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 */ 35 36 #include "namespace.h" 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include "un-namespace.h" 40 #include "local.h" 41 #include "libc_private.h" 42 43 /* 44 * Set one of the three kinds of buffering, optionally including 45 * a buffer. 46 */ 47 int 48 setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size) 49 { 50 int ret, flags; 51 size_t iosize; 52 int ttyflag; 53 54 /* 55 * Verify arguments. The `int' limit on `size' is due to this 56 * particular implementation. Note, buf and size are ignored 57 * when setting _IONBF. 58 */ 59 if (mode != _IONBF) 60 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 61 return (EOF); 62 63 FLOCKFILE(fp); 64 /* 65 * Write current buffer, if any. Discard unread input (including 66 * ungetc data), cancel line buffering, and free old buffer if 67 * malloc()ed. We also clear any eof condition, as if this were 68 * a seek. 69 */ 70 ret = 0; 71 __sflush(fp); 72 if (HASUB(fp)) 73 FREEUB(fp); 74 fp->pub._r = fp->pub._lbfsize = 0; 75 flags = fp->pub._flags; 76 if (flags & __SMBF) 77 free((void *)fp->_bf._base); 78 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF); 79 80 /* If setting unbuffered mode, skip all the hard work. */ 81 if (mode == _IONBF) 82 goto nbf; 83 84 /* 85 * Find optimal I/O size for seek optimization. This also returns 86 * a `tty flag' to suggest that we check isatty(fd), but we do not 87 * care since our caller told us how to buffer. 88 */ 89 flags |= __swhatbuf(fp, &iosize, &ttyflag); 90 if (size == 0) { 91 buf = NULL; /* force local allocation */ 92 size = iosize; 93 } 94 95 /* Allocate buffer if needed. */ 96 if (buf == NULL) { 97 if ((buf = malloc(size)) == NULL) { 98 /* 99 * Unable to honor user's request. We will return 100 * failure, but try again with file system size. 101 */ 102 ret = EOF; 103 if (size != iosize) { 104 size = iosize; 105 buf = malloc(size); 106 } 107 } 108 if (buf == NULL) { 109 /* No luck; switch to unbuffered I/O. */ 110 nbf: 111 fp->pub._flags = flags | __SNBF; 112 fp->pub._w = 0; 113 fp->_bf._base = fp->pub._p = fp->_nbuf; 114 fp->_bf._size = 1; 115 FUNLOCKFILE(fp); 116 return (ret); 117 } 118 flags |= __SMBF; 119 } 120 121 /* 122 * Kill any seek optimization if the buffer is not the 123 * right size. 124 * 125 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 126 */ 127 if (size != iosize) 128 flags |= __SNPT; 129 130 /* 131 * Fix up the FILE fields, and set __cleanup for output flush on 132 * exit (since we are buffered in some way). 133 */ 134 if (mode == _IOLBF) 135 flags |= __SLBF; 136 fp->pub._flags = flags; 137 fp->_bf._base = fp->pub._p = (unsigned char *)buf; 138 fp->_bf._size = size; 139 /* fp->_lbfsize is still 0 */ 140 if (flags & __SWR) { 141 /* 142 * Begin or continue writing: see __swsetup(). Note 143 * that __SNBF is impossible (it was handled earlier). 144 */ 145 if (flags & __SLBF) { 146 fp->pub._w = 0; 147 fp->pub._lbfsize = -fp->_bf._size; 148 } else 149 fp->pub._w = size; 150 } else { 151 /* begin/continue reading, or stay in intermediate state */ 152 fp->pub._w = 0; 153 } 154 __cleanup = _cleanup; 155 156 FUNLOCKFILE(fp); 157 return (ret); 158 } 159