1 /* $NetBSD: refill.c,v 1.4 1995/02/02 02:10:21 jtc 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)refill.c 8.1 (Berkeley) 6/4/93"; 42 #endif 43 static char rcsid[] = "$NetBSD: refill.c,v 1.4 1995/02/02 02:10:21 jtc Exp $"; 44 #endif /* LIBC_SCCS and not lint */ 45 46 #include <errno.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include "local.h" 50 51 static 52 lflush(fp) 53 FILE *fp; 54 { 55 56 if ((fp->_flags & (__SLBF|__SWR)) == __SLBF|__SWR) 57 return (__sflush(fp)); 58 return (0); 59 } 60 61 /* 62 * Refill a stdio buffer. 63 * Return EOF on eof or error, 0 otherwise. 64 */ 65 __srefill(fp) 66 register FILE *fp; 67 { 68 69 /* make sure stdio is set up */ 70 if (!__sdidinit) 71 __sinit(); 72 73 fp->_r = 0; /* largely a convenience for callers */ 74 75 /* SysV does not make this test; take it out for compatibility */ 76 if (fp->_flags & __SEOF) 77 return (EOF); 78 79 /* if not already reading, have to be reading and writing */ 80 if ((fp->_flags & __SRD) == 0) { 81 if ((fp->_flags & __SRW) == 0) { 82 errno = EBADF; 83 return (EOF); 84 } 85 /* switch to reading */ 86 if (fp->_flags & __SWR) { 87 if (__sflush(fp)) 88 return (EOF); 89 fp->_flags &= ~__SWR; 90 fp->_w = 0; 91 fp->_lbfsize = 0; 92 } 93 fp->_flags |= __SRD; 94 } else { 95 /* 96 * We were reading. If there is an ungetc buffer, 97 * we must have been reading from that. Drop it, 98 * restoring the previous buffer (if any). If there 99 * is anything in that buffer, return. 100 */ 101 if (HASUB(fp)) { 102 FREEUB(fp); 103 if ((fp->_r = fp->_ur) != 0) { 104 fp->_p = fp->_up; 105 return (0); 106 } 107 } 108 } 109 110 if (fp->_bf._base == NULL) 111 __smakebuf(fp); 112 113 /* 114 * Before reading from a line buffered or unbuffered file, 115 * flush all line buffered output files, per the ANSI C 116 * standard. 117 */ 118 if (fp->_flags & (__SLBF|__SNBF)) 119 (void) _fwalk(lflush); 120 fp->_p = fp->_bf._base; 121 fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size); 122 fp->_flags &= ~__SMOD; /* buffer contents are again pristine */ 123 if (fp->_r <= 0) { 124 if (fp->_r == 0) 125 fp->_flags |= __SEOF; 126 else { 127 fp->_r = 0; 128 fp->_flags |= __SERR; 129 } 130 return (EOF); 131 } 132 return (0); 133 } 134