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redir.c revision 1.4 
      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[] = "$Header: /tank/opengrok/rsync2/NetBSD/src/bin/sh/redir.c,v 1.4 1993/05/02 01:28:44 sef 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 /* We keep track of whether or not fd0 has been redirected.  This is for
     73    background commands, where we want to redirect fd0 to /dev/null only
     74    if it hasn't already been redirected.  */
     75 int fd0_redirected = 0;
     76 
     77 #ifdef __STDC__
     78 STATIC void openredirect(union node *, char *);
     79 STATIC int openhere(union node *);
     80 #else
     81 STATIC void openredirect();
     82 STATIC int openhere();
     83 #endif
     84 
     85 
     86 
     87 /*
     88  * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
     89  * old file descriptors are stashed away so that the redirection can be
     90  * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
     91  * standard output, and the standard error if it becomes a duplicate of
     92  * stdout, is saved in memory.
     93  */
     94 
     95 void
     96 redirect(redir, flags)
     97 	union node *redir;
     98 	int flags;
     99 	{
    100 	union node *n;
    101 	struct redirtab *sv;
    102 	int i;
    103 	int fd;
    104 	char memory[10];		/* file descriptors to write to memory */
    105 
    106 	for (i = 10 ; --i >= 0 ; )
    107 		memory[i] = 0;
    108 	memory[1] = flags & REDIR_BACKQ;
    109 	if (flags & REDIR_PUSH) {
    110 		sv = ckmalloc(sizeof (struct redirtab));
    111 		for (i = 0 ; i < 10 ; i++)
    112 			sv->renamed[i] = EMPTY;
    113 		sv->next = redirlist;
    114 		redirlist = sv;
    115 	}
    116 	for (n = redir ; n ; n = n->nfile.next) {
    117 		fd = n->nfile.fd;
    118 		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
    119 			INTOFF;
    120 			if ((i = copyfd(fd, 10)) != EMPTY) {
    121 				sv->renamed[fd] = i;
    122 				close(fd);
    123 			}
    124 			INTON;
    125 			if (i == EMPTY)
    126 				error("Out of file descriptors");
    127 		} else {
    128 			close(fd);
    129 		}
    130 		if (fd == 0)
    131 			fd0_redirected++;
    132 		openredirect(n, memory);
    133 	}
    134 	if (memory[1])
    135 		out1 = &memout;
    136 	if (memory[2])
    137 		out2 = &memout;
    138 }
    139 
    140 
    141 STATIC void
    142 openredirect(redir, memory)
    143 	union node *redir;
    144 	char memory[10];
    145 	{
    146 	int fd = redir->nfile.fd;
    147 	char *fname;
    148 	int f;
    149 
    150 	/*
    151 	 * We suppress interrupts so that we won't leave open file
    152 	 * descriptors around.  This may not be such a good idea because
    153 	 * an open of a device or a fifo can block indefinitely.
    154 	 */
    155 	INTOFF;
    156 	memory[fd] = 0;
    157 	switch (redir->nfile.type) {
    158 	case NFROM:
    159 		fname = redir->nfile.expfname;
    160 		if ((f = open(fname, O_RDONLY)) < 0)
    161 			error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
    162 movefd:
    163 		if (f != fd) {
    164 			copyfd(f, fd);
    165 			close(f);
    166 		}
    167 		break;
    168 	case NTO:
    169 		fname = redir->nfile.expfname;
    170 #ifdef O_CREAT
    171 		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
    172 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    173 #else
    174 		if ((f = creat(fname, 0666)) < 0)
    175 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    176 #endif
    177 		goto movefd;
    178 	case NAPPEND:
    179 		fname = redir->nfile.expfname;
    180 #ifdef O_APPEND
    181 		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
    182 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    183 #else
    184 		if ((f = open(fname, O_WRONLY)) < 0
    185 		 && (f = creat(fname, 0666)) < 0)
    186 			error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
    187 		lseek(f, 0L, 2);
    188 #endif
    189 		goto movefd;
    190 	case NTOFD:
    191 	case NFROMFD:
    192 		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
    193 			if (memory[redir->ndup.dupfd])
    194 				memory[fd] = 1;
    195 			else
    196 				copyfd(redir->ndup.dupfd, fd);
    197 		}
    198 		break;
    199 	case NHERE:
    200 	case NXHERE:
    201 		f = openhere(redir);
    202 		goto movefd;
    203 	default:
    204 		abort();
    205 	}
    206 	INTON;
    207 }
    208 
    209 
    210 /*
    211  * Handle here documents.  Normally we fork off a process to write the
    212  * data to a pipe.  If the document is short, we can stuff the data in
    213  * the pipe without forking.
    214  */
    215 
    216 STATIC int
    217 openhere(redir)
    218 	union node *redir;
    219 	{
    220 	int pip[2];
    221 	int len;
    222 
    223 	if (pipe(pip) < 0)
    224 		error("Pipe call failed");
    225 	if (redir->type == NHERE) {
    226 		len = strlen(redir->nhere.doc->narg.text);
    227 		if (len <= PIPESIZE) {
    228 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    229 			goto out;
    230 		}
    231 	}
    232 	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
    233 		close(pip[0]);
    234 		signal(SIGINT, SIG_IGN);
    235 		signal(SIGQUIT, SIG_IGN);
    236 		signal(SIGHUP, SIG_IGN);
    237 #ifdef SIGTSTP
    238 		signal(SIGTSTP, SIG_IGN);
    239 #endif
    240 		signal(SIGPIPE, SIG_DFL);
    241 		if (redir->type == NHERE)
    242 			xwrite(pip[1], redir->nhere.doc->narg.text, len);
    243 		else
    244 			expandhere(redir->nhere.doc, pip[1]);
    245 		_exit(0);
    246 	}
    247 out:
    248 	close(pip[1]);
    249 	return pip[0];
    250 }
    251 
    252 
    253 
    254 /*
    255  * Undo the effects of the last redirection.
    256  */
    257 
    258 void
    259 popredir() {
    260 	register struct redirtab *rp = redirlist;
    261 	int i;
    262 
    263 	for (i = 0 ; i < 10 ; i++) {
    264 		if (rp->renamed[i] != EMPTY) {
    265 			if (i == 0)
    266 				fd0_redirected--;
    267 			close(i);
    268 			if (rp->renamed[i] >= 0) {
    269 				copyfd(rp->renamed[i], i);
    270 				close(rp->renamed[i]);
    271 			}
    272 		}
    273 	}
    274 	INTOFF;
    275 	redirlist = rp->next;
    276 	ckfree(rp);
    277 	INTON;
    278 }
    279 
    280 
    281 
    282 /*
    283  * Undo all redirections.  Called on error or interrupt.
    284  */
    285 
    286 #ifdef mkinit
    287 
    288 INCLUDE "redir.h"
    289 
    290 RESET {
    291 	while (redirlist)
    292 		popredir();
    293 }
    294 
    295 SHELLPROC {
    296 	clearredir();
    297 }
    298 
    299 #endif
    300 
    301 
    302 /*
    303  * Discard all saved file descriptors.
    304  */
    305 
    306 void
    307 clearredir() {
    308 	register struct redirtab *rp;
    309 	int i;
    310 
    311 	for (rp = redirlist ; rp ; rp = rp->next) {
    312 		for (i = 0 ; i < 10 ; i++) {
    313 			if (rp->renamed[i] >= 0) {
    314 				close(rp->renamed[i]);
    315 			}
    316 			rp->renamed[i] = EMPTY;
    317 		}
    318 	}
    319 }
    320 
    321 
    322 
    323 /*
    324  * Copy a file descriptor, like the F_DUPFD option of fcntl.  Returns -1
    325  * if the source file descriptor is closed, EMPTY if there are no unused
    326  * file descriptors left.
    327  */
    328 
    329 int
    330 copyfd(from, to) {
    331 #ifdef F_DUPFD
    332 	int newfd;
    333 
    334 	newfd = fcntl(from, F_DUPFD, to);
    335 	if (newfd < 0 && errno == EMFILE)
    336 		return EMPTY;
    337 	return newfd;
    338 #else
    339 	char toclose[32];
    340 	int i;
    341 	int newfd;
    342 	int e;
    343 
    344 	for (i = 0 ; i < to ; i++)
    345 		toclose[i] = 0;
    346 	INTOFF;
    347 	while ((newfd = dup(from)) >= 0 && newfd < to)
    348 		toclose[newfd] = 1;
    349 	e = errno;
    350 	for (i = 0 ; i < to ; i++) {
    351 		if (toclose[i])
    352 			close(i);
    353 	}
    354 	INTON;
    355 	if (newfd < 0 && e == EMFILE)
    356 		return EMPTY;
    357 	return newfd;
    358 #endif
    359 }
    360 
    361 /* Return true if fd 0 has already been redirected at least once.  */
    362 int
    363 fd0_redirected_p () {
    364 	return fd0_redirected != 0;
    365 }
    366