1 /* $OpenBSD: setvbuf.c,v 1.14 2016/09/21 04:38:56 guenther Exp $ */ 2 /*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Chris Torek. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include "local.h" 37 38 /* 39 * Set one of the three kinds of buffering, optionally including 40 * a buffer. 41 */ 42 int 43 setvbuf(FILE *fp, char *buf, int mode, size_t size) 44 { 45 int ret, flags; 46 size_t iosize; 47 int ttyflag; 48 49 /* 50 * Verify arguments. The `int' limit on `size' is due to this 51 * particular implementation. Note, buf and size are ignored 52 * when setting _IONBF. 53 */ 54 if (mode != _IONBF) 55 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 56 return (EOF); 57 58 /* 59 * Write current buffer, if any. Discard unread input (including 60 * ungetc data), cancel line buffering, and free old buffer if 61 * malloc()ed. We also clear any eof condition, as if this were 62 * a seek. 63 */ 64 FLOCKFILE(fp); 65 ret = 0; 66 (void)__sflush(fp); 67 if (HASUB(fp)) 68 FREEUB(fp); 69 WCIO_FREE(fp); 70 fp->_r = fp->_lbfsize = 0; 71 flags = fp->_flags; 72 if (flags & __SMBF) 73 free(fp->_bf._base); 74 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); 75 76 /* If setting unbuffered mode, skip all the hard work. */ 77 if (mode == _IONBF) 78 goto nbf; 79 80 /* 81 * Find optimal I/O size for seek optimization. This also returns 82 * a `tty flag' to suggest that we check isatty(fd), but we do not 83 * care since our caller told us how to buffer. 84 */ 85 flags |= __swhatbuf(fp, &iosize, &ttyflag); 86 if (size == 0) { 87 buf = NULL; /* force local allocation */ 88 size = iosize; 89 } 90 91 /* Allocate buffer if needed. */ 92 if (buf == NULL) { 93 if ((buf = malloc(size)) == NULL) { 94 /* 95 * Unable to honor user's request. We will return 96 * failure, but try again with file system size. 97 */ 98 ret = EOF; 99 if (size != iosize) { 100 size = iosize; 101 buf = malloc(size); 102 } 103 } 104 if (buf == NULL) { 105 /* No luck; switch to unbuffered I/O. */ 106 nbf: 107 fp->_flags = flags | __SNBF; 108 fp->_w = 0; 109 fp->_bf._base = fp->_p = fp->_nbuf; 110 fp->_bf._size = 1; 111 FUNLOCKFILE(fp); 112 return (ret); 113 } 114 flags |= __SMBF; 115 } 116 117 /* 118 * We're committed to buffering from here, so make sure we've 119 * registered to flush buffers on exit. 120 */ 121 if (!__sdidinit) 122 __sinit(); 123 124 /* 125 * Kill any seek optimization if the buffer is not the 126 * right size. 127 * 128 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 129 */ 130 if (size != iosize) 131 flags |= __SNPT; 132 133 /* 134 * Fix up the FILE fields. 135 */ 136 if (mode == _IOLBF) 137 flags |= __SLBF; 138 fp->_flags = flags; 139 fp->_bf._base = fp->_p = (unsigned char *)buf; 140 fp->_bf._size = size; 141 /* fp->_lbfsize is still 0 */ 142 if (flags & __SWR) { 143 /* 144 * Begin or continue writing: see __swsetup(). Note 145 * that __SNBF is impossible (it was handled earlier). 146 */ 147 if (flags & __SLBF) { 148 fp->_w = 0; 149 fp->_lbfsize = -fp->_bf._size; 150 } else 151 fp->_w = size; 152 } else { 153 /* begin/continue reading, or stay in intermediate state */ 154 fp->_w = 0; 155 } 156 FUNLOCKFILE(fp); 157 158 return (ret); 159 } 160 DEF_STRONG(setvbuf); 161
