findfp.c revision 72472
1/*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#if defined(LIBC_SCCS) && !defined(lint) 38#if 0 39static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94"; 40#endif 41static const char rcsid[] = 42 "$FreeBSD: head/lib/libc/stdio/findfp.c 72472 2001-02-14 05:00:20Z peter $"; 43#endif /* LIBC_SCCS and not lint */ 44 45#include <sys/param.h> 46#include <machine/atomic.h> 47#include <unistd.h> 48#include <stdio.h> 49#include <stdlib.h> 50#include <string.h> 51 52#include <spinlock.h> 53 54#include "libc_private.h" 55#include "local.h" 56#include "glue.h" 57 58int __sdidinit; 59 60#define NDYNAMIC 10 /* add ten more whenever necessary */ 61 62#define std(handle, flags, file) \ 63FILE handle = {0,0,0,flags,file,{0},0,&handle,__sclose,__sread,__sseek,__swrite} 64/* p r w flags file _bf z cookie close read seek write */ 65 66 /* the usual - (stdin + stdout + stderr) */ 67static FILE usual[FOPEN_MAX - 3]; 68static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 69 70std(__stdin, __SRD, STDIN_FILENO); 71std(__stdout, __SWR, STDOUT_FILENO); 72std(__stderr, __SWR|__SNBF, STDERR_FILENO); 73 74static struct glue sglue2 = { &uglue, 1, &__stderr }; 75static struct glue sglue1 = { &sglue2, 1, &__stdout }; 76struct glue __sglue = { &sglue1, 1, &__stdin }; 77static struct glue *lastglue = &uglue; 78 79static struct glue * moreglue __P((int)); 80 81static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 82#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 83#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 84 85#if NOT_YET 86#define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 87#else 88#define SET_GLUE_PTR(ptr, val) ptr = val 89#endif 90 91static struct glue * 92moreglue(n) 93 int n; 94{ 95 struct glue *g; 96 FILE *p; 97 static FILE empty; 98 99 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)); 100 if (g == NULL) 101 return (NULL); 102 p = (FILE *)ALIGN(g + 1); 103 g->next = NULL; 104 g->niobs = n; 105 g->iobs = p; 106 while (--n >= 0) 107 *p++ = empty; 108 return (g); 109} 110 111/* 112 * Find a free FILE for fopen et al. 113 */ 114FILE * 115__sfp() 116{ 117 FILE *fp; 118 int n; 119 struct glue *g; 120 121 if (!__sdidinit) 122 __sinit(); 123 /* 124 * The list must be locked because a FILE may be updated. 125 */ 126 THREAD_LOCK(); 127 for (g = &__sglue; g != NULL; g = g->next) { 128 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 129 if (fp->_flags == 0) 130 goto found; 131 } 132 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 133 if ((g = moreglue(NDYNAMIC)) == NULL) 134 return (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 */ 138 fp = g->iobs; 139found: 140 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 141 THREAD_UNLOCK(); 142 fp->_p = NULL; /* no current pointer */ 143 fp->_w = 0; /* nothing to read or write */ 144 fp->_r = 0; 145 fp->_bf._base = NULL; /* no buffer */ 146 fp->_bf._size = 0; 147 fp->_lbfsize = 0; /* not line buffered */ 148 fp->_file = -1; /* no file */ 149/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 150 fp->_ub._base = NULL; /* no ungetc buffer */ 151 fp->_ub._size = 0; 152 fp->_lb._base = NULL; /* no line buffer */ 153 fp->_lb._size = 0; 154/* fp->_lock = NULL; */ /* once set always set (reused) */ 155 return (fp); 156} 157 158/* 159 * XXX. Force immediate allocation of internal memory. Not used by stdio, 160 * but documented historically for certain applications. Bad applications. 161 */ 162__warn_references(f_prealloc, 163 "warning: this program uses f_prealloc(), which is stupid."); 164 165void 166f_prealloc() 167{ 168 struct glue *g; 169 int n; 170 171 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 172 /* 173 * It should be safe to walk the list without locking it; 174 * new nodes are only added to the end and none are ever 175 * removed. 176 */ 177 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 178 /* void */; 179 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 180 THREAD_LOCK(); 181 SET_GLUE_PTR(lastglue->next, g); 182 lastglue = g; 183 THREAD_UNLOCK(); 184 } 185} 186 187/* 188 * exit() calls _cleanup() through *__cleanup, set whenever we 189 * open or buffer a file. This chicanery is done so that programs 190 * that do not use stdio need not link it all in. 191 * 192 * The name `_cleanup' is, alas, fairly well known outside stdio. 193 */ 194void 195_cleanup() 196{ 197 /* (void) _fwalk(fclose); */ 198 (void) _fwalk(__sflush); /* `cheating' */ 199} 200 201/* 202 * __sinit() is called whenever stdio's internal variables must be set up. 203 */ 204void 205__sinit() 206{ 207 /* Make sure we clean up on exit. */ 208 __cleanup = _cleanup; /* conservative */ 209 __sdidinit = 1; 210} 211