Home | History | Annotate | Line # | Download | only in sh
redir.c revision 1.28 
      1 /*	$NetBSD: redir.c,v 1.28 2003/08/07 09:05:37 agc 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 1.28 2003/08/07 09:05:37 agc 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 
     77 MKINIT
     78 struct redirtab {
     79 	struct redirtab *next;
     80 	short renamed[10];
     81 };
     82 
     83 
     84 MKINIT struct redirtab *redirlist;
     85 
     86 /*
     87  * We keep track of whether or not fd0 has been redirected.  This is for
     88  * background commands, where we want to redirect fd0 to /dev/null only
     89  * if it hasn't already been redirected.
     90 */
     91 int fd0_redirected = 0;
     92 
     93 STATIC void openredirect(union node *, char[10 ]);
     94 STATIC int openhere(union node *);
     95 
     96 
     97 /*
     98  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
     99  * old file descriptors are stashed away so that the redirection can be
    100  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
    101  * standard output, and the standard error if it becomes a duplicate of
    102  * stdout, is saved in memory.
    103  */
    104 
    105 void
    106 redirect(union node *redir, int flags)
    107 {
    108 	union node *n;
    109 	struct redirtab *sv = NULL;
    110 	int i;
    111 	int fd;
    112 	int try;
    113 	char memory[10];	/* file descriptors to write to memory */
    114 
    115 	for (i = 10 ; --i >= 0 ; )
    116 		memory[i] = 0;
    117 	memory[1] = flags & REDIR_BACKQ;
    118 	if (flags & REDIR_PUSH) {
    119 		/* We don't have to worry about REDIR_VFORK here, as
    120 		 * flags & REDIR_PUSH is never true if REDIR_VFORK is set.
    121 		 */
    122 		sv = ckmalloc(sizeof (struct redirtab));
    123 		for (i = 0 ; i < 10 ; i++)
    124 			sv->renamed[i] = EMPTY;
    125 		sv->next = redirlist;
    126 		redirlist = sv;
    127 	}
    128 	for (n = redir ; n ; n = n->nfile.next) {
    129 		fd = n->nfile.fd;
    130 		try = 0;
    131 		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
    132 		    n->ndup.dupfd == fd)
    133 			continue; /* redirect from/to same file descriptor */
    134 
    135 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    136 			INTOFF;
    137 again:
    138 			if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
    139 				switch (errno) {
    140 				case EBADF:
    141 					if (!try) {
    142 						openredirect(n, memory);
    143 						try++;
    144 						goto again;
    145 					}
    146 					/* FALLTHROUGH*/
    147 				default:
    148 					INTON;
    149 					error("%d: %s", fd, strerror(errno));
    150 					/* NOTREACHED */
    151 				}
    152 			}
    153 			if (!try) {
    154 				sv->renamed[fd] = i;
    155 				close(fd);
    156 			}
    157 			INTON;
    158 		} else {
    159 			close(fd);
    160 		}
    161                 if (fd == 0)
    162                         fd0_redirected++;
    163 		if (!try)
    164 			openredirect(n, memory);
    165 	}
    166 	if (memory[1])
    167 		out1 = &memout;
    168 	if (memory[2])
    169 		out2 = &memout;
    170 }
    171 
    172 
    173 STATIC void
    174 openredirect(union node *redir, char memory[10])
    175 {
    176 	int fd = redir->nfile.fd;
    177 	char *fname;
    178 	int f;
    179 	int flags = O_WRONLY|O_CREAT|O_TRUNC;
    180 
    181 	/*
    182 	 * We suppress interrupts so that we won't leave open file
    183 	 * descriptors around.  This may not be such a good idea because
    184 	 * an open of a device or a fifo can block indefinitely.
    185 	 */
    186 	INTOFF;
    187 	memory[fd] = 0;
    188 	switch (redir->nfile.type) {
    189 	case NFROM:
    190 		fname = redir->nfile.expfname;
    191 		if ((f = open(fname, O_RDONLY)) < 0)
    192 			goto eopen;
    193 		break;
    194 	case NFROMTO:
    195 		fname = redir->nfile.expfname;
    196 		if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
    197 			goto ecreate;
    198 		break;
    199 	case NTO:
    200 		if (Cflag)
    201 			flags |= O_EXCL;
    202 		/* FALLTHROUGH */
    203 	case NCLOBBER:
    204 		fname = redir->nfile.expfname;
    205 		if ((f = open(fname, flags, 0666)) < 0)
    206 			goto ecreate;
    207 		break;
    208 	case NAPPEND:
    209 		fname = redir->nfile.expfname;
    210 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    211 			goto ecreate;
    212 		break;
    213 	case NTOFD:
    214 	case NFROMFD:
    215 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    216 			if (memory[redir->ndup.dupfd])
    217 				memory[fd] = 1;
    218 			else
    219 				copyfd(redir->ndup.dupfd, fd);
    220 		}
    221 		INTON;
    222 		return;
    223 	case NHERE:
    224 	case NXHERE:
    225 		f = openhere(redir);
    226 		break;
    227 	default:
    228 		abort();
    229 	}
    230 
    231 	if (f != fd) {
    232 		copyfd(f, fd);
    233 		close(f);
    234 	}
    235 	INTON;
    236 	return;
    237 ecreate:
    238 	error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    239 eopen:
    240 	error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    241 }
    242 
    243 
    244 /*
    245  * Handle here documents.  Normally we fork off a process to write the
    246  * data to a pipe.  If the document is short, we can stuff the data in
    247  * the pipe without forking.
    248  */
    249 
    250 STATIC int
    251 openhere(union node *redir)
    252 {
    253 	int pip[2];
    254 	int len = 0;
    255 
    256 	if (pipe(pip) < 0)
    257 		error("Pipe call failed");
    258 	if (redir->type == NHERE) {
    259 		len = strlen(redir->nhere.doc->narg.text);
    260 		if (len <= PIPESIZE) {
    261 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    262 			goto out;
    263 		}
    264 	}
    265 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
    266 		close(pip[0]);
    267 		signal(SIGINT, SIG_IGN);
    268 		signal(SIGQUIT, SIG_IGN);
    269 		signal(SIGHUP, SIG_IGN);
    270 #ifdef SIGTSTP
    271 		signal(SIGTSTP, SIG_IGN);
    272 #endif
    273 		signal(SIGPIPE, SIG_DFL);
    274 		if (redir->type == NHERE)
    275 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    276 		else
    277 			expandhere(redir->nhere.doc, pip[1]);
    278 		_exit(0);
    279 	}
    280 out:
    281 	close(pip[1]);
    282 	return pip[0];
    283 }
    284 
    285 
    286 
    287 /*
    288  * Undo the effects of the last redirection.
    289  */
    290 
    291 void
    292 popredir(void)
    293 {
    294 	struct redirtab *rp = redirlist;
    295 	int i;
    296 
    297 	for (i = 0 ; i < 10 ; i++) {
    298 		if (rp->renamed[i] != EMPTY) {
    299                         if (i == 0)
    300                                 fd0_redirected--;
    301 			close(i);
    302 			if (rp->renamed[i] >= 0) {
    303 				copyfd(rp->renamed[i], i);
    304 				close(rp->renamed[i]);
    305 			}
    306 		}
    307 	}
    308 	INTOFF;
    309 	redirlist = rp->next;
    310 	ckfree(rp);
    311 	INTON;
    312 }
    313 
    314 /*
    315  * Undo all redirections.  Called on error or interrupt.
    316  */
    317 
    318 #ifdef mkinit
    319 
    320 INCLUDE "redir.h"
    321 
    322 RESET {
    323 	while (redirlist)
    324 		popredir();
    325 }
    326 
    327 SHELLPROC {
    328 	clearredir(0);
    329 }
    330 
    331 #endif
    332 
    333 /* Return true if fd 0 has already been redirected at least once.  */
    334 int
    335 fd0_redirected_p () {
    336         return fd0_redirected != 0;
    337 }
    338 
    339 /*
    340  * Discard all saved file descriptors.
    341  */
    342 
    343 void
    344 clearredir(vforked)
    345 	int vforked;
    346 {
    347 	struct redirtab *rp;
    348 	int i;
    349 
    350 	for (rp = redirlist ; rp ; rp = rp->next) {
    351 		for (i = 0 ; i < 10 ; i++) {
    352 			if (rp->renamed[i] >= 0) {
    353 				close(rp->renamed[i]);
    354 			}
    355 			if (!vforked)
    356 				rp->renamed[i] = EMPTY;
    357 		}
    358 	}
    359 }
    360 
    361 
    362 
    363 /*
    364  * Copy a file descriptor to be >= to.  Returns -1
    365  * if the source file descriptor is closed, EMPTY if there are no unused
    366  * file descriptors left.
    367  */
    368 
    369 int
    370 copyfd(int from, int to)
    371 {
    372 	int newfd;
    373 
    374 	newfd = fcntl(from, F_DUPFD, to);
    375 	if (newfd < 0) {
    376 		if (errno == EMFILE)
    377 			return EMPTY;
    378 		else
    379 			error("%d: %s", from, strerror(errno));
    380 	}
    381 	return newfd;
    382 }
    383