1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/param.h>
36 #include <machine/atomic.h>
37 #include <unistd.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <stdint.h>
41 #include <string.h>
42
43 #include <spinlock.h>
44
45 #include "libc_private.h"
46 #include "local.h"
47 #include "glue.h"
48
49 int __sdidinit;
50
51 #define NDYNAMIC 10 /* add ten more whenever necessary */
52
53 #define std(flags, file) { \
54 ._flags = (flags), \
55 ._file = (file), \
56 ._cookie = __sF + (file), \
57 ._close = __sclose, \
58 ._read = __sread, \
59 ._seek = __sseek, \
60 ._write = __swrite, \
61 ._fl_mutex = PTHREAD_MUTEX_INITIALIZER, \
62 }
63 /* the usual - (stdin + stdout + stderr) */
64 static FILE usual[FOPEN_MAX - 3];
65 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
66
67 static FILE __sF[3] = {
68 std(__SRD, STDIN_FILENO),
69 std(__SWR, STDOUT_FILENO),
70 std(__SWR|__SNBF, STDERR_FILENO)
71 };
72
73 FILE *__stdinp = &__sF[0];
74 FILE *__stdoutp = &__sF[1];
75 FILE *__stderrp = &__sF[2];
76
77 struct glue __sglue = { &uglue, 3, __sF };
78 static struct glue *lastglue = &uglue;
79
80 static struct glue * moreglue(int);
81
82 spinlock_t __stdio_thread_lock = _SPINLOCK_INITIALIZER;
83
84 #if NOT_YET
85 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
86 #else
87 #define SET_GLUE_PTR(ptr, val) ptr = val
88 #endif
89
90 static struct glue *
moreglue(int n)91 moreglue(int n)
92 {
93 struct glue *g;
94 static FILE empty = { ._fl_mutex = PTHREAD_MUTEX_INITIALIZER };
95 FILE *p;
96 size_t align;
97
98 align = __alignof__(FILE);
99 g = (struct glue *)malloc(sizeof(*g) + align + n * sizeof(FILE));
100 if (g == NULL)
101 return (NULL);
102 p = (FILE *)roundup((uintptr_t)(g + 1), align);
103 g->next = NULL;
104 g->niobs = n;
105 g->iobs = p;
106 while (--n >= 0)
107 *p++ = empty;
108 return (g);
109 }
110
111 /*
112 * Find a free FILE for fopen et al.
113 */
114 FILE *
__sfp(void)115 __sfp(void)
116 {
117 FILE *fp;
118 int n;
119 struct glue *g;
120
121 if (!__sdidinit)
122 __sinit();
123 /*
124 * The list must be locked because a FILE may be updated.
125 */
126 STDIO_THREAD_LOCK();
127 for (g = &__sglue; g != NULL; g = g->next) {
128 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
129 if (fp->_flags == 0)
130 goto found;
131 }
132 STDIO_THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */
133 if ((g = moreglue(NDYNAMIC)) == NULL)
134 return (NULL);
135 STDIO_THREAD_LOCK(); /* reacquire the lock */
136 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
137 lastglue = g; /* not atomic; only accessed when locked */
138 fp = g->iobs;
139 found:
140 fp->_flags = 1; /* reserve this slot; caller sets real flags */
141 STDIO_THREAD_UNLOCK();
142 fp->_p = NULL; /* no current pointer */
143 fp->_w = 0; /* nothing to read or write */
144 fp->_r = 0;
145 fp->_bf._base = NULL; /* no buffer */
146 fp->_bf._size = 0;
147 fp->_lbfsize = 0; /* not line buffered */
148 fp->_file = -1; /* no file */
149 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
150 fp->_ub._base = NULL; /* no ungetc buffer */
151 fp->_ub._size = 0;
152 fp->_lb._base = NULL; /* no line buffer */
153 fp->_lb._size = 0;
154 /* fp->_fl_mutex = NULL; */ /* once set always set (reused) */
155 fp->_orientation = 0;
156 memset(&fp->_mbstate, 0, sizeof(mbstate_t));
157 fp->_flags2 = 0;
158 return (fp);
159 }
160
161 /*
162 * XXX. Force immediate allocation of internal memory. Not used by stdio,
163 * but documented historically for certain applications. Bad applications.
164 */
165 __warn_references(f_prealloc,
166 "warning: this program uses f_prealloc(), which is not recommended.");
167 void f_prealloc(void);
168
169 void
f_prealloc(void)170 f_prealloc(void)
171 {
172 struct glue *g;
173 int n;
174
175 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
176 /*
177 * It should be safe to walk the list without locking it;
178 * new nodes are only added to the end and none are ever
179 * removed.
180 */
181 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
182 /* void */;
183 if ((n > 0) && ((g = moreglue(n)) != NULL)) {
184 STDIO_THREAD_LOCK();
185 SET_GLUE_PTR(lastglue->next, g);
186 lastglue = g;
187 STDIO_THREAD_UNLOCK();
188 }
189 }
190
191 /*
192 * exit() calls _cleanup() through *__cleanup, set whenever we
193 * open or buffer a file. This chicanery is done so that programs
194 * that do not use stdio need not link it all in.
195 *
196 * The name `_cleanup' is, alas, fairly well known outside stdio.
197 */
198 void
_cleanup(void)199 _cleanup(void)
200 {
201 /* (void) _fwalk(fclose); */
202 (void) _fwalk(__sflush); /* `cheating' */
203 }
204
205 /*
206 * __sinit() is called whenever stdio's internal variables must be set up.
207 */
208 void
__sinit(void)209 __sinit(void)
210 {
211
212 /* Make sure we clean up on exit. */
213 __cleanup = _cleanup; /* conservative */
214 __sdidinit = 1;
215 }
216