1 /* $OpenBSD: findfp.c,v 1.9 2005/08/08 08:05:36 espie Exp $ */
2 /*-
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Chris Torek.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/param.h>
35 #include <unistd.h>
36 #include <stdio.h>
37 #include <errno.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include "local.h"
41 #include "glue.h"
42 #include "thread_private.h"
43
44 int __sdidinit;
45
46 #define NDYNAMIC 10 /* add ten more whenever necessary */
47
48 #define std(flags, file) \
49 {0,0,0,flags,file,{0,0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
50 {(unsigned char *)(__sFext+file), 0},NULL,0,{0,0,0},{0},{0,0},0,0}
51 /* p r w flags file _bf z cookie close read seek write
52 ext */
53
54 /* the usual - (stdin + stdout + stderr) */
55 static FILE usual[FOPEN_MAX - 3];
56 static struct __sfileext usualext[FOPEN_MAX - 3];
57 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
58 static struct glue *lastglue = &uglue;
59 _THREAD_PRIVATE_MUTEX(__sfp_mutex);
60
61 static struct __sfileext __sFext[3] = {
62 _FILEEXT_INITIALIZER,
63 _FILEEXT_INITIALIZER,
64 _FILEEXT_INITIALIZER,
65 };
66
67 FILE __sF[3] = {
68 std(__SRD, STDIN_FILENO), /* stdin */
69 std(__SWR, STDOUT_FILENO), /* stdout */
70 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */
71 };
72 struct glue __sglue = { &uglue, 3, __sF };
73
74 static struct glue *
moreglue(int n)75 moreglue(int n)
76 {
77 struct glue *g;
78 FILE *p;
79 struct __sfileext *pext;
80 static FILE empty;
81 char *data;
82
83 data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)
84 + n * sizeof(struct __sfileext));
85 if (data == NULL)
86 return (NULL);
87 g = (struct glue *)data;
88 p = (FILE *)ALIGN(data + sizeof(*g));
89 pext = (struct __sfileext *)
90 (ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
91 g->next = NULL;
92 g->niobs = n;
93 g->iobs = p;
94 while (--n >= 0) {
95 *p = empty;
96 _FILEEXT_SETUP(p, pext);
97 p++;
98 pext++;
99 }
100 return (g);
101 }
102
103 /*
104 * Find a free FILE for fopen et al.
105 */
106 FILE *
__sfp(void)107 __sfp(void)
108 {
109 FILE *fp;
110 int n;
111 struct glue *g;
112
113 if (!__sdidinit)
114 __sinit();
115
116 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
117 for (g = &__sglue; g != NULL; g = g->next) {
118 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
119 if (fp->_flags == 0)
120 goto found;
121 }
122
123 /* release lock while mallocing */
124 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
125 if ((g = moreglue(NDYNAMIC)) == NULL)
126 return (NULL);
127 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
128 lastglue->next = g;
129 lastglue = g;
130 fp = g->iobs;
131 found:
132 fp->_flags = 1; /* reserve this slot; caller sets real flags */
133 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
134 fp->_p = NULL; /* no current pointer */
135 fp->_w = 0; /* nothing to read or write */
136 fp->_r = 0;
137 fp->_bf._base = NULL; /* no buffer */
138 fp->_bf._size = 0;
139 fp->_lbfsize = 0; /* not line buffered */
140 fp->_file = -1; /* no file */
141 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
142 fp->_lb._base = NULL; /* no line buffer */
143 fp->_lb._size = 0;
144 _FILEEXT_INIT(fp);
145 return (fp);
146 }
147
148 #if 0
149 #define getdtablesize() sysconf(_SC_OPEN_MAX)
150
151 /*
152 * XXX. Force immediate allocation of internal memory. Not used by stdio,
153 * but documented historically for certain applications. Bad applications.
154 */
155 void
156 f_prealloc(void)
157 {
158 struct glue *g;
159 int n;
160
161 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
162 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
163 /* void */;
164 if (n > 0 && ((g = moreglue(n)) != NULL)) {
165 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
166 lastglue->next = g;
167 lastglue = g;
168 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
169 }
170 }
171 #endif
172
173 /*
174 * exit() and abort() call _cleanup() through the callback registered
175 * with __atexit_register_cleanup(), set whenever we open or buffer a
176 * file. This chicanery is done so that programs that do not use stdio
177 * need not link it all in.
178 *
179 * The name `_cleanup' is, alas, fairly well known outside stdio.
180 */
181 void
_cleanup(void)182 _cleanup(void)
183 {
184 /* (void) _fwalk(fclose); */
185 (void) _fwalk(__sflush); /* `cheating' */
186 }
187
188 /*
189 * __sinit() is called whenever stdio's internal variables must be set up.
190 */
191 void
__sinit(void)192 __sinit(void)
193 {
194 _THREAD_PRIVATE_MUTEX(__sinit_mutex);
195 int i;
196
197 _THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex);
198 if (__sdidinit)
199 goto out; /* bail out if caller lost the race */
200 for (i = 0; i < FOPEN_MAX - 3; i++) {
201 _FILEEXT_SETUP(usual+i, usualext+i);
202 }
203 /* make sure we clean up on exit */
204 __atexit_register_cleanup(_cleanup); /* conservative */
205 __sdidinit = 1;
206 out:
207 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
208 }
209