2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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9 * modification, are permitted provided that the following conditions
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32 * @(#)findfp.c 8.2 (Berkeley) 1/4/94
33 * $FreeBSD: src/lib/libc/stdio/findfp.c,v 1.33 2009/03/01 19:25:40 das Exp $
36 #include <sys/param.h>
37 #include <machine/atomic.h>
45 #include "libc_private.h"
50 #define NDYNAMIC 10 /* add ten more whenever necessary */
52 #define std(flags, file) { \
57 ._cookie = __sF + (file), \
63 /* the usual - (stdin + stdout + stderr) */
64 static FILE usual
[FOPEN_MAX
- 3];
65 static struct glue uglue
= { NULL
, FOPEN_MAX
- 3, usual
};
67 static FILE __sF
[3] = {
68 std(__SRD
, STDIN_FILENO
),
69 std(__SWR
, STDOUT_FILENO
),
70 std(__SWR
|__SNBF
, STDERR_FILENO
)
73 FILE *__stdinp
= &__sF
[0];
74 FILE *__stdoutp
= &__sF
[1];
75 FILE *__stderrp
= &__sF
[2];
77 struct glue __sglue
= { &uglue
, 3, __sF
};
78 static struct glue
*lastglue
= &uglue
;
80 static struct glue
* moreglue(int);
82 static spinlock_t thread_lock
= _SPINLOCK_INITIALIZER
;
83 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock)
84 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
87 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
89 #define SET_GLUE_PTR(ptr, val) ptr = val
99 g
= (struct glue
*)malloc(sizeof(*g
) + ALIGNBYTES
+ n
* sizeof(FILE));
102 p
= (FILE *)ALIGN(g
+ 1);
112 * Find a free FILE for fopen et al.
124 * The list must be locked because a FILE may be updated.
127 for (g
= &__sglue
; g
!= NULL
; g
= g
->next
) {
128 for (fp
= g
->iobs
, n
= g
->niobs
; --n
>= 0; fp
++)
129 if (fp
->pub
._flags
== 0)
132 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */
133 if ((g
= moreglue(NDYNAMIC
)) == NULL
)
135 THREAD_LOCK(); /* reacquire the lock */
136 SET_GLUE_PTR(lastglue
->next
, g
); /* atomically append glue to list */
137 lastglue
= g
; /* not atomic; only accessed when locked */
140 fp
->pub
._flags
= 1; /* reserve this slot; caller sets real flags */
142 fp
->pub
._p
= NULL
; /* no current pointer */
143 fp
->pub
._w
= 0; /* nothing to read or write */
145 fp
->_bf
._base
= NULL
; /* no buffer */
147 fp
->pub
._lbfsize
= 0; /* not line buffered */
148 fp
->pub
._fileno
= -1; /* no file */
149 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
150 fp
->_ub
._base
= NULL
; /* no ungetc buffer */
152 fp
->_lb
._base
= NULL
; /* no line buffer */
154 /* fp->_lock = NULL; */ /* once set always set (reused) */
155 memset(WCIO_GET(fp
), 0, sizeof(struct wchar_io_data
));
160 * XXX. Force immediate allocation of internal memory. Not used by stdio,
161 * but documented historically for certain applications. Bad applications.
163 __warn_references(f_prealloc
,
164 "warning: this program uses f_prealloc(), which is not recommended.");
172 n
= getdtablesize() - FOPEN_MAX
+ 20; /* 20 for slop. */
174 * It should be safe to walk the list without locking it;
175 * new nodes are only added to the end and none are ever
178 for (g
= &__sglue
; (n
-= g
->niobs
) > 0 && g
->next
; g
= g
->next
)
180 if ((n
> 0) && ((g
= moreglue(n
)) != NULL
)) {
182 SET_GLUE_PTR(lastglue
->next
, g
);
189 * exit() calls _cleanup() through *__cleanup, set whenever we
190 * open or buffer a file. This chicanery is done so that programs
191 * that do not use stdio need not link it all in.
193 * The name `_cleanup' is, alas, fairly well known outside stdio.
198 /* _fwalk(fclose); */
199 _fwalk(__sflush
); /* `cheating' */
203 * __sinit() is called whenever stdio's internal variables must be set up.
209 /* Make sure we clean up on exit. */
210 __cleanup
= _cleanup
; /* conservative */