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 = "from: @(#)setvbuf.c 5.5 (Berkeley) 5/6/93";*/ 39 static char *rcsid = "$Id: setvbuf.c,v 1.5 1993/08/26 00:47:23 jtc Exp $"; 40 #endif /* LIBC_SCCS and not lint */ 41 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include "local.h" 45 46 /* 47 * Set one of the three kinds of buffering, optionally including 48 * a buffer. 49 */ 50 setvbuf(fp, buf, mode, size) 51 register FILE *fp; 52 char *buf; 53 register int mode; 54 register size_t size; 55 { 56 register 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) || (int)size < 0) 67 return (EOF); 68 69 /* 70 * Write current buffer, if any. Discard unread input, cancel 71 * line buffering, and free old buffer if malloc()ed. 72 */ 73 ret = 0; 74 (void)__sflush(fp); 75 fp->_r = fp->_lbfsize = 0; 76 flags = fp->_flags; 77 if (flags & __SMBF) 78 free((void *)fp->_bf._base); 79 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT); 80 81 /* If setting unbuffered mode, skip all the hard work. */ 82 if (mode == _IONBF) 83 goto nbf; 84 85 /* 86 * Find optimal I/O size for seek optimization. This also returns 87 * a `tty flag' to suggest that we check isatty(fd), but we do not 88 * care since our caller told us how to buffer. 89 */ 90 flags |= __swhatbuf(fp, &iosize, &ttyflag); 91 if (size == 0) { 92 buf = NULL; /* force local allocation */ 93 size = iosize; 94 } 95 96 /* Allocate buffer if needed. */ 97 if (buf == NULL) { 98 if ((buf = malloc(size)) == NULL) { 99 /* 100 * Unable to honor user's request. We will return 101 * failure, but try again with file system size. 102 */ 103 ret = EOF; 104 if (size != iosize) { 105 size = iosize; 106 buf = malloc(size); 107 } 108 } 109 if (buf == NULL) { 110 /* No luck; switch to unbuffered I/O. */ 111 nbf: 112 fp->_flags = flags | __SNBF; 113 fp->_w = 0; 114 fp->_bf._base = fp->_p = fp->_nbuf; 115 fp->_bf._size = 1; 116 return (ret); 117 } 118 flags |= __SMBF; 119 } 120 121 /* 122 * Kill any seek optimization if the buffer is not the 123 * right size. 124 * 125 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 126 */ 127 if (size != iosize) 128 flags |= __SNPT; 129 130 /* 131 * Fix up the FILE fields, and set __cleanup for output flush on 132 * exit (since we are buffered in some way). If in r/w mode, go 133 * to the intermediate state, so that everyone has to call 134 * __srefill or __swsetup on the first operation -- it is more 135 * trouble than it is worth to set things up correctly here. 136 */ 137 if (mode == _IOLBF) 138 flags |= __SLBF; 139 if (flags & __SRW) 140 flags &= ~(__SRD | __SWR); 141 fp->_w = 0; 142 fp->_flags = flags; 143 fp->_bf._base = fp->_p = (unsigned char *)buf; 144 fp->_bf._size = size; 145 fp->_lbfsize = 0; 146 __cleanup = _cleanup; 147 148 return (ret); 149 } 150