usr/dash/redir.c

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1997-2005
 *	Herbert Xu <herbert@gondor.apana.org.au>.  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.
 */

#include <sys/stat.h>
#include <sys/types.h>
#include <sys/param.h>	/* PIPE_BUF */
#include <signal.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>

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

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


#define REALLY_CLOSED -3	/* fd that was closed and still is */
#define EMPTY -2		/* marks an unused slot in redirtab */
#define CLOSED -1		/* fd opened for redir needs to be closed */

#ifndef PIPE_BUF
# define PIPESIZE 4096		/* amount of buffering in a pipe */
#else
# define PIPESIZE PIPE_BUF
#endif


MKINIT
struct redirtab {
	struct redirtab *next;
	int renamed[10];
	int nullredirs;
};


MKINIT struct redirtab *redirlist;
MKINIT int nullredirs;

STATIC int openredirect(union node *);
#ifdef notyet
STATIC void dupredirect(union node *, int, char[10]);
#else
STATIC void dupredirect(union node *, int);
#endif
STATIC int openhere(union node *);
STATIC int noclobberopen(const char *);


/*
 * 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.
 */

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

	for (i = 10 ; --i >= 0 ; )
		memory[i] = 0;
	memory[1] = flags & REDIR_BACKQ;
#endif
	nullredirs++;
	if (!redir) {
		return;
	}
	sv = NULL;
	INTOFF;
	if (likely(flags & REDIR_PUSH)) {
		struct redirtab *q;
		q = ckmalloc(sizeof (struct redirtab));
		q->next = redirlist;
		redirlist = q;
		q->nullredirs = nullredirs - 1;
		for (i = 0 ; i < 10 ; i++)
			q->renamed[i] = EMPTY;
		nullredirs = 0;
		sv = q;
	}
	n = redir;
	do {
		newfd = openredirect(n);
		if (newfd < -1)
			continue;

		fd = n->nfile.fd;

		if (sv) {
			p = &sv->renamed[fd];
			i = *p;

			if (likely(i == EMPTY)) {
				i = CLOSED;
				if (fd != newfd) {
					i = savefd(fd);
					fd = -1;
				}
			}

			if (i == newfd)
				/* Can only happen if i == newfd == CLOSED */
				i = REALLY_CLOSED;

			*p = i;
		}

		if (fd == newfd)
			continue;

#ifdef notyet
		dupredirect(n, newfd, memory);
#else
		dupredirect(n, newfd);
#endif
	} while ((n = n->nfile.next));
	INTON;
#ifdef notyet
	if (memory[1])
		out1 = &memout;
	if (memory[2])
		out2 = &memout;
#endif
	if (flags & REDIR_SAVEFD2 && sv->renamed[2] >= 0)
		preverrout.fd = sv->renamed[2];
}


STATIC int
openredirect(union node *redir)
{
	char *fname;
	int f;

	switch (redir->nfile.type) {
	case NFROM:
		fname = redir->nfile.expfname;
		if ((f = open64(fname, O_RDONLY)) < 0)
			goto eopen;
		break;
	case NFROMTO:
		fname = redir->nfile.expfname;
		if ((f = open64(fname, O_RDWR|O_CREAT|O_TRUNC, 0666)) < 0)
			goto ecreate;
		break;
	case NTO:
		/* Take care of noclobber mode. */
		if (Cflag) {
			fname = redir->nfile.expfname;
			if ((f = noclobberopen(fname)) < 0)
				goto ecreate;
			break;
		}
		/* FALLTHROUGH */
	case NCLOBBER:
		fname = redir->nfile.expfname;
		if ((f = open64(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666)) < 0)
			goto ecreate;
		break;
	case NAPPEND:
		fname = redir->nfile.expfname;
		if ((f = open64(fname, O_WRONLY|O_CREAT|O_APPEND, 0666)) < 0)
			goto ecreate;
		break;
	case NTOFD:
	case NFROMFD:
		f = redir->ndup.dupfd;
		if (f == redir->nfile.fd)
			f = -2;
		break;
	default:
#ifdef DEBUG
		abort();
#endif
		/* Fall through to eliminate warning. */
	case NHERE:
	case NXHERE:
		f = openhere(redir);
		break;
	}

	return f;
ecreate:
	sh_error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
eopen:
	sh_error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
}


STATIC void
#ifdef notyet
dupredirect(redir, f, memory)
#else
dupredirect(redir, f)
#endif
	union node *redir;
	int f;
#ifdef notyet
	char memory[10];
#endif
	{
	int fd = redir->nfile.fd;
	int err = 0;

#ifdef notyet
	memory[fd] = 0;
#endif
	if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) {
		/* if not ">&-" */
		if (f >= 0) {
#ifdef notyet
			if (memory[f])
				memory[fd] = 1;
			else
#endif
				if (dup2(f, fd) < 0) {
					err = errno;
					goto err;
				}
			return;
		}
		f = fd;
	} else if (dup2(f, fd) < 0)
		err = errno;

	close(f);
	if (err < 0)
		goto err;

	return;

err:
	sh_error("%d: %s", f, strerror(err));
}


/*
 * 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)
{
	int pip[2];
	size_t len = 0;

	if (pipe(pip) < 0)
		sh_error("Pipe call failed");
	if (redir->type == NHERE) {
		len = strlen(redir->nhere.doc->narg.text);
		if (len <= PIPESIZE) {
			xwrite(pip[1], redir->nhere.doc->narg.text, len);
			goto out;
		}
	}
	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);
#ifdef SIGTSTP
		signal(SIGTSTP, SIG_IGN);
#endif
		signal(SIGPIPE, SIG_DFL);
		if (redir->type == NHERE)
			xwrite(pip[1], redir->nhere.doc->narg.text, len);
		else
			expandhere(redir->nhere.doc, pip[1]);
		_exit(0);
	}
out:
	close(pip[1]);
	return pip[0];
}


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

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

	if (--nullredirs >= 0)
		return;
	INTOFF;
	rp = redirlist;
	for (i = 0 ; i < 10 ; i++) {
		switch (rp->renamed[i]) {
		case CLOSED:
			if (!drop)
				close(i);
			break;
		case EMPTY:
		case REALLY_CLOSED:
			break;
		default:
			if (!drop)
				dup2(rp->renamed[i], i);
			close(rp->renamed[i]);
			break;
		}
	}
	redirlist = rp->next;
	nullredirs = rp->nullredirs;
	ckfree(rp);
	INTON;
}

/*
 * Undo all redirections.  Called on error or interrupt.
 */

#ifdef mkinit

INCLUDE "redir.h"

RESET {
	/*
	 * Discard all saved file descriptors.
	 */
	for (;;) {
		nullredirs = 0;
		if (!redirlist)
			break;
		popredir(0);
	}
}

#endif


/*
 * Move a file descriptor to > 10.  Invokes sh_error on error unless
 * the original file dscriptor is not open.
 */

int
savefd(int from)
{
	int newfd;
	int err;

	newfd = fcntl(from, F_DUPFD, 10);
	err = newfd < 0 ? errno : 0;
	if (err != EBADF) {
		close(from);
		if (err)
			sh_error("%d: %s", from, strerror(err));
		else
			fcntl(newfd, F_SETFD, FD_CLOEXEC);
	}

	return newfd;
}


/*
 * Open a file in noclobber mode.
 * The code was copied from bash.
 */
int
noclobberopen(fname)
	const char *fname;
{
	int r, fd;
	struct stat64 finfo, finfo2;

	/*
	 * If the file exists and is a regular file, return an error
	 * immediately.
	 */
	r = stat64(fname, &finfo);
	if (r == 0 && S_ISREG(finfo.st_mode)) {
		errno = EEXIST;
		return -1;
	}

	/*
	 * If the file was not present (r != 0), make sure we open it
	 * exclusively so that if it is created before we open it, our open
	 * will fail.  Make sure that we do not truncate an existing file.
	 * Note that we don't turn on O_EXCL unless the stat failed -- if the
	 * file was not a regular file, we leave O_EXCL off.
	 */
	if (r != 0)
		return open64(fname, O_WRONLY|O_CREAT|O_EXCL, 0666);
	fd = open64(fname, O_WRONLY|O_CREAT, 0666);

	/* If the open failed, return the file descriptor right away. */
	if (fd < 0)
		return fd;

	/*
	 * OK, the open succeeded, but the file may have been changed from a
	 * non-regular file to a regular file between the stat and the open.
	 * We are assuming that the O_EXCL open handles the case where FILENAME
	 * did not exist and is symlinked to an existing file between the stat
	 * and open.
	 */

	/*
	 * If we can open it and fstat the file descriptor, and neither check
	 * revealed that it was a regular file, and the file has not been
	 * replaced, return the file descriptor.
	 */
	 if (fstat64(fd, &finfo2) == 0 && !S_ISREG(finfo2.st_mode) &&
	     finfo.st_dev == finfo2.st_dev && finfo.st_ino == finfo2.st_ino)
	 	return fd;

	/* The file has been replaced.  badness. */
	close(fd);
	errno = EEXIST;
	return -1;
}


int
redirectsafe(union node *redir, int flags)
{
	int err;
	volatile int saveint;
	struct jmploc *volatile savehandler = handler;
	struct jmploc jmploc;

	SAVEINT(saveint);
	if (!(err = setjmp(jmploc.loc) * 2)) {
		handler = &jmploc;
		redirect(redir, flags);
	}
	handler = savehandler;
	if (err && exception != EXERROR)
		longjmp(handler->loc, 1);
	RESTOREINT(saveint);
	return err;
}
1	/*-
2	* Copyright (c) 1991, 1993
3	* The Regents of the University of California. All rights reserved.
4	* Copyright (c) 1997-2005
5	* Herbert Xu <herbert@gondor.apana.org.au>. 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/stat.h>
36	#include <sys/types.h>
37	#include <sys/param.h> /* PIPE_BUF */
38	#include <signal.h>
39	#include <string.h>
40	#include <fcntl.h>
41	#include <unistd.h>
42	#include <stdlib.h>
43
44	/*
45	* Code for dealing with input/output redirection.
46	*/
47
48	#include "main.h"
49	#include "shell.h"
50	#include "nodes.h"
51	#include "jobs.h"
52	#include "options.h"
53	#include "expand.h"
54	#include "redir.h"
55	#include "output.h"
56	#include "memalloc.h"
57	#include "error.h"
58
59
60	#define REALLY_CLOSED -3 /* fd that was closed and still is */
61	#define EMPTY -2 /* marks an unused slot in redirtab */
62	#define CLOSED -1 /* fd opened for redir needs to be closed */
63
64	#ifndef PIPE_BUF
65	# define PIPESIZE 4096 /* amount of buffering in a pipe */
66	#else
67	# define PIPESIZE PIPE_BUF
68	#endif
69
70
71	MKINIT
72	struct redirtab {
73	struct redirtab *next;
74	int renamed[10];
75	int nullredirs;
76	};
77
78
79	MKINIT struct redirtab *redirlist;
80	MKINIT int nullredirs;
81
82	STATIC int openredirect(union node *);
83	#ifdef notyet
84	STATIC void dupredirect(union node *, int, char[10]);
85	#else
86	STATIC void dupredirect(union node *, int);
87	#endif
88	STATIC int openhere(union node *);
89	STATIC int noclobberopen(const char *);
90
91
92	/*
93	* Process a list of redirection commands. If the REDIR_PUSH flag is set,
94	* old file descriptors are stashed away so that the redirection can be
95	* undone by calling popredir. If the REDIR_BACKQ flag is set, then the
96	* standard output, and the standard error if it becomes a duplicate of
97	* stdout, is saved in memory.
98	*/
99
100	void
101	redirect(union node *redir, int flags)
102	{
103	union node *n;
104	struct redirtab *sv;
105	int i;
106	int fd;
107	int newfd;
108	int *p;
109	#if notyet
110	char memory[10]; /* file descriptors to write to memory */
111
112	for (i = 10 ; --i >= 0 ; )
113	memory[i] = 0;
114	memory[1] = flags & REDIR_BACKQ;
115	#endif
116	nullredirs++;
117	if (!redir) {
118	return;
119	}
120	sv = NULL;
121	INTOFF;
122	if (likely(flags & REDIR_PUSH)) {
123	struct redirtab *q;
124	q = ckmalloc(sizeof (struct redirtab));
125	q->next = redirlist;
126	redirlist = q;
127	q->nullredirs = nullredirs - 1;
128	for (i = 0 ; i < 10 ; i++)
129	q->renamed[i] = EMPTY;
130	nullredirs = 0;
131	sv = q;
132	}
133	n = redir;
134	do {
135	newfd = openredirect(n);
136	if (newfd < -1)
137	continue;
138
139	fd = n->nfile.fd;
140
141	if (sv) {
142	p = &sv->renamed[fd];
143	i = *p;
144
145	if (likely(i == EMPTY)) {
146	i = CLOSED;
147	if (fd != newfd) {
148	i = savefd(fd);
149	fd = -1;
150	}
151	}
152
153	if (i == newfd)
154	/* Can only happen if i == newfd == CLOSED */
155	i = REALLY_CLOSED;
156
157	*p = i;
158	}
159
160	if (fd == newfd)
161	continue;
162
163	#ifdef notyet
164	dupredirect(n, newfd, memory);
165	#else
166	dupredirect(n, newfd);
167	#endif
168	} while ((n = n->nfile.next));
169	INTON;
170	#ifdef notyet
171	if (memory[1])
172	out1 = &memout;
173	if (memory[2])
174	out2 = &memout;
175	#endif
176	if (flags & REDIR_SAVEFD2 && sv->renamed[2] >= 0)
177	preverrout.fd = sv->renamed[2];
178	}
179
180
181	STATIC int
182	openredirect(union node *redir)
183	{
184	char *fname;
185	int f;
186
187	switch (redir->nfile.type) {
188	case NFROM:
189	fname = redir->nfile.expfname;
190	if ((f = open64(fname, O_RDONLY)) < 0)
191	goto eopen;
192	break;
193	case NFROMTO:
194	fname = redir->nfile.expfname;
195	if ((f = open64(fname, O_RDWR\|O_CREAT\|O_TRUNC, 0666)) < 0)
196	goto ecreate;
197	break;
198	case NTO:
199	/* Take care of noclobber mode. */
200	if (Cflag) {
201	fname = redir->nfile.expfname;
202	if ((f = noclobberopen(fname)) < 0)
203	goto ecreate;
204	break;
205	}
206	/* FALLTHROUGH */
207	case NCLOBBER:
208	fname = redir->nfile.expfname;
209	if ((f = open64(fname, O_WRONLY\|O_CREAT\|O_TRUNC, 0666)) < 0)
210	goto ecreate;
211	break;
212	case NAPPEND:
213	fname = redir->nfile.expfname;
214	if ((f = open64(fname, O_WRONLY\|O_CREAT\|O_APPEND, 0666)) < 0)
215	goto ecreate;
216	break;
217	case NTOFD:
218	case NFROMFD:
219	f = redir->ndup.dupfd;
220	if (f == redir->nfile.fd)
221	f = -2;
222	break;
223	default:
224	#ifdef DEBUG
225	abort();
226	#endif
227	/* Fall through to eliminate warning. */
228	case NHERE:
229	case NXHERE:
230	f = openhere(redir);
231	break;
232	}
233
234	return f;
235	ecreate:
236	sh_error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
237	eopen:
238	sh_error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
239	}
240
241
242	STATIC void
243	#ifdef notyet
244	dupredirect(redir, f, memory)
245	#else
246	dupredirect(redir, f)
247	#endif
248	union node *redir;
249	int f;
250	#ifdef notyet
251	char memory[10];
252	#endif
253	{
254	int fd = redir->nfile.fd;
255	int err = 0;
256
257	#ifdef notyet
258	memory[fd] = 0;
259	#endif
260	if (redir->nfile.type == NTOFD \|\| redir->nfile.type == NFROMFD) {
261	/* if not ">&-" */
262	if (f >= 0) {
263	#ifdef notyet
264	if (memory[f])
265	memory[fd] = 1;
266	else
267	#endif
268	if (dup2(f, fd) < 0) {
269	err = errno;
270	goto err;
271	}
272	return;
273	}
274	f = fd;
275	} else if (dup2(f, fd) < 0)
276	err = errno;
277
278	close(f);
279	if (err < 0)
280	goto err;
281
282	return;
283
284	err:
285	sh_error("%d: %s", f, strerror(err));
286	}
287
288
289	/*
290	* Handle here documents. Normally we fork off a process to write the
291	* data to a pipe. If the document is short, we can stuff the data in
292	* the pipe without forking.
293	*/
294
295	STATIC int
296	openhere(union node *redir)
297	{
298	int pip[2];
299	size_t len = 0;
300
301	if (pipe(pip) < 0)
302	sh_error("Pipe call failed");
303	if (redir->type == NHERE) {
304	len = strlen(redir->nhere.doc->narg.text);
305	if (len <= PIPESIZE) {
306	xwrite(pip[1], redir->nhere.doc->narg.text, len);
307	goto out;
308	}
309	}
310	if (forkshell((struct job )NULL, (union node )NULL, FORK_NOJOB) == 0) {
311	close(pip[0]);
312	signal(SIGINT, SIG_IGN);
313	signal(SIGQUIT, SIG_IGN);
314	signal(SIGHUP, SIG_IGN);
315	#ifdef SIGTSTP
316	signal(SIGTSTP, SIG_IGN);
317	#endif
318	signal(SIGPIPE, SIG_DFL);
319	if (redir->type == NHERE)
320	xwrite(pip[1], redir->nhere.doc->narg.text, len);
321	else
322	expandhere(redir->nhere.doc, pip[1]);
323	_exit(0);
324	}
325	out:
326	close(pip[1]);
327	return pip[0];
328	}
329
330
331
332	/*
333	* Undo the effects of the last redirection.
334	*/
335
336	void
337	popredir(int drop)
338	{
339	struct redirtab *rp;
340	int i;
341
342	if (--nullredirs >= 0)
343	return;
344	INTOFF;
345	rp = redirlist;
346	for (i = 0 ; i < 10 ; i++) {
347	switch (rp->renamed[i]) {
348	case CLOSED:
349	if (!drop)
350	close(i);
351	break;
352	case EMPTY:
353	case REALLY_CLOSED:
354	break;
355	default:
356	if (!drop)
357	dup2(rp->renamed[i], i);
358	close(rp->renamed[i]);
359	break;
360	}
361	}
362	redirlist = rp->next;
363	nullredirs = rp->nullredirs;
364	ckfree(rp);
365	INTON;
366	}
367
368	/*
369	* Undo all redirections. Called on error or interrupt.
370	*/
371
372	#ifdef mkinit
373
374	INCLUDE "redir.h"
375
376	RESET {
377	/*
378	* Discard all saved file descriptors.
379	*/
380	for (;;) {
381	nullredirs = 0;
382	if (!redirlist)
383	break;
384	popredir(0);
385	}
386	}
387
388	#endif
389
390
391
392	/*
393	* Move a file descriptor to > 10. Invokes sh_error on error unless
394	* the original file dscriptor is not open.
395	*/
396
397	int
398	savefd(int from)
399	{
400	int newfd;
401	int err;
402
403	newfd = fcntl(from, F_DUPFD, 10);
404	err = newfd < 0 ? errno : 0;
405	if (err != EBADF) {
406	close(from);
407	if (err)
408	sh_error("%d: %s", from, strerror(err));
409	else
410	fcntl(newfd, F_SETFD, FD_CLOEXEC);
411	}
412
413	return newfd;
414	}
415
416
417	/*
418	* Open a file in noclobber mode.
419	* The code was copied from bash.
420	*/
421	int
422	noclobberopen(fname)
423	const char *fname;
424	{
425	int r, fd;
426	struct stat64 finfo, finfo2;
427
428	/*
429	* If the file exists and is a regular file, return an error
430	* immediately.
431	*/
432	r = stat64(fname, &finfo);
433	if (r == 0 && S_ISREG(finfo.st_mode)) {
434	errno = EEXIST;
435	return -1;
436	}
437
438	/*
439	* If the file was not present (r != 0), make sure we open it
440	* exclusively so that if it is created before we open it, our open
441	* will fail. Make sure that we do not truncate an existing file.
442	* Note that we don't turn on O_EXCL unless the stat failed -- if the
443	* file was not a regular file, we leave O_EXCL off.
444	*/
445	if (r != 0)
446	return open64(fname, O_WRONLY\|O_CREAT\|O_EXCL, 0666);
447	fd = open64(fname, O_WRONLY\|O_CREAT, 0666);
448
449	/* If the open failed, return the file descriptor right away. */
450	if (fd < 0)
451	return fd;
452
453	/*
454	* OK, the open succeeded, but the file may have been changed from a
455	* non-regular file to a regular file between the stat and the open.
456	* We are assuming that the O_EXCL open handles the case where FILENAME
457	* did not exist and is symlinked to an existing file between the stat
458	* and open.
459	*/
460
461	/*
462	* If we can open it and fstat the file descriptor, and neither check
463	* revealed that it was a regular file, and the file has not been
464	* replaced, return the file descriptor.
465	*/
466	if (fstat64(fd, &finfo2) == 0 && !S_ISREG(finfo2.st_mode) &&
467	finfo.st_dev == finfo2.st_dev && finfo.st_ino == finfo2.st_ino)
468	return fd;
469
470	/* The file has been replaced. badness. */
471	close(fd);
472	errno = EEXIST;
473	return -1;
474	}
475
476
477	int
478	redirectsafe(union node *redir, int flags)
479	{
480	int err;
481	volatile int saveint;
482	struct jmploc *volatile savehandler = handler;
483	struct jmploc jmploc;
484
485	SAVEINT(saveint);
486	if (!(err = setjmp(jmploc.loc) * 2)) {
487	handler = &jmploc;
488	redirect(redir, flags);
489	}
490	handler = savehandler;
491	if (err && exception != EXERROR)
492	longjmp(handler->loc, 1);
493	RESTOREINT(saveint);
494	return err;
495	}