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redir.c revision 1.2 
      1 /*-
      2  * Copyright (c) 1991 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * Kenneth Almquist.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  */
     36 
     37 #ifndef lint
     38 static char sccsid[] = "@(#)redir.c	5.1 (Berkeley) 3/7/91";
     39 static char rcsid[] = "$Id: redir.c,v 1.2 1993/03/22 08:04:00 cgd Exp $";
     40 #endif /* not lint */
     41 
     42 /*
     43  * Code for dealing with input/output redirection.
     44  */
     45 
     46 #include "shell.h"
     47 #include "nodes.h"
     48 #include "jobs.h"
     49 #include "expand.h"
     50 #include "redir.h"
     51 #include "output.h"
     52 #include "memalloc.h"
     53 #include "error.h"
     54 #include <signal.h>
     55 #include <fcntl.h>
     56 #include <errno.h>
     57 
     58 
     59 #define EMPTY -2		/* marks an unused slot in redirtab */
     60 #define PIPESIZE 4096		/* amount of buffering in a pipe */
     61 
     62 
     63 MKINIT
     64 struct redirtab {
     65 	struct redirtab *next;
     66 	short renamed[10];
     67 };
     68 
     69 
     70 MKINIT struct redirtab *redirlist;
     71 
     72 
     73 #ifdef __STDC__
     74 STATIC void openredirect(union node *, char *);
     75 STATIC int openhere(union node *);
     76 #else
     77 STATIC void openredirect();
     78 STATIC int openhere();
     79 #endif
     80 
     81 
     82 
     83 /*
     84  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
     85  * old file descriptors are stashed away so that the redirection can be
     86  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
     87  * standard output, and the standard error if it becomes a duplicate of
     88  * stdout, is saved in memory.
     89  */
     90 
     91 void
     92 redirect(redir, flags)
     93 	union node *redir;
     94 	int flags;
     95 	{
     96 	union node *n;
     97 	struct redirtab *sv;
     98 	int i;
     99 	int fd;
    100 	char memory[10];		/* file descriptors to write to memory */
    101 
    102 	for (i = 10 ; --i >= 0 ; )
    103 		memory[i] = 0;
    104 	memory[1] = flags & REDIR_BACKQ;
    105 	if (flags & REDIR_PUSH) {
    106 		sv = ckmalloc(sizeof (struct redirtab));
    107 		for (i = 0 ; i < 10 ; i++)
    108 			sv->renamed[i] = EMPTY;
    109 		sv->next = redirlist;
    110 		redirlist = sv;
    111 	}
    112 	for (n = redir ; n ; n = n->nfile.next) {
    113 		fd = n->nfile.fd;
    114 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    115 			INTOFF;
    116 			if ((i = copyfd(fd, 10)) != EMPTY) {
    117 				sv->renamed[fd] = i;
    118 				close(fd);
    119 			}
    120 			INTON;
    121 			if (i == EMPTY)
    122 				error("Out of file descriptors");
    123 		} else {
    124 			close(fd);
    125 		}
    126 		openredirect(n, memory);
    127 	}
    128 	if (memory[1])
    129 		out1 = &memout;
    130 	if (memory[2])
    131 		out2 = &memout;
    132 }
    133 
    134 
    135 STATIC void
    136 openredirect(redir, memory)
    137 	union node *redir;
    138 	char memory[10];
    139 	{
    140 	int fd = redir->nfile.fd;
    141 	char *fname;
    142 	int f;
    143 
    144 	/*
    145 	 * We suppress interrupts so that we won't leave open file
    146 	 * descriptors around.  This may not be such a good idea because
    147 	 * an open of a device or a fifo can block indefinitely.
    148 	 */
    149 	INTOFF;
    150 	memory[fd] = 0;
    151 	switch (redir->nfile.type) {
    152 	case NFROM:
    153 		fname = redir->nfile.expfname;
    154 		if ((f = open(fname, O_RDONLY)) < 0)
    155 			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    156 movefd:
    157 		if (f != fd) {
    158 			copyfd(f, fd);
    159 			close(f);
    160 		}
    161 		break;
    162 	case NTO:
    163 		fname = redir->nfile.expfname;
    164 #ifdef O_CREAT
    165 		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
    166 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    167 #else
    168 		if ((f = creat(fname, 0666)) < 0)
    169 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    170 #endif
    171 		goto movefd;
    172 	case NAPPEND:
    173 		fname = redir->nfile.expfname;
    174 #ifdef O_APPEND
    175 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    176 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    177 #else
    178 		if ((f = open(fname, O_WRONLY)) < 0
    179 		 && (f = creat(fname, 0666)) < 0)
    180 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    181 		lseek(f, 0L, 2);
    182 #endif
    183 		goto movefd;
    184 	case NTOFD:
    185 	case NFROMFD:
    186 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    187 			if (memory[redir->ndup.dupfd])
    188 				memory[fd] = 1;
    189 			else
    190 				copyfd(redir->ndup.dupfd, fd);
    191 		}
    192 		break;
    193 	case NHERE:
    194 	case NXHERE:
    195 		f = openhere(redir);
    196 		goto movefd;
    197 	default:
    198 		abort();
    199 	}
    200 	INTON;
    201 }
    202 
    203 
    204 /*
    205  * Handle here documents.  Normally we fork off a process to write the
    206  * data to a pipe.  If the document is short, we can stuff the data in
    207  * the pipe without forking.
    208  */
    209 
    210 STATIC int
    211 openhere(redir)
    212 	union node *redir;
    213 	{
    214 	int pip[2];
    215 	int len;
    216 
    217 	if (pipe(pip) < 0)
    218 		error("Pipe call failed");
    219 	if (redir->type == NHERE) {
    220 		len = strlen(redir->nhere.doc->narg.text);
    221 		if (len <= PIPESIZE) {
    222 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    223 			goto out;
    224 		}
    225 	}
    226 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
    227 		close(pip[0]);
    228 		signal(SIGINT, SIG_IGN);
    229 		signal(SIGQUIT, SIG_IGN);
    230 		signal(SIGHUP, SIG_IGN);
    231 #ifdef SIGTSTP
    232 		signal(SIGTSTP, SIG_IGN);
    233 #endif
    234 		signal(SIGPIPE, SIG_DFL);
    235 		if (redir->type == NHERE)
    236 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    237 		else
    238 			expandhere(redir->nhere.doc, pip[1]);
    239 		_exit(0);
    240 	}
    241 out:
    242 	close(pip[1]);
    243 	return pip[0];
    244 }
    245 
    246 
    247 
    248 /*
    249  * Undo the effects of the last redirection.
    250  */
    251 
    252 void
    253 popredir() {
    254 	register struct redirtab *rp = redirlist;
    255 	int i;
    256 
    257 	for (i = 0 ; i < 10 ; i++) {
    258 		if (rp->renamed[i] != EMPTY) {
    259 			close(i);
    260 			if (rp->renamed[i] >= 0) {
    261 				copyfd(rp->renamed[i], i);
    262 				close(rp->renamed[i]);
    263 			}
    264 		}
    265 	}
    266 	INTOFF;
    267 	redirlist = rp->next;
    268 	ckfree(rp);
    269 	INTON;
    270 }
    271 
    272 
    273 
    274 /*
    275  * Undo all redirections.  Called on error or interrupt.
    276  */
    277 
    278 #ifdef mkinit
    279 
    280 INCLUDE "redir.h"
    281 
    282 RESET {
    283 	while (redirlist)
    284 		popredir();
    285 }
    286 
    287 SHELLPROC {
    288 	clearredir();
    289 }
    290 
    291 #endif
    292 
    293 
    294 /*
    295  * Discard all saved file descriptors.
    296  */
    297 
    298 void
    299 clearredir() {
    300 	register struct redirtab *rp;
    301 	int i;
    302 
    303 	for (rp = redirlist ; rp ; rp = rp->next) {
    304 		for (i = 0 ; i < 10 ; i++) {
    305 			if (rp->renamed[i] >= 0) {
    306 				close(rp->renamed[i]);
    307 			}
    308 			rp->renamed[i] = EMPTY;
    309 		}
    310 	}
    311 }
    312 
    313 
    314 
    315 /*
    316  * Copy a file descriptor, like the F_DUPFD option of fcntl.  Returns -1
    317  * if the source file descriptor is closed, EMPTY if there are no unused
    318  * file descriptors left.
    319  */
    320 
    321 int
    322 copyfd(from, to) {
    323 #ifdef F_DUPFD
    324 	int newfd;
    325 
    326 	newfd = fcntl(from, F_DUPFD, to);
    327 	if (newfd < 0 && errno == EMFILE)
    328 		return EMPTY;
    329 	return newfd;
    330 #else
    331 	char toclose[32];
    332 	int i;
    333 	int newfd;
    334 	int e;
    335 
    336 	for (i = 0 ; i < to ; i++)
    337 		toclose[i] = 0;
    338 	INTOFF;
    339 	while ((newfd = dup(from)) >= 0 && newfd < to)
    340 		toclose[newfd] = 1;
    341 	e = errno;
    342 	for (i = 0 ; i < to ; i++) {
    343 		if (toclose[i])
    344 			close(i);
    345 	}
    346 	INTON;
    347 	if (newfd < 0 && e == EMFILE)
    348 		return EMPTY;
    349 	return newfd;
    350 #endif
    351 }
    352