Colony » Colony Scout » Colony Scout OS

/*-

 * Copyright (c) 1990, 1993

 *        The Regents of the University of California.  All rights reserved.

 *

 * This code is derived from software contributed to Berkeley by

 * Chris Torek.

 *

 * 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/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <errno.h>

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include "local.h"

/*

 * Re-direct an existing, open (probably) file to some other file.

 * ANSI is written such that the original file gets closed if at

 * all possible, no matter what.

 */

FILE *

freopen(file, mode, fp)

        const char *file, *mode;

        FILE *fp;

{

        int f;

        int flags, isopen, oflags, sverrno, wantfd;

        if ((flags = __sflags(mode, &oflags)) == 0) {

                (void) fclose(fp);

                return (NULL);

        }

        if (!__sdidinit)

                __sinit();

        /*

         * There are actually programs that depend on being able to "freopen"

         * descriptors that weren't originally open.  Keep this from breaking.

         * Remember whether the stream was open to begin with, and which file

         * descriptor (if any) was associated with it.  If it was attached to

         * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)

         * should work.  This is unnecessary if it was not a Unix file.

         */

        if (fp->_flags == 0) {

                fp->_flags = __SEOF;        /* hold on to it */

                isopen = 0;

                wantfd = -1;

        } else {

                /* flush the stream; ANSI doesn't require this. */

                if (fp->_flags & __SWR)

                        (void) __sflush(fp);

                /* if close is NULL, closing is a no-op, hence pointless */

                isopen = 1;

                if ((wantfd = fp->_file) < 0 && isopen) {

                        (void) __sclose(fp);

                        isopen = 0;

                }

        }

        /* Get a new descriptor to refer to the new file. */

        f = open(file, oflags, DEFFILEMODE);

        if (f < 0 && isopen) {

                /* If out of fd's close the old one and try again. */

                if (errno == ENFILE || errno == EMFILE) {

                        (void) __sclose(fp);

                        isopen = 0;

                        f = open(file, oflags, DEFFILEMODE);

                }

        }

        sverrno = errno;

        /*

         * Finish closing fp.  Even if the open succeeded above, we cannot

         * keep fp->_base: it may be the wrong size.  This loses the effect

         * of any setbuffer calls, but stdio has always done this before.

         */

        if (isopen)

                (void) __sclose(fp);

        if (fp->_flags & __SMBF)

                free((char *)fp->_bf._base);

        fp->_w = 0;

        fp->_r = 0;

        fp->_p = NULL;

        fp->_bf._base = NULL;

        fp->_bf._size = 0;

        if (HASUB(fp))

                FREEUB(fp);

        fp->_ub._size = 0;

        if (f < 0) {                        /* did not get it after all */

                fp->_flags = 0;                /* set it free */

                errno = sverrno;        /* restore in case _close clobbered */

                return (NULL);

        }

        /*

         * If reopening something that was open before on a real file, try

         * to maintain the descriptor.  Various C library routines (perror)

         * assume stderr is always fd STDERR_FILENO, even if being freopen'd.

         */

        if (wantfd >= 0 && f != wantfd) {

                if (dup2(f, wantfd) >= 0) {

                        (void) close(f);

                        f = wantfd;

                }

        }

        fp->_flags = flags;

        fp->_file = f;

        return (fp);

}