findfp.c revision 81600
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 81600 2001-08-13 21:48:44Z 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(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 74#if LIBC_MAJOR >= 6 75static 76#endif 77FILE __sF[3] = { 78 std(__SRD, STDIN_FILENO), 79 std(__SWR, STDOUT_FILENO), 80 std(__SWR|__SNBF, STDERR_FILENO) 81}; 82 83/* 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. 89 */ 90FILE *__stdinp = &__sF[0]; 91FILE *__stdoutp = &__sF[1]; 92FILE *__stderrp = &__sF[2]; 93 94struct glue __sglue = { &uglue, 3, __sF }; 95static struct glue *lastglue = &uglue; 96 97static struct glue * moreglue __P((int)); 98 99static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 100#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 101#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 102 103#if NOT_YET 104#define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 105#else 106#define SET_GLUE_PTR(ptr, val) ptr = val 107#endif 108 109static struct glue * 110moreglue(n) 111 int n; 112{ 113 struct glue *g; 114 static FILE empty; 115 static struct __sFILEX emptyx; 116 FILE *p; 117 struct __sFILEX *fx; 118 119 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) + 120 n * sizeof(struct __sFILEX)); 121 if (g == NULL) 122 return (NULL); 123 p = (FILE *)ALIGN(g + 1); 124 fx = (struct __sFILEX *)&p[n]; 125 g->next = NULL; 126 g->niobs = n; 127 g->iobs = p; 128 while (--n >= 0) { 129 *p = empty; 130 p->_extra = fx; 131 *p->_extra = emptyx; 132 p++, fx++; 133 } 134 return (g); 135} 136 137/* 138 * Find a free FILE for fopen et al. 139 */ 140FILE * 141__sfp() 142{ 143 FILE *fp; 144 int n; 145 struct glue *g; 146 147 if (!__sdidinit) 148 __sinit(); 149 /* 150 * The list must be locked because a FILE may be updated. 151 */ 152 THREAD_LOCK(); 153 for (g = &__sglue; g != NULL; g = g->next) { 154 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 155 if (fp->_flags == 0) 156 goto found; 157 } 158 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 159 if ((g = moreglue(NDYNAMIC)) == NULL) 160 return (NULL); 161 THREAD_LOCK(); /* reacquire the lock */ 162 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 163 lastglue = g; /* not atomic; only accessed when locked */ 164 fp = g->iobs; 165found: 166 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 167 THREAD_UNLOCK(); 168 fp->_p = NULL; /* no current pointer */ 169 fp->_w = 0; /* nothing to read or write */ 170 fp->_r = 0; 171 fp->_bf._base = NULL; /* no buffer */ 172 fp->_bf._size = 0; 173 fp->_lbfsize = 0; /* not line buffered */ 174 fp->_file = -1; /* no file */ 175/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 176 fp->_ub._base = NULL; /* no ungetc buffer */ 177 fp->_ub._size = 0; 178 fp->_lb._base = NULL; /* no line buffer */ 179 fp->_lb._size = 0; 180/* fp->_lock = NULL; */ /* once set always set (reused) */ 181 return (fp); 182} 183 184/* 185 * XXX. Force immediate allocation of internal memory. Not used by stdio, 186 * but documented historically for certain applications. Bad applications. 187 */ 188__warn_references(f_prealloc, 189 "warning: this program uses f_prealloc(), which is not recommended."); 190 191void 192f_prealloc() 193{ 194 struct glue *g; 195 int n; 196 197 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 198 /* 199 * It should be safe to walk the list without locking it; 200 * new nodes are only added to the end and none are ever 201 * removed. 202 */ 203 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 204 /* void */; 205 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 206 THREAD_LOCK(); 207 SET_GLUE_PTR(lastglue->next, g); 208 lastglue = g; 209 THREAD_UNLOCK(); 210 } 211} 212 213/* 214 * exit() calls _cleanup() through *__cleanup, set whenever we 215 * open or buffer a file. This chicanery is done so that programs 216 * that do not use stdio need not link it all in. 217 * 218 * The name `_cleanup' is, alas, fairly well known outside stdio. 219 */ 220void 221_cleanup() 222{ 223 /* (void) _fwalk(fclose); */ 224 (void) _fwalk(__sflush); /* `cheating' */ 225} 226 227/* 228 * __sinit() is called whenever stdio's internal variables must be set up. 229 */ 230void 231__sinit() 232{ 233 int i; 234 235 THREAD_LOCK(); 236 if (__sdidinit == 0) { 237 /* Set _extra for the usual suspects. */ 238 for (i = 0; i < FOPEN_MAX - 3; i++) 239 usual[i]._extra = &usual_extra[i]; 240 241 /* Make sure we clean up on exit. */ 242 __cleanup = _cleanup; /* conservative */ 243 __sdidinit = 1; 244 } 245 THREAD_UNLOCK(); 246} 247