GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libc/stdio/freopen.c Lines: 0 62 0.0 %
Date: 2017-11-13 Branches: 0 52 0.0 %

Line Branch Exec Source
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/*	$OpenBSD: freopen.c,v 1.16 2016/09/21 04:38:56 guenther Exp $ */
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/*-
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 * Copyright (c) 1990, 1993
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 *	The Regents of the University of California.  All rights reserved.
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 *
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 * This code is derived from software contributed to Berkeley by
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 * Chris Torek.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <limits.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "local.h"
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/*
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 * Re-direct an existing, open (probably) file to some other file.
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 * ANSI is written such that the original file gets closed if at
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 * all possible, no matter what.
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 */
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FILE *
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freopen(const char *file, const char *mode, FILE *fp)
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{
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	int f;
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	int flags, isopen, oflags, sverrno, wantfd;
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	if ((flags = __sflags(mode, &oflags)) == 0) {
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		(void) fclose(fp);
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		return (NULL);
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	}
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	if (!__sdidinit)
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		__sinit();
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	FLOCKFILE(fp);
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	/*
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	 * There are actually programs that depend on being able to "freopen"
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	 * descriptors that weren't originally open.  Keep this from breaking.
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	 * Remember whether the stream was open to begin with, and which file
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	 * descriptor (if any) was associated with it.  If it was attached to
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	 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
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	 * should work.  This is unnecessary if it was not a Unix file.
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	 */
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	if (fp->_flags == 0) {
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		fp->_flags = __SEOF;	/* hold on to it */
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		isopen = 0;
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		wantfd = -1;
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	} else {
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		/* flush the stream; ANSI doesn't require this. */
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		if (fp->_flags & __SWR)
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			(void) __sflush(fp);
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		/* if close is NULL, closing is a no-op, hence pointless */
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		isopen = fp->_close != NULL;
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		if ((wantfd = fp->_file) < 0 && isopen) {
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			(void) (*fp->_close)(fp->_cookie);
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			isopen = 0;
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		}
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	}
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	/* Get a new descriptor to refer to the new file. */
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	f = open(file, oflags, DEFFILEMODE);
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	if (f < 0 && isopen) {
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		/* If out of fd's close the old one and try again. */
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		if (errno == ENFILE || errno == EMFILE) {
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			(void) (*fp->_close)(fp->_cookie);
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			isopen = 0;
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			f = open(file, oflags, DEFFILEMODE);
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		}
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	}
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	sverrno = errno;
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	/*
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	 * Finish closing fp.  Even if the open succeeded above, we cannot
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	 * keep fp->_base: it may be the wrong size.  This loses the effect
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	 * of any setbuffer calls, but stdio has always done this before.
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	 */
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	if (isopen && f != wantfd)
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		(void) (*fp->_close)(fp->_cookie);
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	if (fp->_flags & __SMBF)
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		free((char *)fp->_bf._base);
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	fp->_w = 0;
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	fp->_r = 0;
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	fp->_p = NULL;
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	fp->_bf._base = NULL;
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	fp->_bf._size = 0;
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	fp->_lbfsize = 0;
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	if (HASUB(fp))
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		FREEUB(fp);
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	_UB(fp)._size = 0;
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	WCIO_FREE(fp);
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	if (HASLB(fp))
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		FREELB(fp);
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	fp->_lb._size = 0;
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	if (f < 0) {			/* did not get it after all */
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		fp->_flags = 0;		/* set it free */
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		FUNLOCKFILE(fp);
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		errno = sverrno;	/* restore in case _close clobbered */
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		return (NULL);
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	}
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	/*
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	 * If reopening something that was open before on a real file, try
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	 * to maintain the descriptor.  Various C library routines (perror)
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	 * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
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	 */
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	if (wantfd >= 0 && f != wantfd) {
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		if (dup3(f, wantfd, oflags & O_CLOEXEC) >= 0) {
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			(void) close(f);
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			f = wantfd;
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		}
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	}
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	/* _file is only a short */
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	if (f > SHRT_MAX) {
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		fp->_flags = 0;		/* set it free */
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		FUNLOCKFILE(fp);
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		errno = EMFILE;
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		return (NULL);
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	}
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	fp->_flags = flags;
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	fp->_file = f;
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	fp->_cookie = fp;
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	fp->_read = __sread;
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	fp->_write = __swrite;
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	fp->_seek = __sseek;
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	fp->_close = __sclose;
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	/*
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	 * When opening in append mode, even though we use O_APPEND,
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	 * we need to seek to the end so that ftell() gets the right
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	 * answer.  If the user then alters the seek pointer, or
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	 * the file extends, this will fail, but there is not much
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	 * we can do about this.  (We could set __SAPP and check in
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	 * fseek and ftell.)
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	 */
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	if (oflags & O_APPEND)
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		(void) __sseek(fp, 0, SEEK_END);
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	FUNLOCKFILE(fp);
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	return (fp);
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}
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DEF_STRONG(freopen);