1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)freopen.c 8.1 (Berkeley) 6/4/93"; 39 #endif /* LIBC_SCCS and not lint */ 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "namespace.h" 44 #include <sys/types.h> 45 #include <sys/stat.h> 46 #include <fcntl.h> 47 #include <errno.h> 48 #include <unistd.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include "un-namespace.h" 52 #include "libc_private.h" 53 #include "local.h" 54 55 /* 56 * Re-direct an existing, open (probably) file to some other file. 57 * ANSI is written such that the original file gets closed if at 58 * all possible, no matter what. 59 */ 60 FILE * 61 freopen(file, mode, fp) 62 const char * __restrict file; 63 const char * __restrict mode; 64 FILE *fp; 65 { 66 int f; 67 int flags, isopen, oflags, sverrno, wantfd; 68 69 if ((flags = __sflags(mode, &oflags)) == 0) { 70 (void) fclose(fp); 71 return (NULL); 72 } 73 74 FLOCKFILE(fp); 75 76 if (!__sdidinit) 77 __sinit(); 78 79 /* 80 * There are actually programs that depend on being able to "freopen" 81 * descriptors that weren't originally open. Keep this from breaking. 82 * Remember whether the stream was open to begin with, and which file 83 * descriptor (if any) was associated with it. If it was attached to 84 * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin) 85 * should work. This is unnecessary if it was not a Unix file. 86 */ 87 if (fp->_flags == 0) { 88 fp->_flags = __SEOF; /* hold on to it */ 89 isopen = 0; 90 wantfd = -1; 91 } else { 92 /* flush the stream; ANSI doesn't require this. */ 93 if (fp->_flags & __SWR) 94 (void) __sflush(fp); 95 /* if close is NULL, closing is a no-op, hence pointless */ 96 isopen = fp->_close != NULL; 97 if ((wantfd = fp->_file) < 0 && isopen) { 98 (void) (*fp->_close)(fp->_cookie); 99 isopen = 0; 100 } 101 } 102 103 /* Get a new descriptor to refer to the new file. */ 104 f = _open(file, oflags, DEFFILEMODE); 105 if (f < 0 && isopen) { 106 /* If out of fd's close the old one and try again. */ 107 if (errno == ENFILE || errno == EMFILE) { 108 (void) (*fp->_close)(fp->_cookie); 109 isopen = 0; 110 f = _open(file, oflags, DEFFILEMODE); 111 } 112 } 113 sverrno = errno; 114 115 /* 116 * Finish closing fp. Even if the open succeeded above, we cannot 117 * keep fp->_base: it may be the wrong size. This loses the effect 118 * of any setbuffer calls, but stdio has always done this before. 119 */ 120 if (isopen) 121 (void) (*fp->_close)(fp->_cookie); 122 if (fp->_flags & __SMBF) 123 free((char *)fp->_bf._base); 124 fp->_w = 0; 125 fp->_r = 0; 126 fp->_p = NULL; 127 fp->_bf._base = NULL; 128 fp->_bf._size = 0; 129 fp->_lbfsize = 0; 130 if (HASUB(fp)) 131 FREEUB(fp); 132 fp->_ub._size = 0; 133 if (HASLB(fp)) 134 FREELB(fp); 135 fp->_lb._size = 0; 136 137 if (f < 0) { /* did not get it after all */ 138 fp->_flags = 0; /* set it free */ 139 errno = sverrno; /* restore in case _close clobbered */ 140 FUNLOCKFILE(fp); 141 return (NULL); 142 } 143 144 /* 145 * If reopening something that was open before on a real file, try 146 * to maintain the descriptor. Various C library routines (perror) 147 * assume stderr is always fd STDERR_FILENO, even if being freopen'd. 148 */ 149 if (wantfd >= 0 && f != wantfd) { 150 if (_dup2(f, wantfd) >= 0) { 151 (void)_close(f); 152 f = wantfd; 153 } 154 } 155 156 fp->_flags = flags; 157 fp->_file = f; 158 fp->_cookie = fp; 159 fp->_read = __sread; 160 fp->_write = __swrite; 161 fp->_seek = __sseek; 162 fp->_close = __sclose; 163 FUNLOCKFILE(fp); 164 return (fp); 165 } 166