1/*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. 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 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33#if defined(LIBC_SCCS) && !defined(lint) 34static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 35#endif /* LIBC_SCCS and not lint */ 36#include <sys/cdefs.h> 37__FBSDID("$FreeBSD: src/lib/libc/stdio/makebuf.c,v 1.6 2007/01/09 00:28:07 imp Exp $"); 38 39#include "namespace.h" 40#include <sys/types.h> 41#include <sys/stat.h> 42#include <unistd.h> 43#include <stdio.h> 44#include <stdlib.h> 45#include "un-namespace.h" 46 47#include "libc_private.h" 48#include "local.h" 49 50#ifdef FEATURE_SMALL_STDIOBUF 51# define MAXBUFSIZE (1 << 12) 52#else 53# define MAXBUFSIZE (1 << 16) 54#endif 55 56#define TTYBUFSIZE 4096 57 58/* 59 * Allocate a file buffer, or switch to unbuffered I/O. 60 * Per the ANSI C standard, ALL tty devices default to line buffered. 61 * 62 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 63 * optimisation) right after the _fstat() that finds the buffer size. 64 */ 65void 66__smakebuf(fp) 67 FILE *fp; 68{ 69 void *p; 70 int flags; 71 size_t size; 72 int couldbetty; 73 74 if (fp->_flags & __SNBF) { 75 fp->_bf._base = fp->_p = fp->_nbuf; 76 fp->_bf._size = 1; 77 return; 78 } 79 flags = __swhatbuf(fp, &size, &couldbetty); 80 if (couldbetty && isatty(fp->_file)) { 81 flags |= __SLBF; 82 /* st_blksize for ttys is 128K, so make it more reasonable */ 83 if (size > TTYBUFSIZE) 84 fp->_blksize = size = TTYBUFSIZE; 85 } 86 if ((p = malloc(size)) == NULL) { 87 fp->_flags |= __SNBF; 88 fp->_bf._base = fp->_p = fp->_nbuf; 89 fp->_bf._size = 1; 90 return; 91 } 92 __cleanup = _cleanup; 93 flags |= __SMBF; 94 fp->_bf._base = fp->_p = p; 95 fp->_bf._size = size; 96 fp->_flags |= flags; 97} 98 99/* 100 * Internal routine to determine `proper' buffering for a file. 101 */ 102int 103__swhatbuf(fp, bufsize, couldbetty) 104 FILE *fp; 105 size_t *bufsize; 106 int *couldbetty; 107{ 108 struct stat st; 109 110 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 111 *couldbetty = 0; 112 *bufsize = BUFSIZ; 113 return (__SNPT); 114 } 115 116 /* could be a tty iff it is a character device */ 117 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 118 if (st.st_blksize <= 0) { 119 *bufsize = BUFSIZ; 120 return (__SNPT); 121 } 122 123 /* 124 * Optimise fseek() only if it is a regular file. (The test for 125 * __sseek is mainly paranoia.) It is safe to set _blksize 126 * unconditionally; it will only be used if __SOPT is also set. 127 */ 128 fp->_blksize = *bufsize = st.st_blksize > MAXBUFSIZE ? MAXBUFSIZE : st.st_blksize; 129 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 130 __SOPT : __SNPT); 131} 132