1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)setvbuf.c 8.2 (Berkeley) 11/16/93 37 * $FreeBSD: src/lib/libc/stdio/setvbuf.c,v 1.7 1999/08/28 00:01:16 peter Exp $ 38 * $DragonFly: src/lib/libc/stdio/setvbuf.c,v 1.4 2004/06/07 20:35:41 hmp Exp $ 39 */ 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include "local.h" 44 #include "libc_private.h" 45 46 /* 47 * Set one of the three kinds of buffering, optionally including 48 * a buffer. 49 */ 50 int 51 setvbuf(FILE *fp, char *buf, int mode, size_t size) 52 { 53 int ret, flags; 54 size_t iosize; 55 int ttyflag; 56 57 /* 58 * Verify arguments. The `int' limit on `size' is due to this 59 * particular implementation. Note, buf and size are ignored 60 * when setting _IONBF. 61 */ 62 if (mode != _IONBF) 63 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 64 return (EOF); 65 66 FLOCKFILE(fp); 67 /* 68 * Write current buffer, if any. Discard unread input (including 69 * ungetc data), cancel line buffering, and free old buffer if 70 * malloc()ed. We also clear any eof condition, as if this were 71 * a seek. 72 */ 73 ret = 0; 74 (void)__sflush(fp); 75 if (HASUB(fp)) 76 FREEUB(fp); 77 fp->_r = fp->_lbfsize = 0; 78 flags = fp->_flags; 79 if (flags & __SMBF) 80 free((void *)fp->_bf._base); 81 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 82 83 /* If setting unbuffered mode, skip all the hard work. */ 84 if (mode == _IONBF) 85 goto nbf; 86 87 /* 88 * Find optimal I/O size for seek optimization. This also returns 89 * a `tty flag' to suggest that we check isatty(fd), but we do not 90 * care since our caller told us how to buffer. 91 */ 92 flags |= __swhatbuf(fp, &iosize, &ttyflag); 93 if (size == 0) { 94 buf = NULL; /* force local allocation */ 95 size = iosize; 96 } 97 98 /* Allocate buffer if needed. */ 99 if (buf == NULL) { 100 if ((buf = malloc(size)) == NULL) { 101 /* 102 * Unable to honor user's request. We will return 103 * failure, but try again with file system size. 104 */ 105 ret = EOF; 106 if (size != iosize) { 107 size = iosize; 108 buf = malloc(size); 109 } 110 } 111 if (buf == NULL) { 112 /* No luck; switch to unbuffered I/O. */ 113 nbf: 114 fp->_flags = flags | __SNBF; 115 fp->_w = 0; 116 fp->_bf._base = fp->_p = fp->_nbuf; 117 fp->_bf._size = 1; 118 FUNLOCKFILE(fp); 119 return (ret); 120 } 121 flags |= __SMBF; 122 } 123 124 /* 125 * Kill any seek optimization if the buffer is not the 126 * right size. 127 * 128 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 129 */ 130 if (size != iosize) 131 flags |= __SNPT; 132 133 /* 134 * Fix up the FILE fields, and set __cleanup for output flush on 135 * exit (since we are buffered in some way). 136 */ 137 if (mode == _IOLBF) 138 flags |= __SLBF; 139 fp->_flags = flags; 140 fp->_bf._base = fp->_p = (unsigned char *)buf; 141 fp->_bf._size = size; 142 /* fp->_lbfsize is still 0 */ 143 if (flags & __SWR) { 144 /* 145 * Begin or continue writing: see __swsetup(). Note 146 * that __SNBF is impossible (it was handled earlier). 147 */ 148 if (flags & __SLBF) { 149 fp->_w = 0; 150 fp->_lbfsize = -fp->_bf._size; 151 } else 152 fp->_w = size; 153 } else { 154 /* begin/continue reading, or stay in intermediate state */ 155 fp->_w = 0; 156 } 157 __cleanup = _cleanup; 158 159 FUNLOCKFILE(fp); 160 return (ret); 161 } 162