1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 #ifndef lint
36 #if 0
37 static char sccsid[] = "@(#)redir.c 8.2 (Berkeley) 5/4/95";
38 #endif
39 #endif /* not lint */
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD: head/bin/sh/redir.c 326025 2017-11-20 19:49:47Z pfg $");
42
43 #include <sys/types.h>
44 #include <sys/stat.h>
45 #include <signal.h>
46 #include <string.h>
47 #include <fcntl.h>
48 #include <errno.h>
49 #include <unistd.h>
50 #include <stdlib.h>
51
52 /*
53 * Code for dealing with input/output redirection.
54 */
55
56 #include "shell.h"
57 #include "nodes.h"
58 #include "jobs.h"
59 #include "expand.h"
60 #include "redir.h"
61 #include "output.h"
62 #include "memalloc.h"
63 #include "error.h"
64 #include "options.h"
65
66
67 #define EMPTY -2 /* marks an unused slot in redirtab */
68 #define CLOSED -1 /* fd was not open before redir */
69
70
71 struct redirtab {
72 struct redirtab *next;
73 int renamed[10];
74 int fd0_redirected;
75 unsigned int empty_redirs;
76 };
77
78
79 static struct redirtab *redirlist;
80
81 /*
82 * We keep track of whether or not fd0 has been redirected. This is for
83 * background commands, where we want to redirect fd0 to /dev/null only
84 * if it hasn't already been redirected.
85 */
86 static int fd0_redirected = 0;
87
88 /* Number of redirtabs that have not been allocated. */
89 static unsigned int empty_redirs = 0;
90
91 static void openredirect(union node *, char[10 ]);
92 static int openhere(union node *);
93
94
95 /*
96 * Process a list of redirection commands. If the REDIR_PUSH flag is set,
97 * old file descriptors are stashed away so that the redirection can be
98 * undone by calling popredir. If the REDIR_BACKQ flag is set, then the
99 * standard output, and the standard error if it becomes a duplicate of
100 * stdout, is saved in memory.
101 *
102 * We suppress interrupts so that we won't leave open file
103 * descriptors around. Because the signal handler remains
104 * installed and we do not use system call restart, interrupts
105 * will still abort blocking opens such as fifos (they will fail
106 * with EINTR). There is, however, a race condition if an interrupt
107 * arrives after INTOFF and before open blocks.
108 */
109
110 void
redirect(union node * redir,int flags)111 redirect(union node *redir, int flags)
112 {
113 union node *n;
114 struct redirtab *sv = NULL;
115 int i;
116 int fd;
117 char memory[10]; /* file descriptors to write to memory */
118
119 INTOFF;
120 for (i = 10 ; --i >= 0 ; )
121 memory[i] = 0;
122 memory[1] = flags & REDIR_BACKQ;
123 if (flags & REDIR_PUSH) {
124 empty_redirs++;
125 if (redir != NULL) {
126 sv = ckmalloc(sizeof (struct redirtab));
127 for (i = 0 ; i < 10 ; i++)
128 sv->renamed[i] = EMPTY;
129 sv->fd0_redirected = fd0_redirected;
130 sv->empty_redirs = empty_redirs - 1;
131 sv->next = redirlist;
132 redirlist = sv;
133 empty_redirs = 0;
134 }
135 }
136 for (n = redir ; n ; n = n->nfile.next) {
137 fd = n->nfile.fd;
138 if (fd == 0)
139 fd0_redirected = 1;
140 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
141 n->ndup.dupfd == fd)
142 continue; /* redirect from/to same file descriptor */
143
144 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
145 INTOFF;
146 if ((i = fcntl(fd, F_DUPFD_CLOEXEC_MAYBE, 10)) == -1) {
147 switch (errno) {
148 case EBADF:
149 i = CLOSED;
150 break;
151 default:
152 INTON;
153 error("%d: %s", fd, strerror(errno));
154 break;
155 }
156 }
157 #if !defined(O_CLOEXEC) || !defined(F_DUPFD_CLOEXEC)
158 else {
159 fcntl(i, F_SETFD, FD_CLOEXEC);
160 }
161 #endif
162 sv->renamed[fd] = i;
163 INTON;
164 }
165 openredirect(n, memory);
166 INTON;
167 INTOFF;
168 }
169 if (memory[1])
170 out1 = &memout;
171 if (memory[2])
172 out2 = &memout;
173 INTON;
174 }
175
176
177 static void
openredirect(union node * redir,char memory[10])178 openredirect(union node *redir, char memory[10])
179 {
180 struct stat sb;
181 int fd = redir->nfile.fd;
182 const char *fname;
183 int f;
184 int e;
185
186 memory[fd] = 0;
187 switch (redir->nfile.type) {
188 case NFROM:
189 fname = redir->nfile.expfname;
190 if ((f = open(fname, O_RDONLY)) < 0)
191 error("cannot open %s: %s", fname, strerror(errno));
192 break;
193 case NFROMTO:
194 fname = redir->nfile.expfname;
195 if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
196 error("cannot create %s: %s", fname, strerror(errno));
197 break;
198 case NTO:
199 if (Cflag) {
200 fname = redir->nfile.expfname;
201 if (stat(fname, &sb) == -1) {
202 if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
203 error("cannot create %s: %s", fname, strerror(errno));
204 } else if (!S_ISREG(sb.st_mode)) {
205 if ((f = open(fname, O_WRONLY, 0666)) < 0)
206 error("cannot create %s: %s", fname, strerror(errno));
207 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
208 close(f);
209 error("cannot create %s: %s", fname,
210 strerror(EEXIST));
211 }
212 } else
213 error("cannot create %s: %s", fname,
214 strerror(EEXIST));
215 break;
216 }
217 /* FALLTHROUGH */
218 case NCLOBBER:
219 fname = redir->nfile.expfname;
220 if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
221 error("cannot create %s: %s", fname, strerror(errno));
222 break;
223 case NAPPEND:
224 fname = redir->nfile.expfname;
225 if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
226 error("cannot create %s: %s", fname, strerror(errno));
227 break;
228 case NTOFD:
229 case NFROMFD:
230 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
231 if (memory[redir->ndup.dupfd])
232 memory[fd] = 1;
233 else {
234 if (dup2(redir->ndup.dupfd, fd) < 0)
235 error("%d: %s", redir->ndup.dupfd,
236 strerror(errno));
237 }
238 } else {
239 close(fd);
240 }
241 return;
242 case NHERE:
243 case NXHERE:
244 f = openhere(redir);
245 break;
246 default:
247 abort();
248 }
249 if (f != fd) {
250 if (dup2(f, fd) == -1) {
251 e = errno;
252 close(f);
253 error("%d: %s", fd, strerror(e));
254 }
255 close(f);
256 }
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(union node * redir)267 openhere(union node *redir)
268 {
269 const char *p;
270 int pip[2];
271 size_t len = 0;
272 int flags;
273 ssize_t written = 0;
274
275 if (pipe(pip) < 0)
276 error("Pipe call failed: %s", strerror(errno));
277
278 if (redir->type == NXHERE)
279 p = redir->nhere.expdoc;
280 else
281 p = redir->nhere.doc->narg.text;
282 len = strlen(p);
283 if (len == 0)
284 goto out;
285 flags = fcntl(pip[1], F_GETFL, 0);
286 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
287 written = write(pip[1], p, len);
288 if (written < 0)
289 written = 0;
290 if ((size_t)written == len)
291 goto out;
292 fcntl(pip[1], F_SETFL, flags);
293 }
294
295 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
296 close(pip[0]);
297 signal(SIGINT, SIG_IGN);
298 signal(SIGQUIT, SIG_IGN);
299 signal(SIGHUP, SIG_IGN);
300 signal(SIGTSTP, SIG_IGN);
301 signal(SIGPIPE, SIG_DFL);
302 xwrite(pip[1], p + written, len - written);
303 _exit(0);
304 }
305 out:
306 close(pip[1]);
307 return pip[0];
308 }
309
310
311
312 /*
313 * Undo the effects of the last redirection.
314 */
315
316 void
popredir(void)317 popredir(void)
318 {
319 struct redirtab *rp = redirlist;
320 int i;
321
322 INTOFF;
323 if (empty_redirs > 0) {
324 empty_redirs--;
325 INTON;
326 return;
327 }
328 for (i = 0 ; i < 10 ; i++) {
329 if (rp->renamed[i] != EMPTY) {
330 if (rp->renamed[i] >= 0) {
331 dup2(rp->renamed[i], i);
332 close(rp->renamed[i]);
333 } else {
334 close(i);
335 }
336 }
337 }
338 fd0_redirected = rp->fd0_redirected;
339 empty_redirs = rp->empty_redirs;
340 redirlist = rp->next;
341 ckfree(rp);
342 INTON;
343 }
344
345 /* Return true if fd 0 has already been redirected at least once. */
346 int
fd0_redirected_p(void)347 fd0_redirected_p(void)
348 {
349 return fd0_redirected != 0;
350 }
351
352 /*
353 * Discard all saved file descriptors.
354 */
355
356 void
clearredir(void)357 clearredir(void)
358 {
359 struct redirtab *rp;
360 int i;
361
362 for (rp = redirlist ; rp ; rp = rp->next) {
363 for (i = 0 ; i < 10 ; i++) {
364 if (rp->renamed[i] >= 0) {
365 close(rp->renamed[i]);
366 }
367 rp->renamed[i] = EMPTY;
368 }
369 }
370 }
371