makebuf.c revision 249808
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. 16249808Semaste * 3. Neither the name of the University nor the names of its contributors 171573Srgrimes * may be used to endorse or promote products derived from this software 181573Srgrimes * without specific prior written permission. 191573Srgrimes * 201573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 211573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 221573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 231573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 241573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 251573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 261573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 271573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 281573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 291573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 301573Srgrimes * SUCH DAMAGE. 311573Srgrimes */ 321573Srgrimes 331573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 341573Srgrimesstatic char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; 351573Srgrimes#endif /* LIBC_SCCS and not lint */ 3692986Sobrien#include <sys/cdefs.h> 3792986Sobrien__FBSDID("$FreeBSD: head/lib/libc/stdio/makebuf.c 249808 2013-04-23 13:33:13Z emaste $"); 381573Srgrimes 3971579Sdeischen#include "namespace.h" 401573Srgrimes#include <sys/types.h> 411573Srgrimes#include <sys/stat.h> 421573Srgrimes#include <unistd.h> 431573Srgrimes#include <stdio.h> 441573Srgrimes#include <stdlib.h> 4571579Sdeischen#include "un-namespace.h" 461573Srgrimes 47150040Sstefanf#include "libc_private.h" 48150040Sstefanf#include "local.h" 49150040Sstefanf 501573Srgrimes/* 511573Srgrimes * Allocate a file buffer, or switch to unbuffered I/O. 521573Srgrimes * Per the ANSI C standard, ALL tty devices default to line buffered. 531573Srgrimes * 541573Srgrimes * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek 5571579Sdeischen * optimisation) right after the _fstat() that finds the buffer size. 561573Srgrimes */ 571573Srgrimesvoid 581573Srgrimes__smakebuf(fp) 5992889Sobrien FILE *fp; 601573Srgrimes{ 6192889Sobrien void *p; 6292889Sobrien int flags; 631573Srgrimes size_t size; 641573Srgrimes int couldbetty; 651573Srgrimes 661573Srgrimes if (fp->_flags & __SNBF) { 671573Srgrimes fp->_bf._base = fp->_p = fp->_nbuf; 681573Srgrimes fp->_bf._size = 1; 691573Srgrimes return; 701573Srgrimes } 711573Srgrimes flags = __swhatbuf(fp, &size, &couldbetty); 721573Srgrimes if ((p = malloc(size)) == NULL) { 731573Srgrimes fp->_flags |= __SNBF; 741573Srgrimes fp->_bf._base = fp->_p = fp->_nbuf; 751573Srgrimes fp->_bf._size = 1; 761573Srgrimes return; 771573Srgrimes } 781573Srgrimes __cleanup = _cleanup; 791573Srgrimes flags |= __SMBF; 801573Srgrimes fp->_bf._base = fp->_p = p; 811573Srgrimes fp->_bf._size = size; 821573Srgrimes if (couldbetty && isatty(fp->_file)) 831573Srgrimes flags |= __SLBF; 841573Srgrimes fp->_flags |= flags; 851573Srgrimes} 861573Srgrimes 871573Srgrimes/* 881573Srgrimes * Internal routine to determine `proper' buffering for a file. 891573Srgrimes */ 901573Srgrimesint 911573Srgrimes__swhatbuf(fp, bufsize, couldbetty) 9292889Sobrien FILE *fp; 931573Srgrimes size_t *bufsize; 941573Srgrimes int *couldbetty; 951573Srgrimes{ 961573Srgrimes struct stat st; 971573Srgrimes 9871579Sdeischen if (fp->_file < 0 || _fstat(fp->_file, &st) < 0) { 991573Srgrimes *couldbetty = 0; 1001573Srgrimes *bufsize = BUFSIZ; 1011573Srgrimes return (__SNPT); 1021573Srgrimes } 1031573Srgrimes 1041573Srgrimes /* could be a tty iff it is a character device */ 1051573Srgrimes *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; 1061573Srgrimes if (st.st_blksize <= 0) { 1071573Srgrimes *bufsize = BUFSIZ; 1081573Srgrimes return (__SNPT); 1091573Srgrimes } 1101573Srgrimes 1111573Srgrimes /* 1121573Srgrimes * Optimise fseek() only if it is a regular file. (The test for 1131573Srgrimes * __sseek is mainly paranoia.) It is safe to set _blksize 1141573Srgrimes * unconditionally; it will only be used if __SOPT is also set. 1151573Srgrimes */ 1161573Srgrimes *bufsize = st.st_blksize; 1171573Srgrimes fp->_blksize = st.st_blksize; 1181573Srgrimes return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? 1191573Srgrimes __SOPT : __SNPT); 1201573Srgrimes} 121