1/* $NetBSD: refill.c,v 1.15 2012/03/15 18:22:30 christos Exp $ */ 2 3/*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35#include <sys/cdefs.h> 36#if defined(LIBC_SCCS) && !defined(lint) 37#if 0 38static char sccsid[] = "@(#)refill.c 8.1 (Berkeley) 6/4/93"; 39#else 40__RCSID("$NetBSD: refill.c,v 1.15 2012/03/15 18:22:30 christos Exp $"); 41#endif 42#endif /* LIBC_SCCS and not lint */ 43 44#include <assert.h> 45#include <errno.h> 46#include <stdio.h> 47#include <stdlib.h> 48#include "reentrant.h" 49#include "local.h" 50 51#ifdef _REENTRANT 52extern rwlock_t __sfp_lock; 53#endif 54 55static int 56lflush(FILE *fp) 57{ 58 59 _DIAGASSERT(fp != NULL); 60 61 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) 62 return __sflush(fp); 63 return 0; 64} 65 66/* 67 * Refill a stdio buffer. 68 * Return EOF on eof or error, 0 otherwise. 69 */ 70int 71__srefill(FILE *fp) 72{ 73 74 _DIAGASSERT(fp != NULL); 75 76 /* make sure stdio is set up */ 77 if (!__sdidinit) 78 __sinit(); 79 80 fp->_r = 0; /* largely a convenience for callers */ 81 82 /* SysV does not make this test; take it out for compatibility */ 83 if (fp->_flags & __SEOF) 84 return EOF; 85 86 /* if not already reading, have to be reading and writing */ 87 if ((fp->_flags & __SRD) == 0) { 88 if ((fp->_flags & __SRW) == 0) { 89 errno = EBADF; 90 fp->_flags |= __SERR; 91 return EOF; 92 } 93 /* switch to reading */ 94 if (fp->_flags & __SWR) { 95 if (__sflush(fp)) 96 return EOF; 97 fp->_flags &= ~__SWR; 98 fp->_w = 0; 99 fp->_lbfsize = 0; 100 } 101 fp->_flags |= __SRD; 102 } else { 103 /* 104 * We were reading. If there is an ungetc buffer, 105 * we must have been reading from that. Drop it, 106 * restoring the previous buffer (if any). If there 107 * is anything in that buffer, return. 108 */ 109 if (HASUB(fp)) { 110 FREEUB(fp); 111 if ((fp->_r = fp->_ur) != 0) { 112 fp->_p = fp->_up; 113 return 0; 114 } 115 } 116 } 117 118 if (fp->_bf._base == NULL) 119 __smakebuf(fp); 120 121 /* 122 * Before reading from a line buffered or unbuffered file, 123 * flush all line buffered output files, per the ANSI C 124 * standard. 125 */ 126 if (fp->_flags & (__SLBF|__SNBF)) { 127 rwlock_rdlock(&__sfp_lock); 128 (void) _fwalk(lflush); 129 rwlock_unlock(&__sfp_lock); 130 } 131 fp->_p = fp->_bf._base; 132 fp->_r = (int)(*fp->_read)(fp->_cookie, (char *)fp->_p, 133 (size_t)fp->_bf._size); 134 fp->_flags &= ~__SMOD; /* buffer contents are again pristine */ 135 if (fp->_r <= 0) { 136 if (fp->_r == 0) 137 fp->_flags |= __SEOF; 138 else { 139 fp->_r = 0; 140 fp->_flags |= __SERR; 141 } 142 return EOF; 143 } 144 return 0; 145} 146