setvbuf.c revision 1.18
1 /* $NetBSD: setvbuf.c,v 1.18 2012/03/13 21:13:46 christos 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)setvbuf.c 8.2 (Berkeley) 11/16/93"; 39 #else 40 __RCSID("$NetBSD: setvbuf.c,v 1.18 2012/03/13 21:13:46 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <assert.h> 45 #include <errno.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <wchar.h> 49 #include "reentrant.h" 50 #include "local.h" 51 52 /* 53 * Set one of the three kinds of buffering, optionally including 54 * a buffer. 55 */ 56 int 57 setvbuf(fp, buf, mode, size) 58 FILE *fp; 59 char *buf; 60 int mode; 61 size_t size; 62 { 63 int ret, flags; 64 size_t iosize; 65 int ttyflag; 66 67 _DIAGASSERT(fp != NULL); 68 /* buf may be NULL */ 69 70 /* 71 * Verify arguments. The `int' limit on `size' is due to this 72 * particular implementation. Note, buf and size are ignored 73 * when setting _IONBF. 74 */ 75 if (mode != _IONBF) 76 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 77 return (-1); 78 79 FLOCKFILE(fp); 80 /* 81 * Write current buffer, if any. Discard unread input (including 82 * ungetc data), cancel line buffering, and free old buffer if 83 * malloc()ed. We also clear any eof condition, as if this were 84 * a seek. 85 */ 86 ret = 0; 87 (void)__sflush(fp); 88 if (HASUB(fp)) 89 FREEUB(fp); 90 WCIO_FREE(fp); 91 fp->_r = fp->_lbfsize = 0; 92 flags = fp->_flags; 93 if (flags & __SMBF) 94 free((void *)fp->_bf._base); 95 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 96 97 /* If setting unbuffered mode, skip all the hard work. */ 98 if (mode == _IONBF) 99 goto nbf; 100 101 /* 102 * Find optimal I/O size for seek optimization. This also returns 103 * a `tty flag' to suggest that we check isatty(fd), but we do not 104 * care since our caller told us how to buffer. 105 */ 106 flags |= __swhatbuf(fp, &iosize, &ttyflag); 107 if (size == 0) { 108 buf = NULL; /* force local allocation */ 109 size = iosize; 110 } 111 112 /* Allocate buffer if needed. */ 113 if (buf == NULL) { 114 if ((buf = malloc(size)) == NULL) { 115 /* 116 * Unable to honor user's request. We will return 117 * failure, but try again with file system size. 118 */ 119 ret = -1; 120 if (size != iosize) { 121 size = iosize; 122 buf = malloc(size); 123 } 124 } 125 if (buf == NULL) { 126 /* No luck; switch to unbuffered I/O. */ 127 nbf: 128 fp->_flags = flags | __SNBF; 129 fp->_w = 0; 130 fp->_bf._base = fp->_p = fp->_nbuf; 131 fp->_bf._size = 1; 132 FUNLOCKFILE(fp); 133 return (ret); 134 } 135 flags |= __SMBF; 136 } 137 138 /* 139 * Kill any seek optimization if the buffer is not the 140 * right size. 141 * 142 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 143 */ 144 if (size != iosize) 145 flags |= __SNPT; 146 147 /* 148 * Fix up the FILE fields, and set __cleanup for output flush on 149 * exit (since we are buffered in some way). 150 */ 151 if (mode == _IOLBF) 152 flags |= __SLBF; 153 fp->_flags = flags; 154 fp->_bf._base = fp->_p = (unsigned char *)buf; 155 _DIAGASSERT(__type_fit(int, size)); 156 fp->_bf._size = (int)size; 157 /* fp->_lbfsize is still 0 */ 158 if (flags & __SWR) { 159 /* 160 * Begin or continue writing: see __swsetup(). Note 161 * that __SNBF is impossible (it was handled earlier). 162 */ 163 if (flags & __SLBF) { 164 fp->_w = 0; 165 fp->_lbfsize = -fp->_bf._size; 166 } else { 167 _DIAGASSERT(__type_fit(int, size)); 168 fp->_w = (int)size; 169 } 170 } else { 171 /* begin/continue reading, or stay in intermediate state */ 172 fp->_w = 0; 173 } 174 __cleanup = _cleanup; 175 176 FUNLOCKFILE(fp); 177 return (ret); 178 } 179
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