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redir.c revision 1.14 
      1 /*	$NetBSD: redir.c,v 1.14 1997/01/11 02:04:46 tls 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 #ifndef lint
     40 #if 0
     41 static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
     42 #else
     43 static char rcsid[] = "$NetBSD: redir.c,v 1.14 1997/01/11 02:04:46 tls Exp $";
     44 #endif
     45 #endif /* not lint */
     46 
     47 #include <sys/types.h>
     48 #include <signal.h>
     49 #include <string.h>
     50 #include <fcntl.h>
     51 #include <errno.h>
     52 #include <unistd.h>
     53 #include <stdlib.h>
     54 
     55 /*
     56  * Code for dealing with input/output redirection.
     57  */
     58 
     59 #include "shell.h"
     60 #include "nodes.h"
     61 #include "jobs.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 #define PIPESIZE 4096		/* amount of buffering in a pipe */
     71 
     72 
     73 MKINIT
     74 struct redirtab {
     75 	struct redirtab *next;
     76 	short renamed[10];
     77 };
     78 
     79 
     80 MKINIT struct redirtab *redirlist;
     81 
     82 /*
     83  * We keep track of whether or not fd0 has been redirected.  This is for
     84  * background commands, where we want to redirect fd0 to /dev/null only
     85  * if it hasn't already been redirected.
     86 */
     87 int fd0_redirected = 0;
     88 
     89 STATIC void openredirect __P((union node *, char[10 ]));
     90 STATIC int openhere __P((union node *));
     91 
     92 
     93 /*
     94  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
     95  * old file descriptors are stashed away so that the redirection can be
     96  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
     97  * standard output, and the standard error if it becomes a duplicate of
     98  * stdout, is saved in memory.
     99  */
    100 
    101 void
    102 redirect(redir, flags)
    103 	union node *redir;
    104 	int flags;
    105 	{
    106 	union node *n;
    107 	struct redirtab *sv;
    108 	int i;
    109 	int fd;
    110 	char memory[10];	/* file descriptors to write to memory */
    111 
    112 	for (i = 10 ; --i >= 0 ; )
    113 		memory[i] = 0;
    114 	memory[1] = flags & REDIR_BACKQ;
    115 	if (flags & REDIR_PUSH) {
    116 		sv = ckmalloc(sizeof (struct redirtab));
    117 		for (i = 0 ; i < 10 ; i++)
    118 			sv->renamed[i] = EMPTY;
    119 		sv->next = redirlist;
    120 		redirlist = sv;
    121 	}
    122 	for (n = redir ; n ; n = n->nfile.next) {
    123 		fd = n->nfile.fd;
    124 		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
    125 		    n->ndup.dupfd == fd)
    126 			continue; /* redirect from/to same file descriptor */
    127 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    128 			INTOFF;
    129 			if ((i = copyfd(fd, 10)) != EMPTY) {
    130 				sv->renamed[fd] = i;
    131 				close(fd);
    132 			}
    133 			INTON;
    134 			if (i == EMPTY)
    135 				error("Out of file descriptors");
    136 		} else {
    137 			close(fd);
    138 		}
    139                 if (fd == 0)
    140                         fd0_redirected++;
    141 		openredirect(n, memory);
    142 	}
    143 	if (memory[1])
    144 		out1 = &memout;
    145 	if (memory[2])
    146 		out2 = &memout;
    147 }
    148 
    149 
    150 STATIC void
    151 openredirect(redir, memory)
    152 	union node *redir;
    153 	char memory[10];
    154 	{
    155 	int fd = redir->nfile.fd;
    156 	char *fname;
    157 	int f;
    158 
    159 	/*
    160 	 * We suppress interrupts so that we won't leave open file
    161 	 * descriptors around.  This may not be such a good idea because
    162 	 * an open of a device or a fifo can block indefinitely.
    163 	 */
    164 	INTOFF;
    165 	memory[fd] = 0;
    166 	switch (redir->nfile.type) {
    167 	case NFROM:
    168 		fname = redir->nfile.expfname;
    169 		if ((f = open(fname, O_RDONLY)) < 0)
    170 			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    171 movefd:
    172 		if (f != fd) {
    173 			copyfd(f, fd);
    174 			close(f);
    175 		}
    176 		break;
    177 	case NTO:
    178 		fname = redir->nfile.expfname;
    179 #ifdef O_CREAT
    180 		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
    181 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    182 #else
    183 		if ((f = creat(fname, 0666)) < 0)
    184 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    185 #endif
    186 		goto movefd;
    187 	case NAPPEND:
    188 		fname = redir->nfile.expfname;
    189 #ifdef O_APPEND
    190 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    191 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    192 #else
    193 		if ((f = open(fname, O_WRONLY)) < 0
    194 		 && (f = creat(fname, 0666)) < 0)
    195 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    196 		lseek(f, (off_t)0, 2);
    197 #endif
    198 		goto movefd;
    199 	case NTOFD:
    200 	case NFROMFD:
    201 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    202 			if (memory[redir->ndup.dupfd])
    203 				memory[fd] = 1;
    204 			else
    205 				copyfd(redir->ndup.dupfd, fd);
    206 		}
    207 		break;
    208 	case NHERE:
    209 	case NXHERE:
    210 		f = openhere(redir);
    211 		goto movefd;
    212 	default:
    213 		abort();
    214 	}
    215 	INTON;
    216 }
    217 
    218 
    219 /*
    220  * Handle here documents.  Normally we fork off a process to write the
    221  * data to a pipe.  If the document is short, we can stuff the data in
    222  * the pipe without forking.
    223  */
    224 
    225 STATIC int
    226 openhere(redir)
    227 	union node *redir;
    228 	{
    229 	int pip[2];
    230 	int len = 0;
    231 
    232 	if (pipe(pip) < 0)
    233 		error("Pipe call failed");
    234 	if (redir->type == NHERE) {
    235 		len = strlen(redir->nhere.doc->narg.text);
    236 		if (len <= PIPESIZE) {
    237 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    238 			goto out;
    239 		}
    240 	}
    241 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
    242 		close(pip[0]);
    243 		signal(SIGINT, SIG_IGN);
    244 		signal(SIGQUIT, SIG_IGN);
    245 		signal(SIGHUP, SIG_IGN);
    246 #ifdef SIGTSTP
    247 		signal(SIGTSTP, SIG_IGN);
    248 #endif
    249 		signal(SIGPIPE, SIG_DFL);
    250 		if (redir->type == NHERE)
    251 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    252 		else
    253 			expandhere(redir->nhere.doc, pip[1]);
    254 		_exit(0);
    255 	}
    256 out:
    257 	close(pip[1]);
    258 	return pip[0];
    259 }
    260 
    261 
    262 
    263 /*
    264  * Undo the effects of the last redirection.
    265  */
    266 
    267 void
    268 popredir() {
    269 	struct redirtab *rp = redirlist;
    270 	int i;
    271 
    272 	for (i = 0 ; i < 10 ; i++) {
    273 		if (rp->renamed[i] != EMPTY) {
    274                         if (i == 0)
    275                                 fd0_redirected--;
    276 			close(i);
    277 			if (rp->renamed[i] >= 0) {
    278 				copyfd(rp->renamed[i], i);
    279 				close(rp->renamed[i]);
    280 			}
    281 		}
    282 	}
    283 	INTOFF;
    284 	redirlist = rp->next;
    285 	ckfree(rp);
    286 	INTON;
    287 }
    288 
    289 /*
    290  * Undo all redirections.  Called on error or interrupt.
    291  */
    292 
    293 #ifdef mkinit
    294 
    295 INCLUDE "redir.h"
    296 
    297 RESET {
    298 	while (redirlist)
    299 		popredir();
    300 }
    301 
    302 SHELLPROC {
    303 	clearredir();
    304 }
    305 
    306 #endif
    307 
    308 /* Return true if fd 0 has already been redirected at least once.  */
    309 int
    310 fd0_redirected_p () {
    311         return fd0_redirected != 0;
    312 }
    313 
    314 /*
    315  * Discard all saved file descriptors.
    316  */
    317 
    318 void
    319 clearredir() {
    320 	struct redirtab *rp;
    321 	int i;
    322 
    323 	for (rp = redirlist ; rp ; rp = rp->next) {
    324 		for (i = 0 ; i < 10 ; i++) {
    325 			if (rp->renamed[i] >= 0) {
    326 				close(rp->renamed[i]);
    327 			}
    328 			rp->renamed[i] = EMPTY;
    329 		}
    330 	}
    331 }
    332 
    333 
    334 
    335 /*
    336  * Copy a file descriptor to be >= to.  Returns -1
    337  * if the source file descriptor is closed, EMPTY if there are no unused
    338  * file descriptors left.
    339  */
    340 
    341 int
    342 copyfd(from, to)
    343 	int from;
    344 	int to;
    345 {
    346 	int newfd;
    347 
    348 	newfd = fcntl(from, F_DUPFD, to);
    349 	if (newfd < 0) {
    350 		if (errno == EMFILE)
    351 			return EMPTY;
    352 		else
    353 			error("%d: %s", from, strerror(errno));
    354 	}
    355 	return newfd;
    356 }
    357