findfp.c revision 129583
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) 38static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94"; 39#endif /* LIBC_SCCS and not lint */ 40#include <sys/cdefs.h> 41__FBSDID("$FreeBSD: head/lib/libc/stdio/findfp.c 129583 2004-05-22 15:19:41Z tjr $"); 42 43#include <sys/param.h> 44#include <machine/atomic.h> 45#include <unistd.h> 46#include <stdio.h> 47#include <stdlib.h> 48#include <string.h> 49 50#include <spinlock.h> 51 52#include "libc_private.h" 53#include "local.h" 54#include "glue.h" 55 56int __sdidinit; 57 58#define NDYNAMIC 10 /* add ten more whenever necessary */ 59 60#define std(flags, file) \ 61 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \ 62 {0}, __sFX + file} 63 /* p r w flags file _bf z cookie close read seek write */ 64 /* _ub _extra */ 65 /* the usual - (stdin + stdout + stderr) */ 66static FILE usual[FOPEN_MAX - 3]; 67static struct __sFILEX usual_extra[FOPEN_MAX - 3]; 68static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 69 70static struct __sFILEX __sFX[3]; 71 72/* 73 * We can't make this 'static' until 6.0-current due to binary 74 * compatibility concerns. This also means we cannot change the 75 * sizeof(FILE) until that time either and must continue to use the 76 * __sFILEX stuff to add to FILE. 77 */ 78FILE __sF[3] = { 79 std(__SRD, STDIN_FILENO), 80 std(__SWR, STDOUT_FILENO), 81 std(__SWR|__SNBF, STDERR_FILENO) 82}; 83 84/* 85 * The following kludge is done to ensure enough binary compatibility 86 * with future versions of libc. Or rather it allows us to work with 87 * libraries that have been built with a newer libc that defines these 88 * symbols and expects libc to provide them. We only have need to support 89 * i386 and alpha because they are the only "old" systems we have deployed. 90 */ 91FILE *__stdinp = &__sF[0]; 92FILE *__stdoutp = &__sF[1]; 93FILE *__stderrp = &__sF[2]; 94 95struct glue __sglue = { &uglue, 3, __sF }; 96static struct glue *lastglue = &uglue; 97 98static struct glue * moreglue(int); 99 100static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 101#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 102#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 103 104#if NOT_YET 105#define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 106#else 107#define SET_GLUE_PTR(ptr, val) ptr = val 108#endif 109 110static struct glue * 111moreglue(n) 112 int n; 113{ 114 struct glue *g; 115 static FILE empty; 116 static struct __sFILEX emptyx; 117 FILE *p; 118 struct __sFILEX *fx; 119 120 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) + 121 n * sizeof(struct __sFILEX)); 122 if (g == NULL) 123 return (NULL); 124 p = (FILE *)ALIGN(g + 1); 125 fx = (struct __sFILEX *)&p[n]; 126 g->next = NULL; 127 g->niobs = n; 128 g->iobs = p; 129 while (--n >= 0) { 130 *p = empty; 131 p->_extra = fx; 132 *p->_extra = emptyx; 133 p++, fx++; 134 } 135 return (g); 136} 137 138/* 139 * Find a free FILE for fopen et al. 140 */ 141FILE * 142__sfp() 143{ 144 FILE *fp; 145 int n; 146 struct glue *g; 147 148 if (!__sdidinit) 149 __sinit(); 150 /* 151 * The list must be locked because a FILE may be updated. 152 */ 153 THREAD_LOCK(); 154 for (g = &__sglue; g != NULL; g = g->next) { 155 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 156 if (fp->_flags == 0) 157 goto found; 158 } 159 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 160 if ((g = moreglue(NDYNAMIC)) == NULL) 161 return (NULL); 162 THREAD_LOCK(); /* reacquire the lock */ 163 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 164 lastglue = g; /* not atomic; only accessed when locked */ 165 fp = g->iobs; 166found: 167 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 168 THREAD_UNLOCK(); 169 fp->_p = NULL; /* no current pointer */ 170 fp->_w = 0; /* nothing to read or write */ 171 fp->_r = 0; 172 fp->_bf._base = NULL; /* no buffer */ 173 fp->_bf._size = 0; 174 fp->_lbfsize = 0; /* not line buffered */ 175 fp->_file = -1; /* no file */ 176/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 177 fp->_ub._base = NULL; /* no ungetc buffer */ 178 fp->_ub._size = 0; 179 fp->_lb._base = NULL; /* no line buffer */ 180 fp->_lb._size = 0; 181/* fp->_lock = NULL; */ /* once set always set (reused) */ 182 fp->_extra->orientation = 0; 183 memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t)); 184 return (fp); 185} 186 187/* 188 * XXX. Force immediate allocation of internal memory. Not used by stdio, 189 * but documented historically for certain applications. Bad applications. 190 */ 191__warn_references(f_prealloc, 192 "warning: this program uses f_prealloc(), which is not recommended."); 193 194void 195f_prealloc() 196{ 197 struct glue *g; 198 int n; 199 200 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 201 /* 202 * It should be safe to walk the list without locking it; 203 * new nodes are only added to the end and none are ever 204 * removed. 205 */ 206 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 207 /* void */; 208 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 209 THREAD_LOCK(); 210 SET_GLUE_PTR(lastglue->next, g); 211 lastglue = g; 212 THREAD_UNLOCK(); 213 } 214} 215 216/* 217 * exit() calls _cleanup() through *__cleanup, set whenever we 218 * open or buffer a file. This chicanery is done so that programs 219 * that do not use stdio need not link it all in. 220 * 221 * The name `_cleanup' is, alas, fairly well known outside stdio. 222 */ 223void 224_cleanup() 225{ 226 /* (void) _fwalk(fclose); */ 227 (void) _fwalk(__sflush); /* `cheating' */ 228} 229 230/* 231 * __sinit() is called whenever stdio's internal variables must be set up. 232 */ 233void 234__sinit() 235{ 236 int i; 237 238 THREAD_LOCK(); 239 if (__sdidinit == 0) { 240 /* Set _extra for the usual suspects. */ 241 for (i = 0; i < FOPEN_MAX - 3; i++) 242 usual[i]._extra = &usual_extra[i]; 243 244 /* Make sure we clean up on exit. */ 245 __cleanup = _cleanup; /* conservative */ 246 __sdidinit = 1; 247 } 248 THREAD_UNLOCK(); 249} 250