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 EMPTY -2		/* marks an unused slot in redirtab */
#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 (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 {
		fd = n->nfile.fd;
		if ((n->nfile.type == NTOFD || n->nfile.type == NFROMFD) &&
		    n->ndup.dupfd == fd)
			continue; /* redirect from/to same file descriptor */

		newfd = openredirect(n);
		if (fd == newfd)
			continue;
		if (sv && *(p = &sv->renamed[fd]) == EMPTY) {
			int i = fcntl(fd, F_DUPFD, 10);
			if (i == -1) {
				i = errno;
				if (i != EBADF) {
					const char *m = strerror(i);
					close(newfd);
					sh_error("%d: %s", fd, m);
					/* NOTREACHED */
				}
			} else {
				*p = i;
				close(fd);
			}
		} else {
			close(fd);
		}
#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 && 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;
	default:
#ifdef DEBUG
		abort();
#endif
		/* Fall through to eliminate warning. */
	case NTOFD:
	case NFROMFD:
		f = -1;
		break;
	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;

#ifdef notyet
	memory[fd] = 0;
#endif
	if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) {
		if (redir->ndup.dupfd >= 0) {	/* if not ">&-" */
#ifdef notyet
			if (memory[redir->ndup.dupfd])
				memory[fd] = 1;
			else
#endif
				copyfd(redir->ndup.dupfd, fd);
		}
		return;
	}

	if (f != fd) {
		copyfd(f, fd);
		close(f);
	}
	return;
}


/*
 * 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++) {
		if (rp->renamed[i] != EMPTY) {
			if (!drop) {
				close(i);
				copyfd(rp->renamed[i], i);
			}
			close(rp->renamed[i]);
		}
	}
	redirlist = rp->next;
	nullredirs = rp->nullredirs;
	ckfree(rp);
	INTON;
}

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

#ifdef mkinit

INCLUDE "redir.h"

RESET {
	clearredir(0);
}

#endif

/*
 * Discard all saved file descriptors.
 */

void
clearredir(int drop)
{
	for (;;) {
		nullredirs = 0;
		if (!redirlist)
			break;
		popredir(drop);
	}
}


/*
 * Copy a file descriptor to be >= to.  Returns -1
 * if the source file descriptor is closed, EMPTY if there are no unused
 * file descriptors left.
 */

int
copyfd(int from, int to)
{
	int newfd;

	newfd = fcntl(from, F_DUPFD, to);
	if (newfd < 0) {
		int errno2 = errno;
		if (errno2 == EMFILE)
			return EMPTY;
		else
			sh_error("%d: %s", from, strerror(errno2));
	}
	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 EMPTY -2 /* marks an unused slot in redirtab */
61	#ifndef PIPE_BUF
62	# define PIPESIZE 4096 /* amount of buffering in a pipe */
63	#else
64	# define PIPESIZE PIPE_BUF
65	#endif
66
67
68	MKINIT
69	struct redirtab {
70	struct redirtab *next;
71	int renamed[10];
72	int nullredirs;
73	};
74
75
76	MKINIT struct redirtab *redirlist;
77	MKINIT int nullredirs;
78
79	STATIC int openredirect(union node *);
80	#ifdef notyet
81	STATIC void dupredirect(union node *, int, char[10]);
82	#else
83	STATIC void dupredirect(union node *, int);
84	#endif
85	STATIC int openhere(union node *);
86	STATIC int noclobberopen(const char *);
87
88
89	/*
90	* Process a list of redirection commands. If the REDIR_PUSH flag is set,
91	* old file descriptors are stashed away so that the redirection can be
92	* undone by calling popredir. If the REDIR_BACKQ flag is set, then the
93	* standard output, and the standard error if it becomes a duplicate of
94	* stdout, is saved in memory.
95	*/
96
97	void
98	redirect(union node *redir, int flags)
99	{
100	union node *n;
101	struct redirtab *sv;
102	int i;
103	int fd;
104	int newfd;
105	int *p;
106	#if notyet
107	char memory[10]; /* file descriptors to write to memory */
108
109	for (i = 10 ; --i >= 0 ; )
110	memory[i] = 0;
111	memory[1] = flags & REDIR_BACKQ;
112	#endif
113	nullredirs++;
114	if (!redir) {
115	return;
116	}
117	sv = NULL;
118	INTOFF;
119	if (flags & REDIR_PUSH) {
120	struct redirtab *q;
121	q = ckmalloc(sizeof (struct redirtab));
122	q->next = redirlist;
123	redirlist = q;
124	q->nullredirs = nullredirs - 1;
125	for (i = 0 ; i < 10 ; i++)
126	q->renamed[i] = EMPTY;
127	nullredirs = 0;
128	sv = q;
129	}
130	n = redir;
131	do {
132	fd = n->nfile.fd;
133	if ((n->nfile.type == NTOFD \|\| n->nfile.type == NFROMFD) &&
134	n->ndup.dupfd == fd)
135	continue; /* redirect from/to same file descriptor */
136
137	newfd = openredirect(n);
138	if (fd == newfd)
139	continue;
140	if (sv && *(p = &sv->renamed[fd]) == EMPTY) {
141	int i = fcntl(fd, F_DUPFD, 10);
142	if (i == -1) {
143	i = errno;
144	if (i != EBADF) {
145	const char *m = strerror(i);
146	close(newfd);
147	sh_error("%d: %s", fd, m);
148	/* NOTREACHED */
149	}
150	} else {
151	*p = i;
152	close(fd);
153	}
154	} else {
155	close(fd);
156	}
157	#ifdef notyet
158	dupredirect(n, newfd, memory);
159	#else
160	dupredirect(n, newfd);
161	#endif
162	} while ((n = n->nfile.next));
163	INTON;
164	#ifdef notyet
165	if (memory[1])
166	out1 = &memout;
167	if (memory[2])
168	out2 = &memout;
169	#endif
170	if (flags & REDIR_SAVEFD2 && sv && sv->renamed[2] >= 0)
171	preverrout.fd = sv->renamed[2];
172	}
173
174
175	STATIC int
176	openredirect(union node *redir)
177	{
178	char *fname;
179	int f;
180
181	switch (redir->nfile.type) {
182	case NFROM:
183	fname = redir->nfile.expfname;
184	if ((f = open64(fname, O_RDONLY)) < 0)
185	goto eopen;
186	break;
187	case NFROMTO:
188	fname = redir->nfile.expfname;
189	if ((f = open64(fname, O_RDWR\|O_CREAT\|O_TRUNC, 0666)) < 0)
190	goto ecreate;
191	break;
192	case NTO:
193	/* Take care of noclobber mode. */
194	if (Cflag) {
195	fname = redir->nfile.expfname;
196	if ((f = noclobberopen(fname)) < 0)
197	goto ecreate;
198	break;
199	}
200	/* FALLTHROUGH */
201	case NCLOBBER:
202	fname = redir->nfile.expfname;
203	if ((f = open64(fname, O_WRONLY\|O_CREAT\|O_TRUNC, 0666)) < 0)
204	goto ecreate;
205	break;
206	case NAPPEND:
207	fname = redir->nfile.expfname;
208	if ((f = open64(fname, O_WRONLY\|O_CREAT\|O_APPEND, 0666)) < 0)
209	goto ecreate;
210	break;
211	default:
212	#ifdef DEBUG
213	abort();
214	#endif
215	/* Fall through to eliminate warning. */
216	case NTOFD:
217	case NFROMFD:
218	f = -1;
219	break;
220	case NHERE:
221	case NXHERE:
222	f = openhere(redir);
223	break;
224	}
225
226	return f;
227	ecreate:
228	sh_error("cannot create %s: %s", fname, errmsg(errno, E_CREAT));
229	eopen:
230	sh_error("cannot open %s: %s", fname, errmsg(errno, E_OPEN));
231	}
232
233
234	STATIC void
235	#ifdef notyet
236	dupredirect(redir, f, memory)
237	#else
238	dupredirect(redir, f)
239	#endif
240	union node *redir;
241	int f;
242	#ifdef notyet
243	char memory[10];
244	#endif
245	{
246	int fd = redir->nfile.fd;
247
248	#ifdef notyet
249	memory[fd] = 0;
250	#endif
251	if (redir->nfile.type == NTOFD \|\| redir->nfile.type == NFROMFD) {
252	if (redir->ndup.dupfd >= 0) { /* if not ">&-" */
253	#ifdef notyet
254	if (memory[redir->ndup.dupfd])
255	memory[fd] = 1;
256	else
257	#endif
258	copyfd(redir->ndup.dupfd, fd);
259	}
260	return;
261	}
262
263	if (f != fd) {
264	copyfd(f, fd);
265	close(f);
266	}
267	return;
268	}
269
270
271	/*
272	* Handle here documents. Normally we fork off a process to write the
273	* data to a pipe. If the document is short, we can stuff the data in
274	* the pipe without forking.
275	*/
276
277	STATIC int
278	openhere(union node *redir)
279	{
280	int pip[2];
281	size_t len = 0;
282
283	if (pipe(pip) < 0)
284	sh_error("Pipe call failed");
285	if (redir->type == NHERE) {
286	len = strlen(redir->nhere.doc->narg.text);
287	if (len <= PIPESIZE) {
288	xwrite(pip[1], redir->nhere.doc->narg.text, len);
289	goto out;
290	}
291	}
292	if (forkshell((struct job )NULL, (union node )NULL, FORK_NOJOB) == 0) {
293	close(pip[0]);
294	signal(SIGINT, SIG_IGN);
295	signal(SIGQUIT, SIG_IGN);
296	signal(SIGHUP, SIG_IGN);
297	#ifdef SIGTSTP
298	signal(SIGTSTP, SIG_IGN);
299	#endif
300	signal(SIGPIPE, SIG_DFL);
301	if (redir->type == NHERE)
302	xwrite(pip[1], redir->nhere.doc->narg.text, len);
303	else
304	expandhere(redir->nhere.doc, pip[1]);
305	_exit(0);
306	}
307	out:
308	close(pip[1]);
309	return pip[0];
310	}
311
312
313
314	/*
315	* Undo the effects of the last redirection.
316	*/
317
318	void
319	popredir(int drop)
320	{
321	struct redirtab *rp;
322	int i;
323
324	if (--nullredirs >= 0)
325	return;
326	INTOFF;
327	rp = redirlist;
328	for (i = 0 ; i < 10 ; i++) {
329	if (rp->renamed[i] != EMPTY) {
330	if (!drop) {
331	close(i);
332	copyfd(rp->renamed[i], i);
333	}
334	close(rp->renamed[i]);
335	}
336	}
337	redirlist = rp->next;
338	nullredirs = rp->nullredirs;
339	ckfree(rp);
340	INTON;
341	}
342
343	/*
344	* Undo all redirections. Called on error or interrupt.
345	*/
346
347	#ifdef mkinit
348
349	INCLUDE "redir.h"
350
351	RESET {
352	clearredir(0);
353	}
354
355	#endif
356
357	/*
358	* Discard all saved file descriptors.
359	*/
360
361	void
362	clearredir(int drop)
363	{
364	for (;;) {
365	nullredirs = 0;
366	if (!redirlist)
367	break;
368	popredir(drop);
369	}
370	}
371
372
373
374	/*
375	* Copy a file descriptor to be >= to. Returns -1
376	* if the source file descriptor is closed, EMPTY if there are no unused
377	* file descriptors left.
378	*/
379
380	int
381	copyfd(int from, int to)
382	{
383	int newfd;
384
385	newfd = fcntl(from, F_DUPFD, to);
386	if (newfd < 0) {
387	int errno2 = errno;
388	if (errno2 == EMFILE)
389	return EMPTY;
390	else
391	sh_error("%d: %s", from, strerror(errno2));
392	}
393	return newfd;
394	}
395
396
397	/*
398	* Open a file in noclobber mode.
399	* The code was copied from bash.
400	*/
401	int
402	noclobberopen(fname)
403	const char *fname;
404	{
405	int r, fd;
406	struct stat64 finfo, finfo2;
407
408	/*
409	* If the file exists and is a regular file, return an error
410	* immediately.
411	*/
412	r = stat64(fname, &finfo);
413	if (r == 0 && S_ISREG(finfo.st_mode)) {
414	errno = EEXIST;
415	return -1;
416	}
417
418	/*
419	* If the file was not present (r != 0), make sure we open it
420	* exclusively so that if it is created before we open it, our open
421	* will fail. Make sure that we do not truncate an existing file.
422	* Note that we don't turn on O_EXCL unless the stat failed -- if the
423	* file was not a regular file, we leave O_EXCL off.
424	*/
425	if (r != 0)
426	return open64(fname, O_WRONLY\|O_CREAT\|O_EXCL, 0666);
427	fd = open64(fname, O_WRONLY\|O_CREAT, 0666);
428
429	/* If the open failed, return the file descriptor right away. */
430	if (fd < 0)
431	return fd;
432
433	/*
434	* OK, the open succeeded, but the file may have been changed from a
435	* non-regular file to a regular file between the stat and the open.
436	* We are assuming that the O_EXCL open handles the case where FILENAME
437	* did not exist and is symlinked to an existing file between the stat
438	* and open.
439	*/
440
441	/*
442	* If we can open it and fstat the file descriptor, and neither check
443	* revealed that it was a regular file, and the file has not been
444	* replaced, return the file descriptor.
445	*/
446	if (fstat64(fd, &finfo2) == 0 && !S_ISREG(finfo2.st_mode) &&
447	finfo.st_dev == finfo2.st_dev && finfo.st_ino == finfo2.st_ino)
448	return fd;
449
450	/* The file has been replaced. badness. */
451	close(fd);
452	errno = EEXIST;
453	return -1;
454	}
455
456
457	int
458	redirectsafe(union node *redir, int flags)
459	{
460	int err;
461	volatile int saveint;
462	struct jmploc *volatile savehandler = handler;
463	struct jmploc jmploc;
464
465	SAVEINT(saveint);
466	if (!(err = setjmp(jmploc.loc) * 2)) {
467	handler = &jmploc;
468	redirect(redir, flags);
469	}
470	handler = savehandler;
471	if (err && exception != EXERROR)
472	longjmp(handler->loc, 1);
473	RESTOREINT(saveint);
474	return err;
475	}