Home | History | Annotate | Line # | Download | only in sh
redir.c revision 1.16 
      1 /*	$NetBSD: redir.c,v 1.16 1997/07/04 21:02:21 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 1.16 1997/07/04 21:02:21 christos Exp $");
     45 #endif
     46 #endif /* not lint */
     47 
     48 #include <sys/types.h>
     49 #include <signal.h>
     50 #include <string.h>
     51 #include <fcntl.h>
     52 #include <errno.h>
     53 #include <unistd.h>
     54 #include <stdlib.h>
     55 
     56 /*
     57  * Code for dealing with input/output redirection.
     58  */
     59 
     60 #include "shell.h"
     61 #include "nodes.h"
     62 #include "jobs.h"
     63 #include "expand.h"
     64 #include "redir.h"
     65 #include "output.h"
     66 #include "memalloc.h"
     67 #include "error.h"
     68 
     69 
     70 #define EMPTY -2		/* marks an unused slot in redirtab */
     71 #define PIPESIZE 4096		/* amount of buffering in a pipe */
     72 
     73 
     74 MKINIT
     75 struct redirtab {
     76 	struct redirtab *next;
     77 	short renamed[10];
     78 };
     79 
     80 
     81 MKINIT struct redirtab *redirlist;
     82 
     83 /*
     84  * We keep track of whether or not fd0 has been redirected.  This is for
     85  * background commands, where we want to redirect fd0 to /dev/null only
     86  * if it hasn't already been redirected.
     87 */
     88 int fd0_redirected = 0;
     89 
     90 STATIC void openredirect __P((union node *, char[10 ]));
     91 STATIC int openhere __P((union node *));
     92 
     93 
     94 /*
     95  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
     96  * old file descriptors are stashed away so that the redirection can be
     97  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
     98  * standard output, and the standard error if it becomes a duplicate of
     99  * stdout, is saved in memory.
    100  */
    101 
    102 void
    103 redirect(redir, flags)
    104 	union node *redir;
    105 	int flags;
    106 	{
    107 	union node *n;
    108 	struct redirtab *sv = NULL;
    109 	int i;
    110 	int fd;
    111 	int try;
    112 	char memory[10];	/* file descriptors to write to memory */
    113 
    114 	for (i = 10 ; --i >= 0 ; )
    115 		memory[i] = 0;
    116 	memory[1] = flags & REDIR_BACKQ;
    117 	if (flags & REDIR_PUSH) {
    118 		sv = ckmalloc(sizeof (struct redirtab));
    119 		for (i = 0 ; i < 10 ; i++)
    120 			sv->renamed[i] = EMPTY;
    121 		sv->next = redirlist;
    122 		redirlist = sv;
    123 	}
    124 	for (n = redir ; n ; n = n->nfile.next) {
    125 		fd = n->nfile.fd;
    126 		try = 0;
    127 		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
    128 		    n->ndup.dupfd == fd)
    129 			continue; /* redirect from/to same file descriptor */
    130 
    131 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    132 			INTOFF;
    133 again:
    134 			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
    135 				switch (errno) {
    136 				case EBADF:
    137 					if (!try) {
    138 						openredirect(n, memory);
    139 						try++;
    140 						goto again;
    141 					}
    142 					/* FALLTHROUGH*/
    143 				default:
    144 					INTON;
    145 					error("%d: %s", fd, strerror(errno));
    146 					break;
    147 				}
    148 			}
    149 			if (!try) {
    150 				sv->renamed[fd] = i;
    151 				close(fd);
    152 			}
    153 			INTON;
    154 		} else {
    155 			close(fd);
    156 		}
    157                 if (fd == 0)
    158                         fd0_redirected++;
    159 		if (!try)
    160 			openredirect(n, memory);
    161 	}
    162 	if (memory[1])
    163 		out1 = &memout;
    164 	if (memory[2])
    165 		out2 = &memout;
    166 }
    167 
    168 
    169 STATIC void
    170 openredirect(redir, memory)
    171 	union node *redir;
    172 	char memory[10];
    173 	{
    174 	int fd = redir->nfile.fd;
    175 	char *fname;
    176 	int f;
    177 
    178 	/*
    179 	 * We suppress interrupts so that we won't leave open file
    180 	 * descriptors around.  This may not be such a good idea because
    181 	 * an open of a device or a fifo can block indefinitely.
    182 	 */
    183 	INTOFF;
    184 	memory[fd] = 0;
    185 	switch (redir->nfile.type) {
    186 	case NFROM:
    187 		fname = redir->nfile.expfname;
    188 		if ((f = open(fname, O_RDONLY)) < 0)
    189 			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    190 movefd:
    191 		if (f != fd) {
    192 			copyfd(f, fd);
    193 			close(f);
    194 		}
    195 		break;
    196 	case NTO:
    197 		fname = redir->nfile.expfname;
    198 #ifdef O_CREAT
    199 		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
    200 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    201 #else
    202 		if ((f = creat(fname, 0666)) < 0)
    203 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    204 #endif
    205 		goto movefd;
    206 	case NAPPEND:
    207 		fname = redir->nfile.expfname;
    208 #ifdef O_APPEND
    209 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    210 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    211 #else
    212 		if ((f = open(fname, O_WRONLY)) < 0
    213 		 && (f = creat(fname, 0666)) < 0)
    214 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    215 		lseek(f, (off_t)0, 2);
    216 #endif
    217 		goto movefd;
    218 	case NTOFD:
    219 	case NFROMFD:
    220 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    221 			if (memory[redir->ndup.dupfd])
    222 				memory[fd] = 1;
    223 			else
    224 				copyfd(redir->ndup.dupfd, fd);
    225 		}
    226 		break;
    227 	case NHERE:
    228 	case NXHERE:
    229 		f = openhere(redir);
    230 		goto movefd;
    231 	default:
    232 		abort();
    233 	}
    234 	INTON;
    235 }
    236 
    237 
    238 /*
    239  * Handle here documents.  Normally we fork off a process to write the
    240  * data to a pipe.  If the document is short, we can stuff the data in
    241  * the pipe without forking.
    242  */
    243 
    244 STATIC int
    245 openhere(redir)
    246 	union node *redir;
    247 	{
    248 	int pip[2];
    249 	int len = 0;
    250 
    251 	if (pipe(pip) < 0)
    252 		error("Pipe call failed");
    253 	if (redir->type == NHERE) {
    254 		len = strlen(redir->nhere.doc->narg.text);
    255 		if (len <= PIPESIZE) {
    256 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    257 			goto out;
    258 		}
    259 	}
    260 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
    261 		close(pip[0]);
    262 		signal(SIGINT, SIG_IGN);
    263 		signal(SIGQUIT, SIG_IGN);
    264 		signal(SIGHUP, SIG_IGN);
    265 #ifdef SIGTSTP
    266 		signal(SIGTSTP, SIG_IGN);
    267 #endif
    268 		signal(SIGPIPE, SIG_DFL);
    269 		if (redir->type == NHERE)
    270 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    271 		else
    272 			expandhere(redir->nhere.doc, pip[1]);
    273 		_exit(0);
    274 	}
    275 out:
    276 	close(pip[1]);
    277 	return pip[0];
    278 }
    279 
    280 
    281 
    282 /*
    283  * Undo the effects of the last redirection.
    284  */
    285 
    286 void
    287 popredir() {
    288 	struct redirtab *rp = redirlist;
    289 	int i;
    290 
    291 	for (i = 0 ; i < 10 ; i++) {
    292 		if (rp->renamed[i] != EMPTY) {
    293                         if (i == 0)
    294                                 fd0_redirected--;
    295 			close(i);
    296 			if (rp->renamed[i] >= 0) {
    297 				copyfd(rp->renamed[i], i);
    298 				close(rp->renamed[i]);
    299 			}
    300 		}
    301 	}
    302 	INTOFF;
    303 	redirlist = rp->next;
    304 	ckfree(rp);
    305 	INTON;
    306 }
    307 
    308 /*
    309  * Undo all redirections.  Called on error or interrupt.
    310  */
    311 
    312 #ifdef mkinit
    313 
    314 INCLUDE "redir.h"
    315 
    316 RESET {
    317 	while (redirlist)
    318 		popredir();
    319 }
    320 
    321 SHELLPROC {
    322 	clearredir();
    323 }
    324 
    325 #endif
    326 
    327 /* Return true if fd 0 has already been redirected at least once.  */
    328 int
    329 fd0_redirected_p () {
    330         return fd0_redirected != 0;
    331 }
    332 
    333 /*
    334  * Discard all saved file descriptors.
    335  */
    336 
    337 void
    338 clearredir() {
    339 	struct redirtab *rp;
    340 	int i;
    341 
    342 	for (rp = redirlist ; rp ; rp = rp->next) {
    343 		for (i = 0 ; i < 10 ; i++) {
    344 			if (rp->renamed[i] >= 0) {
    345 				close(rp->renamed[i]);
    346 			}
    347 			rp->renamed[i] = EMPTY;
    348 		}
    349 	}
    350 }
    351 
    352 
    353 
    354 /*
    355  * Copy a file descriptor to be >= to.  Returns -1
    356  * if the source file descriptor is closed, EMPTY if there are no unused
    357  * file descriptors left.
    358  */
    359 
    360 int
    361 copyfd(from, to)
    362 	int from;
    363 	int to;
    364 {
    365 	int newfd;
    366 
    367 	newfd = fcntl(from, F_DUPFD, to);
    368 	if (newfd < 0) {
    369 		if (errno == EMFILE)
    370 			return EMPTY;
    371 		else
    372 			error("%d: %s", from, strerror(errno));
    373 	}
    374 	return newfd;
    375 }
    376