Annotation of prex-old/usr/lib/libc/stdio/freopen.c, Revision 1.1
1.1 ! nbrk 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. Neither the name of the University nor the names of its contributors
! 17: * may be used to endorse or promote products derived from this software
! 18: * without specific prior written permission.
! 19: *
! 20: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 21: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 22: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 23: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 24: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 25: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 26: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 27: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 28: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 29: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 30: * SUCH DAMAGE.
! 31: */
! 32:
! 33: #include <sys/types.h>
! 34: #include <sys/stat.h>
! 35: #include <fcntl.h>
! 36: #include <errno.h>
! 37: #include <unistd.h>
! 38: #include <stdio.h>
! 39: #include <stdlib.h>
! 40: #include "local.h"
! 41:
! 42: /*
! 43: * Re-direct an existing, open (probably) file to some other file.
! 44: * ANSI is written such that the original file gets closed if at
! 45: * all possible, no matter what.
! 46: */
! 47: FILE *
! 48: freopen(file, mode, fp)
! 49: const char *file, *mode;
! 50: FILE *fp;
! 51: {
! 52: int f;
! 53: int flags, isopen, oflags, sverrno, wantfd;
! 54:
! 55: if ((flags = __sflags(mode, &oflags)) == 0) {
! 56: (void) fclose(fp);
! 57: return (NULL);
! 58: }
! 59:
! 60: if (!__sdidinit)
! 61: __sinit();
! 62:
! 63: /*
! 64: * There are actually programs that depend on being able to "freopen"
! 65: * descriptors that weren't originally open. Keep this from breaking.
! 66: * Remember whether the stream was open to begin with, and which file
! 67: * descriptor (if any) was associated with it. If it was attached to
! 68: * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
! 69: * should work. This is unnecessary if it was not a Unix file.
! 70: */
! 71: if (fp->_flags == 0) {
! 72: fp->_flags = __SEOF; /* hold on to it */
! 73: isopen = 0;
! 74: wantfd = -1;
! 75: } else {
! 76: /* flush the stream; ANSI doesn't require this. */
! 77: if (fp->_flags & __SWR)
! 78: (void) __sflush(fp);
! 79: /* if close is NULL, closing is a no-op, hence pointless */
! 80: isopen = 1;
! 81: if ((wantfd = fp->_file) < 0 && isopen) {
! 82: (void) __sclose(fp);
! 83: isopen = 0;
! 84: }
! 85: }
! 86:
! 87: /* Get a new descriptor to refer to the new file. */
! 88: f = open(file, oflags, DEFFILEMODE);
! 89: if (f < 0 && isopen) {
! 90: /* If out of fd's close the old one and try again. */
! 91: if (errno == ENFILE || errno == EMFILE) {
! 92: (void) __sclose(fp);
! 93: isopen = 0;
! 94: f = open(file, oflags, DEFFILEMODE);
! 95: }
! 96: }
! 97: sverrno = errno;
! 98:
! 99: /*
! 100: * Finish closing fp. Even if the open succeeded above, we cannot
! 101: * keep fp->_base: it may be the wrong size. This loses the effect
! 102: * of any setbuffer calls, but stdio has always done this before.
! 103: */
! 104: if (isopen)
! 105: (void) __sclose(fp);
! 106: if (fp->_flags & __SMBF)
! 107: free((char *)fp->_bf._base);
! 108: fp->_w = 0;
! 109: fp->_r = 0;
! 110: fp->_p = NULL;
! 111: fp->_bf._base = NULL;
! 112: fp->_bf._size = 0;
! 113: if (HASUB(fp))
! 114: FREEUB(fp);
! 115: fp->_ub._size = 0;
! 116:
! 117: if (f < 0) { /* did not get it after all */
! 118: fp->_flags = 0; /* set it free */
! 119: errno = sverrno; /* restore in case _close clobbered */
! 120: return (NULL);
! 121: }
! 122:
! 123: /*
! 124: * If reopening something that was open before on a real file, try
! 125: * to maintain the descriptor. Various C library routines (perror)
! 126: * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
! 127: */
! 128: if (wantfd >= 0 && f != wantfd) {
! 129: if (dup2(f, wantfd) >= 0) {
! 130: (void) close(f);
! 131: f = wantfd;
! 132: }
! 133: }
! 134:
! 135: fp->_flags = flags;
! 136: fp->_file = f;
! 137: return (fp);
! 138: }
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