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input.c revision 1.45 
      1 /*	$NetBSD: input.c,v 1.45 2012/03/28 20:11:25 christos 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 1.45 2012/03/28 20:11:25 christos 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 	int something;
    242 	char savec;
    243 
    244 	if (parsefile->strpush) {
    245 		popstring();
    246 		if (--parsenleft >= 0)
    247 			return (*parsenextc++);
    248 	}
    249 	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
    250 		return PEOF;
    251 	flushout(&output);
    252 	flushout(&errout);
    253 
    254 again:
    255 	if (parselleft <= 0) {
    256 		if ((parselleft = preadfd()) == -1) {
    257 			parselleft = parsenleft = EOF_NLEFT;
    258 			return PEOF;
    259 		}
    260 	}
    261 
    262 	q = p = parsenextc;
    263 
    264 	/* delete nul characters */
    265 	something = 0;
    266 	for (more = 1; more;) {
    267 		switch (*p) {
    268 		case '\0':
    269 			p++;	/* Skip nul */
    270 			goto check;
    271 
    272 		case '\t':
    273 		case ' ':
    274 			break;
    275 
    276 		case '\n':
    277 			parsenleft = q - parsenextc;
    278 			more = 0; /* Stop processing here */
    279 			break;
    280 
    281 		default:
    282 			something = 1;
    283 			break;
    284 		}
    285 
    286 		*q++ = *p++;
    287 check:
    288 		if (--parselleft <= 0) {
    289 			parsenleft = q - parsenextc - 1;
    290 			if (parsenleft < 0)
    291 				goto again;
    292 			*q = '\0';
    293 			more = 0;
    294 		}
    295 	}
    296 
    297 	savec = *q;
    298 	*q = '\0';
    299 
    300 #ifndef SMALL
    301 	if (parsefile->fd == 0 && hist && something) {
    302 		HistEvent he;
    303 		INTOFF;
    304 		history(hist, &he, whichprompt == 1? H_ENTER : H_APPEND,
    305 		    parsenextc);
    306 		INTON;
    307 	}
    308 #endif
    309 
    310 	if (vflag) {
    311 		out2str(parsenextc);
    312 		flushout(out2);
    313 	}
    314 
    315 	*q = savec;
    316 
    317 	return *parsenextc++;
    318 }
    319 
    320 /*
    321  * Undo the last call to pgetc.  Only one character may be pushed back.
    322  * PEOF may be pushed back.
    323  */
    324 
    325 void
    326 pungetc(void)
    327 {
    328 	parsenleft++;
    329 	parsenextc--;
    330 }
    331 
    332 /*
    333  * Push a string back onto the input at this current parsefile level.
    334  * We handle aliases this way.
    335  */
    336 void
    337 pushstring(char *s, int len, void *ap)
    338 {
    339 	struct strpush *sp;
    340 
    341 	INTOFF;
    342 /*debugprintf("*** calling pushstring: %s, %d\n", s, len);*/
    343 	if (parsefile->strpush) {
    344 		sp = ckmalloc(sizeof (struct strpush));
    345 		sp->prev = parsefile->strpush;
    346 		parsefile->strpush = sp;
    347 	} else
    348 		sp = parsefile->strpush = &(parsefile->basestrpush);
    349 	sp->prevstring = parsenextc;
    350 	sp->prevnleft = parsenleft;
    351 	sp->prevlleft = parselleft;
    352 	sp->ap = (struct alias *)ap;
    353 	if (ap)
    354 		((struct alias *)ap)->flag |= ALIASINUSE;
    355 	parsenextc = s;
    356 	parsenleft = len;
    357 	INTON;
    358 }
    359 
    360 void
    361 popstring(void)
    362 {
    363 	struct strpush *sp = parsefile->strpush;
    364 
    365 	INTOFF;
    366 	parsenextc = sp->prevstring;
    367 	parsenleft = sp->prevnleft;
    368 	parselleft = sp->prevlleft;
    369 /*debugprintf("*** calling popstring: restoring to '%s'\n", parsenextc);*/
    370 	if (sp->ap)
    371 		sp->ap->flag &= ~ALIASINUSE;
    372 	parsefile->strpush = sp->prev;
    373 	if (sp != &(parsefile->basestrpush))
    374 		ckfree(sp);
    375 	INTON;
    376 }
    377 
    378 /*
    379  * Set the input to take input from a file.  If push is set, push the
    380  * old input onto the stack first.
    381  */
    382 
    383 void
    384 setinputfile(const char *fname, int push)
    385 {
    386 	unsigned char magic[4];
    387 	int fd;
    388 	int fd2;
    389 
    390 	INTOFF;
    391 	if ((fd = open(fname, O_RDONLY)) < 0)
    392 		error("Can't open %s", fname);
    393 
    394 	/* Since the message "Syntax error: "(" unexpected" is not very
    395 	 * helpful, we check if the file starts with the ELF magic to
    396 	 * avoid that message. The first lseek tries to make sure that
    397 	 * we can later rewind the file.
    398 	 */
    399 	if (lseek(fd, 0, SEEK_SET) == 0) {
    400 		if (read(fd, magic, 4) == 4) {
    401 			if (memcmp(magic, "\177ELF", 4) == 0)
    402 				error("Cannot execute ELF binary %s", fname);
    403 		}
    404 		if (lseek(fd, 0, SEEK_SET) != 0)
    405 			error("Cannot rewind the file %s", fname);
    406 	}
    407 
    408 	if (fd < 10) {
    409 		fd2 = copyfd(fd, 10, 0);
    410 		close(fd);
    411 		if (fd2 < 0)
    412 			error("Out of file descriptors");
    413 		fd = fd2;
    414 	}
    415 	setinputfd(fd, push);
    416 	INTON;
    417 }
    418 
    419 
    420 /*
    421  * Like setinputfile, but takes an open file descriptor.  Call this with
    422  * interrupts off.
    423  */
    424 
    425 void
    426 setinputfd(int fd, int push)
    427 {
    428 	(void) fcntl(fd, F_SETFD, FD_CLOEXEC);
    429 	if (push) {
    430 		pushfile();
    431 		parsefile->buf = ckmalloc(BUFSIZ);
    432 	}
    433 	if (parsefile->fd > 0)
    434 		close(parsefile->fd);
    435 	parsefile->fd = fd;
    436 	if (parsefile->buf == NULL)
    437 		parsefile->buf = ckmalloc(BUFSIZ);
    438 	parselleft = parsenleft = 0;
    439 	plinno = 1;
    440 }
    441 
    442 
    443 /*
    444  * Like setinputfile, but takes input from a string.
    445  */
    446 
    447 void
    448 setinputstring(char *string, int push)
    449 {
    450 	INTOFF;
    451 	if (push)
    452 		pushfile();
    453 	parsenextc = string;
    454 	parselleft = parsenleft = strlen(string);
    455 	parsefile->buf = NULL;
    456 	plinno = 1;
    457 	INTON;
    458 }
    459 
    460 
    461 
    462 /*
    463  * To handle the "." command, a stack of input files is used.  Pushfile
    464  * adds a new entry to the stack and popfile restores the previous level.
    465  */
    466 
    467 STATIC void
    468 pushfile(void)
    469 {
    470 	struct parsefile *pf;
    471 
    472 	parsefile->nleft = parsenleft;
    473 	parsefile->lleft = parselleft;
    474 	parsefile->nextc = parsenextc;
    475 	parsefile->linno = plinno;
    476 	pf = (struct parsefile *)ckmalloc(sizeof (struct parsefile));
    477 	pf->prev = parsefile;
    478 	pf->fd = -1;
    479 	pf->strpush = NULL;
    480 	pf->basestrpush.prev = NULL;
    481 	parsefile = pf;
    482 }
    483 
    484 
    485 void
    486 popfile(void)
    487 {
    488 	struct parsefile *pf = parsefile;
    489 
    490 	INTOFF;
    491 	if (pf->fd >= 0)
    492 		close(pf->fd);
    493 	if (pf->buf)
    494 		ckfree(pf->buf);
    495 	while (pf->strpush)
    496 		popstring();
    497 	parsefile = pf->prev;
    498 	ckfree(pf);
    499 	parsenleft = parsefile->nleft;
    500 	parselleft = parsefile->lleft;
    501 	parsenextc = parsefile->nextc;
    502 	plinno = parsefile->linno;
    503 	INTON;
    504 }
    505 
    506 
    507 /*
    508  * Return to top level.
    509  */
    510 
    511 void
    512 popallfiles(void)
    513 {
    514 	while (parsefile != &basepf)
    515 		popfile();
    516 }
    517 
    518 
    519 
    520 /*
    521  * Close the file(s) that the shell is reading commands from.  Called
    522  * after a fork is done.
    523  *
    524  * Takes one arg, vfork, which tells it to not modify its global vars
    525  * as it is still running in the parent.
    526  *
    527  * This code is (probably) unnecessary as the 'close on exec' flag is
    528  * set and should be enough.  In the vfork case it is definitely wrong
    529  * to close the fds as another fork() may be done later to feed data
    530  * from a 'here' document into a pipe and we don't want to close the
    531  * pipe!
    532  */
    533 
    534 void
    535 closescript(int vforked)
    536 {
    537 	if (vforked)
    538 		return;
    539 	popallfiles();
    540 	if (parsefile->fd > 0) {
    541 		close(parsefile->fd);
    542 		parsefile->fd = 0;
    543 	}
    544 }
    545