1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)setvbuf.c 8.2 (Berkeley) 11/16/93"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "namespace.h" 42 #include <limits.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include "un-namespace.h" 46 #include "local.h" 47 #include "libc_private.h" 48 49 /* 50 * Set one of the three kinds of buffering, optionally including 51 * a buffer. 52 */ 53 int 54 setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size) 55 { 56 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) || size > INT_MAX) 67 return (EOF); 68 69 FLOCKFILE_CANCELSAFE(fp); 70 /* 71 * Write current buffer, if any. Discard unread input (including 72 * ungetc data), cancel line buffering, and free old buffer if 73 * malloc()ed. We also clear any eof condition, as if this were 74 * a seek. 75 */ 76 ret = 0; 77 (void)__sflush(fp); 78 if (HASUB(fp)) 79 FREEUB(fp); 80 fp->_r = fp->_lbfsize = 0; 81 flags = fp->_flags; 82 if (flags & __SMBF) 83 free((void *)fp->_bf._base); 84 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF); 85 86 /* If setting unbuffered mode, skip all the hard work. */ 87 if (mode == _IONBF) 88 goto nbf; 89 90 /* 91 * Find optimal I/O size for seek optimization. This also returns 92 * a `tty flag' to suggest that we check isatty(fd), but we do not 93 * care since our caller told us how to buffer. 94 */ 95 flags |= __swhatbuf(fp, &iosize, &ttyflag); 96 if (size == 0) { 97 buf = NULL; /* force local allocation */ 98 size = iosize; 99 } 100 101 /* Allocate buffer if needed. */ 102 if (buf == NULL) { 103 if ((buf = malloc(size)) == NULL) { 104 /* 105 * Unable to honor user's request. We will return 106 * failure, but try again with file system size. 107 */ 108 ret = EOF; 109 if (size != iosize) { 110 size = iosize; 111 buf = malloc(size); 112 } 113 } 114 if (buf == NULL) { 115 /* No luck; switch to unbuffered I/O. */ 116 nbf: 117 fp->_flags = flags | __SNBF; 118 fp->_w = 0; 119 fp->_bf._base = fp->_p = fp->_nbuf; 120 fp->_bf._size = 1; 121 goto end; 122 } 123 flags |= __SMBF; 124 } 125 126 /* 127 * Kill any seek optimization if the buffer is not the 128 * right size. 129 * 130 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 131 */ 132 if (size != iosize) 133 flags |= __SNPT; 134 135 /* 136 * Fix up the FILE fields, and set __cleanup for output flush on 137 * exit (since we are buffered in some way). 138 */ 139 if (mode == _IOLBF) 140 flags |= __SLBF; 141 fp->_flags = flags; 142 fp->_bf._base = fp->_p = (unsigned char *)buf; 143 fp->_bf._size = size; 144 /* fp->_lbfsize is still 0 */ 145 if (flags & __SWR) { 146 /* 147 * Begin or continue writing: see __swsetup(). Note 148 * that __SNBF is impossible (it was handled earlier). 149 */ 150 if (flags & __SLBF) { 151 fp->_w = 0; 152 fp->_lbfsize = -fp->_bf._size; 153 } else 154 fp->_w = size; 155 } else { 156 /* begin/continue reading, or stay in intermediate state */ 157 fp->_w = 0; 158 } 159 __cleanup = _cleanup; 160 161 end: 162 FUNLOCKFILE_CANCELSAFE(); 163 return (ret); 164 } 165