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}
54
55 /* the usual - (stdin + stdout + stderr) */
56 static FILE usual[FOPEN_MAX - 3];
57 static struct __sfileext usualext[FOPEN_MAX - 3];
58 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
59 static struct glue *lastglue = &uglue;
60 _THREAD_PRIVATE_MUTEX(__sfp_mutex);
61
62 static struct __sfileext __sFext[3];
63 FILE __sF[3] = {
64 std(__SRD, STDIN_FILENO), /* stdin */
65 std(__SWR, STDOUT_FILENO), /* stdout */
66 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */
67 };
68 FILE* stdin = &__sF[0];
69 FILE* stdout = &__sF[1];
70 FILE* stderr = &__sF[2];
71 struct glue __sglue = { &uglue, 3, __sF };
72
73 static struct glue *
moreglue(int n)74 moreglue(int n)
75 {
76 struct glue *g;
77 FILE *p;
78 struct __sfileext *pext;
79 static FILE empty;
80 char *data;
81
82 data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)
83 + n * sizeof(struct __sfileext));
84 if (data == NULL)
85 return (NULL);
86 g = (struct glue *)data;
87 p = (FILE *)ALIGN(data + sizeof(*g));
88 pext = (struct __sfileext *)
89 (ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
90 g->next = NULL;
91 g->niobs = n;
92 g->iobs = p;
93 while (--n >= 0) {
94 *p = empty;
95 _FILEEXT_SETUP(p, pext);
96 p++;
97 pext++;
98 }
99 return (g);
100 }
101
102 /*
103 * Find a free FILE for fopen et al.
104 */
105 FILE *
__sfp(void)106 __sfp(void)
107 {
108 FILE *fp;
109 int n;
110 struct glue *g;
111
112 if (!__sdidinit)
113 __sinit();
114
115 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
116 for (g = &__sglue; g != NULL; g = g->next) {
117 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
118 if (fp->_flags == 0)
119 goto found;
120 }
121
122 /* release lock while mallocing */
123 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
124 if ((g = moreglue(NDYNAMIC)) == NULL)
125 return (NULL);
126 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex);
127 lastglue->next = g;
128 lastglue = g;
129 fp = g->iobs;
130 found:
131 fp->_flags = 1; /* reserve this slot; caller sets real flags */
132 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex);
133 fp->_p = NULL; /* no current pointer */
134 fp->_w = 0; /* nothing to read or write */
135 fp->_r = 0;
136 fp->_bf._base = NULL; /* no buffer */
137 fp->_bf._size = 0;
138 fp->_lbfsize = 0; /* not line buffered */
139 fp->_file = -1; /* no file */
140 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
141 fp->_lb._base = NULL; /* no line buffer */
142 fp->_lb._size = 0;
143 _FILEEXT_INIT(fp);
144 return (fp);
145 }
146
147 /*
148 * exit() and abort() call _cleanup() through the callback registered
149 * with __atexit_register_cleanup(), set whenever we open or buffer a
150 * file. This chicanery is done so that programs that do not use stdio
151 * need not link it all in.
152 *
153 * The name `_cleanup' is, alas, fairly well known outside stdio.
154 */
155 void
_cleanup(void)156 _cleanup(void)
157 {
158 /* (void) _fwalk(fclose); */
159 (void) _fwalk(__sflush); /* `cheating' */
160 }
161
162 /*
163 * __sinit() is called whenever stdio's internal variables must be set up.
164 */
165 void
__sinit(void)166 __sinit(void)
167 {
168 _THREAD_PRIVATE_MUTEX(__sinit_mutex);
169
170 _THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex);
171 if (__sdidinit) {
172 /* bail out if caller lost the race */
173 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
174 return;
175 }
176
177 /* Initialize stdin/stdout/stderr (for the recursive mutex). http://b/18208568. */
178 for (size_t i = 0; i < 3; ++i) {
179 _FILEEXT_SETUP(__sF+i, __sFext+i);
180 }
181 /* Initialize the pre-allocated (but initially unused) streams. */
182 for (size_t i = 0; i < FOPEN_MAX - 3; ++i) {
183 _FILEEXT_SETUP(usual+i, usualext+i);
184 }
185
186 /* make sure we clean up on exit */
187 __atexit_register_cleanup(_cleanup); /* conservative */
188 __sdidinit = 1;
189
190 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex);
191 }
192