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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)setvbuf.c 8.2 (Berkeley) 11/16/93 33 * $FreeBSD: src/lib/libc/stdio/setvbuf.c,v 1.14 2007/01/09 00:28:07 imp Exp $ 34 * $DragonFly: src/lib/libc/stdio/setvbuf.c,v 1.7 2005/11/20 11:07:30 swildner Exp $ 35 */ 36 37 #include "namespace.h" 38 #include <stdio.h> 39 #include <stdlib.h> 40 #include "un-namespace.h" 41 #include "local.h" 42 #include "libc_private.h" 43 #include "priv_stdio.h" 44 45 /* 46 * Set one of the three kinds of buffering, optionally including 47 * a buffer. 48 */ 49 int 50 setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size) 51 { 52 int ret, flags; 53 size_t iosize; 54 int ttyflag; 55 56 /* 57 * Verify arguments. The `int' limit on `size' is due to this 58 * particular implementation. Note, buf and size are ignored 59 * when setting _IONBF. 60 */ 61 if (mode != _IONBF) 62 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 63 return (EOF); 64 65 FLOCKFILE(fp); 66 /* 67 * Write current buffer, if any. Discard unread input (including 68 * ungetc data), cancel line buffering, and free old buffer if 69 * malloc()ed. We also clear any eof condition, as if this were 70 * a seek. 71 */ 72 ret = 0; 73 __sflush(fp); 74 if (HASUB(fp)) 75 FREEUB(fp); 76 fp->pub._r = fp->pub._lbfsize = 0; 77 flags = fp->pub._flags; 78 if (flags & __SMBF) 79 free((void *)fp->_bf._base); 80 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF); 81 82 /* If setting unbuffered mode, skip all the hard work. */ 83 if (mode == _IONBF) 84 goto nbf; 85 86 /* 87 * Find optimal I/O size for seek optimization. This also returns 88 * a `tty flag' to suggest that we check isatty(fd), but we do not 89 * care since our caller told us how to buffer. 90 */ 91 flags |= __swhatbuf(fp, &iosize, &ttyflag); 92 if (size == 0) { 93 buf = NULL; /* force local allocation */ 94 size = iosize; 95 } 96 97 /* Allocate buffer if needed. */ 98 if (buf == NULL) { 99 if ((buf = malloc(size)) == NULL) { 100 /* 101 * Unable to honor user's request. We will return 102 * failure, but try again with file system size. 103 */ 104 ret = EOF; 105 if (size != iosize) { 106 size = iosize; 107 buf = malloc(size); 108 } 109 } 110 if (buf == NULL) { 111 /* No luck; switch to unbuffered I/O. */ 112 nbf: 113 fp->pub._flags = flags | __SNBF; 114 fp->pub._w = 0; 115 fp->_bf._base = fp->pub._p = fp->_nbuf; 116 fp->_bf._size = 1; 117 FUNLOCKFILE(fp); 118 return (ret); 119 } 120 flags |= __SMBF; 121 } 122 123 /* 124 * Kill any seek optimization if the buffer is not the 125 * right size. 126 * 127 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 128 */ 129 if (size != iosize) 130 flags |= __SNPT; 131 132 /* 133 * Fix up the FILE fields, and set __cleanup for output flush on 134 * exit (since we are buffered in some way). 135 */ 136 if (mode == _IOLBF) 137 flags |= __SLBF; 138 fp->pub._flags = flags; 139 fp->_bf._base = fp->pub._p = (unsigned char *)buf; 140 fp->_bf._size = size; 141 /* fp->_lbfsize is still 0 */ 142 if (flags & __SWR) { 143 /* 144 * Begin or continue writing: see __swsetup(). Note 145 * that __SNBF is impossible (it was handled earlier). 146 */ 147 if (flags & __SLBF) { 148 fp->pub._w = 0; 149 fp->pub._lbfsize = -fp->_bf._size; 150 } else 151 fp->pub._w = size; 152 } else { 153 /* begin/continue reading, or stay in intermediate state */ 154 fp->pub._w = 0; 155 } 156 __cleanup = _cleanup; 157 158 FUNLOCKFILE(fp); 159 return (ret); 160 } 161