setvbuf.c revision 1.11
1 /* $NetBSD: setvbuf.c,v 1.11 1998/01/22 06:35:02 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 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)setvbuf.c 8.2 (Berkeley) 11/16/93"; 43 #else 44 __RCSID("$NetBSD: setvbuf.c,v 1.11 1998/01/22 06:35:02 jtc Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include "local.h" 51 #include "reentrant.h" 52 53 /* 54 * Set one of the three kinds of buffering, optionally including 55 * a buffer. 56 */ 57 int 58 setvbuf(fp, buf, mode, size) 59 register FILE *fp; 60 char *buf; 61 register int mode; 62 register size_t size; 63 { 64 register int ret, flags; 65 size_t iosize; 66 int ttyflag; 67 68 /* 69 * Verify arguments. The `int' limit on `size' is due to this 70 * particular implementation. Note, buf and size are ignored 71 * when setting _IONBF. 72 */ 73 if (mode != _IONBF) 74 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 75 return (-1); 76 77 FLOCKFILE(fp); 78 /* 79 * Write current buffer, if any. Discard unread input (including 80 * ungetc data), cancel line buffering, and free old buffer if 81 * malloc()ed. We also clear any eof condition, as if this were 82 * a seek. 83 */ 84 ret = 0; 85 (void)__sflush(fp); 86 if (HASUB(fp)) 87 FREEUB(fp); 88 fp->_r = fp->_lbfsize = 0; 89 flags = fp->_flags; 90 if (flags & __SMBF) 91 free((void *)fp->_bf._base); 92 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 93 94 /* If setting unbuffered mode, skip all the hard work. */ 95 if (mode == _IONBF) 96 goto nbf; 97 98 /* 99 * Find optimal I/O size for seek optimization. This also returns 100 * a `tty flag' to suggest that we check isatty(fd), but we do not 101 * care since our caller told us how to buffer. 102 */ 103 flags |= __swhatbuf(fp, &iosize, &ttyflag); 104 if (size == 0) { 105 buf = NULL; /* force local allocation */ 106 size = iosize; 107 } 108 109 /* Allocate buffer if needed. */ 110 if (buf == NULL) { 111 if ((buf = malloc(size)) == NULL) { 112 /* 113 * Unable to honor user's request. We will return 114 * failure, but try again with file system size. 115 */ 116 ret = -1; 117 if (size != iosize) { 118 size = iosize; 119 buf = malloc(size); 120 } 121 } 122 if (buf == NULL) { 123 /* No luck; switch to unbuffered I/O. */ 124 nbf: 125 fp->_flags = flags | __SNBF; 126 fp->_w = 0; 127 fp->_bf._base = fp->_p = fp->_nbuf; 128 fp->_bf._size = 1; 129 FUNLOCKFILE(fp); 130 return (ret); 131 } 132 flags |= __SMBF; 133 } 134 135 /* 136 * Kill any seek optimization if the buffer is not the 137 * right size. 138 * 139 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 140 */ 141 if (size != iosize) 142 flags |= __SNPT; 143 144 /* 145 * Fix up the FILE fields, and set __cleanup for output flush on 146 * exit (since we are buffered in some way). 147 */ 148 if (mode == _IOLBF) 149 flags |= __SLBF; 150 fp->_flags = flags; 151 fp->_bf._base = fp->_p = (unsigned char *)buf; 152 fp->_bf._size = size; 153 /* fp->_lbfsize is still 0 */ 154 if (flags & __SWR) { 155 /* 156 * Begin or continue writing: see __swsetup(). Note 157 * that __SNBF is impossible (it was handled earlier). 158 */ 159 if (flags & __SLBF) { 160 fp->_w = 0; 161 fp->_lbfsize = -fp->_bf._size; 162 } else 163 fp->_w = size; 164 } else { 165 /* begin/continue reading, or stay in intermediate state */ 166 fp->_w = 0; 167 } 168 __cleanup = _cleanup; 169 170 FUNLOCKFILE(fp); 171 return (ret); 172 } 173
Indexes created Sun Sep 21 15:09:59 GMT 2025