summary refs log tree commit diff
path: root/bin/1sh/redir.c
blob: 616053cf8b1976d8b647b5432cd0c8a42cad9cc1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: releng/12.0/bin/sh/redir.c 326025 2017-11-20 19:49:47Z pfg $");

#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>

/*
 * Code for dealing with input/output redirection.
 */

#include "shell.h"
#include "nodes.h"
#include "jobs.h"
#include "expand.h"
#include "redir.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "options.h"


#define EMPTY -2		/* marks an unused slot in redirtab */
#define CLOSED -1		/* fd was not open before redir */


struct redirtab {
	struct redirtab *next;
	int renamed[10];
	int fd0_redirected;
	unsigned int empty_redirs;
};


static struct redirtab *redirlist;

/*
 * We keep track of whether or not fd0 has been redirected.  This is for
 * background commands, where we want to redirect fd0 to /dev/null only
 * if it hasn't already been redirected.
*/
static int fd0_redirected = 0;

/* Number of redirtabs that have not been allocated. */
static unsigned int empty_redirs = 0;

static void openredirect(union node *, char[10 ]);
static int openhere(union node *);


/*
 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
 * old file descriptors are stashed away so that the redirection can be
 * undone by calling popredir.  If the REDIR_BACKQ flag is set, then the
 * standard output, and the standard error if it becomes a duplicate of
 * stdout, is saved in memory.
*
 * We suppress interrupts so that we won't leave open file
 * descriptors around.  Because the signal handler remains
 * installed and we do not use system call restart, interrupts
 * will still abort blocking opens such as fifos (they will fail
 * with EINTR). There is, however, a race condition if an interrupt
 * arrives after INTOFF and before open blocks.
 */

void
redirect(union node *redir, int flags)
{
	union node *n;
	struct redirtab *sv = NULL;
	int i;
	int fd;
	char memory[10];	/* file descriptors to write to memory */

	INTOFF;
	for (i = 10 ; --i >= 0 ; )
		memory[i] = 0;
	memory[1] = flags & REDIR_BACKQ;
	if (flags & REDIR_PUSH) {
		empty_redirs++;
		if (redir != NULL) {
			sv = ckmalloc(sizeof (struct redirtab));
			for (i = 0 ; i < 10 ; i++)
				sv->renamed[i] = EMPTY;
			sv->fd0_redirected = fd0_redirected;
			sv->empty_redirs = empty_redirs - 1;
			sv->next = redirlist;
			redirlist = sv;
			empty_redirs = 0;
		}
	}
	for (n = redir ; n ; n = n->nfile.next) {
		fd = n->nfile.fd;
		if (fd == 0)
			fd0_redirected = 1;
		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
		    n->ndup.dupfd == fd)
			continue; /* redirect from/to same file descriptor */

		if ((flags & REDIR_PUSH) && sv->renamed[fd] == EMPTY) {
			INTOFF;
			if ((i = fcntl(fd, F_DUPFD_CLOEXEC, 10)) == -1) {
				switch (errno) {
				case EBADF:
					i = CLOSED;
					break;
				default:
					INTON;
					error("%d: %s", fd, strerror(errno));
					break;
				}
			}
			sv->renamed[fd] = i;
			INTON;
		}
		openredirect(n, memory);
		INTON;
		INTOFF;
	}
	if (memory[1])
		out1 = &memout;
	if (memory[2])
		out2 = &memout;
	INTON;
}


static void
openredirect(union node *redir, char memory[10])
{
	struct stat sb;
	int fd = redir->nfile.fd;
	const char *fname;
	int f;
	int e;

	memory[fd] = 0;
	switch (redir->nfile.type) {
	case NFROM:
		fname = redir->nfile.expfname;
		if ((f = open(fname, O_RDONLY)) < 0)
			error("cannot open %s: %s", fname, strerror(errno));
		break;
	case NFROMTO:
		fname = redir->nfile.expfname;
		if ((f = open(fname, O_RDWR|O_CREAT, 0666)) < 0)
			error("cannot create %s: %s", fname, strerror(errno));
		break;
	case NTO:
		if (Cflag) {
			fname = redir->nfile.expfname;
			if (stat(fname, &sb) == -1) {
				if ((f = open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666)) < 0)
					error("cannot create %s: %s", fname, strerror(errno));
			} else if (!S_ISREG(sb.st_mode)) {
				if ((f = open(fname, O_WRONLY, 0666)) < 0)
					error("cannot create %s: %s", fname, strerror(errno));
				if (fstat(f, &sb) != -1 && S_ISREG(sb.st_mode)) {
					close(f);
					error("cannot create %s: %s", fname,
					    strerror(EEXIST));
				}
			} else
				error("cannot create %s: %s", fname,
				    strerror(EEXIST));
			break;
		}
		/* FALLTHROUGH */
	case NCLOBBER:
		fname = redir->nfile.expfname;
		if ((f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
			error("cannot create %s: %s", fname, strerror(errno));
		break;
	case NAPPEND:
		fname = redir->nfile.expfname;
		if ((f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
			error("cannot create %s: %s", fname, strerror(errno));
		break;
	case NTOFD:
	case NFROMFD:
		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
			if (memory[redir->ndup.dupfd])
				memory[fd] = 1;
			else {
				if (dup2(redir->ndup.dupfd, fd) < 0)
					error("%d: %s", redir->ndup.dupfd,
							strerror(errno));
			}
		} else {
			close(fd);
		}
		return;
	case NHERE:
	case NXHERE:
		f = openhere(redir);
		break;
	default:
		abort();
	}
	if (f != fd) {
		if (dup2(f, fd) == -1) {
			e = errno;
			close(f);
			error("%d: %s", fd, strerror(e));
		}
		close(f);
	}
}


/*
 * Handle here documents.  Normally we fork off a process to write the
 * data to a pipe.  If the document is short, we can stuff the data in
 * the pipe without forking.
 */

static int
openhere(union node *redir)
{
	const char *p;
	int pip[2];
	size_t len = 0;
	int flags;
	ssize_t written = 0;

	if (pipe(pip) < 0)
		error("Pipe call failed: %s", strerror(errno));

	if (redir->type == NXHERE)
		p = redir->nhere.expdoc;
	else
		p = redir->nhere.doc->narg.text;
	len = strlen(p);
	if (len == 0)
		goto out;
	flags = fcntl(pip[1], F_GETFL, 0);
	if (flags != -1 && fcntl(pip[1], F_SETFL, flags | O_NONBLOCK) != -1) {
		written = write(pip[1], p, len);
		if (written < 0)
			written = 0;
		if ((size_t)written == len)
			goto out;
		fcntl(pip[1], F_SETFL, flags);
	}

	if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
		close(pip[0]);
		signal(SIGINT, SIG_IGN);
		signal(SIGQUIT, SIG_IGN);
		signal(SIGHUP, SIG_IGN);
		signal(SIGTSTP, SIG_IGN);
		signal(SIGPIPE, SIG_DFL);
		xwrite(pip[1], p + written, len - written);
		_exit(0);
	}
out:
	close(pip[1]);
	return pip[0];
}



/*
 * Undo the effects of the last redirection.
 */

void
popredir(void)
{
	struct redirtab *rp = redirlist;
	int i;

	INTOFF;
	if (empty_redirs > 0) {
		empty_redirs--;
		INTON;
		return;
	}
	for (i = 0 ; i < 10 ; i++) {
		if (rp->renamed[i] != EMPTY) {
			if (rp->renamed[i] >= 0) {
				dup2(rp->renamed[i], i);
				close(rp->renamed[i]);
			} else {
				close(i);
			}
		}
	}
	fd0_redirected = rp->fd0_redirected;
	empty_redirs = rp->empty_redirs;
	redirlist = rp->next;
	ckfree(rp);
	INTON;
}

/* Return true if fd 0 has already been redirected at least once.  */
int
fd0_redirected_p(void)
{
        return fd0_redirected != 0;
}

/*
 * Discard all saved file descriptors.
 */

void
clearredir(void)
{
	struct redirtab *rp;
	int i;

	for (rp = redirlist ; rp ; rp = rp->next) {
		for (i = 0 ; i < 10 ; i++) {
			if (rp->renamed[i] >= 0) {
				close(rp->renamed[i]);
			}
			rp->renamed[i] = EMPTY;
		}
	}
}