1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * 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 sccsid[] = "@(#)setvbuf.c 5.5 (Berkeley) 5/6/93"; 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 setvbuf(fp, buf, mode, size) 50 register FILE *fp; 51 char *buf; 52 register int mode; 53 register size_t size; 54 { 55 register int ret, flags; 56 size_t iosize; 57 int ttyflag; 58 59 /* 60 * Verify arguments. The `int' limit on `size' is due to this 61 * particular implementation. Note, buf and size are ignored 62 * when setting _IONBF. 63 */ 64 if (mode != _IONBF) 65 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 66 return (EOF); 67 68 /* 69 * Write current buffer, if any. Discard unread input, cancel 70 * line buffering, and free old buffer if malloc()ed. 71 */ 72 ret = 0; 73 (void)__sflush(fp); 74 fp->_r = fp->_lbfsize = 0; 75 flags = fp->_flags; 76 if (flags & __SMBF) 77 free((void *)fp->_bf._base); 78 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT); 79 80 /* If setting unbuffered mode, skip all the hard work. */ 81 if (mode == _IONBF) 82 goto nbf; 83 84 /* 85 * Find optimal I/O size for seek optimization. This also returns 86 * a `tty flag' to suggest that we check isatty(fd), but we do not 87 * care since our caller told us how to buffer. 88 */ 89 flags |= __swhatbuf(fp, &iosize, &ttyflag); 90 if (size == 0) { 91 buf = NULL; /* force local allocation */ 92 size = iosize; 93 } 94 95 /* Allocate buffer if needed. */ 96 if (buf == NULL) { 97 if ((buf = malloc(size)) == NULL) { 98 /* 99 * Unable to honor user's request. We will return 100 * failure, but try again with file system size. 101 */ 102 ret = EOF; 103 if (size != iosize) { 104 size = iosize; 105 buf = malloc(size); 106 } 107 } 108 if (buf == NULL) { 109 /* No luck; switch to unbuffered I/O. */ 110 nbf: 111 fp->_flags = flags | __SNBF; 112 fp->_w = 0; 113 fp->_bf._base = fp->_p = fp->_nbuf; 114 fp->_bf._size = 1; 115 return (ret); 116 } 117 flags |= __SMBF; 118 } 119 120 /* 121 * Kill any seek optimization if the buffer is not the 122 * right size. 123 * 124 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 125 */ 126 if (size != iosize) 127 flags |= __SNPT; 128 129 /* 130 * Fix up the FILE fields, and set __cleanup for output flush on 131 * exit (since we are buffered in some way). If in r/w mode, go 132 * to the intermediate state, so that everyone has to call 133 * __srefill or __swsetup on the first operation -- it is more 134 * trouble than it is worth to set things up correctly here. 135 */ 136 if (mode == _IOLBF) 137 flags |= __SLBF; 138 if (flags & __SRW) 139 flags &= ~(__SRD | __SWR); 140 fp->_w = 0; 141 fp->_flags = flags; 142 fp->_bf._base = fp->_p = (unsigned char *)buf; 143 fp->_bf._size = size; 144 fp->_lbfsize = 0; 145 __cleanup = _cleanup; 146 147 return (ret); 148 } 149