xref: /titanic_41/usr/src/lib/libbc/libc/stdio/common/findiop.c (revision 5d54f3d8999eac1762fe0a8c7177d20f1f201fae)
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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 1987 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*      Copyright (c) 1984 AT&T */
28 /*        All Rights Reserved   */
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 /*LINTLIBRARY*/
33 #include <stdio.h>
34 #include <errno.h>
35 #include <malloc.h>
36 #include "iob.h"
37 
38 #define active(iop)	((iop)->_flag & (_IOREAD|_IOWRT|_IORW))
39 
40 static unsigned char sbuf[NSTATIC][_SBFSIZ];
41 unsigned char (*_smbuf)[_SBFSIZ] = sbuf;
42 static	FILE	**iobglue;
43 static	FILE	**endglue;
44 
45 /*
46  * Find a free FILE for fopen et al.
47  * We have a fixed static array of entries, and in addition
48  * may allocate additional entries dynamically, up to the kernel
49  * limit on the number of open files.
50  * At first just check for a free slot in the fixed static array.
51  * If none are available, then we allocate a structure to glue together
52  * the old and new FILE entries, which are then no longer contiguous.
53  */
54 FILE *
_findiop(void)55 _findiop(void)
56 {
57 	FILE **iov, *iop;
58 	FILE *fp;
59 
60 	if(iobglue == NULL) {
61 		for(iop = _iob; iop < _iob + NSTATIC; iop++)
62 			if(!active(iop))
63 				return(iop);
64 
65 		if(_f_morefiles() == 0) {
66 			errno = ENOMEM;
67 			return(NULL);
68 		}
69 	}
70 
71 	iov = iobglue;
72 	while(*iov != NULL && active(*iov))
73 		if (++iov >= endglue) {
74 			errno = EMFILE;
75 			return(NULL);
76 		}
77 
78 	if(*iov == NULL)
79 		*iov = (FILE *)calloc(1, sizeof **iov);
80 
81 	return(*iov);
82 }
83 
84 int
_f_morefiles(void)85 _f_morefiles(void)
86 {
87 	FILE **iov;
88 	FILE *fp;
89 	unsigned char *cp;
90 	int nfiles;
91 
92 	nfiles = getdtablesize();
93 
94 	iobglue = (FILE **)calloc(nfiles, sizeof *iobglue);
95 	if(iobglue == NULL)
96 		return(0);
97 
98 	if((_smbuf = (unsigned char (*)[_SBFSIZ])malloc(nfiles * sizeof *_smbuf)) == NULL) {
99 		free((char *)iobglue);
100 		iobglue = NULL;
101 		return(0);
102 	}
103 
104 	endglue = iobglue + nfiles;
105 
106 	for(fp = _iob, iov = iobglue; fp < &_iob[NSTATIC]; /* void */)
107 		*iov++ = fp++;
108 
109 	return(1);
110 }
111 
112 void
f_prealloc(void)113 f_prealloc(void)
114 {
115 	FILE **iov;
116 	FILE *fp;
117 
118 	if(iobglue == NULL && _f_morefiles() == 0)
119 		return;
120 
121 	for(iov = iobglue; iov < endglue; iov++)
122 		if(*iov == NULL)
123 			*iov = (FILE *)calloc(1, sizeof **iov);
124 }
125 
126 void
_fwalk(int (* function)(FILE *))127 _fwalk(int (*function)(FILE *))
128 {
129 	FILE **iov;
130 	FILE *fp;
131 
132 	if(function == NULL)
133 		return;
134 
135 	if(iobglue == NULL) {
136 		for(fp = _iob; fp < &_iob[NSTATIC]; fp++)
137 			if(active(fp))
138 				(*function)(fp);
139 	} else {
140 		for(iov = iobglue; iov < endglue; iov++)
141 			if(*iov && active(*iov))
142 				(*function)(*iov);
143 	}
144 }
145