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
43 int __sdidinit;
44
45 #define NDYNAMIC 10 /* add ten more whenever necessary */
46
47 #define std(flags, file) \
48 {0,0,0,flags,file,{0,0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
49 {(unsigned char *)(__sFext+file), 0},NULL,0,{0,0,0},{0},{0,0},0,0}
50 /* p r w flags file _bf z cookie close read seek write
51 ext */
52
53 /* the usual - (stdin + stdout + stderr) */
54 static FILE usual[FOPEN_MAX - 3];
55 static struct __sfileext usualext[FOPEN_MAX - 3];
56 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
57
58 struct __sfileext __sFext[3];
59 FILE __sF[3] = {
60 std(__SRD, STDIN_FILENO), /* stdin */
61 std(__SWR, STDOUT_FILENO), /* stdout */
62 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */
63 };
64 struct glue __sglue = { &uglue, 3, __sF };
65
66 static struct glue *
moreglue(int n)67 moreglue(int n)
68 {
69 struct glue *g;
70 FILE *p;
71 struct __sfileext *pext;
72 static FILE empty;
73 char *data;
74
75 data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)
76 + n * sizeof(struct __sfileext));
77 if (data == NULL)
78 return (NULL);
79 g = (struct glue *)data;
80 p = (FILE *)ALIGN(data + sizeof(*g));
81 pext = (struct __sfileext *)
82 (ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
83 g->next = NULL;
84 g->niobs = n;
85 g->iobs = p;
86 while (--n >= 0) {
87 *p = empty;
88 _FILEEXT_SETUP(p, pext);
89 p++;
90 pext++;
91 }
92 return (g);
93 }
94
95 /*
96 * Find a free FILE for fopen et al.
97 */
98 FILE *
__sfp(void)99 __sfp(void)
100 {
101 FILE *fp;
102 int n;
103 struct glue *g;
104
105 if (!__sdidinit)
106 __sinit();
107 for (g = &__sglue;; g = g->next) {
108 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
109 if (fp->_flags == 0)
110 goto found;
111 if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL)
112 break;
113 }
114 return (NULL);
115 found:
116 fp->_flags = 1; /* reserve this slot; caller sets real flags */
117 fp->_p = NULL; /* no current pointer */
118 fp->_w = 0; /* nothing to read or write */
119 fp->_r = 0;
120 fp->_bf._base = NULL; /* no buffer */
121 fp->_bf._size = 0;
122 fp->_lbfsize = 0; /* not line buffered */
123 fp->_file = -1; /* no file */
124 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
125 fp->_lb._base = NULL; /* no line buffer */
126 fp->_lb._size = 0;
127 _FILEEXT_INIT(fp);
128 return (fp);
129 }
130
131 #if 0
132 #define getdtablesize() sysconf(_SC_OPEN_MAX)
133
134 /*
135 * XXX. Force immediate allocation of internal memory. Not used by stdio,
136 * but documented historically for certain applications. Bad applications.
137 */
138 void
139 f_prealloc(void)
140 {
141 struct glue *g;
142 int n;
143
144 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
145 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
146 /* void */;
147 if (n > 0)
148 g->next = moreglue(n);
149 }
150 #endif
151
152 /*
153 * exit() and abort() call _cleanup() through the callback registered
154 * with __atexit_register_cleanup(), set whenever we open or buffer a
155 * file. This chicanery is done so that programs that do not use stdio
156 * need not link it all in.
157 *
158 * The name `_cleanup' is, alas, fairly well known outside stdio.
159 */
160 void
_cleanup(void)161 _cleanup(void)
162 {
163 /* (void) _fwalk(fclose); */
164 (void) _fwalk(__sflush); /* `cheating' */
165 }
166
167 /*
168 * __sinit() is called whenever stdio's internal variables must be set up.
169 */
170 void
__sinit(void)171 __sinit(void)
172 {
173 int i;
174
175 for (i = 0; i < FOPEN_MAX - 3; i++) {
176 _FILEEXT_SETUP(usual+i, usualext+i);
177 }
178 /* make sure we clean up on exit */
179 __atexit_register_cleanup(_cleanup); /* conservative */
180 __sdidinit = 1;
181 }
182