		sp->ap->flag &= ~ALIASINUSE;
379 	parsefile->strpush = sp->prev;
380 	if (sp != &(parsefile->basestrpush))
381 		ckfree(sp);
382 	INTON;
383 }
384 
385 /*
386  * Set the input to take input from a file.  If push is set, push the
387  * old input onto the stack first.
388  */
389 
390 void
391 setinputfile(const char *fname, int push)
392 {
393 	int fd;
394 	int fd2;
395 
396 	INTOFF;
397 	if ((fd = open(fname, O_RDONLY | O_CLOEXEC)) < 0)
398 		error("cannot open %s: %s", fname, strerror(errno));
399 	if (fd < 10) {
400 		fd2 = fcntl(fd, F_DUPFD_CLOEXEC, 10);
401 		close(fd);
402 		if (fd2 < 0)
403 			error("Out of file descriptors");
404 		fd = fd2;
405 	}
406 	setinputfd(fd, push);
407 	INTON;
408 }
409 
410 
411 /*
412  * Like setinputfile, but takes an open file descriptor (which should have
413  * its FD_CLOEXEC flag already set).  Call this with interrupts off.
414  */
415 
416 void
417 setinputfd(int fd, int push)
418 {
419 	if (push) {
420 		pushfile();
421 		parsefile->buf = ckmalloc(BUFSIZ + 1);
422 	}
423 	if (parsefile->fd > 0)
424 		close(parsefile->fd);
425 	parsefile->fd = fd;
426 	if (parsefile->buf == NULL)
427 		parsefile->buf = ckmalloc(BUFSIZ + 1);
428 	parselleft = parsenleft = 0;
429 	plinno = 1;
430 }
431 
432 
433 /*
434  * Like setinputfile, but takes input from a string.
435  */
436 
437 void
438 setinputstring(const char *string, int push)
439 {
440 	INTOFF;
441 	if (push)
442 		pushfile();
443 	parsenextc = string;
444 	parselleft = parsenleft = strlen(string);
445 	parsefile->buf = NULL;
446 	plinno = 1;
447 	INTON;
448 }
449 
450 
451 
452 /*
453  * To handle the "." command, a stack of input files is used.  Pushfile
454  * adds a new entry to the stack and popfile restores the previous level.
455  */
456 
457 static void
458 pushfile(void)
459 {
460 	struct parsefile *pf;
461 
462 	parsefile->nleft = parsenleft;
463 	parsefile->lleft = parselleft;
464 	parsefile->nextc = parsenextc;
465 	parsefile->linno = plinno;
466 	pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
467 	pf->prev = parsefile;
468 	pf->fd = -1;
469 	pf->strpush = NULL;
470 	pf->basestrpush.prev = NULL;
471 	parsefile = pf;
472 }
473 
474 
475 void
476 popfile(void)
477 {
478 	struct parsefile *pf = parsefile;
479 
480 	INTOFF;
481 	if (pf->fd >= 0)
482 		close(pf->fd);
483 	if (pf->buf)
484 		ckfree(pf->buf);
485 	while (pf->strpush)
486 		popstring();
487 	parsefile = pf->prev;
488 	ckfree(pf);
489 	parsenleft = parsefile->nleft;
490 	parselleft = parsefile->lleft;
491 	parsenextc = parsefile->nextc;
492 	plinno = parsefile->linno;
493 	INTON;
494 }
495 
496 
497 /*
498  * Return current file (to go back to it later using popfilesupto()).
499  */
500 
501 struct parsefile *
502 getcurrentfile(void)
503 {
504 	return parsefile;
505 }
506 
507 
508 /*
509  * Pop files until the given file is on top again. Useful for regular
510  * builtins that read shell commands from files or strings.
511  * If the given file is not an active file, an error is raised.
512  */
513 
514 void
515 popfilesupto(struct parsefile *file)
516 {
517 	while (parsefile != file && parsefile != &basepf)
518 		popfile();
519 	if (parsefile != file)
520 		error("popfilesupto() misused");
521 }
522 
523 /*
524  * Return to top level.
525  */
526 
527 void
528 popallfiles(void)
529 {
530 	while (parsefile != &basepf)
531 		popfile();
532 }
533 
534 
535 
536 /*
537  * Close the file(s) that the shell is reading commands from.  Called
538  * after a fork is done.
539  */
540 
541 void
542 closescript(void)
543 {
544 	popallfiles();
545 	if (parsefile->fd > 0) {
546 		close(parsefile->fd);
547 		parsefile->fd = 0;
548 	}
549 }
550