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1 /*	$OpenBSD: findfp.c,v 1.9 2005/08/08 08:05:36 espie Exp $ */
2 /*-
3  * Copyright (c) 1990, 1993
4  *	The Regents of the University of California.  All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * Chris Torek.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #include <sys/param.h>
35 #include <unistd.h>
36 #include <stdio.h>
37 #include <errno.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include "local.h"
41 #include "glue.h"
42 #include "thread_private.h"
43 
44 int	__sdidinit;
45 
46 #define	NDYNAMIC 10		/* add ten more whenever necessary */
47 
48 #define	std(flags, file) \
49 	{0,0,0,flags,file,{0,0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
50 	 {(unsigned char *)(__sFext+file), 0},NULL,0,{0,0,0},{0},{0,0},0,0}
51 /*	 p r w flags file _bf z  cookie      close    read    seek    write
52 	 ext */
53 
54 /* the usual - (stdin + stdout + stderr) */
55 static FILE usual[FOPEN_MAX - 3];
56 static struct __sfileext usualext[FOPEN_MAX - 3];
57 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
58 static struct glue *lastglue = &uglue;
59 _THREAD_PRIVATE_MUTEX(__sfp_mutex);
60 
61 static struct __sfileext __sFext[3] = {
62 	_FILEEXT_INITIALIZER,
63 	_FILEEXT_INITIALIZER,
64 	_FILEEXT_INITIALIZER,
65 };
66 
67 FILE __sF[3] = {
68 	std(__SRD, STDIN_FILENO),		/* stdin */
69 	std(__SWR, STDOUT_FILENO),		/* stdout */
70 	std(__SWR|__SNBF, STDERR_FILENO)	/* stderr */
71 };
72 struct glue __sglue = { &uglue, 3, __sF };
73 
74 static struct glue *
moreglue(int n)75 moreglue(int n)
76 {
77 	struct glue *g;
78 	FILE *p;
79 	struct __sfileext *pext;
80 	static FILE empty;
81 	char *data;
82 
83 	data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)
84 	    + n * sizeof(struct __sfileext));
85 	if (data == NULL)
86 		return (NULL);
87 	g = (struct glue *)data;
88 	p = (FILE *)ALIGN(data + sizeof(*g));
89 	pext = (struct __sfileext *)
90 	    (ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
91 	g->next = NULL;
92 	g->niobs = n;
93 	g->iobs = p;
94 	while (--n >= 0) {
95 		*p = empty;
96 		_FILEEXT_SETUP(p, pext);
97 		p++;
98 		pext++;
99 	}
100 	return (g);
101 }
102 
103 /*
104  * Find a free FILE for fopen et al.
105  */
106 FILE *
__sfp(void)107 __sfp(void)
108 {
109 	FILE *fp;
110 	int n;
111 	struct glue *g;
112 
113 	if (!__sdidinit)
114 		__sinit();
115 
116 	_THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
117 	for (g = &__sglue; g != NULL; g = g->next) {
118 		for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
119 			if (fp->_flags == 0)
120 				goto found;
121 	}
122 
123 	/* release lock while mallocing */
124 	_THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
125 	if ((g = moreglue(NDYNAMIC)) == NULL)
126 		return (NULL);
127 	_THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
128 	lastglue->next = g;
129 	lastglue = g;
130 	fp = g->iobs;
131 found:
132 	fp->_flags = 1;		/* reserve this slot; caller sets real flags */
133 	_THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
134 	fp->_p = NULL;		/* no current pointer */
135 	fp->_w = 0;		/* nothing to read or write */
136 	fp->_r = 0;
137 	fp->_bf._base = NULL;	/* no buffer */
138 	fp->_bf._size = 0;
139 	fp->_lbfsize = 0;	/* not line buffered */
140 	fp->_file = -1;		/* no file */
141 /*	fp->_cookie = <any>; */	/* caller sets cookie, _read/_write etc */
142 	fp->_lb._base = NULL;	/* no line buffer */
143 	fp->_lb._size = 0;
144 	_FILEEXT_INIT(fp);
145 	return (fp);
146 }
147 
148 #if 0
149 #define getdtablesize()	sysconf(_SC_OPEN_MAX)
150 
151 /*
152  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
153  * but documented historically for certain applications.  Bad applications.
154  */
155 void
156 f_prealloc(void)
157 {
158 	struct glue *g;
159 	int n;
160 
161 	n = getdtablesize() - FOPEN_MAX + 20;		/* 20 for slop. */
162 	for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
163 		/* void */;
164 	if (n > 0 && ((g = moreglue(n)) != NULL)) {
165 		_THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
166 		lastglue->next = g;
167 		lastglue = g;
168 		_THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
169 	}
170 }
171 #endif
172 
173 /*
174  * exit() and abort() call _cleanup() through the callback registered
175  * with __atexit_register_cleanup(), set whenever we open or buffer a
176  * file. This chicanery is done so that programs that do not use stdio
177  * need not link it all in.
178  *
179  * The name `_cleanup' is, alas, fairly well known outside stdio.
180  */
181 void
_cleanup(void)182 _cleanup(void)
183 {
184 	/* (void) _fwalk(fclose); */
185 	(void) _fwalk(__sflush);		/* `cheating' */
186 }
187 
188 /*
189  * __sinit() is called whenever stdio's internal variables must be set up.
190  */
191 void
__sinit(void)192 __sinit(void)
193 {
194 	_THREAD_PRIVATE_MUTEX(__sinit_mutex);
195 	int i;
196 
197 	_THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex);
198 	if (__sdidinit)
199 		goto out;	/* bail out if caller lost the race */
200 	for (i = 0; i < FOPEN_MAX - 3; i++) {
201 		_FILEEXT_SETUP(usual+i, usualext+i);
202 	}
203 	/* make sure we clean up on exit */
204 	__atexit_register_cleanup(_cleanup); /* conservative */
205 	__sdidinit = 1;
206 out:
207 	_THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
208 }
209