/*- * SPDX-License-Identifier: BSD-3-Clause * * 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 "namespace.h" #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <errno.h> #include <limits.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include "un-namespace.h" #include "libc_private.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(const char * __restrict file, const char * __restrict mode, FILE * __restrict fp) { int f; int dflags, fdflags, flags, isopen, oflags, sverrno, wantfd; if ((flags = __sflags(mode, &oflags)) == 0) { sverrno = errno; (void) fclose(fp); errno = sverrno; return (NULL); } FLOCKFILE_CANCELSAFE(fp); if (!__sdidinit) __sinit(); /* * If the filename is a NULL pointer, the caller is asking us to * re-open the same file with a different mode. We allow this only * if the modes are compatible. */ if (file == NULL) { /* See comment below regarding freopen() of closed files. */ if (fp->_flags == 0) { errno = EINVAL; fp = NULL; goto end; } if ((dflags = _fcntl(fp->_file, F_GETFL)) < 0) { sverrno = errno; fclose(fp); errno = sverrno; fp = NULL; goto end; } /* Work around incorrect O_ACCMODE. */ if ((dflags & O_ACCMODE) != O_RDWR && (dflags & (O_ACCMODE | O_EXEC)) != (oflags & O_ACCMODE)) { fclose(fp); errno = EBADF; fp = NULL; goto end; } if (fp->_flags & __SWR) (void) __sflush(fp); if ((oflags ^ dflags) & O_APPEND) { dflags &= ~O_APPEND; dflags |= oflags & O_APPEND; if (_fcntl(fp->_file, F_SETFL, dflags) < 0) { sverrno = errno; fclose(fp); errno = sverrno; fp = NULL; goto end; } } if (oflags & O_TRUNC) (void) ftruncate(fp->_file, (off_t)0); if (!(oflags & O_APPEND)) (void) _sseek(fp, (fpos_t)0, SEEK_SET); if ((oflags & O_CLOEXEC) != 0) { fdflags = _fcntl(fp->_file, F_GETFD, 0); if (fdflags != -1 && (fdflags & FD_CLOEXEC) == 0) (void) _fcntl(fp->_file, F_SETFD, fdflags | FD_CLOEXEC); } f = fp->_file; isopen = 0; wantfd = -1; goto finish; } /* * 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 = fp->_close != NULL; if ((wantfd = fp->_file) < 0 && isopen) { (void) (*fp->_close)(fp->_cookie); isopen = 0; } } /* Get a new descriptor to refer to the new file. */ f = _open(file, oflags, DEFFILEMODE); /* If out of fd's close the old one and try again. */ if (f < 0 && isopen && wantfd > STDERR_FILENO && (errno == ENFILE || errno == EMFILE)) { (void) (*fp->_close)(fp->_cookie); isopen = 0; wantfd = -1; f = _open(file, oflags, DEFFILEMODE); } sverrno = errno; finish: /* * 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. * * Leave the existing file descriptor open until dup2() is called * below to avoid races where a concurrent open() in another thread * could claim the existing descriptor. */ 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; fp->_lbfsize = 0; if (HASUB(fp)) FREEUB(fp); fp->_ub._size = 0; if (HASLB(fp)) FREELB(fp); fp->_lb._size = 0; fp->_orientation = 0; memset(&fp->_mbstate, 0, sizeof(mbstate_t)); fp->_flags2 = 0; if (f < 0) { /* did not get it after all */ if (isopen) (void) (*fp->_close)(fp->_cookie); fp->_flags = 0; /* set it free */ errno = sverrno; /* restore in case _close clobbered */ fp = NULL; goto end; } /* * 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) { if ((oflags & O_CLOEXEC ? _fcntl(f, F_DUP2FD_CLOEXEC, wantfd) : _dup2(f, wantfd)) >= 0) { (void)_close(f); f = wantfd; } else (void)_close(fp->_file); } /* * File descriptors are a full int, but _file is only a short. * If we get a valid file descriptor that is greater than * SHRT_MAX, then the fd will get sign-extended into an * invalid file descriptor. Handle this case by failing the * open. */ if (f > SHRT_MAX) { fp->_flags = 0; /* set it free */ errno = EMFILE; fp = NULL; goto end; } fp->_flags = flags; fp->_file = f; fp->_cookie = fp; fp->_read = __sread; fp->_write = __swrite; fp->_seek = __sseek; fp->_close = __sclose; /* * When opening in append mode, even though we use O_APPEND, * we need to seek to the end so that ftell() gets the right * answer. If the user then alters the seek pointer, or * the file extends, this will fail, but there is not much * we can do about this. (We could set __SAPP and check in * fseek and ftell.) */ if (oflags & O_APPEND) { fp->_flags2 |= __S2OAP; (void) _sseek(fp, (fpos_t)0, SEEK_END); } end: FUNLOCKFILE_CANCELSAFE(); return (fp); }
