1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)findfp.c	8.2 (Berkeley) 1/4/94";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: src/lib/libc/stdio/findfp.c,v 1.34 2009/12/05 19:31:38 ed Exp $");
38
39#include <TargetConditionals.h>
40
41#include <sys/param.h>
42#include <machine/atomic.h>
43#include <unistd.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <libkern/OSAtomic.h>
48#include <errno.h>
49
50#include <pthread.h>
51#include <spinlock.h>
52
53#include "libc_private.h"
54#include "local.h"
55#include "glue.h"
56
57int	__sdidinit;
58
59#if !TARGET_OS_EMBEDDED
60#define	NDYNAMIC 10		/* add ten more whenever necessary */
61#else
62#define	NDYNAMIC 1		/* add one at a time on embedded */
63#endif
64
65#define	std(flags, file) {		\
66	._flags = (flags),		\
67	._file = (file),		\
68	._cookie = __sF + (file),	\
69	._close = __sclose,		\
70	._read = __sread,		\
71	._seek = __sseek,		\
72	._write = __swrite,		\
73	._extra = __sFX + file,         \
74}
75#define __sFXInit       {.fl_mutex = PTHREAD_MUTEX_INITIALIZER}
76  /* set counted */
77#define __sFXInit3      {.fl_mutex = PTHREAD_MUTEX_INITIALIZER, .counted = 1}
78
79static int __scounted;		/* streams counted against STREAM_MAX */
80static int __stream_max;
81
82#if !TARGET_OS_EMBEDDED
83/* usual and usual_extra are data pigs. See 7929728. For embedded we should
84 * always allocate dynamically, and probably should for desktop too. */
85				/* the usual - (stdin + stdout + stderr) */
86static FILE usual[FOPEN_MAX - 3];
87static struct __sFILEX usual_extra[FOPEN_MAX - 3];
88static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
89#endif /* !TARGET_OS_EMBEDDED */
90
91static struct __sFILEX __sFX[3] = {__sFXInit3, __sFXInit3, __sFXInit3};
92
93/*
94 * We can't make this 'static' due to binary compatibility concerns.
95 * This also means we cannot change the sizeof(FILE) and must continue to
96 * use the __sFILEX stuff to add to FILE.
97 */
98FILE __sF[3] = {
99	std(__SRD, STDIN_FILENO),
100	std(__SWR, STDOUT_FILENO),
101	std(__SWR|__SNBF, STDERR_FILENO)
102};
103
104FILE *__stdinp = &__sF[0];
105FILE *__stdoutp = &__sF[1];
106FILE *__stderrp = &__sF[2];
107
108#if !TARGET_OS_EMBEDDED
109struct glue __sglue = { &uglue, 3, __sF };
110static struct glue *lastglue = &uglue;
111#else
112struct glue __sglue = { NULL, 3, __sF };
113static struct glue *lastglue = &__sglue;
114#endif
115
116static struct glue *	moreglue(int);
117
118static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
119#define THREAD_LOCK()	if (__isthreaded) _SPINLOCK(&thread_lock)
120#define THREAD_UNLOCK()	if (__isthreaded) _SPINUNLOCK(&thread_lock)
121
122#if NOT_YET
123#define	SET_GLUE_PTR(ptr, val)	atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
124#else
125#define	SET_GLUE_PTR(ptr, val)	ptr = val
126#endif
127
128static struct glue *
129moreglue(n)
130	int n;
131{
132	struct glue *g;
133	static const FILE empty;
134	FILE *p;
135	static const struct __sFILEX emptyx = __sFXInit;
136	struct __sFILEX *fx;
137
138	g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
139	    n * sizeof(struct __sFILEX));
140	if (g == NULL)
141		return (NULL);
142	p = (FILE *)ALIGN(g + 1);
143	fx = (struct __sFILEX *)&p[n];
144	g->next = NULL;
145	g->niobs = n;
146	g->iobs = p;
147
148	while (--n >= 0) {
149		*p = empty;
150		p->_extra = fx;
151		*p->_extra = emptyx;
152		p++, fx++;
153	}
154	return (g);
155}
156
157/*
158 * Find a free FILE for fopen et al.
159 */
160FILE *
161__sfp(int count)
162{
163	FILE	*fp;
164	int	n;
165	struct glue *g;
166
167	if (!__sdidinit)
168		__sinit();
169
170	if (count) {
171		if (__scounted >= __stream_max) {
172			THREAD_UNLOCK();
173			errno = EMFILE;
174			return NULL;
175		}
176		OSAtomicIncrement32(&__scounted);
177	}
178	/*
179	 * The list must be locked because a FILE may be updated.
180	 */
181	THREAD_LOCK();
182	for (g = &__sglue; g != NULL; g = g->next) {
183		for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
184			if (fp->_flags == 0)
185				goto found;
186	}
187	THREAD_UNLOCK();	/* don't hold lock while malloc()ing. */
188	if ((g = moreglue(NDYNAMIC)) == NULL)
189		return (NULL);
190	THREAD_LOCK();		/* reacquire the lock */
191	SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
192	lastglue = g;		/* not atomic; only accessed when locked */
193	fp = g->iobs;
194found:
195	fp->_flags = 1;		/* reserve this slot; caller sets real flags */
196	THREAD_UNLOCK();
197	fp->_p = NULL;		/* no current pointer */
198	fp->_w = 0;		/* nothing to read or write */
199	fp->_r = 0;
200	fp->_bf._base = NULL;	/* no buffer */
201	fp->_bf._size = 0;
202	fp->_lbfsize = 0;	/* not line buffered */
203	fp->_file = -1;		/* no file */
204/*	fp->_cookie = <any>; */	/* caller sets cookie, _read/_write etc */
205	fp->_ub._base = NULL;	/* no ungetc buffer */
206	fp->_ub._size = 0;
207	fp->_lb._base = NULL;	/* no line buffer */
208	fp->_lb._size = 0;
209/*	fp->_lock = NULL; */	/* once set always set (reused) */
210	INITEXTRA(fp);
211	fp->_extra->counted = count ? 1 : 0;
212	return (fp);
213}
214
215/*
216 * Mark as free and update count as needed
217 */
218__private_extern__ void
219__sfprelease(FILE *fp)
220{
221	if (fp->_counted) {
222		OSAtomicDecrement32(&__scounted);
223		fp->_counted = 0;
224	}
225	fp->_flags = 0;
226}
227
228/*
229 * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
230 * but documented historically for certain applications.  Bad applications.
231 */
232__warn_references(f_prealloc,
233	"warning: this program uses f_prealloc(), which is not recommended.");
234
235void
236f_prealloc(void)
237{
238	struct glue *g;
239	int n;
240
241	n = getdtablesize() - FOPEN_MAX + 20;		/* 20 for slop. */
242	/*
243	 * It should be safe to walk the list without locking it;
244	 * new nodes are only added to the end and none are ever
245	 * removed.
246	 */
247	for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
248		/* void */;
249	if ((n > 0) && ((g = moreglue(n)) != NULL)) {
250		THREAD_LOCK();
251		SET_GLUE_PTR(lastglue->next, g);
252		lastglue = g;
253		THREAD_UNLOCK();
254	}
255}
256
257/*
258 * exit() calls _cleanup() through *__cleanup, set whenever we
259 * open or buffer a file.  This chicanery is done so that programs
260 * that do not use stdio need not link it all in.
261 *
262 * The name `_cleanup' is, alas, fairly well known outside stdio.
263 */
264void
265_cleanup()
266{
267	/* (void) _fwalk(fclose); */
268	(void) _fwalk(__sflush);		/* `cheating' */
269}
270
271/*
272 * __sinit() is called whenever stdio's internal variables must be set up.
273 */
274void
275__sinit()
276{
277	THREAD_LOCK();
278	if (__sdidinit == 0) {
279#if !TARGET_OS_EMBEDDED
280		int i;
281#endif
282		/* Make sure we clean up on exit. */
283		__cleanup = _cleanup;		/* conservative */
284		__stream_max = sysconf(_SC_STREAM_MAX);
285		__scounted = 3;			/* std{in,out,err} already exists */
286
287#if !TARGET_OS_EMBEDDED
288		/* Set _extra for the usual suspects. */
289		for (i = 0; i < FOPEN_MAX - 3; i++) {
290			usual[i]._extra = &usual_extra[i];
291			INITEXTRA(&usual[i]);
292		}
293#endif
294
295		__sdidinit = 1;
296	}
297	THREAD_UNLOCK();
298}
299