1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)refill.c 8.1 (Berkeley) 6/4/93"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 #include "namespace.h" 40 #include <errno.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include "un-namespace.h" 44 45 #include "libc_private.h" 46 #include "local.h" 47 48 static int lflush(FILE *); 49 50 static int 51 lflush(FILE *fp) 52 { 53 int ret = 0; 54 55 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) { 56 FLOCKFILE_CANCELSAFE(fp); 57 ret = __sflush(fp); 58 FUNLOCKFILE_CANCELSAFE(); 59 } 60 return (ret); 61 } 62 63 /* 64 * Refill a stdio buffer. 65 * Return EOF on eof or error, 0 otherwise. 66 */ 67 int 68 __srefill(FILE *fp) 69 { 70 71 /* make sure stdio is set up */ 72 if (!__sdidinit) 73 __sinit(); 74 75 ORIENT(fp, -1); 76 77 fp->_r = 0; /* largely a convenience for callers */ 78 79 /* SysV does not make this test; take it out for compatibility */ 80 if (fp->_flags & __SEOF) 81 return (EOF); 82 83 /* if not already reading, have to be reading and writing */ 84 if ((fp->_flags & __SRD) == 0) { 85 if ((fp->_flags & __SRW) == 0) { 86 errno = EBADF; 87 fp->_flags |= __SERR; 88 return (EOF); 89 } 90 /* switch to reading */ 91 if (fp->_flags & __SWR) { 92 if (__sflush(fp)) 93 return (EOF); 94 fp->_flags &= ~__SWR; 95 fp->_w = 0; 96 fp->_lbfsize = 0; 97 } 98 fp->_flags |= __SRD; 99 } else { 100 /* 101 * We were reading. If there is an ungetc buffer, 102 * we must have been reading from that. Drop it, 103 * restoring the previous buffer (if any). If there 104 * is anything in that buffer, return. 105 */ 106 if (HASUB(fp)) { 107 FREEUB(fp); 108 if ((fp->_r = fp->_ur) != 0) { 109 fp->_p = fp->_up; 110 return (0); 111 } 112 } 113 } 114 115 if (fp->_bf._base == NULL) 116 __smakebuf(fp); 117 118 /* 119 * Before reading from a line buffered or unbuffered file, 120 * flush all line buffered output files, per the ANSI C 121 * standard. 122 */ 123 if (fp->_flags & (__SLBF|__SNBF)) { 124 /* Ignore this file in _fwalk to avoid potential deadlock. */ 125 fp->_flags |= __SIGN; 126 (void) _fwalk(lflush); 127 fp->_flags &= ~__SIGN; 128 129 /* Now flush this file without locking it. */ 130 if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR)) 131 __sflush(fp); 132 } 133 fp->_p = fp->_bf._base; 134 fp->_r = _sread(fp, (char *)fp->_p, fp->_bf._size); 135 fp->_flags &= ~__SMOD; /* buffer contents are again pristine */ 136 if (fp->_r <= 0) { 137 if (fp->_r == 0) 138 fp->_flags |= __SEOF; 139 else { 140 fp->_r = 0; 141 fp->_flags |= __SERR; 142 } 143 return (EOF); 144 } 145 return (0); 146 } 147