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      1 /*	$NetBSD: redir.c,v 1.29 2004/07/08 03:57:33 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[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
     39 #else
     40 __RCSID("$NetBSD: redir.c,v 1.29 2004/07/08 03:57:33 christos Exp $");
     41 #endif
     42 #endif /* not lint */
     43 
     44 #include <sys/types.h>
     45 #include <sys/param.h>	/* PIPE_BUF */
     46 #include <signal.h>
     47 #include <string.h>
     48 #include <fcntl.h>
     49 #include <errno.h>
     50 #include <unistd.h>
     51 #include <stdlib.h>
     52 
     53 /*
     54  * Code for dealing with input/output redirection.
     55  */
     56 
     57 #include "main.h"
     58 #include "shell.h"
     59 #include "nodes.h"
     60 #include "jobs.h"
     61 #include "options.h"
     62 #include "expand.h"
     63 #include "redir.h"
     64 #include "output.h"
     65 #include "memalloc.h"
     66 #include "error.h"
     67 
     68 
     69 #define EMPTY -2		/* marks an unused slot in redirtab */
     70 #ifndef PIPE_BUF
     71 # define PIPESIZE 4096		/* amount of buffering in a pipe */
     72 #else
     73 # define PIPESIZE PIPE_BUF
     74 #endif
     75 
     76 #define signal bsd_signal
     77 
     78 MKINIT
     79 struct redirtab {
     80 	struct redirtab *next;
     81 	short renamed[10];
     82 };
     83 
     84 
     85 MKINIT struct redirtab *redirlist;
     86 
     87 /*
     88  * We keep track of whether or not fd0 has been redirected.  This is for
     89  * background commands, where we want to redirect fd0 to /dev/null only
     90  * if it hasn't already been redirected.
     91 */
     92 int fd0_redirected = 0;
     93 
     94 STATIC void openredirect(union node *, char[10], int);
     95 STATIC int openhere(union node *);
     96 
     97 
     98 /*
     99  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
    100  * old file descriptors are stashed away so that the redirection can be
    101  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
    102  * standard output, and the standard error if it becomes a duplicate of
    103  * stdout, is saved in memory.
    104  */
    105 
    106 void
    107 redirect(union node *redir, int flags)
    108 {
    109 	union node *n;
    110 	struct redirtab *sv = NULL;
    111 	int i;
    112 	int fd;
    113 	int try;
    114 	char memory[10];	/* file descriptors to write to memory */
    115 
    116 	for (i = 10 ; --i >= 0 ; )
    117 		memory[i] = 0;
    118 	memory[1] = flags & REDIR_BACKQ;
    119 	if (flags & REDIR_PUSH) {
    120 		/* We don't have to worry about REDIR_VFORK here, as
    121 		 * flags & REDIR_PUSH is never true if REDIR_VFORK is set.
    122 		 */
    123 		sv = ckmalloc(sizeof (struct redirtab));
    124 		for (i = 0 ; i < 10 ; i++)
    125 			sv->renamed[i] = EMPTY;
    126 		sv->next = redirlist;
    127 		redirlist = sv;
    128 	}
    129 	for (n = redir ; n ; n = n->nfile.next) {
    130 		fd = n->nfile.fd;
    131 		try = 0;
    132 		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
    133 		    n->ndup.dupfd == fd)
    134 			continue; /* redirect from/to same file descriptor */
    135 
    136 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    137 			INTOFF;
    138 again:
    139 			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
    140 				switch (errno) {
    141 				case EBADF:
    142 					if (!try) {
    143 						openredirect(n, memory, flags);
    144 						try++;
    145 						goto again;
    146 					}
    147 					/* FALLTHROUGH*/
    148 				default:
    149 					INTON;
    150 					error("%d: %s", fd, strerror(errno));
    151 					/* NOTREACHED */
    152 				}
    153 			}
    154 			if (!try) {
    155 				sv->renamed[fd] = i;
    156 				close(fd);
    157 			}
    158 			INTON;
    159 		} else {
    160 			close(fd);
    161 		}
    162                 if (fd == 0)
    163                         fd0_redirected++;
    164 		if (!try)
    165 			openredirect(n, memory, flags);
    166 	}
    167 	if (memory[1])
    168 		out1 = &memout;
    169 	if (memory[2])
    170 		out2 = &memout;
    171 }
    172 
    173 
    174 STATIC void
    175 openredirect(union node *redir, char memory[10], int flags)
    176 {
    177 	int fd = redir->nfile.fd;
    178 	char *fname;
    179 	int f;
    180 	int oflags = O_WRONLY|O_CREAT|O_TRUNC, eflags;
    181 
    182 	/*
    183 	 * We suppress interrupts so that we won't leave open file
    184 	 * descriptors around.  This may not be such a good idea because
    185 	 * an open of a device or a fifo can block indefinitely.
    186 	 */
    187 	INTOFF;
    188 	memory[fd] = 0;
    189 	switch (redir->nfile.type) {
    190 	case NFROM:
    191 		fname = redir->nfile.expfname;
    192 		if (flags & REDIR_VFORK)
    193 			eflags = O_NONBLOCK;
    194 		else
    195 			eflags = 0;
    196 		if ((f = open(fname, O_RDONLY|eflags)) < 0)
    197 			goto eopen;
    198 		if (eflags)
    199 			(void)fcntl(f, F_SETFL, fcntl(f, F_GETFL, 0) & ~eflags);
    200 		break;
    201 	case NFROMTO:
    202 		fname = redir->nfile.expfname;
    203 		if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
    204 			goto ecreate;
    205 		break;
    206 	case NTO:
    207 		if (Cflag)
    208 			oflags |= O_EXCL;
    209 		/* FALLTHROUGH */
    210 	case NCLOBBER:
    211 		fname = redir->nfile.expfname;
    212 		if ((f = open(fname, oflags, 0666)) < 0)
    213 			goto ecreate;
    214 		break;
    215 	case NAPPEND:
    216 		fname = redir->nfile.expfname;
    217 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    218 			goto ecreate;
    219 		break;
    220 	case NTOFD:
    221 	case NFROMFD:
    222 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    223 			if (memory[redir->ndup.dupfd])
    224 				memory[fd] = 1;
    225 			else
    226 				copyfd(redir->ndup.dupfd, fd);
    227 		}
    228 		INTON;
    229 		return;
    230 	case NHERE:
    231 	case NXHERE:
    232 		f = openhere(redir);
    233 		break;
    234 	default:
    235 		abort();
    236 	}
    237 
    238 	if (f != fd) {
    239 		copyfd(f, fd);
    240 		close(f);
    241 	}
    242 	INTON;
    243 	return;
    244 ecreate:
    245 	error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    246 eopen:
    247 	error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    248 }
    249 
    250 
    251 /*
    252  * Handle here documents.  Normally we fork off a process to write the
    253  * data to a pipe.  If the document is short, we can stuff the data in
    254  * the pipe without forking.
    255  */
    256 
    257 STATIC int
    258 openhere(union node *redir)
    259 {
    260 	int pip[2];
    261 	int len = 0;
    262 
    263 	if (pipe(pip) < 0)
    264 		error("Pipe call failed");
    265 	if (redir->type == NHERE) {
    266 		len = strlen(redir->nhere.doc->narg.text);
    267 		if (len <= PIPESIZE) {
    268 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    269 			goto out;
    270 		}
    271 	}
    272 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
    273 		close(pip[0]);
    274 		signal(SIGINT, SIG_IGN);
    275 		signal(SIGQUIT, SIG_IGN);
    276 		signal(SIGHUP, SIG_IGN);
    277 #ifdef SIGTSTP
    278 		signal(SIGTSTP, SIG_IGN);
    279 #endif
    280 		signal(SIGPIPE, SIG_DFL);
    281 		if (redir->type == NHERE)
    282 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    283 		else
    284 			expandhere(redir->nhere.doc, pip[1]);
    285 		_exit(0);
    286 	}
    287 out:
    288 	close(pip[1]);
    289 	return pip[0];
    290 }
    291 
    292 
    293 
    294 /*
    295  * Undo the effects of the last redirection.
    296  */
    297 
    298 void
    299 popredir(void)
    300 {
    301 	struct redirtab *rp = redirlist;
    302 	int i;
    303 
    304 	for (i = 0 ; i < 10 ; i++) {
    305 		if (rp->renamed[i] != EMPTY) {
    306                         if (i == 0)
    307                                 fd0_redirected--;
    308 			close(i);
    309 			if (rp->renamed[i] >= 0) {
    310 				copyfd(rp->renamed[i], i);
    311 				close(rp->renamed[i]);
    312 			}
    313 		}
    314 	}
    315 	INTOFF;
    316 	redirlist = rp->next;
    317 	ckfree(rp);
    318 	INTON;
    319 }
    320 
    321 /*
    322  * Undo all redirections.  Called on error or interrupt.
    323  */
    324 
    325 #ifdef mkinit
    326 
    327 INCLUDE "redir.h"
    328 
    329 RESET {
    330 	while (redirlist)
    331 		popredir();
    332 }
    333 
    334 SHELLPROC {
    335 	clearredir(0);
    336 }
    337 
    338 #endif
    339 
    340 /* Return true if fd 0 has already been redirected at least once.  */
    341 int
    342 fd0_redirected_p () {
    343         return fd0_redirected != 0;
    344 }
    345 
    346 /*
    347  * Discard all saved file descriptors.
    348  */
    349 
    350 void
    351 clearredir(vforked)
    352 	int vforked;
    353 {
    354 	struct redirtab *rp;
    355 	int i;
    356 
    357 	for (rp = redirlist ; rp ; rp = rp->next) {
    358 		for (i = 0 ; i < 10 ; i++) {
    359 			if (rp->renamed[i] >= 0) {
    360 				close(rp->renamed[i]);
    361 			}
    362 			if (!vforked)
    363 				rp->renamed[i] = EMPTY;
    364 		}
    365 	}
    366 }
    367 
    368 
    369 
    370 /*
    371  * Copy a file descriptor to be >= to.  Returns -1
    372  * if the source file descriptor is closed, EMPTY if there are no unused
    373  * file descriptors left.
    374  */
    375 
    376 int
    377 copyfd(int from, int to)
    378 {
    379 	int newfd;
    380 
    381 	newfd = fcntl(from, F_DUPFD, to);
    382 	if (newfd < 0) {
    383 		if (errno == EMFILE)
    384 			return EMPTY;
    385 		else
    386 			error("%d: %s", from, strerror(errno));
    387 	}
    388 	return newfd;
    389 }
    390