1 /* $NetBSD: redir.c,v 1.37 2014/10/23 21:03:25 christos 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 1.37 2014/10/23 21:03:25 christos 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 #define CLOSED -1 /* fd was not open before redir */
71 #ifndef PIPE_BUF
72 # define PIPESIZE 4096 /* amount of buffering in a pipe */
73 #else
74 # define PIPESIZE PIPE_BUF
75 #endif
76
77
78 MKINIT
79 struct redirtab {
80 struct redirtab *next;
81 short renamed[10];
82 };
83
84
85 MKINIT struct redirtab *redirlist;
86
87 /*
88 * We keep track of whether or not fd0 has been redirected. This is for
89 * background commands, where we want to redirect fd0 to /dev/null only
90 * if it hasn't already been redirected.
91 */
92 int fd0_redirected = 0;
93
94 STATIC void openredirect(union node *, char[10], int);
95 STATIC int openhere(const union node *);
96
97
98 /*
99 * Process a list of redirection commands. If the REDIR_PUSH flag is set,
100 * old file descriptors are stashed away so that the redirection can be
101 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the
102 * standard output, and the standard error if it becomes a duplicate of
103 * stdout, is saved in memory.
104 */
105
106 void
redirect(union node * redir,int flags)107 redirect(union node *redir, int flags)
108 {
109 union node *n;
110 struct redirtab *sv = NULL;
111 int i;
112 int fd;
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 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
131 n->ndup.dupfd == fd)
132 continue; /* redirect from/to same file descriptor */
133
134 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
135 INTOFF;
136 if ((i = fcntl(fd, F_DUPFD, 10)) == -1) {
137 switch (errno) {
138 case EBADF:
139 i = CLOSED;
140 break;
141 default:
142 INTON;
143 error("%d: %s", fd, strerror(errno));
144 /* NOTREACHED */
145 }
146 } else
147 (void)fcntl(i, F_SETFD, FD_CLOEXEC);
148 sv->renamed[fd] = i;
149 INTON;
150 } else {
151 close(fd);
152 }
153 if (fd == 0)
154 fd0_redirected++;
155 openredirect(n, memory, flags);
156 }
157 if (memory[1])
158 out1 = &memout;
159 if (memory[2])
160 out2 = &memout;
161 }
162
163
164 STATIC void
openredirect(union node * redir,char memory[10],int flags)165 openredirect(union node *redir, char memory[10], int flags)
166 {
167 struct stat sb;
168 int fd = redir->nfile.fd;
169 char *fname;
170 int f;
171 int eflags;
172
173 /*
174 * We suppress interrupts so that we won't leave open file
175 * descriptors around. This may not be such a good idea because
176 * an open of a device or a fifo can block indefinitely.
177 */
178 INTOFF;
179 memory[fd] = 0;
180 switch (redir->nfile.type) {
181 case NFROM:
182 fname = redir->nfile.expfname;
183 if (flags & REDIR_VFORK)
184 eflags = O_NONBLOCK;
185 else
186 eflags = 0;
187 if ((f = open(fname, O_RDONLY|eflags)) < 0)
188 goto eopen;
189 if (eflags)
190 (void)fcntl(f, F_SETFL, fcntl(f, F_GETFL, 0) & ~eflags);
191 break;
192 case NFROMTO:
193 fname = redir->nfile.expfname;
194 if ((f = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
195 goto ecreate;
196 break;
197 case NTO:
198 if (Cflag) {
199 fname = redir->nfile.expfname;
200 if ((f = open(fname, O_WRONLY)) == -1) {
201 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL,
202 0666)) < 0)
203 goto ecreate;
204 } else if (fstat(f, &sb) == -1) {
205 int serrno = errno;
206 close(f);
207 errno = serrno;
208 goto ecreate;
209 } else if (S_ISREG(sb.st_mode)) {
210 close(f);
211 errno = EEXIST;
212 goto ecreate;
213 }
214 break;
215 }
216 /* FALLTHROUGH */
217 case NCLOBBER:
218 fname = redir->nfile.expfname;
219 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
220 goto ecreate;
221 break;
222 case NAPPEND:
223 fname = redir->nfile.expfname;
224 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
225 goto ecreate;
226 break;
227 case NTOFD:
228 case NFROMFD:
229 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
230 if (memory[redir->ndup.dupfd])
231 memory[fd] = 1;
232 else
233 copyfd(redir->ndup.dupfd, fd, 1);
234 }
235 INTON;
236 return;
237 case NHERE:
238 case NXHERE:
239 f = openhere(redir);
240 break;
241 default:
242 abort();
243 }
244
245 if (f != fd) {
246 copyfd(f, fd, 1);
247 close(f);
248 }
249 INTON;
250 return;
251 ecreate:
252 exerrno = 1;
253 error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
254 eopen:
255 exerrno = 1;
256 error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
257 }
258
259
260 /*
261 * Handle here documents. Normally we fork off a process to write the
262 * data to a pipe. If the document is short, we can stuff the data in
263 * the pipe without forking.
264 */
265
266 STATIC int
openhere(const union node * redir)267 openhere(const union node *redir)
268 {
269 int pip[2];
270 int len = 0;
271
272 if (pipe(pip) < 0)
273 error("Pipe call failed");
274 if (redir->type == NHERE) {
275 len = strlen(redir->nhere.doc->narg.text);
276 if (len <= PIPESIZE) {
277 xwrite(pip[1], redir->nhere.doc->narg.text, len);
278 goto out;
279 }
280 }
281 if (forkshell(NULL, NULL, FORK_NOJOB) == 0) {
282 close(pip[0]);
283 signal(SIGINT, SIG_IGN);
284 signal(SIGQUIT, SIG_IGN);
285 signal(SIGHUP, SIG_IGN);
286 #ifdef SIGTSTP
287 signal(SIGTSTP, SIG_IGN);
288 #endif
289 signal(SIGPIPE, SIG_DFL);
290 if (redir->type == NHERE)
291 xwrite(pip[1], redir->nhere.doc->narg.text, len);
292 else
293 expandhere(redir->nhere.doc, pip[1]);
294 _exit(0);
295 }
296 out:
297 close(pip[1]);
298 return pip[0];
299 }
300
301
302
303 /*
304 * Undo the effects of the last redirection.
305 */
306
307 void
popredir(void)308 popredir(void)
309 {
310 struct redirtab *rp = redirlist;
311 int i;
312
313 for (i = 0 ; i < 10 ; i++) {
314 if (rp->renamed[i] != EMPTY) {
315 if (i == 0)
316 fd0_redirected--;
317 close(i);
318 if (rp->renamed[i] >= 0) {
319 copyfd(rp->renamed[i], i, 1);
320 close(rp->renamed[i]);
321 }
322 }
323 }
324 INTOFF;
325 redirlist = rp->next;
326 ckfree(rp);
327 INTON;
328 }
329
330 /*
331 * Undo all redirections. Called on error or interrupt.
332 */
333
334 #ifdef mkinit
335
336 INCLUDE "redir.h"
337
338 RESET {
339 while (redirlist)
340 popredir();
341 }
342
343 SHELLPROC {
344 clearredir(0);
345 }
346
347 #endif
348
349 /* Return true if fd 0 has already been redirected at least once. */
350 int
fd0_redirected_p(void)351 fd0_redirected_p (void) {
352 return fd0_redirected != 0;
353 }
354
355 /*
356 * Discard all saved file descriptors.
357 */
358
359 void
clearredir(int vforked)360 clearredir(int vforked)
361 {
362 struct redirtab *rp;
363 int i;
364
365 for (rp = redirlist ; rp ; rp = rp->next) {
366 for (i = 0 ; i < 10 ; i++) {
367 if (rp->renamed[i] >= 0) {
368 close(rp->renamed[i]);
369 }
370 if (!vforked)
371 rp->renamed[i] = EMPTY;
372 }
373 }
374 }
375
376
377
378 /*
379 * Copy a file descriptor to be >= to. Returns -1
380 * if the source file descriptor is closed, EMPTY if there are no unused
381 * file descriptors left.
382 */
383
384 int
copyfd(int from,int to,int equal)385 copyfd(int from, int to, int equal)
386 {
387 int newfd;
388
389 if (equal)
390 newfd = dup2(from, to);
391 else
392 newfd = fcntl(from, F_DUPFD, to);
393 if (newfd < 0) {
394 if (errno == EMFILE)
395 return EMPTY;
396 else
397 error("%d: %s", from, strerror(errno));
398 }
399 return newfd;
400 }
401