setvbuf.c revision 1.3
1 1.1 cgd /*- 2 1.1 cgd * Copyright (c) 1990 The Regents of the University of California. 3 1.1 cgd * All rights reserved. 4 1.1 cgd * 5 1.1 cgd * This code is derived from software contributed to Berkeley by 6 1.1 cgd * Chris Torek. 7 1.1 cgd * 8 1.1 cgd * Redistribution and use in source and binary forms, with or without 9 1.1 cgd * modification, are permitted provided that the following conditions 10 1.1 cgd * are met: 11 1.1 cgd * 1. Redistributions of source code must retain the above copyright 12 1.1 cgd * notice, this list of conditions and the following disclaimer. 13 1.1 cgd * 2. Redistributions in binary form must reproduce the above copyright 14 1.1 cgd * notice, this list of conditions and the following disclaimer in the 15 1.1 cgd * documentation and/or other materials provided with the distribution. 16 1.1 cgd * 3. All advertising materials mentioning features or use of this software 17 1.1 cgd * must display the following acknowledgement: 18 1.1 cgd * This product includes software developed by the University of 19 1.1 cgd * California, Berkeley and its contributors. 20 1.1 cgd * 4. Neither the name of the University nor the names of its contributors 21 1.1 cgd * may be used to endorse or promote products derived from this software 22 1.1 cgd * without specific prior written permission. 23 1.1 cgd * 24 1.1 cgd * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 1.1 cgd * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 1.1 cgd * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 1.1 cgd * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 1.1 cgd * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 1.1 cgd * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 1.1 cgd * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 1.1 cgd * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 1.1 cgd * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 1.1 cgd * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 1.1 cgd * SUCH DAMAGE. 35 1.1 cgd */ 36 1.1 cgd 37 1.1 cgd #if defined(LIBC_SCCS) && !defined(lint) 38 1.2 cgd static char sccsid[] = "@(#)setvbuf.c 5.5 (Berkeley) 5/6/93"; 39 1.1 cgd #endif /* LIBC_SCCS and not lint */ 40 1.1 cgd 41 1.1 cgd #include <stdio.h> 42 1.1 cgd #include <stdlib.h> 43 1.1 cgd #include "local.h" 44 1.1 cgd 45 1.1 cgd /* 46 1.1 cgd * Set one of the three kinds of buffering, optionally including 47 1.1 cgd * a buffer. 48 1.1 cgd */ 49 1.1 cgd setvbuf(fp, buf, mode, size) 50 1.1 cgd register FILE *fp; 51 1.1 cgd char *buf; 52 1.1 cgd register int mode; 53 1.1 cgd register size_t size; 54 1.1 cgd { 55 1.2 cgd register int ret, flags; 56 1.2 cgd size_t iosize; 57 1.2 cgd int ttyflag; 58 1.1 cgd 59 1.1 cgd /* 60 1.1 cgd * Verify arguments. The `int' limit on `size' is due to this 61 1.2 cgd * particular implementation. Note, buf and size are ignored 62 1.2 cgd * when setting _IONBF. 63 1.1 cgd */ 64 1.2 cgd if (mode != _IONBF) 65 1.2 cgd if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) 66 1.2 cgd return (EOF); 67 1.1 cgd 68 1.1 cgd /* 69 1.2 cgd * Write current buffer, if any. Discard unread input, cancel 70 1.2 cgd * line buffering, and free old buffer if malloc()ed. 71 1.1 cgd */ 72 1.2 cgd ret = 0; 73 1.2 cgd (void)__sflush(fp); 74 1.2 cgd fp->_r = fp->_lbfsize = 0; 75 1.2 cgd flags = fp->_flags; 76 1.2 cgd if (flags & __SMBF) 77 1.1 cgd free((void *)fp->_bf._base); 78 1.2 cgd flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT); 79 1.1 cgd 80 1.2 cgd /* If setting unbuffered mode, skip all the hard work. */ 81 1.2 cgd if (mode == _IONBF) 82 1.2 cgd goto nbf; 83 1.2 cgd 84 1.1 cgd /* 85 1.2 cgd * Find optimal I/O size for seek optimization. This also returns 86 1.2 cgd * a `tty flag' to suggest that we check isatty(fd), but we do not 87 1.2 cgd * care since our caller told us how to buffer. 88 1.1 cgd */ 89 1.2 cgd flags |= __swhatbuf(fp, &iosize, &ttyflag); 90 1.2 cgd if (size == 0) { 91 1.2 cgd buf = NULL; /* force local allocation */ 92 1.2 cgd size = iosize; 93 1.2 cgd } 94 1.1 cgd 95 1.2 cgd /* Allocate buffer if needed. */ 96 1.2 cgd if (buf == NULL) { 97 1.2 cgd if ((buf = malloc(size)) == NULL) { 98 1.2 cgd /* 99 1.2 cgd * Unable to honor user's request. We will return 100 1.2 cgd * failure, but try again with file system size. 101 1.2 cgd */ 102 1.2 cgd ret = EOF; 103 1.2 cgd if (size != iosize) { 104 1.2 cgd size = iosize; 105 1.2 cgd buf = malloc(size); 106 1.2 cgd } 107 1.2 cgd } 108 1.2 cgd if (buf == NULL) { 109 1.2 cgd /* No luck; switch to unbuffered I/O. */ 110 1.2 cgd nbf: 111 1.2 cgd fp->_flags = flags | __SNBF; 112 1.2 cgd fp->_w = 0; 113 1.2 cgd fp->_bf._base = fp->_p = fp->_nbuf; 114 1.2 cgd fp->_bf._size = 1; 115 1.2 cgd return (ret); 116 1.2 cgd } 117 1.2 cgd flags |= __SMBF; 118 1.2 cgd } 119 1.1 cgd 120 1.2 cgd /* 121 1.2 cgd * Kill any seek optimization if the buffer is not the 122 1.2 cgd * right size. 123 1.2 cgd * 124 1.2 cgd * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 125 1.2 cgd */ 126 1.2 cgd if (size != iosize) 127 1.2 cgd flags |= __SNPT; 128 1.1 cgd 129 1.1 cgd /* 130 1.2 cgd * Fix up the FILE fields, and set __cleanup for output flush on 131 1.3 cgd * exit (since we are buffered in some way). If in r/w mode, go 132 1.3 cgd * to the intermediate state, so that everyone has to call 133 1.3 cgd * __srefill or __swsetup on the first operation -- it is more 134 1.3 cgd * trouble than it is worth to set things up correctly here. 135 1.1 cgd */ 136 1.3 cgd if (mode == _IOLBF) 137 1.2 cgd flags |= __SLBF; 138 1.3 cgd if (flags & __SRW) 139 1.3 cgd flags &= ~(__SRD | __SWR); 140 1.3 cgd fp->_w = 0; 141 1.2 cgd fp->_flags = flags; 142 1.2 cgd fp->_bf._base = fp->_p = (unsigned char *)buf; 143 1.2 cgd fp->_bf._size = size; 144 1.3 cgd fp->_lbfsize = 0; 145 1.2 cgd __cleanup = _cleanup; 146 1.1 cgd 147 1.2 cgd return (ret); 148 1.1 cgd } 149
Indexes created Sat Sep 20 22:09:52 GMT 2025