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36 * @(#)findfp.c 8.2 (Berkeley) 1/4/94
37 * $FreeBSD: src/lib/libc/stdio/findfp.c,v 1.7.2.3 2001/08/17 02:56:31 peter Exp $
38 * $DragonFly: src/lib/libc/stdio/findfp.c,v 1.7 2005/05/09 12:43:40 davidxu Exp $
41 #include <sys/param.h>
42 #include <machine/atomic.h>
50 #include <libc_private.h>
56 #define NDYNAMIC 10 /* add ten more whenever necessary */
58 #define std(flags, file) \
59 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
61 /* p r w flags file _bf z cookie close read seek write */
64 /* the usual - (stdin + stdout + stderr) */
65 static FILE usual[FOPEN_MAX - 3];
66 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
67 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
69 static struct __sFILEX __sFX[3];
72 std(__SRD, STDIN_FILENO), /* stdin */
73 std(__SWR, STDOUT_FILENO), /* stdout */
74 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */
78 * note: __sglue starts the walk chain for exit flushing and other things.
80 struct glue __sglue = { &uglue, 3, __sF }; /* GLOBAL, START OF LIST */
81 static struct glue *lastglue = &uglue;
84 * The following kludge is done to ensure enough binary compatibility
85 * with future versions of libc. Or rather it allows us to work with
86 * libraries that have been built with a newer libc that defines these
87 * symbols and expects libc to provide them. We only have need to support
88 * i386 and alpha because they are the only "old" systems we have deployed.
90 FILE *__stdinp = &__sF[0];
91 FILE *__stdoutp = &__sF[1];
92 FILE *__stderrp = &__sF[2];
94 static struct glue * moreglue (int);
96 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
97 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock)
98 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
101 #define SET_GLUE_PTR(ptr, val) atomic_set_ptr(&(ptr), (uintptr_t)(val))
103 #define SET_GLUE_PTR(ptr, val) ptr = val
112 static struct __sFILEX emptyx;
116 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
117 n * sizeof(struct __sFILEX));
120 p = (FILE *)ALIGN(g + 1);
121 fx = (struct __sFILEX *)&p[n];
135 * Find a free FILE for fopen et al.
147 * The list must be locked because a FILE may be updated.
150 for (g = &__sglue; g != NULL; g = g->next) {
151 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
155 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */
156 if ((g = moreglue(NDYNAMIC)) == NULL)
158 THREAD_LOCK(); /* reacquire the lock */
159 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
160 lastglue = g; /* not atomic; only accessed when locked */
163 fp->_flags = 1; /* reserve this slot; caller sets real flags */
165 fp->_p = NULL; /* no current pointer */
166 fp->_w = 0; /* nothing to read or write */
168 fp->_bf._base = NULL; /* no buffer */
170 fp->_lbfsize = 0; /* not line buffered */
171 fp->_file = -1; /* no file */
172 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
173 fp->_ub._base = NULL; /* no ungetc buffer */
175 fp->_lb._base = NULL; /* no line buffer */
177 /* fp->_lock = NULL; */
182 * XXX. Force immediate allocation of internal memory. Not used by stdio,
183 * but documented historically for certain applications. Bad applications.
185 __warn_references(f_prealloc,
186 "warning: this program uses f_prealloc(), which is not recommended.");
194 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
196 * It should be safe to walk the list without locking it;
197 * new nodes are only added to the end and none are ever
200 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
202 if ((n > 0) && ((g = moreglue(n)) != NULL)) {
204 SET_GLUE_PTR(lastglue->next, g);
211 * exit() calls _cleanup() through *__cleanup, set whenever we
212 * open or buffer a file. This chicanery is done so that programs
213 * that do not use stdio need not link it all in.
215 * The name `_cleanup' is, alas, fairly well known outside stdio.
220 /* (void) _fwalk(fclose); */
221 (void) _fwalk(__sflush); /* `cheating' */
225 * __sinit() is called whenever stdio's internal variables must be set up.
233 if (__sdidinit == 0) {
234 /* Set _extra for the usual suspects. */
235 for (i = 0; i < FOPEN_MAX - 3; i++)
236 usual[i]._extra = &usual_extra[i];
238 /* Make sure we clean up on exit. */
239 __cleanup = _cleanup; /* conservative */