1 /* $NetBSD: setvbuf.c,v 1.10 1997/12/19 14:08:43 kleink 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 1.10 1997/12/19 14:08:43 kleink Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include "local.h" 51 52 /* 53 * Set one of the three kinds of buffering, optionally including 54 * a buffer. 55 */ 56 int 57 setvbuf(fp, buf, mode, size) 58 register FILE *fp; 59 char *buf; 60 register int mode; 61 register size_t size; 62 { 63 register int ret, flags; 64 size_t iosize; 65 int ttyflag; 66 67 /* 68 * Verify arguments. The `int' limit on `size' is due to this 69 * particular implementation. Note, buf and size are ignored 70 * when setting _IONBF. 71 */ 72 if (mode != _IONBF) 73 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 74 return (-1); 75 76 /* 77 * Write current buffer, if any. Discard unread input (including 78 * ungetc data), cancel line buffering, and free old buffer if 79 * malloc()ed. We also clear any eof condition, as if this were 80 * a seek. 81 */ 82 ret = 0; 83 (void)__sflush(fp); 84 if (HASUB(fp)) 85 FREEUB(fp); 86 fp->_r = fp->_lbfsize = 0; 87 flags = fp->_flags; 88 if (flags & __SMBF) 89 free((void *)fp->_bf._base); 90 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 91 92 /* If setting unbuffered mode, skip all the hard work. */ 93 if (mode == _IONBF) 94 goto nbf; 95 96 /* 97 * Find optimal I/O size for seek optimization. This also returns 98 * a `tty flag' to suggest that we check isatty(fd), but we do not 99 * care since our caller told us how to buffer. 100 */ 101 flags |= __swhatbuf(fp, &iosize, &ttyflag); 102 if (size == 0) { 103 buf = NULL; /* force local allocation */ 104 size = iosize; 105 } 106 107 /* Allocate buffer if needed. */ 108 if (buf == NULL) { 109 if ((buf = malloc(size)) == NULL) { 110 /* 111 * Unable to honor user's request. We will return 112 * failure, but try again with file system size. 113 */ 114 ret = -1; 115 if (size != iosize) { 116 size = iosize; 117 buf = malloc(size); 118 } 119 } 120 if (buf == NULL) { 121 /* No luck; switch to unbuffered I/O. */ 122 nbf: 123 fp->_flags = flags | __SNBF; 124 fp->_w = 0; 125 fp->_bf._base = fp->_p = fp->_nbuf; 126 fp->_bf._size = 1; 127 return (ret); 128 } 129 flags |= __SMBF; 130 } 131 132 /* 133 * Kill any seek optimization if the buffer is not the 134 * right size. 135 * 136 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 137 */ 138 if (size != iosize) 139 flags |= __SNPT; 140 141 /* 142 * Fix up the FILE fields, and set __cleanup for output flush on 143 * exit (since we are buffered in some way). 144 */ 145 if (mode == _IOLBF) 146 flags |= __SLBF; 147 fp->_flags = flags; 148 fp->_bf._base = fp->_p = (unsigned char *)buf; 149 fp->_bf._size = size; 150 /* fp->_lbfsize is still 0 */ 151 if (flags & __SWR) { 152 /* 153 * Begin or continue writing: see __swsetup(). Note 154 * that __SNBF is impossible (it was handled earlier). 155 */ 156 if (flags & __SLBF) { 157 fp->_w = 0; 158 fp->_lbfsize = -fp->_bf._size; 159 } else 160 fp->_w = size; 161 } else { 162 /* begin/continue reading, or stay in intermediate state */ 163 fp->_w = 0; 164 } 165 __cleanup = _cleanup; 166 167 return (ret); 168 } 169