1*f14fb602SLionel Sambuc /* $NetBSD: freopen.c,v 1.19 2012/03/27 15:05:42 christos Exp $ */
2b7061124SArun Thomas
32fe8fb19SBen Gras /*-
42fe8fb19SBen Gras * Copyright (c) 1990, 1993
52fe8fb19SBen Gras * The Regents of the University of California. All rights reserved.
62fe8fb19SBen Gras *
72fe8fb19SBen Gras * This code is derived from software contributed to Berkeley by
82fe8fb19SBen Gras * Chris Torek.
92fe8fb19SBen Gras *
102fe8fb19SBen Gras * Redistribution and use in source and binary forms, with or without
112fe8fb19SBen Gras * modification, are permitted provided that the following conditions
122fe8fb19SBen Gras * are met:
132fe8fb19SBen Gras * 1. Redistributions of source code must retain the above copyright
142fe8fb19SBen Gras * notice, this list of conditions and the following disclaimer.
152fe8fb19SBen Gras * 2. Redistributions in binary form must reproduce the above copyright
162fe8fb19SBen Gras * notice, this list of conditions and the following disclaimer in the
172fe8fb19SBen Gras * documentation and/or other materials provided with the distribution.
182fe8fb19SBen Gras * 3. Neither the name of the University nor the names of its contributors
192fe8fb19SBen Gras * may be used to endorse or promote products derived from this software
202fe8fb19SBen Gras * without specific prior written permission.
212fe8fb19SBen Gras *
222fe8fb19SBen Gras * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
232fe8fb19SBen Gras * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
242fe8fb19SBen Gras * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
252fe8fb19SBen Gras * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
262fe8fb19SBen Gras * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
272fe8fb19SBen Gras * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
282fe8fb19SBen Gras * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
292fe8fb19SBen Gras * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
302fe8fb19SBen Gras * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
312fe8fb19SBen Gras * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
322fe8fb19SBen Gras * SUCH DAMAGE.
332fe8fb19SBen Gras */
342fe8fb19SBen Gras
352fe8fb19SBen Gras #include <sys/cdefs.h>
362fe8fb19SBen Gras #if defined(LIBC_SCCS) && !defined(lint)
372fe8fb19SBen Gras #if 0
382fe8fb19SBen Gras static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93";
392fe8fb19SBen Gras #else
40*f14fb602SLionel Sambuc __RCSID("$NetBSD: freopen.c,v 1.19 2012/03/27 15:05:42 christos Exp $");
41b7061124SArun Thomas #endif
422fe8fb19SBen Gras #endif /* LIBC_SCCS and not lint */
432fe8fb19SBen Gras
442fe8fb19SBen Gras #include <sys/types.h>
45b7061124SArun Thomas #include <sys/stat.h>
46b7061124SArun Thomas
472fe8fb19SBen Gras #include <assert.h>
482fe8fb19SBen Gras #include <errno.h>
492fe8fb19SBen Gras #include <fcntl.h>
502fe8fb19SBen Gras #include <unistd.h>
512fe8fb19SBen Gras #include <stdio.h>
522fe8fb19SBen Gras #include <stdlib.h>
532fe8fb19SBen Gras #include <wchar.h>
542fe8fb19SBen Gras #include <limits.h>
552fe8fb19SBen Gras #include "reentrant.h"
562fe8fb19SBen Gras #include "local.h"
57b7061124SArun Thomas
582fe8fb19SBen Gras /*
592fe8fb19SBen Gras * Re-direct an existing, open (probably) file to some other file.
602fe8fb19SBen Gras * ANSI is written such that the original file gets closed if at
612fe8fb19SBen Gras * all possible, no matter what.
62b7061124SArun Thomas */
63b7061124SArun Thomas FILE *
freopen(const char * file,const char * mode,FILE * fp)64*f14fb602SLionel Sambuc freopen(const char *file, const char *mode, FILE *fp)
65b7061124SArun Thomas {
662fe8fb19SBen Gras int f;
672fe8fb19SBen Gras int flags, isopen, oflags, sverrno, wantfd;
68b7061124SArun Thomas
692fe8fb19SBen Gras _DIAGASSERT(file != NULL);
702fe8fb19SBen Gras _DIAGASSERT(mode != NULL);
712fe8fb19SBen Gras _DIAGASSERT(fp != NULL);
72b7061124SArun Thomas
732fe8fb19SBen Gras if ((flags = __sflags(mode, &oflags)) == 0) {
742fe8fb19SBen Gras (void) fclose(fp);
75*f14fb602SLionel Sambuc return NULL;
7651d9144eSBen Gras }
7751d9144eSBen Gras
782fe8fb19SBen Gras if (!__sdidinit)
792fe8fb19SBen Gras __sinit();
8051d9144eSBen Gras
812fe8fb19SBen Gras /*
822fe8fb19SBen Gras * There are actually programs that depend on being able to "freopen"
832fe8fb19SBen Gras * descriptors that weren't originally open. Keep this from breaking.
842fe8fb19SBen Gras * Remember whether the stream was open to begin with, and which file
852fe8fb19SBen Gras * descriptor (if any) was associated with it. If it was attached to
862fe8fb19SBen Gras * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
872fe8fb19SBen Gras * should work. This is unnecessary if it was not a Unix file.
882fe8fb19SBen Gras */
892fe8fb19SBen Gras if (fp->_flags == 0) {
902fe8fb19SBen Gras fp->_flags = __SEOF; /* hold on to it */
912fe8fb19SBen Gras isopen = 0;
922fe8fb19SBen Gras wantfd = -1;
93b7061124SArun Thomas } else {
942fe8fb19SBen Gras /* flush the stream; ANSI doesn't require this. */
952fe8fb19SBen Gras if (fp->_flags & __SWR)
962fe8fb19SBen Gras (void)__sflush(fp);
972fe8fb19SBen Gras /* if close is NULL, closing is a no-op, hence pointless */
982fe8fb19SBen Gras isopen = fp->_close != NULL;
992fe8fb19SBen Gras if ((wantfd = __sfileno(fp)) == -1 && isopen) {
1002fe8fb19SBen Gras (void) (*fp->_close)(fp->_cookie);
1012fe8fb19SBen Gras isopen = 0;
1022fe8fb19SBen Gras }
103b7061124SArun Thomas }
104b7061124SArun Thomas
1052fe8fb19SBen Gras /* Get a new descriptor to refer to the new file. */
1062fe8fb19SBen Gras f = open(file, oflags, DEFFILEMODE);
1072fe8fb19SBen Gras if (f < 0 && isopen) {
1082fe8fb19SBen Gras /* If out of fd's close the old one and try again. */
1092fe8fb19SBen Gras if (errno == ENFILE || errno == EMFILE) {
1102fe8fb19SBen Gras (void) (*fp->_close)(fp->_cookie);
1112fe8fb19SBen Gras isopen = 0;
1122fe8fb19SBen Gras f = open(file, oflags, DEFFILEMODE);
1132fe8fb19SBen Gras }
1142fe8fb19SBen Gras }
1152fe8fb19SBen Gras sverrno = errno;
116b7061124SArun Thomas
1172fe8fb19SBen Gras /*
1182fe8fb19SBen Gras * Finish closing fp. Even if the open succeeded above, we cannot
1192fe8fb19SBen Gras * keep fp->_base: it may be the wrong size. This loses the effect
1202fe8fb19SBen Gras * of any setbuffer calls, but stdio has always done this before.
1212fe8fb19SBen Gras */
1222fe8fb19SBen Gras if (isopen && f != wantfd)
1232fe8fb19SBen Gras (void) (*fp->_close)(fp->_cookie);
1242fe8fb19SBen Gras if (fp->_flags & __SMBF)
1252fe8fb19SBen Gras free((char *)fp->_bf._base);
1262fe8fb19SBen Gras fp->_w = 0;
1272fe8fb19SBen Gras fp->_r = 0;
1282fe8fb19SBen Gras fp->_p = NULL;
1292fe8fb19SBen Gras fp->_bf._base = NULL;
1302fe8fb19SBen Gras fp->_bf._size = 0;
1312fe8fb19SBen Gras fp->_lbfsize = 0;
1322fe8fb19SBen Gras if (HASUB(fp))
1332fe8fb19SBen Gras FREEUB(fp);
1342fe8fb19SBen Gras WCIO_FREE(fp);
1352fe8fb19SBen Gras _UB(fp)._size = 0;
1362fe8fb19SBen Gras FREELB(fp);
1372fe8fb19SBen Gras
1382fe8fb19SBen Gras if (f < 0) { /* did not get it after all */
1392fe8fb19SBen Gras fp->_flags = 0; /* set it free */
1402fe8fb19SBen Gras errno = sverrno; /* restore in case _close clobbered */
141*f14fb602SLionel Sambuc return NULL;
1422fe8fb19SBen Gras }
1432fe8fb19SBen Gras
1442fe8fb19SBen Gras if (oflags & O_NONBLOCK) {
1452fe8fb19SBen Gras struct stat st;
1462fe8fb19SBen Gras if (fstat(f, &st) == -1) {
1472fe8fb19SBen Gras sverrno = errno;
1482fe8fb19SBen Gras (void)close(f);
1492fe8fb19SBen Gras errno = sverrno;
150*f14fb602SLionel Sambuc return NULL;
1512fe8fb19SBen Gras }
1522fe8fb19SBen Gras if (!S_ISREG(st.st_mode)) {
1532fe8fb19SBen Gras (void)close(f);
1542fe8fb19SBen Gras errno = EFTYPE;
155*f14fb602SLionel Sambuc return NULL;
1562fe8fb19SBen Gras }
1572fe8fb19SBen Gras }
1582fe8fb19SBen Gras
1592fe8fb19SBen Gras /*
1602fe8fb19SBen Gras * If reopening something that was open before on a real file, try
1612fe8fb19SBen Gras * to maintain the descriptor. Various C library routines (perror)
1622fe8fb19SBen Gras * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
1632fe8fb19SBen Gras */
1642fe8fb19SBen Gras if (wantfd >= 0 && f != wantfd) {
1652fe8fb19SBen Gras if (dup2(f, wantfd) >= 0) {
1662fe8fb19SBen Gras (void) close(f);
1672fe8fb19SBen Gras f = wantfd;
1682fe8fb19SBen Gras }
1692fe8fb19SBen Gras }
1702fe8fb19SBen Gras
1712fe8fb19SBen Gras /*
1722fe8fb19SBen Gras * File descriptors are a full int, but _file is only a short.
1732fe8fb19SBen Gras * If we get a valid file descriptor that is greater or equal to
1742fe8fb19SBen Gras * USHRT_MAX, then the fd will get sign-extended into an
1752fe8fb19SBen Gras * invalid file descriptor. Handle this case by failing the
1762fe8fb19SBen Gras * open. (We treat the short as unsigned, and special-case -1).
1772fe8fb19SBen Gras */
1782fe8fb19SBen Gras if (f >= USHRT_MAX) {
1792fe8fb19SBen Gras (void)close(f);
1802fe8fb19SBen Gras errno = EMFILE;
1812fe8fb19SBen Gras return NULL;
1822fe8fb19SBen Gras }
1832fe8fb19SBen Gras
1842fe8fb19SBen Gras fp->_flags = flags;
1852fe8fb19SBen Gras fp->_file = f;
1862fe8fb19SBen Gras fp->_cookie = fp;
1872fe8fb19SBen Gras fp->_read = __sread;
1882fe8fb19SBen Gras fp->_write = __swrite;
1892fe8fb19SBen Gras fp->_seek = __sseek;
1902fe8fb19SBen Gras fp->_close = __sclose;
1912fe8fb19SBen Gras
1922fe8fb19SBen Gras /*
1932fe8fb19SBen Gras * When reopening in append mode, even though we use O_APPEND,
1942fe8fb19SBen Gras * we need to seek to the end so that ftell() gets the right
1952fe8fb19SBen Gras * answer. If the user then alters the seek pointer, or
1962fe8fb19SBen Gras * the file extends, this will fail, but there is not much
1972fe8fb19SBen Gras * we can do about this. (We could set __SAPP and check in
1982fe8fb19SBen Gras * fseek and ftell.)
1992fe8fb19SBen Gras */
2002fe8fb19SBen Gras if (oflags & O_APPEND)
201*f14fb602SLionel Sambuc (void) __sseek((void *)fp, (off_t)0, SEEK_END);
202*f14fb602SLionel Sambuc return fp;
203b7061124SArun Thomas }
204