summaryrefslogtreecommitdiffstats
path: root/lib/libc/stdio/findfp.c
blob: 270ec8aa6f17fe039de410ba8d9712b12cab80d2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)findfp.c	8.2 (Berkeley) 1/4/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <machine/atomic.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <spinlock.h>

#include "libc_private.h"
#include "local.h"
#include "glue.h"

int	__sdidinit;

#define	NDYNAMIC 10		/* add ten more whenever necessary */

#define	std(flags, file) \
  	{0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
	 {0}, __sFX + file}
  /*	 p r w flags file _bf z  cookie      close    read    seek    write */
  /*     _ub _extra */
				/* the usual - (stdin + stdout + stderr) */
static FILE usual[FOPEN_MAX - 3];
static struct __sFILEX usual_extra[FOPEN_MAX - 3];
static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };

static struct __sFILEX __sFX[3];

/*
 * We can't make this 'static' until 6.0-current due to binary
 * compatibility concerns.  This also means we cannot change the
 * sizeof(FILE) until that time either and must continue to use the
 * __sFILEX stuff to add to FILE.
 */
FILE __sF[3] = {
	std(__SRD, STDIN_FILENO),
	std(__SWR, STDOUT_FILENO),
	std(__SWR|__SNBF, STDERR_FILENO)
};

/*
 * The following kludge is done to ensure enough binary compatibility
 * with future versions of libc.  Or rather it allows us to work with
 * libraries that have been built with a newer libc that defines these
 * symbols and expects libc to provide them.  We only have need to support
 * i386 and alpha because they are the only "old" systems we have deployed.
 */
FILE *__stdinp = &__sF[0];
FILE *__stdoutp = &__sF[1];
FILE *__stderrp = &__sF[2];

struct glue __sglue = { &uglue, 3, __sF };
static struct glue *lastglue = &uglue;

static struct glue *	moreglue(int);

static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
#define THREAD_LOCK()	if (__isthreaded) _SPINLOCK(&thread_lock)
#define THREAD_UNLOCK()	if (__isthreaded) _SPINUNLOCK(&thread_lock)

#if NOT_YET
#define	SET_GLUE_PTR(ptr, val)	atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
#else
#define	SET_GLUE_PTR(ptr, val)	ptr = val
#endif

static struct glue *
moreglue(n)
	int n;
{
	struct glue *g;
	static FILE empty;
	static struct __sFILEX emptyx;
	FILE *p;
	struct __sFILEX *fx;

	g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
	    n * sizeof(struct __sFILEX));
	if (g == NULL)
		return (NULL);
	p = (FILE *)ALIGN(g + 1);
	fx = (struct __sFILEX *)&p[n];
	g->next = NULL;
	g->niobs = n;
	g->iobs = p;
	while (--n >= 0) {
		*p = empty;
		p->_extra = fx;
		*p->_extra = emptyx;
		p++, fx++;
	}
	return (g);
}

/*
 * Find a free FILE for fopen et al.
 */
FILE *
__sfp()
{
	FILE	*fp;
	int	n;
	struct glue *g;

	if (!__sdidinit)
		__sinit();
	/*
	 * The list must be locked because a FILE may be updated.
	 */
	THREAD_LOCK();
	for (g = &__sglue; g != NULL; g = g->next) {
		for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
			if (fp->_flags == 0)
				goto found;
	}
	THREAD_UNLOCK();	/* don't hold lock while malloc()ing. */
	if ((g = moreglue(NDYNAMIC)) == NULL)
		return (NULL);
	THREAD_LOCK();		/* reacquire the lock */
	SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
	lastglue = g;		/* not atomic; only accessed when locked */
	fp = g->iobs;
found:
	fp->_flags = 1;		/* reserve this slot; caller sets real flags */
	THREAD_UNLOCK();
	fp->_p = NULL;		/* no current pointer */
	fp->_w = 0;		/* nothing to read or write */
	fp->_r = 0;
	fp->_bf._base = NULL;	/* no buffer */
	fp->_bf._size = 0;
	fp->_lbfsize = 0;	/* not line buffered */
	fp->_file = -1;		/* no file */
/*	fp->_cookie = <any>; */	/* caller sets cookie, _read/_write etc */
	fp->_ub._base = NULL;	/* no ungetc buffer */
	fp->_ub._size = 0;
	fp->_lb._base = NULL;	/* no line buffer */
	fp->_lb._size = 0;
/*	fp->_lock = NULL; */	/* once set always set (reused) */
	fp->_extra->orientation = 0;
#ifdef notdef
	/* Stateful encoding/decoding is not yet supported. */
	memset(&fp->_extra->wstate, 0, sizeof(mbstate_t));
	memset(&fp->_extra->rstate, 0, sizeof(mbstate_t));
#endif
	return (fp);
}

/*
 * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 * but documented historically for certain applications.  Bad applications.
 */
__warn_references(f_prealloc, 
	"warning: this program uses f_prealloc(), which is not recommended.");

void
f_prealloc()
{
	struct glue *g;
	int n;

	n = getdtablesize() - FOPEN_MAX + 20;		/* 20 for slop. */
	/*
	 * It should be safe to walk the list without locking it;
	 * new nodes are only added to the end and none are ever
	 * removed.
	 */
	for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
		/* void */;
	if ((n > 0) && ((g = moreglue(n)) != NULL)) {
		THREAD_LOCK();
		SET_GLUE_PTR(lastglue->next, g);
		lastglue = g;
		THREAD_UNLOCK();
	}
}

/*
 * exit() calls _cleanup() through *__cleanup, set whenever we
 * open or buffer a file.  This chicanery is done so that programs
 * that do not use stdio need not link it all in.
 *
 * The name `_cleanup' is, alas, fairly well known outside stdio.
 */
void
_cleanup()
{
	/* (void) _fwalk(fclose); */
	(void) _fwalk(__sflush);		/* `cheating' */
}

/*
 * __sinit() is called whenever stdio's internal variables must be set up.
 */
void
__sinit()
{
	int	i;

	THREAD_LOCK();
	if (__sdidinit == 0) {
		/* Set _extra for the usual suspects. */
		for (i = 0; i < FOPEN_MAX - 3; i++)
			usual[i]._extra = &usual_extra[i];

		/* Make sure we clean up on exit. */
		__cleanup = _cleanup;		/* conservative */
		__sdidinit = 1;
	}
	THREAD_UNLOCK();
}
OpenPOWER on IntegriCloud