findfp.c revision 72550
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 72550 2001-02-16 21:09:49Z imp $"; 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(flags, file) \ 63 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \ 64 {0}, __sFX + file} 65 /* p r w flags file _bf z cookie close read seek write */ 66 /* _ub _extra */ 67 /* the usual - (stdin + stdout + stderr) */ 68static FILE usual[FOPEN_MAX - 3]; 69static struct __sFILEX usual_extra[FOPEN_MAX - 3]; 70static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 71 72static struct __sFILEX __sFX[3]; 73 74FILE __sF[3] = { 75 std(__SRD, STDIN_FILENO), 76 std(__SWR, STDOUT_FILENO), 77 std(__SWR|__SNBF, STDERR_FILENO) 78}; 79 80struct glue __sglue = { &uglue, 3, __sF }; 81static struct glue *lastglue = &uglue; 82 83static struct glue * moreglue __P((int)); 84 85static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 86#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 87#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 88 89#if NOT_YET 90#define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 91#else 92#define SET_GLUE_PTR(ptr, val) ptr = val 93#endif 94 95static struct glue * 96moreglue(n) 97 int n; 98{ 99 struct glue *g; 100 static FILE empty; 101 static struct __sFILEX emptyx; 102 FILE *p; 103 struct __sFILEX *fx; 104 105 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) + 106 n * sizeof(struct __sFILEX)); 107 if (g == NULL) 108 return (NULL); 109 p = (FILE *)ALIGN(g + 1); 110 fx = (struct __sFILEX *)&p[n]; 111 g->next = NULL; 112 g->niobs = n; 113 g->iobs = p; 114 while (--n >= 0) { 115 *p = empty; 116 p->_extra = fx; 117 *p->_extra = emptyx; 118 p++, fx++; 119 } 120 return (g); 121} 122 123/* 124 * Find a free FILE for fopen et al. 125 */ 126FILE * 127__sfp() 128{ 129 FILE *fp; 130 int n; 131 struct glue *g; 132 133 if (!__sdidinit) 134 __sinit(); 135 /* 136 * The list must be locked because a FILE may be updated. 137 */ 138 THREAD_LOCK(); 139 for (g = &__sglue; g != NULL; g = g->next) { 140 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 141 if (fp->_flags == 0) 142 goto found; 143 } 144 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 145 if ((g = moreglue(NDYNAMIC)) == NULL) 146 return (NULL); 147 THREAD_LOCK(); /* reacquire the lock */ 148 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 149 lastglue = g; /* not atomic; only accessed when locked */ 150 fp = g->iobs; 151found: 152 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 153 THREAD_UNLOCK(); 154 fp->_p = NULL; /* no current pointer */ 155 fp->_w = 0; /* nothing to read or write */ 156 fp->_r = 0; 157 fp->_bf._base = NULL; /* no buffer */ 158 fp->_bf._size = 0; 159 fp->_lbfsize = 0; /* not line buffered */ 160 fp->_file = -1; /* no file */ 161/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 162 fp->_ub._base = NULL; /* no ungetc buffer */ 163 fp->_ub._size = 0; 164 fp->_lb._base = NULL; /* no line buffer */ 165 fp->_lb._size = 0; 166/* fp->_lock = NULL; */ /* once set always set (reused) */ 167 return (fp); 168} 169 170/* 171 * XXX. Force immediate allocation of internal memory. Not used by stdio, 172 * but documented historically for certain applications. Bad applications. 173 */ 174__warn_references(f_prealloc, 175 "warning: this program uses f_prealloc(), which is stupid."); 176 177void 178f_prealloc() 179{ 180 struct glue *g; 181 int n; 182 183 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 184 /* 185 * It should be safe to walk the list without locking it; 186 * new nodes are only added to the end and none are ever 187 * removed. 188 */ 189 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 190 /* void */; 191 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 192 THREAD_LOCK(); 193 SET_GLUE_PTR(lastglue->next, g); 194 lastglue = g; 195 THREAD_UNLOCK(); 196 } 197} 198 199/* 200 * exit() calls _cleanup() through *__cleanup, set whenever we 201 * open or buffer a file. This chicanery is done so that programs 202 * that do not use stdio need not link it all in. 203 * 204 * The name `_cleanup' is, alas, fairly well known outside stdio. 205 */ 206void 207_cleanup() 208{ 209 /* (void) _fwalk(fclose); */ 210 (void) _fwalk(__sflush); /* `cheating' */ 211} 212 213/* 214 * __sinit() is called whenever stdio's internal variables must be set up. 215 */ 216void 217__sinit() 218{ 219 int i; 220 221 THREAD_LOCK(); 222 if (__sdidinit == 0) { 223 /* Set _extra for the usual suspects. */ 224 for (i = 0; i < FOPEN_MAX - 3; i++) 225 usual[i]._extra = &usual_extra[i]; 226 227 /* Make sure we clean up on exit. */ 228 __cleanup = _cleanup; /* conservative */ 229 __sdidinit = 1; 230 } 231 THREAD_UNLOCK(); 232} 233