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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"
47 #include "priv_stdio.h"
51 #define NDYNAMIC 10 /* add ten more whenever necessary */
53 #define std(flags, file) { \
58 ._cookie = __sF + (file), \
64 /* the usual - (stdin + stdout + stderr) */
65 static FILE usual[FOPEN_MAX - 3];
66 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
68 static FILE __sF[3] = {
69 std(__SRD, STDIN_FILENO),
70 std(__SWR, STDOUT_FILENO),
71 std(__SWR|__SNBF, STDERR_FILENO)
74 FILE *__stdinp = &__sF[0];
75 FILE *__stdoutp = &__sF[1];
76 FILE *__stderrp = &__sF[2];
78 struct glue __sglue = { &uglue, 3, __sF };
79 static struct glue *lastglue = &uglue;
81 static struct glue * moreglue(int);
83 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
84 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock)
85 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
88 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
90 #define SET_GLUE_PTR(ptr, val) ptr = val
100 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE));
103 p = (FILE *)ALIGN(g + 1);
113 * Find a free FILE for fopen et al.
125 * The list must be locked because a FILE may be updated.
128 for (g = &__sglue; g != NULL; g = g->next) {
129 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
130 if (fp->pub._flags == 0)
133 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */
134 if ((g = moreglue(NDYNAMIC)) == NULL)
136 THREAD_LOCK(); /* reacquire the lock */
137 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
138 lastglue = g; /* not atomic; only accessed when locked */
141 fp->pub._flags = 1; /* reserve this slot; caller sets real flags */
143 fp->pub._p = NULL; /* no current pointer */
144 fp->pub._w = 0; /* nothing to read or write */
146 fp->_bf._base = NULL; /* no buffer */
148 fp->pub._lbfsize = 0; /* not line buffered */
149 fp->pub._fileno = -1; /* no file */
150 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
151 fp->_ub._base = NULL; /* no ungetc buffer */
153 fp->_lb._base = NULL; /* no line buffer */
155 /* fp->_lock = NULL; */ /* once set always set (reused) */
156 memset(WCIO_GET(fp), 0, sizeof(struct wchar_io_data));
161 * XXX. Force immediate allocation of internal memory. Not used by stdio,
162 * but documented historically for certain applications. Bad applications.
164 __warn_references(f_prealloc,
165 "warning: this program uses f_prealloc(), which is not recommended.");
173 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
175 * It should be safe to walk the list without locking it;
176 * new nodes are only added to the end and none are ever
179 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
181 if ((n > 0) && ((g = moreglue(n)) != NULL)) {
183 SET_GLUE_PTR(lastglue->next, g);
190 * exit() calls _cleanup() through *__cleanup, set whenever we
191 * open or buffer a file. This chicanery is done so that programs
192 * that do not use stdio need not link it all in.
194 * The name `_cleanup' is, alas, fairly well known outside stdio.
199 /* _fwalk(fclose); */
200 _fwalk(__sflush); /* `cheating' */
204 * __sinit() is called whenever stdio's internal variables must be set up.
210 /* Make sure we clean up on exit. */
211 __cleanup = _cleanup; /* conservative */