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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 static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94";
39 #endif /* LIBC_SCCS and not lint */
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD: src/lib/libc/stdio/findfp.c,v 1.29 2004/05/22 15:19:41 tjr Exp $");
42
43 #include <sys/param.h>
44 #include <machine/atomic.h>
45 #include <unistd.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <string.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
57 int __sdidinit;
58
59 #define NDYNAMIC 10 /* add ten more whenever necessary */
60
61 #define std(flags, file) \
62 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
63 {0}, __sFX + file}
64 /* p r w flags file _bf z cookie close read seek write */
65 /* _ub _extra */
66 #define __sFXInit {0, PTHREAD_MUTEX_INITIALIZER}
67 /* the usual - (stdin + stdout + stderr) */
68 static FILE usual[FOPEN_MAX - 3];
69 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
70 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
71
72 static struct __sFILEX __sFX[3] = {__sFXInit, __sFXInit, __sFXInit};
73
74 /*
75 * We can't make this 'static' until 6.0-current due to binary
76 * compatibility concerns. This also means we cannot change the
77 * sizeof(FILE) until that time either and must continue to use the
78 * __sFILEX stuff to add to FILE.
79 */
80 FILE __sF[3] = {
81 std(__SRD, STDIN_FILENO),
82 std(__SWR, STDOUT_FILENO),
83 std(__SWR|__SNBF, STDERR_FILENO)
84 };
85
86 /*
87 * The following kludge is done to ensure enough binary compatibility
88 * with future versions of libc. Or rather it allows us to work with
89 * libraries that have been built with a newer libc that defines these
90 * symbols and expects libc to provide them. We only have need to support
91 * i386 and alpha because they are the only "old" systems we have deployed.
92 */
93 FILE *__stdinp = &__sF[0];
94 FILE *__stdoutp = &__sF[1];
95 FILE *__stderrp = &__sF[2];
96
97 struct glue __sglue = { &uglue, 3, __sF };
98 static struct glue *lastglue = &uglue;
99
100 static struct glue * moreglue(int);
101
102 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
103 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock)
104 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
105
106 #if NOT_YET
107 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
108 #else
109 #define SET_GLUE_PTR(ptr, val) ptr = val
110 #endif
111
112 static struct glue *
113 moreglue(n)
114 int n;
115 {
116 struct glue *g;
117 static FILE empty;
118 static struct __sFILEX emptyx = __sFXInit;
119 FILE *p;
120 struct __sFILEX *fx;
121
122 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
123 n * sizeof(struct __sFILEX));
124 if (g == NULL)
125 return (NULL);
126 p = (FILE *)ALIGN(g + 1);
127 fx = (struct __sFILEX *)&p[n];
128 g->next = NULL;
129 g->niobs = n;
130 g->iobs = p;
131 while (--n >= 0) {
132 *p = empty;
133 p->_extra = fx;
134 *p->_extra = emptyx;
135 p++, fx++;
136 }
137 return (g);
138 }
139
140 /*
141 * Find a free FILE for fopen et al.
142 */
143 FILE *
144 __sfp()
145 {
146 FILE *fp;
147 int n;
148 struct glue *g;
149
150 if (!__sdidinit)
151 __sinit();
152 /*
153 * The list must be locked because a FILE may be updated.
154 */
155 THREAD_LOCK();
156 for (g = &__sglue; g != NULL; g = g->next) {
157 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
158 if (fp->_flags == 0)
159 goto found;
160 }
161 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */
162 if ((g = moreglue(NDYNAMIC)) == NULL)
163 return (NULL);
164 THREAD_LOCK(); /* reacquire the lock */
165 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
166 lastglue = g; /* not atomic; only accessed when locked */
167 fp = g->iobs;
168 found:
169 fp->_flags = 1; /* reserve this slot; caller sets real flags */
170 THREAD_UNLOCK();
171 fp->_p = NULL; /* no current pointer */
172 fp->_w = 0; /* nothing to read or write */
173 fp->_r = 0;
174 fp->_bf._base = NULL; /* no buffer */
175 fp->_bf._size = 0;
176 fp->_lbfsize = 0; /* not line buffered */
177 fp->_file = -1; /* no file */
178 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
179 fp->_ub._base = NULL; /* no ungetc buffer */
180 fp->_ub._size = 0;
181 fp->_lb._base = NULL; /* no line buffer */
182 fp->_lb._size = 0;
183 /* fp->_lock = NULL; */ /* once set always set (reused) */
184 fp->_extra->fl_mutex = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
185 fp->_extra->orientation = 0;
186 memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
187 return (fp);
188 }
189
190 /*
191 * XXX. Force immediate allocation of internal memory. Not used by stdio,
192 * but documented historically for certain applications. Bad applications.
193 */
194 __warn_references(f_prealloc,
195 "warning: this program uses f_prealloc(), which is not recommended.");
196
197 void
198 f_prealloc()
199 {
200 struct glue *g;
201 int n;
202
203 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
204 /*
205 * It should be safe to walk the list without locking it;
206 * new nodes are only added to the end and none are ever
207 * removed.
208 */
209 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
210 /* void */;
211 if ((n > 0) && ((g = moreglue(n)) != NULL)) {
212 THREAD_LOCK();
213 SET_GLUE_PTR(lastglue->next, g);
214 lastglue = g;
215 THREAD_UNLOCK();
216 }
217 }
218
219 /*
220 * exit() calls _cleanup() through *__cleanup, set whenever we
221 * open or buffer a file. This chicanery is done so that programs
222 * that do not use stdio need not link it all in.
223 *
224 * The name `_cleanup' is, alas, fairly well known outside stdio.
225 */
226 void
227 _cleanup()
228 {
229 /* (void) _fwalk(fclose); */
230 (void) _fwalk(__sflush); /* `cheating' */
231 }
232
233 /*
234 * __sinit() is called whenever stdio's internal variables must be set up.
235 */
236 void
237 __sinit()
238 {
239 int i;
240
241 THREAD_LOCK();
242 if (__sdidinit == 0) {
243 /* Set _extra for the usual suspects. */
244 for (i = 0; i < FOPEN_MAX - 3; i++)
245 usual[i]._extra = &usual_extra[i];
246
247 /* Make sure we clean up on exit. */
248 __cleanup = _cleanup; /* conservative */
249 __sdidinit = 1;
250 }
251 THREAD_UNLOCK();
252 }