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. 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 * @(#)makebuf.c 8.1 (Berkeley) 6/4/93 33 * $FreeBSD: src/lib/libc/stdio/makebuf.c,v 1.6 2007/01/09 00:28:07 imp Exp $ 34 */ 35 36 #include "namespace.h" 37 #include <sys/types.h> 38 #include <sys/stat.h> 39 #include <unistd.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include "un-namespace.h" 43 44 #include "libc_private.h" 45 #include "local.h" 46 47 /* 48 * Allocate a file buffer, or switch to unbuffered I/O. 49 * Per the ANSI C standard, ALL tty devices default to line buffered. 50 * 51 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 52 * optimisation) right after the _fstat() that finds the buffer size. 53 */ 54 void 55 __smakebuf(FILE *fp) 56 { 57 void *p; 58 int flags; 59 size_t size; 60 int couldbetty; 61 62 if (fp->pub._flags & __SNBF) { 63 fp->_bf._base = fp->pub._p = fp->_nbuf; 64 fp->_bf._size = 1; 65 return; 66 } 67 flags = __swhatbuf(fp, &size, &couldbetty); 68 if ((p = malloc(size)) == NULL) { 69 fp->pub._flags |= __SNBF; 70 fp->_bf._base = fp->pub._p = fp->_nbuf; 71 fp->_bf._size = 1; 72 return; 73 } 74 __cleanup = _cleanup; 75 flags |= __SMBF; 76 fp->_bf._base = fp->pub._p = p; 77 fp->_bf._size = size; 78 if (couldbetty && isatty(fp->pub._fileno)) 79 flags |= __SLBF; 80 fp->pub._flags |= flags; 81 } 82 83 /* 84 * Internal routine to determine `proper' buffering for a file. 85 */ 86 int 87 __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty) 88 { 89 struct stat st; 90 91 if (fp->pub._fileno < 0 || _fstat(fp->pub._fileno, &st) < 0) { 92 *couldbetty = 0; 93 *bufsize = BUFSIZ; 94 return (__SNPT); 95 } 96 97 /* could be a tty iff it is a character device */ 98 *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 99 if (st.st_blksize <= 0) { 100 *bufsize = BUFSIZ; 101 return (__SNPT); 102 } 103 104 /* 105 * Optimise fseek() only if it is a regular file. (The test for 106 * __sseek is mainly paranoia.) It is safe to set _blksize 107 * unconditionally; it will only be used if __SOPT is also set. 108 */ 109 *bufsize = st.st_blksize; 110 fp->_blksize = st.st_blksize; 111 return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 112 __SOPT : __SNPT); 113 } 114