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 #undef stdin
48 #undef stdout
49 #undef stderr
50
51 int __sdidinit;
52
53 #define NDYNAMIC 10 /* add ten more whenever necessary */
54
55 #define std(flags, file) \
56 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
57 {(unsigned char *)(__sFext+file), 0},NULL,0,{0},{0},{0},0,0}
58
59 /* the usual - (stdin + stdout + stderr) */
60 static FILE usual[FOPEN_MAX - 3];
61 static struct __sfileext usualext[FOPEN_MAX - 3];
62 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
63 static struct glue *lastglue = &uglue;
64 _THREAD_PRIVATE_MUTEX(__sfp_mutex);
65
66 static struct __sfileext __sFext[3];
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 FILE* stdin = &__sF[0];
73 FILE* stdout = &__sF[1];
74 FILE* stderr = &__sF[2];
75 struct glue __sglue = { &uglue, 3, __sF };
76
77 static struct glue *
moreglue(int n)78 moreglue(int n)
79 {
80 struct glue *g;
81 FILE *p;
82 struct __sfileext *pext;
83 static FILE empty;
84 char *data;
85
86 data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)
87 + n * sizeof(struct __sfileext));
88 if (data == NULL)
89 return (NULL);
90 g = (struct glue *)data;
91 p = (FILE *)ALIGN(data + sizeof(*g));
92 pext = (struct __sfileext *)
93 (ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
94 g->next = NULL;
95 g->niobs = n;
96 g->iobs = p;
97 while (--n >= 0) {
98 *p = empty;
99 _FILEEXT_SETUP(p, pext);
100 p++;
101 pext++;
102 }
103 return (g);
104 }
105
106 /*
107 * Find a free FILE for fopen et al.
108 */
109 FILE *
__sfp(void)110 __sfp(void)
111 {
112 FILE *fp;
113 int n;
114 struct glue *g;
115
116 if (!__sdidinit)
117 __sinit();
118
119 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
120 for (g = &__sglue; g != NULL; g = g->next) {
121 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
122 if (fp->_flags == 0)
123 goto found;
124 }
125
126 /* release lock while mallocing */
127 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
128 if ((g = moreglue(NDYNAMIC)) == NULL)
129 return (NULL);
130 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
131 lastglue->next = g;
132 lastglue = g;
133 fp = g->iobs;
134 found:
135 fp->_flags = 1; /* reserve this slot; caller sets real flags */
136 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
137 fp->_p = NULL; /* no current pointer */
138 fp->_w = 0; /* nothing to read or write */
139 fp->_r = 0;
140 fp->_bf._base = NULL; /* no buffer */
141 fp->_bf._size = 0;
142 fp->_lbfsize = 0; /* not line buffered */
143 fp->_file = -1; /* no file */
144 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
145 fp->_lb._base = NULL; /* no line buffer */
146 fp->_lb._size = 0;
147 _FILEEXT_INIT(fp);
148 return (fp);
149 }
150
151 /*
152 * exit() and abort() call _cleanup() through the callback registered
153 * with __atexit_register_cleanup(), set whenever we open or buffer a
154 * file. This chicanery is done so that programs that do not use stdio
155 * need not link it all in.
156 *
157 * The name `_cleanup' is, alas, fairly well known outside stdio.
158 */
159 void
_cleanup(void)160 _cleanup(void)
161 {
162 /* (void) _fwalk(fclose); */
163 (void) _fwalk(__sflush); /* `cheating' */
164 }
165
166 /*
167 * __sinit() is called whenever stdio's internal variables must be set up.
168 */
169 void
__sinit(void)170 __sinit(void)
171 {
172 _THREAD_PRIVATE_MUTEX(__sinit_mutex);
173
174 _THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex);
175 if (__sdidinit) {
176 /* bail out if caller lost the race */
177 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
178 return;
179 }
180
181 /* Initialize stdin/stdout/stderr (for the recursive mutex). http://b/18208568. */
182 for (size_t i = 0; i < 3; ++i) {
183 _FILEEXT_SETUP(__sF+i, __sFext+i);
184 }
185 /* Initialize the pre-allocated (but initially unused) streams. */
186 for (size_t i = 0; i < FOPEN_MAX - 3; ++i) {
187 _FILEEXT_SETUP(usual+i, usualext+i);
188 }
189
190 /* make sure we clean up on exit */
191 __atexit_register_cleanup(_cleanup); /* conservative */
192 __sdidinit = 1;
193
194 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
195 }
196