findfp.c revision 50476 
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 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#if defined(LIBC_SCCS) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)findfp.c	8.2 (Berkeley) 1/4/94";
40#endif
41static const char rcsid[] =
42  "$FreeBSD: head/lib/libc/stdio/findfp.c 50476 1999-08-28 00:22:10Z peter $";
43#endif /* LIBC_SCCS and not lint */
44
45#include <sys/param.h>
46#include <unistd.h>
47#include <stdio.h>
48#include <errno.h>
49#include <stdlib.h>
50#include <string.h>
51#include "local.h"
52#include "glue.h"
53
54int	__sdidinit;
55
56#define	NDYNAMIC 10		/* add ten more whenever necessary */
57
58#define	std(flags, file) \
59	{0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite}
60/*	 p r w flags file _bf z  cookie      close    read    seek    write */
61
62				/* the usual - (stdin + stdout + stderr) */
63static FILE usual[FOPEN_MAX - 3];
64static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
65
66FILE __sF[3] = {
67	std(__SRD, STDIN_FILENO),		/* stdin */
68	std(__SWR, STDOUT_FILENO),		/* stdout */
69	std(__SWR|__SNBF, STDERR_FILENO)	/* stderr */
70};
71struct glue __sglue = { &uglue, 3, __sF };
72
73static struct glue *	moreglue __P((int));
74
75static struct glue *
76moreglue(n)
77	register int n;
78{
79	register struct glue *g;
80	register FILE *p;
81	static FILE empty;
82
83	g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE));
84	if (g == NULL)
85		return (NULL);
86	p = (FILE *)ALIGN(g + 1);
87	g->next = NULL;
88	g->niobs = n;
89	g->iobs = p;
90	while (--n >= 0)
91		*p++ = empty;
92	return (g);
93}
94
95/*
96 * Find a free FILE for fopen et al.
97 */
98FILE *
99__sfp()
100{
101	register FILE *fp;
102	register int n;
103	register struct glue *g;
104
105	if (!__sdidinit)
106		__sinit();
107	for (g = &__sglue;; g = g->next) {
108		for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
109			if (fp->_flags == 0)
110				goto found;
111		if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL)
112			break;
113	}
114	return (NULL);
115found:
116	fp->_flags = 1;		/* reserve this slot; caller sets real flags */
117	fp->_p = NULL;		/* no current pointer */
118	fp->_w = 0;		/* nothing to read or write */
119	fp->_r = 0;
120	fp->_bf._base = NULL;	/* no buffer */
121	fp->_bf._size = 0;
122	fp->_lbfsize = 0;	/* not line buffered */
123	fp->_file = -1;		/* no file */
124/*	fp->_cookie = <any>; */	/* caller sets cookie, _read/_write etc */
125	fp->_ub._base = NULL;	/* no ungetc buffer */
126	fp->_ub._size = 0;
127	fp->_lb._base = NULL;	/* no line buffer */
128	fp->_lb._size = 0;
129	return (fp);
130}
131
132/*
133 * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
134 * but documented historically for certain applications.  Bad applications.
135 */
136__warn_references(f_prealloc,
137	"warning: this program uses f_prealloc(), which is stupid.");
138
139void
140f_prealloc()
141{
142	register struct glue *g;
143	int n;
144
145	n = getdtablesize() - FOPEN_MAX + 20;		/* 20 for slop. */
146	for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
147		/* void */;
148	if (n > 0)
149		g->next = moreglue(n);
150}
151
152/*
153 * exit() calls _cleanup() through *__cleanup, set whenever we
154 * open or buffer a file.  This chicanery is done so that programs
155 * that do not use stdio need not link it all in.
156 *
157 * The name `_cleanup' is, alas, fairly well known outside stdio.
158 */
159void
160_cleanup()
161{
162	/* (void) _fwalk(fclose); */
163	(void) _fwalk(__sflush);		/* `cheating' */
164}
165
166/*
167 * __sinit() is called whenever stdio's internal variables must be set up.
168 */
169void
170__sinit()
171{
172	/* make sure we clean up on exit */
173	__cleanup = _cleanup;		/* conservative */
174	__sdidinit = 1;
175}
176