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. 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)
34 static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94";
35 #endif /* LIBC_SCCS and not lint */
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38
39 #include <sys/param.h>
40 #include <machine/atomic.h>
41 #include <unistd.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <stdint.h>
45 #include <string.h>
46
47 #include <spinlock.h>
48
49 #include "libc_private.h"
50 #include "local.h"
51 #include "glue.h"
52
53 int __sdidinit;
54
55 #define NDYNAMIC 10 /* add ten more whenever necessary */
56
57 #define std(flags, file) { \
58 ._flags = (flags), \
59 ._file = (file), \
60 ._cookie = __sF + (file), \
61 ._close = __sclose, \
62 ._read = __sread, \
63 ._seek = __sseek, \
64 ._write = __swrite, \
65 ._fl_mutex = PTHREAD_MUTEX_INITIALIZER, \
66 }
67 /* the usual - (stdin + stdout + stderr) */
68 static FILE usual[FOPEN_MAX - 3];
69 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
70
71 static FILE __sF[3] = {
72 std(__SRD, STDIN_FILENO),
73 std(__SWR, STDOUT_FILENO),
74 std(__SWR|__SNBF, STDERR_FILENO)
75 };
76
77 FILE *__stdinp = &__sF[0];
78 FILE *__stdoutp = &__sF[1];
79 FILE *__stderrp = &__sF[2];
80
81 struct glue __sglue = { &uglue, 3, __sF };
82 static struct glue *lastglue = &uglue;
83
84 static struct glue * moreglue(int);
85
86 spinlock_t __stdio_thread_lock = _SPINLOCK_INITIALIZER;
87
88 #if NOT_YET
89 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
90 #else
91 #define SET_GLUE_PTR(ptr, val) ptr = val
92 #endif
93
94 static struct glue *
moreglue(int n)95 moreglue(int n)
96 {
97 struct glue *g;
98 static FILE empty = { ._fl_mutex = PTHREAD_MUTEX_INITIALIZER };
99 FILE *p;
100 size_t align;
101
102 align = __alignof__(FILE);
103 g = (struct glue *)malloc(sizeof(*g) + align + n * sizeof(FILE));
104 if (g == NULL)
105 return (NULL);
106 p = (FILE *)roundup((uintptr_t)(g + 1), align);
107 g->next = NULL;
108 g->niobs = n;
109 g->iobs = p;
110 while (--n >= 0)
111 *p++ = empty;
112 return (g);
113 }
114
115 /*
116 * Find a free FILE for fopen et al.
117 */
118 FILE *
__sfp(void)119 __sfp(void)
120 {
121 FILE *fp;
122 int n;
123 struct glue *g;
124
125 if (!__sdidinit)
126 __sinit();
127 /*
128 * The list must be locked because a FILE may be updated.
129 */
130 STDIO_THREAD_LOCK();
131 for (g = &__sglue; g != NULL; g = g->next) {
132 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
133 if (fp->_flags == 0)
134 goto found;
135 }
136 STDIO_THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */
137 if ((g = moreglue(NDYNAMIC)) == NULL)
138 return (NULL);
139 STDIO_THREAD_LOCK(); /* reacquire the lock */
140 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
141 lastglue = g; /* not atomic; only accessed when locked */
142 fp = g->iobs;
143 found:
144 fp->_flags = 1; /* reserve this slot; caller sets real flags */
145 STDIO_THREAD_UNLOCK();
146 fp->_p = NULL; /* no current pointer */
147 fp->_w = 0; /* nothing to read or write */
148 fp->_r = 0;
149 fp->_bf._base = NULL; /* no buffer */
150 fp->_bf._size = 0;
151 fp->_lbfsize = 0; /* not line buffered */
152 fp->_file = -1; /* no file */
153 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
154 fp->_ub._base = NULL; /* no ungetc buffer */
155 fp->_ub._size = 0;
156 fp->_lb._base = NULL; /* no line buffer */
157 fp->_lb._size = 0;
158 /* fp->_fl_mutex = NULL; */ /* once set always set (reused) */
159 fp->_orientation = 0;
160 memset(&fp->_mbstate, 0, sizeof(mbstate_t));
161 fp->_flags2 = 0;
162 return (fp);
163 }
164
165 /*
166 * XXX. Force immediate allocation of internal memory. Not used by stdio,
167 * but documented historically for certain applications. Bad applications.
168 */
169 __warn_references(f_prealloc,
170 "warning: this program uses f_prealloc(), which is not recommended.");
171 void f_prealloc(void);
172
173 void
f_prealloc(void)174 f_prealloc(void)
175 {
176 struct glue *g;
177 int n;
178
179 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
180 /*
181 * It should be safe to walk the list without locking it;
182 * new nodes are only added to the end and none are ever
183 * removed.
184 */
185 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
186 /* void */;
187 if ((n > 0) && ((g = moreglue(n)) != NULL)) {
188 STDIO_THREAD_LOCK();
189 SET_GLUE_PTR(lastglue->next, g);
190 lastglue = g;
191 STDIO_THREAD_UNLOCK();
192 }
193 }
194
195 /*
196 * exit() calls _cleanup() through *__cleanup, set whenever we
197 * open or buffer a file. This chicanery is done so that programs
198 * that do not use stdio need not link it all in.
199 *
200 * The name `_cleanup' is, alas, fairly well known outside stdio.
201 */
202 void
_cleanup(void)203 _cleanup(void)
204 {
205 /* (void) _fwalk(fclose); */
206 (void) _fwalk(__sflush); /* `cheating' */
207 }
208
209 /*
210 * __sinit() is called whenever stdio's internal variables must be set up.
211 */
212 void
__sinit(void)213 __sinit(void)
214 {
215
216 /* Make sure we clean up on exit. */
217 __cleanup = _cleanup; /* conservative */
218 __sdidinit = 1;
219 }
220