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 * 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 * $FreeBSD: src/lib/libc/stdio/makebuf.c,v 1.1.1.1.14.1 2001/03/05 11:27:49 obrien Exp $ 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 41 #endif /* LIBC_SCCS and not lint */ 42 43 #include <sys/types.h> 44 #include <sys/stat.h> 45 #include <unistd.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include "local.h" 49 50 /* 51 * Allocate a file buffer, or switch to unbuffered I/O. 52 * Per the ANSI C standard, ALL tty devices default to line buffered. 53 * 54 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 55 * optimisation) right after the fstat() that finds the buffer size. 56 */ 57 void 58 __smakebuf(fp) 59 register FILE *fp; 60 { 61 register void *p; 62 register int flags; 63 size_t size; 64 int couldbetty; 65 66 if (fp->_flags & __SNBF) { 67 fp->_bf._base = fp->_p = fp->_nbuf; 68 fp->_bf._size = 1; 69 return; 70 } 71 flags = __swhatbuf(fp, &size, &couldbetty); 72 if ((p = malloc(size)) == NULL) { 73 fp->_flags |= __SNBF; 74 fp->_bf._base = fp->_p = fp->_nbuf; 75 fp->_bf._size = 1; 76 return; 77 } 78 __cleanup = _cleanup; 79 flags |= __SMBF; 80 fp->_bf._base = fp->_p = p; 81 fp->_bf._size = size; 82 if (couldbetty && isatty(fp->_file)) 83 flags |= __SLBF; 84 fp->_flags |= flags; 85 } 86 87 /* 88 * Internal routine to determine `proper' buffering for a file. 89 */ 90 int 91 __swhatbuf(fp, bufsize, couldbetty) 92 register FILE *fp; 93 size_t *bufsize; 94 int *couldbetty; 95 { 96 struct stat st; 97 98 if (fp->_file < 0 || fstat(fp->_file, &st) < 0) { 99 *couldbetty = 0; 100 *bufsize = BUFSIZ; 101 return (__SNPT); 102 } 103 104 /* could be a tty iff it is a character device */ 105 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 106 if (st.st_blksize <= 0) { 107 *bufsize = BUFSIZ; 108 return (__SNPT); 109 } 110 111 /* 112 * Optimise fseek() only if it is a regular file. (The test for 113 * __sseek is mainly paranoia.) It is safe to set _blksize 114 * unconditionally; it will only be used if __SOPT is also set. 115 */ 116 *bufsize = st.st_blksize; 117 fp->_blksize = st.st_blksize; 118 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 119 __SOPT : __SNPT); 120 } 121