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 * $DragonFly: src/lib/libc/stdio/makebuf.c,v 1.5 2005/01/31 22:29:40 dillon Exp $ 38 * 39 * @(#)makebuf.c 8.1 (Berkeley) 6/4/93 40 */ 41 42 #include "namespace.h" 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 #include "un-namespace.h" 50 51 /* 52 * Allocate a file buffer, or switch to unbuffered I/O. 53 * Per the ANSI C standard, ALL tty devices default to line buffered. 54 * 55 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 56 * optimisation) right after the _fstat() that finds the buffer size. 57 */ 58 void 59 __smakebuf(FILE *fp) 60 { 61 void *p; 62 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(FILE *fp, size_t *bufsize, int *couldbetty) 92 { 93 struct stat st; 94 95 if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 96 *couldbetty = 0; 97 *bufsize = BUFSIZ; 98 return (__SNPT); 99 } 100 101 /* could be a tty iff it is a character device */ 102 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 103 if (st.st_blksize <= 0) { 104 *bufsize = BUFSIZ; 105 return (__SNPT); 106 } 107 108 /* 109 * Optimise fseek() only if it is a regular file. (The test for 110 * __sseek is mainly paranoia.) It is safe to set _blksize 111 * unconditionally; it will only be used if __SOPT is also set. 112 */ 113 *bufsize = st.st_blksize; 114 fp->_blksize = st.st_blksize; 115 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 116 __SOPT : __SNPT); 117 } 118