findfp.c
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上传日期:2007-04-14
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文件大小:5k
- /*-
- * Copyright (c) 1990 The Regents of the University of California.
- * Copyright (c) 1993, 1994 Chris Provenzano.
- * All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Chris Torek.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by the University of
- * California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
- #if defined(LIBC_SCCS) && !defined(lint)
- /*static char *sccsid = "from: @(#)findfp.c 5.10 (Berkeley) 2/24/91";*/
- static char *rcsid = "$Id$";
- #endif /* LIBC_SCCS and not lint */
- #include <pthread.h>
- #include <stdlib.h>
- #include <stdio.h>
- #include <errno.h>
- #include <string.h>
- #include "local.h"
- #include "glue.h"
- #define NSTATIC 20 /* stdin + stdout + stderr + the usual */
- #define NDYNAMIC 10 /* add ten more whenever necessary */
- #define std(flags, file)
- {0,0,0,flags,file,{0},0 }
- /* p r w flags file _bf z */
- static FILE usual[NSTATIC - 3]; /* the usual */
- static struct glue uglue = { 0, NSTATIC - 3, usual };
- FILE __sF[3] = {
- std(__SRD, 0), /* stdin */
- std(__SWR, 1), /* stdout */
- std(__SWR|__SNBF, 2) /* stderr */
- };
- struct glue __sglue = { &uglue, 3, __sF };
- FILE *__iob = __sF;
- FILE *_iob = __sF;
- pthread_mutex_t __sfp_mutex = PTHREAD_MUTEX_INITIALIZER;
- pthread_cond_t __sfp_cond = PTHREAD_COND_INITIALIZER;
- /*
- * __sfp_state = 0, when free, > 0 when in _fwalk
- * This allows multiple readers in _fwalk, but only one writer __sfp,
- * or freopen() at a time.
- */
- int __sfp_state = 0;
- static struct glue *moreglue(register int n)
- {
- register struct glue *g;
- register FILE *p;
- static FILE empty;
- g = (struct glue *)malloc(sizeof(struct glue) + n * sizeof(FILE));
- if (g == NULL)
- return (NULL);
- p = (FILE *)(g + 1);
- g->next = NULL;
- g->niobs = n;
- g->iobs = p;
- while (--n >= 0)
- *p++ = empty;
- return (g);
- }
- /*
- * Find a free FILE for fopen et al.
- */
- FILE *__sfp()
- {
- register FILE *fp;
- register int n;
- register struct glue *g;
- for (g = &__sglue;; g = g->next) {
- for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
- if (fp->_flags == 0) {
- fp->_flags = 1; /* reserve this slot; caller sets real flags */
- 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->_ub._base = NULL; /* no ungetc buffer */
- fp->_ub._size = 0;
- fp->_lb._base = NULL; /* no line buffer */
- fp->_lb._size = 0;
- goto __sfp_done;
- }
- if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL) {
- fp = NULL;
- break;
- }
- }
- __sfp_done:;
- return (fp);
- }
- /*
- * exit() calls _cleanup() through *__cleanup, set whenever we
- * open or buffer a file. This chicanery is done so that programs
- * that do not use stdio need not link it all in.
- *
- * The name `_cleanup' is, alas, fairly well known outside stdio.
- */
- void _cleanup()
- {
- (void) __swalk_sflush();
- }
- /*
- * __sinit() is called whenever stdio's internal variables must be set up.
- * Do the pthread_once stuff here to keep pthread_once_t out of the
- * header files. No reason sprintf.c &c should need to include pthread.h...
- */
- static void __s_real_init ()
- {
- /* make sure we clean up on exit */
- __cleanup = _cleanup;
- }
- static pthread_once_t sdidinit = PTHREAD_ONCE_INIT;
- void __sinit ()
- {
- pthread_once (&sdidinit, __s_real_init);
- }