input.c revision 1.54 
1/*	$NetBSD: input.c,v 1.54 2017/05/03 04:13:53 kre Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)input.c	8.3 (Berkeley) 6/9/95";
39#else
40__RCSID("$NetBSD: input.c,v 1.54 2017/05/03 04:13:53 kre Exp $");
41#endif
42#endif /* not lint */
43
44#include <stdio.h>	/* defines BUFSIZ */
45#include <fcntl.h>
46#include <errno.h>
47#include <unistd.h>
48#include <limits.h>
49#include <stdlib.h>
50#include <string.h>
51#include <sys/stat.h>
52
53/*
54 * This file implements the input routines used by the parser.
55 */
56
57#include "shell.h"
58#include "redir.h"
59#include "syntax.h"
60#include "input.h"
61#include "output.h"
62#include "options.h"
63#include "memalloc.h"
64#include "error.h"
65#include "alias.h"
66#include "parser.h"
67#include "myhistedit.h"
68
69#define EOF_NLEFT -99		/* value of parsenleft when EOF pushed back */
70
71MKINIT
72struct strpush {
73	struct strpush *prev;	/* preceding string on stack */
74	char *prevstring;
75	int prevnleft;
76	int prevlleft;
77	struct alias *ap;	/* if push was associated with an alias */
78};
79
80/*
81 * The parsefile structure pointed to by the global variable parsefile
82 * contains information about the current file being read.
83 */
84
85MKINIT
86struct parsefile {
87	struct parsefile *prev;	/* preceding file on stack */
88	int linno;		/* current line */
89	int fd;			/* file descriptor (or -1 if string) */
90	int nleft;		/* number of chars left in this line */
91	int lleft;		/* number of chars left in this buffer */
92	char *nextc;		/* next char in buffer */
93	char *buf;		/* input buffer */
94	struct strpush *strpush; /* for pushing strings at this level */
95	struct strpush basestrpush; /* so pushing one is fast */
96};
97
98
99int plinno = 1;			/* input line number */
100int parsenleft;			/* copy of parsefile->nleft */
101MKINIT int parselleft;		/* copy of parsefile->lleft */
102char *parsenextc;		/* copy of parsefile->nextc */
103MKINIT struct parsefile basepf;	/* top level input file */
104MKINIT char basebuf[BUFSIZ];	/* buffer for top level input file */
105struct parsefile *parsefile = &basepf;	/* current input file */
106int init_editline = 0;		/* editline library initialized? */
107int whichprompt;		/* 1 == PS1, 2 == PS2 */
108
109STATIC void pushfile(void);
110static int preadfd(void);
111
112#ifdef mkinit
113INCLUDE <stdio.h>
114INCLUDE "input.h"
115INCLUDE "error.h"
116
117INIT {
118	basepf.nextc = basepf.buf = basebuf;
119}
120
121RESET {
122	if (exception != EXSHELLPROC)
123		parselleft = parsenleft = 0;	/* clear input buffer */
124	popallfiles();
125}
126
127SHELLPROC {
128	popallfiles();
129}
130#endif
131
132
133/*
134 * Read a line from the script.
135 */
136
137char *
138pfgets(char *line, int len)
139{
140	char *p = line;
141	int nleft = len;
142	int c;
143
144	while (--nleft > 0) {
145		c = pgetc_macro();
146		if (c == PEOF) {
147			if (p == line)
148				return NULL;
149			break;
150		}
151		*p++ = c;
152		if (c == '\n')
153			break;
154	}
155	*p = '\0';
156	return line;
157}
158
159
160
161/*
162 * Read a character from the script, returning PEOF on end of file.
163 * Nul characters in the input are silently discarded.
164 */
165
166int
167pgetc(void)
168{
169	return pgetc_macro();
170}
171
172
173static int
174preadfd(void)
175{
176	int nr;
177	char *buf =  parsefile->buf;
178	parsenextc = buf;
179
180retry:
181#ifndef SMALL
182	if (parsefile->fd == 0 && el) {
183		static const char *rl_cp;
184		static int el_len;
185
186		if (rl_cp == NULL)
187			rl_cp = el_gets(el, &el_len);
188		if (rl_cp == NULL)
189			nr = el_len == 0 ? 0 : -1;
190		else {
191			nr = el_len;
192			if (nr > BUFSIZ - 8)
193				nr = BUFSIZ - 8;
194			memcpy(buf, rl_cp, nr);
195			if (nr != el_len) {
196				el_len -= nr;
197				rl_cp += nr;
198			} else
199				rl_cp = 0;
200		}
201
202	} else
203#endif
204		nr = read(parsefile->fd, buf, BUFSIZ - 8);
205
206
207	if (nr <= 0) {
208                if (nr < 0) {
209                        if (errno == EINTR)
210                                goto retry;
211                        if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
212                                int flags = fcntl(0, F_GETFL, 0);
213                                if (flags >= 0 && flags & O_NONBLOCK) {
214                                        flags &=~ O_NONBLOCK;
215                                        if (fcntl(0, F_SETFL, flags) >= 0) {
216						out2str("sh: turning off NDELAY mode\n");
217                                                goto retry;
218                                        }
219                                }
220                        }
221                }
222                nr = -1;
223	}
224	return nr;
225}
226
227/*
228 * Refill the input buffer and return the next input character:
229 *
230 * 1) If a string was pushed back on the input, pop it;
231 * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
232 *    from a string so we can't refill the buffer, return EOF.
233 * 3) If the is more stuff in this buffer, use it else call read to fill it.
234 * 4) Process input up to the next newline, deleting nul characters.
235 */
236
237int
238preadbuffer(void)
239{
240	char *p, *q;
241	int more;
242#ifndef SMALL
243	int something;
244#endif
245	char savec;
246
247	if (parsefile->strpush) {
248		popstring();
249		if (--parsenleft >= 0)
250			return (*parsenextc++);
251	}
252	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
253		return PEOF;
254	flushout(&output);
255	flushout(&errout);
256
257again:
258	if (parselleft <= 0) {
259		if ((parselleft = preadfd()) == -1) {
260			parselleft = parsenleft = EOF_NLEFT;
261			return PEOF;
262		}
263	}
264
265	q = p = parsenextc;
266
267	/* delete nul characters */
268#ifndef SMALL
269	something = 0;
270#endif
271	for (more = 1; more;) {
272		switch (*p) {
273		case '\0':
274			p++;	/* Skip nul */
275			goto check;
276
277		case '\t':
278		case ' ':
279			break;
280
281		case '\n':
282			parsenleft = q - parsenextc;
283			more = 0; /* Stop processing here */
284			break;
285
286		default:
287#ifndef SMALL
288			something = 1;
289#endif
290			break;
291		}
292
293		*q++ = *p++;
294check:
295		if (--parselleft <= 0) {
296			parsenleft = q - parsenextc - 1;
297			if (parsenleft < 0)
298				goto again;
299			*q = '\0';
300			more = 0;
301		}
302	}
303
304	savec = *q;
305	*q = '\0';
306
307#ifndef SMALL
308	if (parsefile->fd == 0 && hist && something) {
309		HistEvent he;
310		INTOFF;
311		history(hist, &he, whichprompt == 1? H_ENTER : H_APPEND,
312		    parsenextc);
313		INTON;
314	}
315#endif
316
317	if (vflag) {
318		out2str(parsenextc);
319		flushout(out2);
320	}
321
322	*q = savec;
323
324	return *parsenextc++;
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
332void
333pungetc(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 */
343void
344pushstring(char *s, int len, struct alias *ap)
345{
346	struct strpush *sp;
347
348	INTOFF;
349/*debugprintf("*** 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
367void
368popstring(void)
369{
370	struct strpush *sp = parsefile->strpush;
371
372	INTOFF;
373	parsenextc = sp->prevstring;
374	parsenleft = sp->prevnleft;
375	parselleft = sp->prevlleft;
376/*debugprintf("*** 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
390void
391setinputfile(const char *fname, int push)
392{
393	unsigned char magic[4];
394	int fd;
395	int fd2;
396	struct stat sb;
397
398	INTOFF;
399	if ((fd = open(fname, O_RDONLY)) < 0)
400		error("Can't open %s", fname);
401
402	/* Since the message "Syntax error: "(" unexpected" is not very
403	 * helpful, we check if the file starts with the ELF magic to
404	 * avoid that message. The first lseek tries to make sure that
405	 * we can later rewind the file.
406	 */
407	if (fstat(fd, &sb) == 0 && S_ISREG(sb.st_mode) &&
408	    lseek(fd, 0, SEEK_SET) == 0) {
409		if (read(fd, magic, 4) == 4) {
410			if (memcmp(magic, "\177ELF", 4) == 0) {
411				(void)close(fd);
412				error("Cannot execute ELF binary %s", fname);
413			}
414		}
415		if (lseek(fd, 0, SEEK_SET) != 0) {
416			(void)close(fd);
417			error("Cannot rewind the file %s", fname);
418		}
419	}
420
421	fd2 = to_upper_fd(fd);	/* closes fd, returns higher equiv */
422	if (fd2 == fd) {
423		(void) close(fd);
424		error("Out of file descriptors");
425	}
426
427	setinputfd(fd2, push);
428	INTON;
429}
430
431/*
432 * When a shell fd needs to be altered (when the user wants to use
433 * the same fd - rare, but happens - we need to locate the ref to
434 * the fd, and update it.  This happens via a callback.
435 * This is the callback func for fd's used for shell input
436 */
437static void
438input_fd_swap(int from, int to)
439{
440	struct parsefile *pf;
441
442	pf = parsefile;
443	while (pf != NULL) {		/* don't need to stop at basepf */
444		if (pf->fd == from)
445			pf->fd = to;
446		pf = pf->prev;
447	}
448}
449
450/*
451 * Like setinputfile, but takes an open file descriptor.  Call this with
452 * interrupts off.
453 */
454
455void
456setinputfd(int fd, int push)
457{
458	register_sh_fd(fd, input_fd_swap);
459	(void) fcntl(fd, F_SETFD, FD_CLOEXEC);
460	if (push) {
461		pushfile();
462		parsefile->buf = ckmalloc(BUFSIZ);
463	}
464	if (parsefile->fd > 0)
465		sh_close(parsefile->fd);
466	parsefile->fd = fd;
467	if (parsefile->buf == NULL)
468		parsefile->buf = ckmalloc(BUFSIZ);
469	parselleft = parsenleft = 0;
470	plinno = 1;
471}
472
473
474/*
475 * Like setinputfile, but takes input from a string.
476 */
477
478void
479setinputstring(char *string, int push)
480{
481
482	INTOFF;
483	if (push)
484		pushfile();
485	parsenextc = string;
486	parselleft = parsenleft = strlen(string);
487	parsefile->buf = NULL;
488	plinno = 1;
489	INTON;
490}
491
492
493
494/*
495 * To handle the "." command, a stack of input files is used.  Pushfile
496 * adds a new entry to the stack and popfile restores the previous level.
497 */
498
499STATIC void
500pushfile(void)
501{
502	struct parsefile *pf;
503
504	parsefile->nleft = parsenleft;
505	parsefile->lleft = parselleft;
506	parsefile->nextc = parsenextc;
507	parsefile->linno = plinno;
508	pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
509	pf->prev = parsefile;
510	pf->fd = -1;
511	pf->strpush = NULL;
512	pf->basestrpush.prev = NULL;
513	parsefile = pf;
514}
515
516
517void
518popfile(void)
519{
520	struct parsefile *pf = parsefile;
521
522	INTOFF;
523	if (pf->fd >= 0)
524		sh_close(pf->fd);
525	if (pf->buf)
526		ckfree(pf->buf);
527	while (pf->strpush)
528		popstring();
529	parsefile = pf->prev;
530	ckfree(pf);
531	parsenleft = parsefile->nleft;
532	parselleft = parsefile->lleft;
533	parsenextc = parsefile->nextc;
534	plinno = parsefile->linno;
535	INTON;
536}
537
538
539/*
540 * Return to top level.
541 */
542
543void
544popallfiles(void)
545{
546	while (parsefile != &basepf)
547		popfile();
548}
549
550
551
552/*
553 * Close the file(s) that the shell is reading commands from.  Called
554 * after a fork is done.
555 *
556 * Takes one arg, vfork, which tells it to not modify its global vars
557 * as it is still running in the parent.
558 *
559 * This code is (probably) unnecessary as the 'close on exec' flag is
560 * set and should be enough.  In the vfork case it is definitely wrong
561 * to close the fds as another fork() may be done later to feed data
562 * from a 'here' document into a pipe and we don't want to close the
563 * pipe!
564 */
565
566void
567closescript(int vforked)
568{
569	if (vforked)
570		return;
571	popallfiles();
572	if (parsefile->fd > 0) {
573		sh_close(parsefile->fd);
574		parsefile->fd = 0;
575	}
576}
577