1 /* $NetBSD: setvbuf.c,v 1.14 1999/09/20 04:39:32 lukem 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 1.14 1999/09/20 04:39:32 lukem Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <assert.h> 49 #include <errno.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include "local.h" 53 #include "reentrant.h" 54 55 /* 56 * Set one of the three kinds of buffering, optionally including 57 * a buffer. 58 */ 59 int 60 setvbuf(fp, buf, mode, size) 61 FILE *fp; 62 char *buf; 63 int mode; 64 size_t size; 65 { 66 int ret, flags; 67 size_t iosize; 68 int ttyflag; 69 70 _DIAGASSERT(fp != NULL); 71 /* buf may be NULL */ 72 73 /* 74 * Verify arguments. The `int' limit on `size' is due to this 75 * particular implementation. Note, buf and size are ignored 76 * when setting _IONBF. 77 */ 78 if (mode != _IONBF) 79 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 80 return (-1); 81 82 FLOCKFILE(fp); 83 /* 84 * Write current buffer, if any. Discard unread input (including 85 * ungetc data), cancel line buffering, and free old buffer if 86 * malloc()ed. We also clear any eof condition, as if this were 87 * a seek. 88 */ 89 ret = 0; 90 (void)__sflush(fp); 91 if (HASUB(fp)) 92 FREEUB(fp); 93 fp->_r = fp->_lbfsize = 0; 94 flags = fp->_flags; 95 if (flags & __SMBF) 96 free((void *)fp->_bf._base); 97 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 98 99 /* If setting unbuffered mode, skip all the hard work. */ 100 if (mode == _IONBF) 101 goto nbf; 102 103 /* 104 * Find optimal I/O size for seek optimization. This also returns 105 * a `tty flag' to suggest that we check isatty(fd), but we do not 106 * care since our caller told us how to buffer. 107 */ 108 flags |= __swhatbuf(fp, &iosize, &ttyflag); 109 if (size == 0) { 110 buf = NULL; /* force local allocation */ 111 size = iosize; 112 } 113 114 /* Allocate buffer if needed. */ 115 if (buf == NULL) { 116 if ((buf = malloc(size)) == NULL) { 117 /* 118 * Unable to honor user's request. We will return 119 * failure, but try again with file system size. 120 */ 121 ret = -1; 122 if (size != iosize) { 123 size = iosize; 124 buf = malloc(size); 125 } 126 } 127 if (buf == NULL) { 128 /* No luck; switch to unbuffered I/O. */ 129 nbf: 130 fp->_flags = flags | __SNBF; 131 fp->_w = 0; 132 fp->_bf._base = fp->_p = fp->_nbuf; 133 fp->_bf._size = 1; 134 FUNLOCKFILE(fp); 135 return (ret); 136 } 137 flags |= __SMBF; 138 } 139 140 /* 141 * Kill any seek optimization if the buffer is not the 142 * right size. 143 * 144 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 145 */ 146 if (size != iosize) 147 flags |= __SNPT; 148 149 /* 150 * Fix up the FILE fields, and set __cleanup for output flush on 151 * exit (since we are buffered in some way). 152 */ 153 if (mode == _IOLBF) 154 flags |= __SLBF; 155 fp->_flags = flags; 156 fp->_bf._base = fp->_p = (unsigned char *)buf; 157 fp->_bf._size = size; 158 /* fp->_lbfsize is still 0 */ 159 if (flags & __SWR) { 160 /* 161 * Begin or continue writing: see __swsetup(). Note 162 * that __SNBF is impossible (it was handled earlier). 163 */ 164 if (flags & __SLBF) { 165 fp->_w = 0; 166 fp->_lbfsize = -fp->_bf._size; 167 } else 168 fp->_w = size; 169 } else { 170 /* begin/continue reading, or stay in intermediate state */ 171 fp->_w = 0; 172 } 173 __cleanup = _cleanup; 174 175 FUNLOCKFILE(fp); 176 return (ret); 177 } 178