1 /* $NetBSD: makebuf.c,v 1.13 2003/01/18 11:29:55 thorpej Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 43 #else 44 __RCSID("$NetBSD: makebuf.c,v 1.13 2003/01/18 11:29:55 thorpej Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include "namespace.h" 49 50 #include <sys/types.h> 51 #include <sys/stat.h> 52 #include <assert.h> 53 #include <stdio.h> 54 #include <stdlib.h> 55 #include <unistd.h> 56 #include "reentrant.h" 57 #include "local.h" 58 59 /* 60 * Allocate a file buffer, or switch to unbuffered I/O. 61 * Per the ANSI C standard, ALL tty devices default to line buffered. 62 * 63 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 64 * optimisation) right after the fstat() that finds the buffer size. 65 */ 66 void 67 __smakebuf(fp) 68 FILE *fp; 69 { 70 void *p; 71 int flags; 72 size_t size; 73 int couldbetty; 74 75 _DIAGASSERT(fp != NULL); 76 77 if (fp->_flags & __SNBF) { 78 fp->_bf._base = fp->_p = fp->_nbuf; 79 fp->_bf._size = 1; 80 return; 81 } 82 flags = __swhatbuf(fp, &size, &couldbetty); 83 if ((p = malloc(size)) == NULL) { 84 fp->_flags |= __SNBF; 85 fp->_bf._base = fp->_p = fp->_nbuf; 86 fp->_bf._size = 1; 87 return; 88 } 89 __cleanup = _cleanup; 90 flags |= __SMBF; 91 fp->_bf._base = fp->_p = p; 92 fp->_bf._size = size; 93 if (couldbetty && isatty(fp->_file)) 94 flags |= __SLBF; 95 fp->_flags |= flags; 96 } 97 98 /* 99 * Internal routine to determine `proper' buffering for a file. 100 */ 101 int 102 __swhatbuf(fp, bufsize, couldbetty) 103 FILE *fp; 104 size_t *bufsize; 105 int *couldbetty; 106 { 107 struct stat st; 108 109 _DIAGASSERT(fp != NULL); 110 _DIAGASSERT(bufsize != NULL); 111 _DIAGASSERT(couldbetty != NULL); 112 113 if (fp->_file < 0 || fstat(fp->_file, &st) < 0) { 114 *couldbetty = 0; 115 *bufsize = BUFSIZ; 116 return (__SNPT); 117 } 118 119 /* could be a tty iff it is a character device */ 120 *couldbetty = S_ISCHR(st.st_mode); 121 if (st.st_blksize == 0) { 122 *bufsize = BUFSIZ; 123 return (__SNPT); 124 } 125 126 /* 127 * Optimise fseek() only if it is a regular file. (The test for 128 * __sseek is mainly paranoia.) It is safe to set _blksize 129 * unconditionally; it will only be used if __SOPT is also set. 130 */ 131 *bufsize = st.st_blksize; 132 fp->_blksize = st.st_blksize; 133 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 134 __SOPT : __SNPT); 135 } 136