/*
* Find a free FILE for fopen et al.
*/
FILE *
__sfp(void)
{
FILE *fp;
int n;
struct glue *g;
if (!__sdidinit)
__sinit();
/*
* The list must be locked because a FILE may be updated.
*/
STDIO_THREAD_LOCK();
for (g = &__sglue; g != NULL; g = g->next) {
for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
if (fp->_flags == 0)
goto found;
}
STDIO_THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */
if ((g = moreglue(NDYNAMIC)) == NULL)
return (NULL);
STDIO_THREAD_LOCK(); /* reacquire the lock */
SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
lastglue = g; /* not atomic; only accessed when locked */
fp = g->iobs;
found:
fp->_flags = 1; /* reserve this slot; caller sets real flags */
STDIO_THREAD_UNLOCK();
fp->_p = NULL; /* no current pointer */
fp->_w = 0; /* nothing to read or write */
fp->_r = 0;
fp->_bf._base = NULL; /* no buffer */
fp->_bf._size = 0;
fp->_lbfsize = 0; /* not line buffered */
fp->_file = -1; /* no file */
/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
fp->_ub._base = NULL; /* no ungetc buffer */
fp->_ub._size = 0;
fp->_lb._base = NULL; /* no line buffer */
fp->_lb._size = 0;
/* fp->_fl_mutex = NULL; */ /* once set always set (reused) */
fp->_orientation = 0;
memset(&fp->_mbstate, 0, sizeof(mbstate_t));
return (fp);
}
void
f_prealloc(void)
{
struct glue *g;
int n;
n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */
/*
* It should be safe to walk the list without locking it;
* new nodes are only added to the end and none are ever
* removed.
*/
for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
/* void */;
if ((n > 0) && ((g = moreglue(n)) != NULL)) {
STDIO_THREAD_LOCK();
SET_GLUE_PTR(lastglue->next, g);
lastglue = g;
STDIO_THREAD_UNLOCK();
}
}
int
fclose(FILE *fp)
{
int r;
if (fp->_flags == 0) { /* not open! */
errno = EBADF;
return (EOF);
}
FLOCKFILE(fp);
r = fp->_flags & __SWR ? __sflush(fp) : 0;
if (fp->_close != NULL && (*fp->_close)(fp->_cookie) < 0)
r = EOF;
if (fp->_flags & __SMBF)
free((char *)fp->_bf._base);
if (HASUB(fp))
FREEUB(fp);
if (HASLB(fp))
FREELB(fp);
fp->_file = -1;
fp->_r = fp->_w = 0; /* Mess up if reaccessed. */
/*
* Lock the spinlock used to protect __sglue list walk in
* __sfp(). The __sfp() uses fp->_flags == 0 test as an
* indication of the unused FILE.
*
* Taking the lock prevents possible compiler or processor
* reordering of the writes performed before the final _flags
* cleanup, making sure that we are done with the FILE before
* it is considered available.
*/
STDIO_THREAD_LOCK();
fp->_flags = 0; /* Release this FILE for reuse. */
STDIO_THREAD_UNLOCK();
FUNLOCKFILE(fp);
return (r);
}
