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	niro	532	/*-
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			}