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#include <errno.h>
36#include <fcntl.h>
37#include <signal.h>
38#include <stdlib.h>
39#include <string.h>
40#include <sys/stat.h>
41#include <sys/types.h>
42#include <unistd.h>
43
44/*
45 * Code for dealing with input/output redirection.
46 */
47
48#include "error.h"
49#include "expand.h"
50#include "jobs.h"
51#include "memalloc.h"
52#include "nodes.h"
53#include "options.h"
54#include "output.h"
55#include "redir.h"
56#include "shell.h"
57
58#define EMPTY -2 /* marks an unused slot in redirtab */
59#define CLOSED -1 /* fd was not open before redir */
60
61struct redirtab {
62 struct redirtab *next;
63 int renamed[10];
64 int fd0_redirected;
65 unsigned int empty_redirs;
66};
67
68static struct redirtab *redirlist;
69
70/*
71 * We keep track of whether or not fd0 has been redirected. This is for
72 * background commands, where we want to redirect fd0 to /dev/null only
73 * if it hasn't already been redirected.
74 */
75static int fd0_redirected = 0;
76
77/* Number of redirtabs that have not been allocated. */
78static unsigned int empty_redirs = 0;
79
80static void openredirect(union node *, char[10]);
81static int openhere(union node *);
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 * We suppress interrupts so that we won't leave open file
91 * descriptors around. Because the signal handler remains
92 * installed and we do not use system call restart, interrupts
93 * will still abort blocking opens such as fifos (they will fail
94 * with EINTR). There is, however, a race condition if an interrupt
95 * arrives after INTOFF and before open blocks.
96 */
97
98void
99redirect(union node *redir, int flags)
100{
101 union node *n;
102 struct redirtab *sv = NULL;
103 int i;
104 int fd;
105 char memory[10]; /* file descriptors to write to memory */
106
107 INTOFF;
108 for (i = 10; --i >= 0;)
109 memory[i] = 0;
110 memory[1] = flags & REDIR_BACKQ;
111 if (flags & REDIR_PUSH) {
112 empty_redirs++;
113 if (redir != NULL) {
114 sv = ckmalloc(sizeof(struct redirtab));
115 for (i = 0; i < 10; i++)
116 sv->renamed[i] = EMPTY;
117 sv->fd0_redirected = fd0_redirected;
118 sv->empty_redirs = empty_redirs - 1;
119 sv->next = redirlist;
120 redirlist = sv;
121 empty_redirs = 0;
122 }
123 }
124 for (n = redir; n; n = n->nfile.next) {
125 fd = n->nfile.fd;
126 if (fd == 0)
127 fd0_redirected = 1;
128 if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) && n->ndup.dupfd == fd)
129 continue; /* redirect from/to same file descriptor */
130
131 if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
132 INTOFF;
133 if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) {
134 switch (errno) {
135 case EBADF:
136 i = CLOSED;
137 break;
138 default:
139 INTON;
140 error("%d: %s", fd, strerror(errno));
141 break;
142 }
143 }
144 sv->renamed[fd] = i;
145 INTON;
146 }
147 openredirect(n, memory);
148 INTON;
149 INTOFF;
150 }
151 if (memory[1])
152 out1 = &memout;
153 if (memory[2])
154 out2 = &memout;
155 INTON;
156}
157
158static void
159openredirect(union node *redir, char memory[10])
160{
161 struct stat sb;
162 int fd = redir->nfile.fd;
163 const char *fname;
164 int f;
165 int e;
166
167 memory[fd] = 0;
168 switch (redir->nfile.type) {
169 case NFROM:
170 fname = redir->nfile.expfname;
171 if ((f = open(fname, O_RDONLY)) < 0)
172 error("cannot open %s: %s", fname, strerror(errno));
173 break;
174 case NFROMTO:
175 fname = redir->nfile.expfname;
176 if ((f = open(fname, O_RDWR | O_CREAT, 0666)) < 0)
177 error("cannot create %s: %s", fname, strerror(errno));
178 break;
179 case NTO:
180 if (Cflag) {
181 fname = redir->nfile.expfname;
182 if (stat(fname, &sb) == -1) {
183 if ((f = open(fname, O_WRONLY | O_CREAT | O_EXCL, 0666)) < 0)
184 error("cannot create %s: %s", fname, strerror(errno));
185 } else if (!S_ISREG(sb.st_mode)) {
186 if ((f = open(fname, O_WRONLY, 0666)) < 0)
187 error("cannot create %s: %s", fname, strerror(errno));
188 if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
189 close(f);
190 error("cannot create %s: %s", fname, strerror(EEXIST));
191 }
192 } else
193 error("cannot create %s: %s", fname, strerror(EEXIST));
194 break;
195 }
196 /* FALLTHROUGH */
197 case NCLOBBER:
198 fname = redir->nfile.expfname;
199 if ((f = open(fname, O_WRONLY | O_CREAT | O_TRUNC, 0666)) < 0)
200 error("cannot create %s: %s", fname, strerror(errno));
201 break;
202 case NAPPEND:
203 fname = redir->nfile.expfname;
204 if ((f = open(fname, O_WRONLY | O_CREAT | O_APPEND, 0666)) < 0)
205 error("cannot create %s: %s", fname, strerror(errno));
206 break;
207 case NTOFD:
208 case NFROMFD:
209 if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
210 if (memory[redir->ndup.dupfd])
211 memory[fd] = 1;
212 else {
213 if (dup2(redir->ndup.dupfd, fd) < 0)
214 error("%d: %s", redir->ndup.dupfd, strerror(errno));
215 }
216 } else {
217 close(fd);
218 }
219 return;
220 case NHERE:
221 case NXHERE:
222 f = openhere(redir);
223 break;
224 default:
225 abort();
226 }
227 if (f != fd) {
228 if (dup2(f, fd) == -1) {
229 e = errno;
230 close(f);
231 error("%d: %s", fd, strerror(e));
232 }
233 close(f);
234 }
235}
236
237/*
238 * Handle here documents. Normally we fork off a process to write the
239 * data to a pipe. If the document is short, we can stuff the data in
240 * the pipe without forking.
241 */
242
243static int
244openhere(union node *redir)
245{
246 const char *p;
247 int pip[2];
248 size_t len = 0;
249 int flags;
250 ssize_t written = 0;
251
252 if (pipe(pip) < 0)
253 error("Pipe call failed: %s", strerror(errno));
254
255 if (redir->type == NXHERE)
256 p = redir->nhere.expdoc;
257 else
258 p = redir->nhere.doc->narg.text;
259 len = strlen(p);
260 if (len == 0)
261 goto out;
262 flags = fcntl(pip[1], F_GETFL, 0);
263 if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
264 written = write(pip[1], p, len);
265 if (written < 0)
266 written = 0;
267 if ((size_t)written == len)
268 goto out;
269 fcntl(pip[1], F_SETFL, flags);
270 }
271
272 if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
273 close(pip[0]);
274 signal(SIGINT, SIG_IGN);
275 signal(SIGQUIT, SIG_IGN);
276 signal(SIGHUP, SIG_IGN);
277 signal(SIGTSTP, SIG_IGN);
278 signal(SIGPIPE, SIG_DFL);
279 xwrite(pip[1], p + written, len - written);
280 _exit(0);
281 }
282out:
283 close(pip[1]);
284 return pip[0];
285}
286
287/*
288 * Undo the effects of the last redirection.
289 */
290
291void
292popredir(void)
293{
294 struct redirtab *rp = redirlist;
295 int i;
296
297 INTOFF;
298 if (empty_redirs > 0) {
299 empty_redirs--;
300 INTON;
301 return;
302 }
303 for (i = 0; i < 10; i++) {
304 if (rp->renamed[i] != EMPTY) {
305 if (rp->renamed[i] >= 0) {
306 dup2(rp->renamed[i], i);
307 close(rp->renamed[i]);
308 } else {
309 close(i);
310 }
311 }
312 }
313 fd0_redirected = rp->fd0_redirected;
314 empty_redirs = rp->empty_redirs;
315 redirlist = rp->next;
316 ckfree(rp);
317 INTON;
318}
319
320/* Return true if fd 0 has already been redirected at least once. */
321int
322fd0_redirected_p(void)
323{
324 return fd0_redirected != 0;
325}
326
327/*
328 * Discard all saved file descriptors.
329 */
330
331void
332clearredir(void)
333{
334 struct redirtab *rp;
335 int i;
336
337 for (rp = redirlist; rp; rp = rp->next) {
338 for (i = 0; i < 10; i++) {
339 if (rp->renamed[i] >= 0) {
340 close(rp->renamed[i]);
341 }
342 rp->renamed[i] = EMPTY;
343 }
344 }
345}
