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input.c revision 1.46 
      1 /*	$NetBSD: input.c,v 1.46 2013/10/30 08:38:40 mrg 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
     38 static char sccsid[] = "@(#)input.c	8.3 (Berkeley) 6/9/95";
     39 #else
     40 __RCSID("$NetBSD: input.c,v 1.46 2013/10/30 08:38:40 mrg 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 
     52 /*
     53  * This file implements the input routines used by the parser.
     54  */
     55 
     56 #include "shell.h"
     57 #include "redir.h"
     58 #include "syntax.h"
     59 #include "input.h"
     60 #include "output.h"
     61 #include "options.h"
     62 #include "memalloc.h"
     63 #include "error.h"
     64 #include "alias.h"
     65 #include "parser.h"
     66 #include "myhistedit.h"
     67 
     68 #define EOF_NLEFT -99		/* value of parsenleft when EOF pushed back */
     69 
     70 MKINIT
     71 struct strpush {
     72 	struct strpush *prev;	/* preceding string on stack */
     73 	char *prevstring;
     74 	int prevnleft;
     75 	int prevlleft;
     76 	struct alias *ap;	/* if push was associated with an alias */
     77 };
     78 
     79 /*
     80  * The parsefile structure pointed to by the global variable parsefile
     81  * contains information about the current file being read.
     82  */
     83 
     84 MKINIT
     85 struct parsefile {
     86 	struct parsefile *prev;	/* preceding file on stack */
     87 	int linno;		/* current line */
     88 	int fd;			/* file descriptor (or -1 if string) */
     89 	int nleft;		/* number of chars left in this line */
     90 	int lleft;		/* number of chars left in this buffer */
     91 	char *nextc;		/* next char in buffer */
     92 	char *buf;		/* input buffer */
     93 	struct strpush *strpush; /* for pushing strings at this level */
     94 	struct strpush basestrpush; /* so pushing one is fast */
     95 };
     96 
     97 
     98 int plinno = 1;			/* input line number */
     99 int parsenleft;			/* copy of parsefile->nleft */
    100 MKINIT int parselleft;		/* copy of parsefile->lleft */
    101 char *parsenextc;		/* copy of parsefile->nextc */
    102 MKINIT struct parsefile basepf;	/* top level input file */
    103 MKINIT char basebuf[BUFSIZ];	/* buffer for top level input file */
    104 struct parsefile *parsefile = &basepf;	/* current input file */
    105 int init_editline = 0;		/* editline library initialized? */
    106 int whichprompt;		/* 1 == PS1, 2 == PS2 */
    107 
    108 STATIC void pushfile(void);
    109 static int preadfd(void);
    110 
    111 #ifdef mkinit
    112 INCLUDE <stdio.h>
    113 INCLUDE "input.h"
    114 INCLUDE "error.h"
    115 
    116 INIT {
    117 	basepf.nextc = basepf.buf = basebuf;
    118 }
    119 
    120 RESET {
    121 	if (exception != EXSHELLPROC)
    122 		parselleft = parsenleft = 0;	/* clear input buffer */
    123 	popallfiles();
    124 }
    125 
    126 SHELLPROC {
    127 	popallfiles();
    128 }
    129 #endif
    130 
    131 
    132 /*
    133  * Read a line from the script.
    134  */
    135 
    136 char *
    137 pfgets(char *line, int len)
    138 {
    139 	char *p = line;
    140 	int nleft = len;
    141 	int c;
    142 
    143 	while (--nleft > 0) {
    144 		c = pgetc_macro();
    145 		if (c == PEOF) {
    146 			if (p == line)
    147 				return NULL;
    148 			break;
    149 		}
    150 		*p++ = c;
    151 		if (c == '\n')
    152 			break;
    153 	}
    154 	*p = '\0';
    155 	return line;
    156 }
    157 
    158 
    159 
    160 /*
    161  * Read a character from the script, returning PEOF on end of file.
    162  * Nul characters in the input are silently discarded.
    163  */
    164 
    165 int
    166 pgetc(void)
    167 {
    168 	return pgetc_macro();
    169 }
    170 
    171 
    172 static int
    173 preadfd(void)
    174 {
    175 	int nr;
    176 	char *buf =  parsefile->buf;
    177 	parsenextc = buf;
    178 
    179 retry:
    180 #ifndef SMALL
    181 	if (parsefile->fd == 0 && el) {
    182 		static const char *rl_cp;
    183 		static int el_len;
    184 
    185 		if (rl_cp == NULL)
    186 			rl_cp = el_gets(el, &el_len);
    187 		if (rl_cp == NULL)
    188 			nr = el_len == 0 ? 0 : -1;
    189 		else {
    190 			nr = el_len;
    191 			if (nr > BUFSIZ - 8)
    192 				nr = BUFSIZ - 8;
    193 			memcpy(buf, rl_cp, nr);
    194 			if (nr != el_len) {
    195 				el_len -= nr;
    196 				rl_cp += nr;
    197 			} else
    198 				rl_cp = 0;
    199 		}
    200 
    201 	} else
    202 #endif
    203 		nr = read(parsefile->fd, buf, BUFSIZ - 8);
    204 
    205 
    206 	if (nr <= 0) {
    207                 if (nr < 0) {
    208                         if (errno == EINTR)
    209                                 goto retry;
    210                         if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
    211                                 int flags = fcntl(0, F_GETFL, 0);
    212                                 if (flags >= 0 && flags & O_NONBLOCK) {
    213                                         flags &=~ O_NONBLOCK;
    214                                         if (fcntl(0, F_SETFL, flags) >= 0) {
    215 						out2str("sh: turning off NDELAY mode\n");
    216                                                 goto retry;
    217                                         }
    218                                 }
    219                         }
    220                 }
    221                 nr = -1;
    222 	}
    223 	return nr;
    224 }
    225 
    226 /*
    227  * Refill the input buffer and return the next input character:
    228  *
    229  * 1) If a string was pushed back on the input, pop it;
    230  * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
    231  *    from a string so we can't refill the buffer, return EOF.
    232  * 3) If the is more stuff in this buffer, use it else call read to fill it.
    233  * 4) Process input up to the next newline, deleting nul characters.
    234  */
    235 
    236 int
    237 preadbuffer(void)
    238 {
    239 	char *p, *q;
    240 	int more;
    241 #ifndef SMALL
    242 	int something;
    243 #endif
    244 	char savec;
    245 
    246 	if (parsefile->strpush) {
    247 		popstring();
    248 		if (--parsenleft >= 0)
    249 			return (*parsenextc++);
    250 	}
    251 	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
    252 		return PEOF;
    253 	flushout(&output);
    254 	flushout(&errout);
    255 
    256 again:
    257 	if (parselleft <= 0) {
    258 		if ((parselleft = preadfd()) == -1) {
    259 			parselleft = parsenleft = EOF_NLEFT;
    260 			return PEOF;
    261 		}
    262 	}
    263 
    264 	q = p = parsenextc;
    265 
    266 	/* delete nul characters */
    267 #ifndef SMALL
    268 	something = 0;
    269 #endif
    270 	for (more = 1; more;) {
    271 		switch (*p) {
    272 		case '\0':
    273 			p++;	/* Skip nul */
    274 			goto check;
    275 
    276 		case '\t':
    277 		case ' ':
    278 			break;
    279 
    280 		case '\n':
    281 			parsenleft = q - parsenextc;
    282 			more = 0; /* Stop processing here */
    283 			break;
    284 
    285 		default:
    286 #ifndef SMALL
    287 			something = 1;
    288 #endif
    289 			break;
    290 		}
    291 
    292 		*q++ = *p++;
    293 check:
    294 		if (--parselleft <= 0) {
    295 			parsenleft = q - parsenextc - 1;
    296 			if (parsenleft < 0)
    297 				goto again;
    298 			*q = '\0';
    299 			more = 0;
    300 		}
    301 	}
    302 
    303 	savec = *q;
    304 	*q = '\0';
    305 
    306 #ifndef SMALL
    307 	if (parsefile->fd == 0 && hist && something) {
    308 		HistEvent he;
    309 		INTOFF;
    310 		history(hist, &he, whichprompt == 1? H_ENTER : H_APPEND,
    311 		    parsenextc);
    312 		INTON;
    313 	}
    314 #endif
    315 
    316 	if (vflag) {
    317 		out2str(parsenextc);
    318 		flushout(out2);
    319 	}
    320 
    321 	*q = savec;
    322 
    323 	return *parsenextc++;
    324 }
    325 
    326 /*
    327  * Undo the last call to pgetc.  Only one character may be pushed back.
    328  * PEOF may be pushed back.
    329  */
    330 
    331 void
    332 pungetc(void)
    333 {
    334 	parsenleft++;
    335 	parsenextc--;
    336 }
    337 
    338 /*
    339  * Push a string back onto the input at this current parsefile level.
    340  * We handle aliases this way.
    341  */
    342 void
    343 pushstring(char *s, int len, void *ap)
    344 {
    345 	struct strpush *sp;
    346 
    347 	INTOFF;
    348 /*debugprintf("*** calling pushstring: %s, %d\n", s, len);*/
    349 	if (parsefile->strpush) {
    350 		sp = ckmalloc(sizeof (struct strpush));
    351 		sp->prev = parsefile->strpush;
    352 		parsefile->strpush = sp;
    353 	} else
    354 		sp = parsefile->strpush = &(parsefile->basestrpush);
    355 	sp->prevstring = parsenextc;
    356 	sp->prevnleft = parsenleft;
    357 	sp->prevlleft = parselleft;
    358 	sp->ap = (struct alias *)ap;
    359 	if (ap)
    360 		((struct alias *)ap)->flag |= ALIASINUSE;
    361 	parsenextc = s;
    362 	parsenleft = len;
    363 	INTON;
    364 }
    365 
    366 void
    367 popstring(void)
    368 {
    369 	struct strpush *sp = parsefile->strpush;
    370 
    371 	INTOFF;
    372 	parsenextc = sp->prevstring;
    373 	parsenleft = sp->prevnleft;
    374 	parselleft = sp->prevlleft;
    375 /*debugprintf("*** calling popstring: restoring to '%s'\n", parsenextc);*/
    376 	if (sp->ap)
    377 		sp->ap->flag &= ~ALIASINUSE;
    378 	parsefile->strpush = sp->prev;
    379 	if (sp != &(parsefile->basestrpush))
    380 		ckfree(sp);
    381 	INTON;
    382 }
    383 
    384 /*
    385  * Set the input to take input from a file.  If push is set, push the
    386  * old input onto the stack first.
    387  */
    388 
    389 void
    390 setinputfile(const char *fname, int push)
    391 {
    392 	unsigned char magic[4];
    393 	int fd;
    394 	int fd2;
    395 
    396 	INTOFF;
    397 	if ((fd = open(fname, O_RDONLY)) < 0)
    398 		error("Can't open %s", fname);
    399 
    400 	/* Since the message "Syntax error: "(" unexpected" is not very
    401 	 * helpful, we check if the file starts with the ELF magic to
    402 	 * avoid that message. The first lseek tries to make sure that
    403 	 * we can later rewind the file.
    404 	 */
    405 	if (lseek(fd, 0, SEEK_SET) == 0) {
    406 		if (read(fd, magic, 4) == 4) {
    407 			if (memcmp(magic, "\177ELF", 4) == 0)
    408 				error("Cannot execute ELF binary %s", fname);
    409 		}
    410 		if (lseek(fd, 0, SEEK_SET) != 0)
    411 			error("Cannot rewind the file %s", fname);
    412 	}
    413 
    414 	if (fd < 10) {
    415 		fd2 = copyfd(fd, 10, 0);
    416 		close(fd);
    417 		if (fd2 < 0)
    418 			error("Out of file descriptors");
    419 		fd = fd2;
    420 	}
    421 	setinputfd(fd, push);
    422 	INTON;
    423 }
    424 
    425 
    426 /*
    427  * Like setinputfile, but takes an open file descriptor.  Call this with
    428  * interrupts off.
    429  */
    430 
    431 void
    432 setinputfd(int fd, int push)
    433 {
    434 	(void) fcntl(fd, F_SETFD, FD_CLOEXEC);
    435 	if (push) {
    436 		pushfile();
    437 		parsefile->buf = ckmalloc(BUFSIZ);
    438 	}
    439 	if (parsefile->fd > 0)
    440 		close(parsefile->fd);
    441 	parsefile->fd = fd;
    442 	if (parsefile->buf == NULL)
    443 		parsefile->buf = ckmalloc(BUFSIZ);
    444 	parselleft = parsenleft = 0;
    445 	plinno = 1;
    446 }
    447 
    448 
    449 /*
    450  * Like setinputfile, but takes input from a string.
    451  */
    452 
    453 void
    454 setinputstring(char *string, int push)
    455 {
    456 	INTOFF;
    457 	if (push)
    458 		pushfile();
    459 	parsenextc = string;
    460 	parselleft = parsenleft = strlen(string);
    461 	parsefile->buf = NULL;
    462 	plinno = 1;
    463 	INTON;
    464 }
    465 
    466 
    467 
    468 /*
    469  * To handle the "." command, a stack of input files is used.  Pushfile
    470  * adds a new entry to the stack and popfile restores the previous level.
    471  */
    472 
    473 STATIC void
    474 pushfile(void)
    475 {
    476 	struct parsefile *pf;
    477 
    478 	parsefile->nleft = parsenleft;
    479 	parsefile->lleft = parselleft;
    480 	parsefile->nextc = parsenextc;
    481 	parsefile->linno = plinno;
    482 	pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
    483 	pf->prev = parsefile;
    484 	pf->fd = -1;
    485 	pf->strpush = NULL;
    486 	pf->basestrpush.prev = NULL;
    487 	parsefile = pf;
    488 }
    489 
    490 
    491 void
    492 popfile(void)
    493 {
    494 	struct parsefile *pf = parsefile;
    495 
    496 	INTOFF;
    497 	if (pf->fd >= 0)
    498 		close(pf->fd);
    499 	if (pf->buf)
    500 		ckfree(pf->buf);
    501 	while (pf->strpush)
    502 		popstring();
    503 	parsefile = pf->prev;
    504 	ckfree(pf);
    505 	parsenleft = parsefile->nleft;
    506 	parselleft = parsefile->lleft;
    507 	parsenextc = parsefile->nextc;
    508 	plinno = parsefile->linno;
    509 	INTON;
    510 }
    511 
    512 
    513 /*
    514  * Return to top level.
    515  */
    516 
    517 void
    518 popallfiles(void)
    519 {
    520 	while (parsefile != &basepf)
    521 		popfile();
    522 }
    523 
    524 
    525 
    526 /*
    527  * Close the file(s) that the shell is reading commands from.  Called
    528  * after a fork is done.
    529  *
    530  * Takes one arg, vfork, which tells it to not modify its global vars
    531  * as it is still running in the parent.
    532  *
    533  * This code is (probably) unnecessary as the 'close on exec' flag is
    534  * set and should be enough.  In the vfork case it is definitely wrong
    535  * to close the fds as another fork() may be done later to feed data
    536  * from a 'here' document into a pipe and we don't want to close the
    537  * pipe!
    538  */
    539 
    540 void
    541 closescript(int vforked)
    542 {
    543 	if (vforked)
    544 		return;
    545 	popallfiles();
    546 	if (parsefile->fd > 0) {
    547 		close(parsefile->fd);
    548 		parsefile->fd = 0;
    549 	}
    550 }
    551