1 /* $OpenBSD: findfp.c,v 1.15 2013/12/17 16:33:27 deraadt 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 "private/thread_private.h"
43
44 #define ALIGNBYTES (sizeof(uintptr_t) - 1)
45 #define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) &~ ALIGNBYTES)
46
47 int __sdidinit;
48
49 #define NDYNAMIC 10 /* add ten more whenever necessary */
50
51 #define std(flags, file) \
52 {0,0,0,flags,file,{0,0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
53 {(unsigned char *)(__sFext+file), 0},NULL,0,{0,0,0},{0},{0,0},0,0}
54 /* p r w flags file _bf z cookie close read seek write
55 ext */
56
57 /* the usual - (stdin + stdout + stderr) */
58 static FILE usual[FOPEN_MAX - 3];
59 static struct __sfileext usualext[FOPEN_MAX - 3];
60 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
61 static struct glue *lastglue = &uglue;
62 _THREAD_PRIVATE_MUTEX(__sfp_mutex);
63
64 static struct __sfileext __sFext[3];
65 FILE __sF[3] = {
66 std(__SRD, STDIN_FILENO), /* stdin */
67 std(__SWR, STDOUT_FILENO), /* stdout */
68 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */
69 };
70 struct glue __sglue = { &uglue, 3, __sF };
71
72 static struct glue *
moreglue(int n)73 moreglue(int n)
74 {
75 struct glue *g;
76 FILE *p;
77 struct __sfileext *pext;
78 static FILE empty;
79 char *data;
80
81 data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)
82 + n * sizeof(struct __sfileext));
83 if (data == NULL)
84 return (NULL);
85 g = (struct glue *)data;
86 p = (FILE *)ALIGN(data + sizeof(*g));
87 pext = (struct __sfileext *)
88 (ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
89 g->next = NULL;
90 g->niobs = n;
91 g->iobs = p;
92 while (--n >= 0) {
93 *p = empty;
94 _FILEEXT_SETUP(p, pext);
95 p++;
96 pext++;
97 }
98 return (g);
99 }
100
101 /*
102 * Find a free FILE for fopen et al.
103 */
104 FILE *
__sfp(void)105 __sfp(void)
106 {
107 FILE *fp;
108 int n;
109 struct glue *g;
110
111 if (!__sdidinit)
112 __sinit();
113
114 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
115 for (g = &__sglue; g != NULL; g = g->next) {
116 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
117 if (fp->_flags == 0)
118 goto found;
119 }
120
121 /* release lock while mallocing */
122 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
123 if ((g = moreglue(NDYNAMIC)) == NULL)
124 return (NULL);
125 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
126 lastglue->next = g;
127 lastglue = g;
128 fp = g->iobs;
129 found:
130 fp->_flags = 1; /* reserve this slot; caller sets real flags */
131 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
132 fp->_p = NULL; /* no current pointer */
133 fp->_w = 0; /* nothing to read or write */
134 fp->_r = 0;
135 fp->_bf._base = NULL; /* no buffer */
136 fp->_bf._size = 0;
137 fp->_lbfsize = 0; /* not line buffered */
138 fp->_file = -1; /* no file */
139 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
140 fp->_lb._base = NULL; /* no line buffer */
141 fp->_lb._size = 0;
142 _FILEEXT_INIT(fp);
143 return (fp);
144 }
145
146 /*
147 * exit() and abort() call _cleanup() through the callback registered
148 * with __atexit_register_cleanup(), set whenever we open or buffer a
149 * file. This chicanery is done so that programs that do not use stdio
150 * need not link it all in.
151 *
152 * The name `_cleanup' is, alas, fairly well known outside stdio.
153 */
154 void
_cleanup(void)155 _cleanup(void)
156 {
157 /* (void) _fwalk(fclose); */
158 (void) _fwalk(__sflush); /* `cheating' */
159 }
160
161 /*
162 * __sinit() is called whenever stdio's internal variables must be set up.
163 */
164 void
__sinit(void)165 __sinit(void)
166 {
167 _THREAD_PRIVATE_MUTEX(__sinit_mutex);
168 int i;
169
170 _THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex);
171 if (__sdidinit)
172 goto out; /* bail out if caller lost the race */
173 for (i = 0; i < FOPEN_MAX - 3; i++) {
174 _FILEEXT_SETUP(usual+i, usualext+i);
175 }
176 /* make sure we clean up on exit */
177 __atexit_register_cleanup(_cleanup); /* conservative */
178 __sdidinit = 1;
179 out:
180 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
181 }
182