makebuf.c revision 92986
11573Srgrimes/*- 21573Srgrimes * Copyright (c) 1990, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Chris Torek. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 3. All advertising materials mentioning features or use of this software 171573Srgrimes * must display the following acknowledgement: 181573Srgrimes * This product includes software developed by the University of 191573Srgrimes * California, Berkeley and its contributors. 201573Srgrimes * 4. Neither the name of the University nor the names of its contributors 211573Srgrimes * may be used to endorse or promote products derived from this software 221573Srgrimes * without specific prior written permission. 231573Srgrimes * 241573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341573Srgrimes * SUCH DAMAGE. 351573Srgrimes */ 361573Srgrimes 371573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 381573Srgrimesstatic char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 391573Srgrimes#endif /* LIBC_SCCS and not lint */ 4092986Sobrien#include <sys/cdefs.h> 4192986Sobrien__FBSDID("$FreeBSD: head/lib/libc/stdio/makebuf.c 92986 2002-03-22 21:53:29Z obrien $"); 421573Srgrimes 4371579Sdeischen#include "namespace.h" 441573Srgrimes#include <sys/types.h> 451573Srgrimes#include <sys/stat.h> 461573Srgrimes#include <unistd.h> 471573Srgrimes#include <stdio.h> 481573Srgrimes#include <stdlib.h> 491573Srgrimes#include "local.h" 5071579Sdeischen#include "un-namespace.h" 511573Srgrimes 521573Srgrimes/* 531573Srgrimes * Allocate a file buffer, or switch to unbuffered I/O. 541573Srgrimes * Per the ANSI C standard, ALL tty devices default to line buffered. 551573Srgrimes * 561573Srgrimes * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 5771579Sdeischen * optimisation) right after the _fstat() that finds the buffer size. 581573Srgrimes */ 591573Srgrimesvoid 601573Srgrimes__smakebuf(fp) 6192889Sobrien FILE *fp; 621573Srgrimes{ 6392889Sobrien void *p; 6492889Sobrien int flags; 651573Srgrimes size_t size; 661573Srgrimes int couldbetty; 671573Srgrimes 681573Srgrimes if (fp->_flags & __SNBF) { 691573Srgrimes fp->_bf._base = fp->_p = fp->_nbuf; 701573Srgrimes fp->_bf._size = 1; 711573Srgrimes return; 721573Srgrimes } 731573Srgrimes flags = __swhatbuf(fp, &size, &couldbetty); 741573Srgrimes if ((p = malloc(size)) == NULL) { 751573Srgrimes fp->_flags |= __SNBF; 761573Srgrimes fp->_bf._base = fp->_p = fp->_nbuf; 771573Srgrimes fp->_bf._size = 1; 781573Srgrimes return; 791573Srgrimes } 801573Srgrimes __cleanup = _cleanup; 811573Srgrimes flags |= __SMBF; 821573Srgrimes fp->_bf._base = fp->_p = p; 831573Srgrimes fp->_bf._size = size; 841573Srgrimes if (couldbetty && isatty(fp->_file)) 851573Srgrimes flags |= __SLBF; 861573Srgrimes fp->_flags |= flags; 871573Srgrimes} 881573Srgrimes 891573Srgrimes/* 901573Srgrimes * Internal routine to determine `proper' buffering for a file. 911573Srgrimes */ 921573Srgrimesint 931573Srgrimes__swhatbuf(fp, bufsize, couldbetty) 9492889Sobrien FILE *fp; 951573Srgrimes size_t *bufsize; 961573Srgrimes int *couldbetty; 971573Srgrimes{ 981573Srgrimes struct stat st; 991573Srgrimes 10071579Sdeischen if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 1011573Srgrimes *couldbetty = 0; 1021573Srgrimes *bufsize = BUFSIZ; 1031573Srgrimes return (__SNPT); 1041573Srgrimes } 1051573Srgrimes 1061573Srgrimes /* could be a tty iff it is a character device */ 1071573Srgrimes *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 1081573Srgrimes if (st.st_blksize <= 0) { 1091573Srgrimes *bufsize = BUFSIZ; 1101573Srgrimes return (__SNPT); 1111573Srgrimes } 1121573Srgrimes 1131573Srgrimes /* 1141573Srgrimes * Optimise fseek() only if it is a regular file. (The test for 1151573Srgrimes * __sseek is mainly paranoia.) It is safe to set _blksize 1161573Srgrimes * unconditionally; it will only be used if __SOPT is also set. 1171573Srgrimes */ 1181573Srgrimes *bufsize = st.st_blksize; 1191573Srgrimes fp->_blksize = st.st_blksize; 1201573Srgrimes return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 1211573Srgrimes __SOPT : __SNPT); 1221573Srgrimes} 123