setvbuf.c revision 1.16
1 /* $NetBSD: setvbuf.c,v 1.16 2003/01/18 11:29:57 thorpej 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 1.16 2003/01/18 11:29:57 thorpej 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 <wchar.h> 53 #include "reentrant.h" 54 #include "local.h" 55 56 /* 57 * Set one of the three kinds of buffering, optionally including 58 * a buffer. 59 */ 60 int 61 setvbuf(fp, buf, mode, size) 62 FILE *fp; 63 char *buf; 64 int mode; 65 size_t size; 66 { 67 int ret, flags; 68 size_t iosize; 69 int ttyflag; 70 71 _DIAGASSERT(fp != NULL); 72 /* buf may be NULL */ 73 74 /* 75 * Verify arguments. The `int' limit on `size' is due to this 76 * particular implementation. Note, buf and size are ignored 77 * when setting _IONBF. 78 */ 79 if (mode != _IONBF) 80 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 81 return (-1); 82 83 FLOCKFILE(fp); 84 /* 85 * Write current buffer, if any. Discard unread input (including 86 * ungetc data), cancel line buffering, and free old buffer if 87 * malloc()ed. We also clear any eof condition, as if this were 88 * a seek. 89 */ 90 ret = 0; 91 (void)__sflush(fp); 92 if (HASUB(fp)) 93 FREEUB(fp); 94 WCIO_FREE(fp); 95 fp->_r = fp->_lbfsize = 0; 96 flags = fp->_flags; 97 if (flags & __SMBF) 98 free((void *)fp->_bf._base); 99 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 100 101 /* If setting unbuffered mode, skip all the hard work. */ 102 if (mode == _IONBF) 103 goto nbf; 104 105 /* 106 * Find optimal I/O size for seek optimization. This also returns 107 * a `tty flag' to suggest that we check isatty(fd), but we do not 108 * care since our caller told us how to buffer. 109 */ 110 flags |= __swhatbuf(fp, &iosize, &ttyflag); 111 if (size == 0) { 112 buf = NULL; /* force local allocation */ 113 size = iosize; 114 } 115 116 /* Allocate buffer if needed. */ 117 if (buf == NULL) { 118 if ((buf = malloc(size)) == NULL) { 119 /* 120 * Unable to honor user's request. We will return 121 * failure, but try again with file system size. 122 */ 123 ret = -1; 124 if (size != iosize) { 125 size = iosize; 126 buf = malloc(size); 127 } 128 } 129 if (buf == NULL) { 130 /* No luck; switch to unbuffered I/O. */ 131 nbf: 132 fp->_flags = flags | __SNBF; 133 fp->_w = 0; 134 fp->_bf._base = fp->_p = fp->_nbuf; 135 fp->_bf._size = 1; 136 FUNLOCKFILE(fp); 137 return (ret); 138 } 139 flags |= __SMBF; 140 } 141 142 /* 143 * Kill any seek optimization if the buffer is not the 144 * right size. 145 * 146 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 147 */ 148 if (size != iosize) 149 flags |= __SNPT; 150 151 /* 152 * Fix up the FILE fields, and set __cleanup for output flush on 153 * exit (since we are buffered in some way). 154 */ 155 if (mode == _IOLBF) 156 flags |= __SLBF; 157 fp->_flags = flags; 158 fp->_bf._base = fp->_p = (unsigned char *)buf; 159 fp->_bf._size = size; 160 /* fp->_lbfsize is still 0 */ 161 if (flags & __SWR) { 162 /* 163 * Begin or continue writing: see __swsetup(). Note 164 * that __SNBF is impossible (it was handled earlier). 165 */ 166 if (flags & __SLBF) { 167 fp->_w = 0; 168 fp->_lbfsize = -fp->_bf._size; 169 } else 170 fp->_w = size; 171 } else { 172 /* begin/continue reading, or stay in intermediate state */ 173 fp->_w = 0; 174 } 175 __cleanup = _cleanup; 176 177 FUNLOCKFILE(fp); 178 return (ret); 179 } 180
Indexes created Sun Sep 21 15:09:59 GMT 2025