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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 * exit() calls _cleanup() through *__cleanup, set whenever we
161 * open or buffer a file. This chicanery is done so that programs
162 * that do not use stdio need not link it all in.
164 * The name `_cleanup' is, alas, fairly well known outside stdio.
169 /* _fwalk(fclose); */
170 _fwalk(__sflush); /* `cheating' */
174 * __sinit() is called whenever stdio's internal variables must be set up.
180 /* Make sure we clean up on exit. */
181 __cleanup = _cleanup; /* conservative */