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redir.c revision 1.25 
      1 /*	$NetBSD: redir.c,v 1.25 2002/09/27 22:56:24 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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * 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 REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #ifndef lint
     41 #if 0
     42 static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
     43 #else
     44 __RCSID("$NetBSD: redir.c,v 1.25 2002/09/27 22:56:24 christos Exp $");
     45 #endif
     46 #endif /* not lint */
     47 
     48 #include <sys/types.h>
     49 #include <sys/param.h>	/* PIPE_BUF */
     50 #include <signal.h>
     51 #include <string.h>
     52 #include <fcntl.h>
     53 #include <errno.h>
     54 #include <unistd.h>
     55 #include <stdlib.h>
     56 
     57 /*
     58  * Code for dealing with input/output redirection.
     59  */
     60 
     61 #include "main.h"
     62 #include "shell.h"
     63 #include "nodes.h"
     64 #include "jobs.h"
     65 #include "options.h"
     66 #include "expand.h"
     67 #include "redir.h"
     68 #include "output.h"
     69 #include "memalloc.h"
     70 #include "error.h"
     71 
     72 
     73 #define EMPTY -2		/* marks an unused slot in redirtab */
     74 #ifndef PIPE_BUF
     75 # define PIPESIZE 4096		/* amount of buffering in a pipe */
     76 #else
     77 # define PIPESIZE PIPE_BUF
     78 #endif
     79 
     80 
     81 MKINIT
     82 struct redirtab {
     83 	struct redirtab *next;
     84 	short renamed[10];
     85 };
     86 
     87 
     88 MKINIT struct redirtab *redirlist;
     89 
     90 /*
     91  * We keep track of whether or not fd0 has been redirected.  This is for
     92  * background commands, where we want to redirect fd0 to /dev/null only
     93  * if it hasn't already been redirected.
     94 */
     95 int fd0_redirected = 0;
     96 
     97 STATIC void openredirect __P((union node *, char[10 ]));
     98 STATIC int openhere __P((union node *));
     99 
    100 
    101 /*
    102  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
    103  * old file descriptors are stashed away so that the redirection can be
    104  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
    105  * standard output, and the standard error if it becomes a duplicate of
    106  * stdout, is saved in memory.
    107  */
    108 
    109 void
    110 redirect(redir, flags)
    111 	union node *redir;
    112 	int flags;
    113 	{
    114 	union node *n;
    115 	struct redirtab *sv = NULL;
    116 	int i;
    117 	int fd;
    118 	int try;
    119 	char memory[10];	/* file descriptors to write to memory */
    120 
    121 	for (i = 10 ; --i >= 0 ; )
    122 		memory[i] = 0;
    123 	memory[1] = flags & REDIR_BACKQ;
    124 	if (flags & REDIR_PUSH) {
    125 		/* We don't have to worry about REDIR_VFORK here, as
    126 		 * flags & REDIR_PUSH is never true if REDIR_VFORK is set.
    127 		 */
    128 		sv = ckmalloc(sizeof (struct redirtab));
    129 		for (i = 0 ; i < 10 ; i++)
    130 			sv->renamed[i] = EMPTY;
    131 		sv->next = redirlist;
    132 		redirlist = sv;
    133 	}
    134 	for (n = redir ; n ; n = n->nfile.next) {
    135 		fd = n->nfile.fd;
    136 		try = 0;
    137 		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
    138 		    n->ndup.dupfd == fd)
    139 			continue; /* redirect from/to same file descriptor */
    140 
    141 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    142 			INTOFF;
    143 again:
    144 			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
    145 				switch (errno) {
    146 				case EBADF:
    147 					if (!try) {
    148 						openredirect(n, memory);
    149 						try++;
    150 						goto again;
    151 					}
    152 					/* FALLTHROUGH*/
    153 				default:
    154 					INTON;
    155 					error("%d: %s", fd, strerror(errno));
    156 					/* NOTREACHED */
    157 				}
    158 			}
    159 			if (!try) {
    160 				sv->renamed[fd] = i;
    161 				close(fd);
    162 			}
    163 			INTON;
    164 		} else {
    165 			close(fd);
    166 		}
    167                 if (fd == 0)
    168                         fd0_redirected++;
    169 		if (!try)
    170 			openredirect(n, memory);
    171 	}
    172 	if (memory[1])
    173 		out1 = &memout;
    174 	if (memory[2])
    175 		out2 = &memout;
    176 }
    177 
    178 
    179 STATIC void
    180 openredirect(redir, memory)
    181 	union node *redir;
    182 	char memory[10];
    183 	{
    184 	int fd = redir->nfile.fd;
    185 	char *fname;
    186 	int f;
    187 	int flags = O_WRONLY|O_CREAT|O_TRUNC;
    188 
    189 	/*
    190 	 * We suppress interrupts so that we won't leave open file
    191 	 * descriptors around.  This may not be such a good idea because
    192 	 * an open of a device or a fifo can block indefinitely.
    193 	 */
    194 	INTOFF;
    195 	memory[fd] = 0;
    196 	switch (redir->nfile.type) {
    197 	case NFROM:
    198 		fname = redir->nfile.expfname;
    199 		if ((f = open(fname, O_RDONLY)) < 0)
    200 			goto eopen;
    201 		break;
    202 	case NFROMTO:
    203 		fname = redir->nfile.expfname;
    204 		if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
    205 			goto ecreate;
    206 		break;
    207 	case NTO:
    208 		if (Cflag)
    209 			flags |= O_EXCL;
    210 		/* FALLTHROUGH */
    211 	case NCLOBBER:
    212 		fname = redir->nfile.expfname;
    213 		if ((f = open(fname, flags, 0666)) < 0)
    214 			goto ecreate;
    215 		break;
    216 	case NAPPEND:
    217 		fname = redir->nfile.expfname;
    218 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    219 			goto ecreate;
    220 		break;
    221 	case NTOFD:
    222 	case NFROMFD:
    223 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    224 			if (memory[redir->ndup.dupfd])
    225 				memory[fd] = 1;
    226 			else
    227 				copyfd(redir->ndup.dupfd, fd);
    228 		}
    229 		INTON;
    230 		return;
    231 	case NHERE:
    232 	case NXHERE:
    233 		f = openhere(redir);
    234 		break;
    235 	default:
    236 		abort();
    237 	}
    238 
    239 	if (f != fd) {
    240 		copyfd(f, fd);
    241 		close(f);
    242 	}
    243 	INTON;
    244 	return;
    245 ecreate:
    246 	error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    247 eopen:
    248 	error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    249 }
    250 
    251 
    252 /*
    253  * Handle here documents.  Normally we fork off a process to write the
    254  * data to a pipe.  If the document is short, we can stuff the data in
    255  * the pipe without forking.
    256  */
    257 
    258 STATIC int
    259 openhere(redir)
    260 	union node *redir;
    261 	{
    262 	int pip[2];
    263 	int len = 0;
    264 	int isroot = rootshell;
    265 
    266 	if (pipe(pip) < 0)
    267 		error("Pipe call failed");
    268 	if (redir->type == NHERE) {
    269 		len = strlen(redir->nhere.doc->narg.text);
    270 		if (len <= PIPESIZE) {
    271 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    272 			goto out;
    273 		}
    274 	}
    275 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB, &isroot) == 0) {
    276 		close(pip[0]);
    277 		signal(SIGINT, SIG_IGN);
    278 		signal(SIGQUIT, SIG_IGN);
    279 		signal(SIGHUP, SIG_IGN);
    280 #ifdef SIGTSTP
    281 		signal(SIGTSTP, SIG_IGN);
    282 #endif
    283 		signal(SIGPIPE, SIG_DFL);
    284 		if (redir->type == NHERE)
    285 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    286 		else
    287 			expandhere(redir->nhere.doc, pip[1]);
    288 		_exit(0);
    289 	}
    290 out:
    291 	close(pip[1]);
    292 	return pip[0];
    293 }
    294 
    295 
    296 
    297 /*
    298  * Undo the effects of the last redirection.
    299  */
    300 
    301 void
    302 popredir() {
    303 	struct redirtab *rp = redirlist;
    304 	int i;
    305 
    306 	for (i = 0 ; i < 10 ; i++) {
    307 		if (rp->renamed[i] != EMPTY) {
    308                         if (i == 0)
    309                                 fd0_redirected--;
    310 			close(i);
    311 			if (rp->renamed[i] >= 0) {
    312 				copyfd(rp->renamed[i], i);
    313 				close(rp->renamed[i]);
    314 			}
    315 		}
    316 	}
    317 	INTOFF;
    318 	redirlist = rp->next;
    319 	ckfree(rp);
    320 	INTON;
    321 }
    322 
    323 /*
    324  * Undo all redirections.  Called on error or interrupt.
    325  */
    326 
    327 #ifdef mkinit
    328 
    329 INCLUDE "redir.h"
    330 
    331 RESET {
    332 	while (redirlist)
    333 		popredir();
    334 }
    335 
    336 SHELLPROC {
    337 	clearredir(0);
    338 }
    339 
    340 #endif
    341 
    342 /* Return true if fd 0 has already been redirected at least once.  */
    343 int
    344 fd0_redirected_p () {
    345         return fd0_redirected != 0;
    346 }
    347 
    348 /*
    349  * Discard all saved file descriptors.
    350  */
    351 
    352 void
    353 clearredir(vforked)
    354 	int vforked;
    355 {
    356 	struct redirtab *rp;
    357 	int i;
    358 
    359 	for (rp = redirlist ; rp ; rp = rp->next) {
    360 		for (i = 0 ; i < 10 ; i++) {
    361 			if (rp->renamed[i] >= 0) {
    362 				close(rp->renamed[i]);
    363 			}
    364 			if (!vforked)
    365 				rp->renamed[i] = EMPTY;
    366 		}
    367 	}
    368 }
    369 
    370 
    371 
    372 /*
    373  * Copy a file descriptor to be >= to.  Returns -1
    374  * if the source file descriptor is closed, EMPTY if there are no unused
    375  * file descriptors left.
    376  */
    377 
    378 int
    379 copyfd(from, to)
    380 	int from;
    381 	int to;
    382 {
    383 	int newfd;
    384 
    385 	newfd = fcntl(from, F_DUPFD, to);
    386 	if (newfd < 0) {
    387 		if (errno == EMFILE)
    388 			return EMPTY;
    389 		else
    390 			error("%d: %s", from, strerror(errno));
    391 	}
    392 	return newfd;
    393 }
    394