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redir.c revision 1.11 
      1 /*	$NetBSD: redir.c,v 1.11 1995/03/21 09:10:04 cgd 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	8.1 (Berkeley) 5/31/93";
     42 #else
     43 static char rcsid[] = "$NetBSD: redir.c,v 1.11 1995/03/21 09:10:04 cgd Exp $";
     44 #endif
     45 #endif /* not lint */
     46 
     47 /*
     48  * Code for dealing with input/output redirection.
     49  */
     50 
     51 #include "shell.h"
     52 #include "nodes.h"
     53 #include "jobs.h"
     54 #include "expand.h"
     55 #include "redir.h"
     56 #include "output.h"
     57 #include "memalloc.h"
     58 #include "error.h"
     59 #include <sys/types.h>
     60 #include <signal.h>
     61 #include <string.h>
     62 #include <fcntl.h>
     63 #include <errno.h>
     64 #include <unistd.h>
     65 
     66 
     67 #define EMPTY -2		/* marks an unused slot in redirtab */
     68 #define PIPESIZE 4096		/* amount of buffering in a pipe */
     69 
     70 
     71 MKINIT
     72 struct redirtab {
     73 	struct redirtab *next;
     74 	short renamed[10];
     75 };
     76 
     77 
     78 MKINIT struct redirtab *redirlist;
     79 
     80 /*
     81  * We keep track of whether or not fd0 has been redirected.  This is for
     82  * background commands, where we want to redirect fd0 to /dev/null only
     83  * if it hasn't already been redirected.
     84 */
     85 int fd0_redirected = 0;
     86 
     87 #ifdef __STDC__
     88 STATIC void openredirect(union node *, char *);
     89 STATIC int openhere(union node *);
     90 #else
     91 STATIC void openredirect();
     92 STATIC int openhere();
     93 #endif
     94 
     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(redir, flags)
    107 	union node *redir;
    108 	int flags;
    109 	{
    110 	union node *n;
    111 	struct redirtab *sv;
    112 	int i;
    113 	int fd;
    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 		sv = ckmalloc(sizeof (struct redirtab));
    121 		for (i = 0 ; i < 10 ; i++)
    122 			sv->renamed[i] = EMPTY;
    123 		sv->next = redirlist;
    124 		redirlist = sv;
    125 	}
    126 	for (n = redir ; n ; n = n->nfile.next) {
    127 		fd = n->nfile.fd;
    128 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    129 			INTOFF;
    130 			if ((i = copyfd(fd, 10)) != EMPTY) {
    131 				sv->renamed[fd] = i;
    132 				close(fd);
    133 			}
    134 			INTON;
    135 			if (i == EMPTY)
    136 				error("Out of file descriptors");
    137 		} else {
    138 			close(fd);
    139 		}
    140                 if (fd == 0)
    141                         fd0_redirected++;
    142 		openredirect(n, memory);
    143 	}
    144 	if (memory[1])
    145 		out1 = &memout;
    146 	if (memory[2])
    147 		out2 = &memout;
    148 }
    149 
    150 
    151 STATIC void
    152 openredirect(redir, memory)
    153 	union node *redir;
    154 	char memory[10];
    155 	{
    156 	int fd = redir->nfile.fd;
    157 	char *fname;
    158 	int f;
    159 
    160 	/*
    161 	 * We suppress interrupts so that we won't leave open file
    162 	 * descriptors around.  This may not be such a good idea because
    163 	 * an open of a device or a fifo can block indefinitely.
    164 	 */
    165 	INTOFF;
    166 	memory[fd] = 0;
    167 	switch (redir->nfile.type) {
    168 	case NFROM:
    169 		fname = redir->nfile.expfname;
    170 		if ((f = open(fname, O_RDONLY)) < 0)
    171 			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    172 movefd:
    173 		if (f != fd) {
    174 			copyfd(f, fd);
    175 			close(f);
    176 		}
    177 		break;
    178 	case NTO:
    179 		fname = redir->nfile.expfname;
    180 #ifdef O_CREAT
    181 		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
    182 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    183 #else
    184 		if ((f = creat(fname, 0666)) < 0)
    185 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    186 #endif
    187 		goto movefd;
    188 	case NAPPEND:
    189 		fname = redir->nfile.expfname;
    190 #ifdef O_APPEND
    191 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    192 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    193 #else
    194 		if ((f = open(fname, O_WRONLY)) < 0
    195 		 && (f = creat(fname, 0666)) < 0)
    196 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    197 		lseek(f, (off_t)0, 2);
    198 #endif
    199 		goto movefd;
    200 	case NTOFD:
    201 	case NFROMFD:
    202 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    203 			if (memory[redir->ndup.dupfd])
    204 				memory[fd] = 1;
    205 			else
    206 				copyfd(redir->ndup.dupfd, fd);
    207 		}
    208 		break;
    209 	case NHERE:
    210 	case NXHERE:
    211 		f = openhere(redir);
    212 		goto movefd;
    213 	default:
    214 		abort();
    215 	}
    216 	INTON;
    217 }
    218 
    219 
    220 /*
    221  * Handle here documents.  Normally we fork off a process to write the
    222  * data to a pipe.  If the document is short, we can stuff the data in
    223  * the pipe without forking.
    224  */
    225 
    226 STATIC int
    227 openhere(redir)
    228 	union node *redir;
    229 	{
    230 	int pip[2];
    231 	int len;
    232 
    233 	if (pipe(pip) < 0)
    234 		error("Pipe call failed");
    235 	if (redir->type == NHERE) {
    236 		len = strlen(redir->nhere.doc->narg.text);
    237 		if (len <= PIPESIZE) {
    238 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    239 			goto out;
    240 		}
    241 	}
    242 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
    243 		close(pip[0]);
    244 		signal(SIGINT, SIG_IGN);
    245 		signal(SIGQUIT, SIG_IGN);
    246 		signal(SIGHUP, SIG_IGN);
    247 #ifdef SIGTSTP
    248 		signal(SIGTSTP, SIG_IGN);
    249 #endif
    250 		signal(SIGPIPE, SIG_DFL);
    251 		if (redir->type == NHERE)
    252 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    253 		else
    254 			expandhere(redir->nhere.doc, pip[1]);
    255 		_exit(0);
    256 	}
    257 out:
    258 	close(pip[1]);
    259 	return pip[0];
    260 }
    261 
    262 
    263 
    264 /*
    265  * Undo the effects of the last redirection.
    266  */
    267 
    268 void
    269 popredir() {
    270 	register struct redirtab *rp = redirlist;
    271 	int i;
    272 
    273 	for (i = 0 ; i < 10 ; i++) {
    274 		if (rp->renamed[i] != EMPTY) {
    275                         if (i == 0)
    276                                 fd0_redirected--;
    277 			close(i);
    278 			if (rp->renamed[i] >= 0) {
    279 				copyfd(rp->renamed[i], i);
    280 				close(rp->renamed[i]);
    281 			}
    282 		}
    283 	}
    284 	INTOFF;
    285 	redirlist = rp->next;
    286 	ckfree(rp);
    287 	INTON;
    288 }
    289 
    290 /*
    291  * Undo all redirections.  Called on error or interrupt.
    292  */
    293 
    294 #ifdef mkinit
    295 
    296 INCLUDE "redir.h"
    297 
    298 RESET {
    299 	while (redirlist)
    300 		popredir();
    301 }
    302 
    303 SHELLPROC {
    304 	clearredir();
    305 }
    306 
    307 #endif
    308 
    309 /* Return true if fd 0 has already been redirected at least once.  */
    310 int
    311 fd0_redirected_p () {
    312         return fd0_redirected != 0;
    313 }
    314 
    315 /*
    316  * Discard all saved file descriptors.
    317  */
    318 
    319 void
    320 clearredir() {
    321 	register struct redirtab *rp;
    322 	int i;
    323 
    324 	for (rp = redirlist ; rp ; rp = rp->next) {
    325 		for (i = 0 ; i < 10 ; i++) {
    326 			if (rp->renamed[i] >= 0) {
    327 				close(rp->renamed[i]);
    328 			}
    329 			rp->renamed[i] = EMPTY;
    330 		}
    331 	}
    332 }
    333 
    334 
    335 
    336 /*
    337  * Copy a file descriptor to be >= to.  Returns -1
    338  * if the source file descriptor is closed, EMPTY if there are no unused
    339  * file descriptors left.
    340  */
    341 
    342 int
    343 copyfd(from, to)
    344 	int from;
    345 	int to;
    346 {
    347 	int newfd;
    348 
    349 	newfd = fcntl(from, F_DUPFD, to);
    350 	if (newfd < 0 && errno == EMFILE)
    351 		return EMPTY;
    352 	return newfd;
    353 }
    354