findfp.c revision 104941
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 104941 2002-10-11 22:38:17Z peter $"); 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 72static FILE __sF[3] = { 73 std(__SRD, STDIN_FILENO), 74 std(__SWR, STDOUT_FILENO), 75 std(__SWR|__SNBF, STDERR_FILENO) 76}; 77 78/* 79 * The following kludge is done to ensure enough binary compatibility 80 * with future versions of libc. Or rather it allows us to work with 81 * libraries that have been built with a newer libc that defines these 82 * symbols and expects libc to provide them. We only have need to support 83 * i386 and alpha because they are the only "old" systems we have deployed. 84 */ 85FILE *__stdinp = &__sF[0]; 86FILE *__stdoutp = &__sF[1]; 87FILE *__stderrp = &__sF[2]; 88 89struct glue __sglue = { &uglue, 3, __sF }; 90static struct glue *lastglue = &uglue; 91 92static struct glue * moreglue(int); 93 94static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 95#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 96#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 97 98#if NOT_YET 99#define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 100#else 101#define SET_GLUE_PTR(ptr, val) ptr = val 102#endif 103 104static struct glue * 105moreglue(n) 106 int n; 107{ 108 struct glue *g; 109 static FILE empty; 110 static struct __sFILEX emptyx; 111 FILE *p; 112 struct __sFILEX *fx; 113 114 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) + 115 n * sizeof(struct __sFILEX)); 116 if (g == NULL) 117 return (NULL); 118 p = (FILE *)ALIGN(g + 1); 119 fx = (struct __sFILEX *)&p[n]; 120 g->next = NULL; 121 g->niobs = n; 122 g->iobs = p; 123 while (--n >= 0) { 124 *p = empty; 125 p->_extra = fx; 126 *p->_extra = emptyx; 127 p++, fx++; 128 } 129 return (g); 130} 131 132/* 133 * Find a free FILE for fopen et al. 134 */ 135FILE * 136__sfp() 137{ 138 FILE *fp; 139 int n; 140 struct glue *g; 141 142 if (!__sdidinit) 143 __sinit(); 144 /* 145 * The list must be locked because a FILE may be updated. 146 */ 147 THREAD_LOCK(); 148 for (g = &__sglue; g != NULL; g = g->next) { 149 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 150 if (fp->_flags == 0) 151 goto found; 152 } 153 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 154 if ((g = moreglue(NDYNAMIC)) == NULL) 155 return (NULL); 156 THREAD_LOCK(); /* reacquire the lock */ 157 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 158 lastglue = g; /* not atomic; only accessed when locked */ 159 fp = g->iobs; 160found: 161 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 162 THREAD_UNLOCK(); 163 fp->_p = NULL; /* no current pointer */ 164 fp->_w = 0; /* nothing to read or write */ 165 fp->_r = 0; 166 fp->_bf._base = NULL; /* no buffer */ 167 fp->_bf._size = 0; 168 fp->_lbfsize = 0; /* not line buffered */ 169 fp->_file = -1; /* no file */ 170/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 171 fp->_ub._base = NULL; /* no ungetc buffer */ 172 fp->_ub._size = 0; 173 fp->_lb._base = NULL; /* no line buffer */ 174 fp->_lb._size = 0; 175/* fp->_lock = NULL; */ /* once set always set (reused) */ 176 fp->_extra->orientation = 0; 177#ifdef notdef 178 /* Stateful encoding/decoding is not yet supported. */ 179 memset(&fp->_extra->wstate, 0, sizeof(mbstate_t)); 180 memset(&fp->_extra->rstate, 0, sizeof(mbstate_t)); 181#endif 182 return (fp); 183} 184 185/* 186 * XXX. Force immediate allocation of internal memory. Not used by stdio, 187 * but documented historically for certain applications. Bad applications. 188 */ 189__warn_references(f_prealloc, 190 "warning: this program uses f_prealloc(), which is not recommended."); 191 192void 193f_prealloc() 194{ 195 struct glue *g; 196 int n; 197 198 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 199 /* 200 * It should be safe to walk the list without locking it; 201 * new nodes are only added to the end and none are ever 202 * removed. 203 */ 204 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 205 /* void */; 206 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 207 THREAD_LOCK(); 208 SET_GLUE_PTR(lastglue->next, g); 209 lastglue = g; 210 THREAD_UNLOCK(); 211 } 212} 213 214/* 215 * exit() calls _cleanup() through *__cleanup, set whenever we 216 * open or buffer a file. This chicanery is done so that programs 217 * that do not use stdio need not link it all in. 218 * 219 * The name `_cleanup' is, alas, fairly well known outside stdio. 220 */ 221void 222_cleanup() 223{ 224 /* (void) _fwalk(fclose); */ 225 (void) _fwalk(__sflush); /* `cheating' */ 226} 227 228/* 229 * __sinit() is called whenever stdio's internal variables must be set up. 230 */ 231void 232__sinit() 233{ 234 int i; 235 236 THREAD_LOCK(); 237 if (__sdidinit == 0) { 238 /* Set _extra for the usual suspects. */ 239 for (i = 0; i < FOPEN_MAX - 3; i++) 240 usual[i]._extra = &usual_extra[i]; 241 242 /* Make sure we clean up on exit. */ 243 __cleanup = _cleanup; /* conservative */ 244 __sdidinit = 1; 245 } 246 THREAD_UNLOCK(); 247} 248