xref: /illumos-gate/usr/src/lib/libc/port/stdio/setbuf.c (revision cd62a92d)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved	*/
29 
30 /*
31  * Copyright 2020 Robert Mustacchi
32  */
33 
34 #include "lint.h"
35 #include "file64.h"
36 #include "mtlib.h"
37 #include <sys/types.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <thread.h>
41 #include <synch.h>
42 #include "stdiom.h"
43 
44 void
setbuf(FILE * iop,char * abuf)45 setbuf(FILE *iop, char *abuf)
46 {
47 	Uchar *buf = (Uchar *)abuf;
48 	int fno = _get_fd(iop);  /* file number */
49 	int size = BUFSIZ - _SMBFSZ;
50 	Uchar *temp;
51 	rmutex_t *lk;
52 
53 	FLOCKFILE(lk, iop);
54 	if ((iop->_base != NULL) && (iop->_flag & _IOMYBUF))
55 		free((char *)iop->_base - PUSHBACK);
56 	iop->_flag &= ~(_IOMYBUF | _IONBF | _IOLBF);
57 	if (buf == NULL) {
58 		iop->_flag |= _IONBF;
59 		if (fno == 0 || fno == 1) {
60 			/* use special buffer for std{in,out} */
61 			buf = (fno == 0) ? _sibuf : _sobuf;
62 		} else if (fno >= 2 && fno < _NFILE) {
63 			buf = _smbuf[fno];
64 			size = _SMBFSZ - PUSHBACK;
65 		} else if ((buf = (Uchar *)malloc(_SMBFSZ *
66 		    sizeof (Uchar))) != NULL) {
67 			iop->_flag |= _IOMYBUF;
68 			size = _SMBFSZ - PUSHBACK;
69 		}
70 	} else {	/* regular buffered I/O, standard buffer size */
71 		if (fno != -1 && isatty(fno))
72 			iop->_flag |= _IOLBF;
73 	}
74 	if (buf == NULL) {
75 		FUNLOCKFILE(lk);
76 		return;		/* malloc() failed */
77 	}
78 	temp = buf + PUSHBACK;
79 	iop->_base = temp;
80 	_setbufend(iop, temp + size);
81 	iop->_ptr = temp;
82 	iop->_cnt = 0;
83 	FUNLOCKFILE(lk);
84 }
85