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 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char rcsid[] = "$OpenBSD: setvbuf.c,v 1.3 2001/07/09 06:57:44 deraadt Exp $"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include "local.h" 44 45 /* 46 * Set one of the three kinds of buffering, optionally including 47 * a buffer. 48 */ 49 int 50 setvbuf(fp, buf, mode, size) 51 register FILE *fp; 52 char *buf; 53 register int mode; 54 register size_t size; 55 { 56 register int ret, flags; 57 size_t iosize; 58 int ttyflag; 59 60 /* 61 * Verify arguments. The `int' limit on `size' is due to this 62 * particular implementation. Note, buf and size are ignored 63 * when setting _IONBF. 64 */ 65 if (mode != _IONBF) 66 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 67 return (EOF); 68 69 /* 70 * Write current buffer, if any. Discard unread input (including 71 * ungetc data), cancel line buffering, and free old buffer if 72 * malloc()ed. We also clear any eof condition, as if this were 73 * a seek. 74 */ 75 ret = 0; 76 (void)__sflush(fp); 77 if (HASUB(fp)) 78 FREEUB(fp); 79 fp->_r = fp->_lbfsize = 0; 80 flags = fp->_flags; 81 if (flags & __SMBF) 82 free((void *)fp->_bf._base); 83 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 84 85 /* If setting unbuffered mode, skip all the hard work. */ 86 if (mode == _IONBF) 87 goto nbf; 88 89 /* 90 * Find optimal I/O size for seek optimization. This also returns 91 * a `tty flag' to suggest that we check isatty(fd), but we do not 92 * care since our caller told us how to buffer. 93 */ 94 flags |= __swhatbuf(fp, &iosize, &ttyflag); 95 if (size == 0) { 96 buf = NULL; /* force local allocation */ 97 size = iosize; 98 } 99 100 /* Allocate buffer if needed. */ 101 if (buf == NULL) { 102 if ((buf = malloc(size)) == NULL) { 103 /* 104 * Unable to honor user's request. We will return 105 * failure, but try again with file system size. 106 */ 107 ret = EOF; 108 if (size != iosize) { 109 size = iosize; 110 buf = malloc(size); 111 } 112 } 113 if (buf == NULL) { 114 /* No luck; switch to unbuffered I/O. */ 115 nbf: 116 fp->_flags = flags | __SNBF; 117 fp->_w = 0; 118 fp->_bf._base = fp->_p = fp->_nbuf; 119 fp->_bf._size = 1; 120 return (ret); 121 } 122 flags |= __SMBF; 123 } 124 125 /* 126 * Kill any seek optimization if the buffer is not the 127 * right size. 128 * 129 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 130 */ 131 if (size != iosize) 132 flags |= __SNPT; 133 134 /* 135 * Fix up the FILE fields, and set __cleanup for output flush on 136 * exit (since we are buffered in some way). 137 */ 138 if (mode == _IOLBF) 139 flags |= __SLBF; 140 fp->_flags = flags; 141 fp->_bf._base = fp->_p = (unsigned char *)buf; 142 fp->_bf._size = size; 143 /* fp->_lbfsize is still 0 */ 144 if (flags & __SWR) { 145 /* 146 * Begin or continue writing: see __swsetup(). Note 147 * that __SNBF is impossible (it was handled earlier). 148 */ 149 if (flags & __SLBF) { 150 fp->_w = 0; 151 fp->_lbfsize = -fp->_bf._size; 152 } else 153 fp->_w = size; 154 } else { 155 /* begin/continue reading, or stay in intermediate state */ 156 fp->_w = 0; 157 } 158 __cleanup = _cleanup; 159 160 return (ret); 161 } 162