1 /*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * %sccs.include.redist.c%
9 */
10
11 #if defined(LIBC_SCCS) && !defined(lint)
12 static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 01/04/94";
13 #endif /* LIBC_SCCS and not lint */
14
15 #include <sys/param.h>
16 #include <unistd.h>
17 #include <stdio.h>
18 #include <errno.h>
19 #include <stdlib.h>
20 #include <string.h>
21 #include "local.h"
22 #include "glue.h"
23
24 int __sdidinit;
25
26 #define NDYNAMIC 10 /* add ten more whenever necessary */
27
28 #define std(flags, file) \
29 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite}
30 /* p r w flags file _bf z cookie close read seek write */
31
32 /* the usual - (stdin + stdout + stderr) */
33 static FILE usual[FOPEN_MAX - 3];
34 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
35
36 FILE __sF[3] = {
37 std(__SRD, STDIN_FILENO), /* stdin */
38 std(__SWR, STDOUT_FILENO), /* stdout */
39 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */
40 };
41 struct glue __sglue = { &uglue, 3, __sF };
42
43 static struct glue *
moreglue(n)44 moreglue(n)
45 register int n;
46 {
47 register struct glue *g;
48 register FILE *p;
49 static FILE empty;
50
51 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE));
52 if (g == NULL)
53 return (NULL);
54 p = (FILE *)ALIGN(g + 1);
55 g->next = NULL;
56 g->niobs = n;
57 g->iobs = p;
58 while (--n >= 0)
59 *p++ = empty;
60 return (g);
61 }
62
63 /*
64 * Find a free FILE for fopen et al.
65 */
66 FILE *
__sfp()67 __sfp()
68 {
69 register FILE *fp;
70 register int n;
71 register struct glue *g;
72
73 if (!__sdidinit)
74 __sinit();
75 for (g = &__sglue;; g = g->next) {
76 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
77 if (fp->_flags == 0)
78 goto found;
79 if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL)
80 break;
81 }
82 return (NULL);
83 found:
84 fp->_flags = 1; /* reserve this slot; caller sets real flags */
85 fp->_p = NULL; /* no current pointer */
86 fp->_w = 0; /* nothing to read or write */
87 fp->_r = 0;
88 fp->_bf._base = NULL; /* no buffer */
89 fp->_bf._size = 0;
90 fp->_lbfsize = 0; /* not line buffered */
91 fp->_file = -1; /* no file */
92 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
93 fp->_ub._base = NULL; /* no ungetc buffer */
94 fp->_ub._size = 0;
95 fp->_lb._base = NULL; /* no line buffer */
96 fp->_lb._size = 0;
97 return (fp);
98 }
99
100 /*
101 * XXX. Force immediate allocation of internal memory. Not used by stdio,
102 * but documented historically for certain applications. Bad applications.
103 */
f_prealloc()104 f_prealloc()
105 {
106 register struct glue *g;
107 int n;
108
109 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
110 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
111 /* void */;
112 if (n > 0)
113 g->next = moreglue(n);
114 }
115
116 /*
117 * exit() calls _cleanup() through *__cleanup, set whenever we
118 * open or buffer a file. This chicanery is done so that programs
119 * that do not use stdio need not link it all in.
120 *
121 * The name `_cleanup' is, alas, fairly well known outside stdio.
122 */
123 void
_cleanup()124 _cleanup()
125 {
126 /* (void) _fwalk(fclose); */
127 (void) _fwalk(__sflush); /* `cheating' */
128 }
129
130 /*
131 * __sinit() is called whenever stdio's internal variables must be set up.
132 */
133 void
__sinit()134 __sinit()
135 {
136 /* make sure we clean up on exit */
137 __cleanup = _cleanup; /* conservative */
138 __sdidinit = 1;
139 }
140