findfp.c revision 72732
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 72732 2001-02-20 01:56:52Z 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 74FILE __sF[3] = { 75 std(__SRD, STDIN_FILENO), 76 std(__SWR, STDOUT_FILENO), 77 std(__SWR|__SNBF, STDERR_FILENO) 78}; 79 80/* 81 * The following kludge is done to ensure enough binary compatibility 82 * with future versions of libc. Or rather it allows us to work with 83 * libraries that have been built with a newer libc that defines these 84 * symbols and expects libc to provide them. We only have need to support 85 * i386 and alpha because they are the only "old" systems we have deployed. 86 */ 87#if defined(__i386__) 88#define FILE_SIZE 88 89#elif defined(__alpha__) 90#define FILE_SIZE 152 91#endif 92#ifndef FILE_SIZE 93#error "You must define FILE_SIZE for this platform" 94#endif 95#define X(loc, sym) __strong_reference(loc, sym) 96X(__sF + FILE_SIZE * 0, __stdin); 97X(__sF + FILE_SIZE * 1, __stdout); 98X(__sF + FILE_SIZE * 2, __stderr); 99 100struct glue __sglue = { &uglue, 3, __sF }; 101static struct glue *lastglue = &uglue; 102 103static struct glue * moreglue __P((int)); 104 105static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 106#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 107#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 108 109#if NOT_YET 110#define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 111#else 112#define SET_GLUE_PTR(ptr, val) ptr = val 113#endif 114 115static struct glue * 116moreglue(n) 117 int n; 118{ 119 struct glue *g; 120 static FILE empty; 121 static struct __sFILEX emptyx; 122 FILE *p; 123 struct __sFILEX *fx; 124 125 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) + 126 n * sizeof(struct __sFILEX)); 127 if (g == NULL) 128 return (NULL); 129 p = (FILE *)ALIGN(g + 1); 130 fx = (struct __sFILEX *)&p[n]; 131 g->next = NULL; 132 g->niobs = n; 133 g->iobs = p; 134 while (--n >= 0) { 135 *p = empty; 136 p->_extra = fx; 137 *p->_extra = emptyx; 138 p++, fx++; 139 } 140 return (g); 141} 142 143/* 144 * Find a free FILE for fopen et al. 145 */ 146FILE * 147__sfp() 148{ 149 FILE *fp; 150 int n; 151 struct glue *g; 152 153 if (!__sdidinit) 154 __sinit(); 155 /* 156 * The list must be locked because a FILE may be updated. 157 */ 158 THREAD_LOCK(); 159 for (g = &__sglue; g != NULL; g = g->next) { 160 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 161 if (fp->_flags == 0) 162 goto found; 163 } 164 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 165 if ((g = moreglue(NDYNAMIC)) == NULL) 166 return (NULL); 167 THREAD_LOCK(); /* reacquire the lock */ 168 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 169 lastglue = g; /* not atomic; only accessed when locked */ 170 fp = g->iobs; 171found: 172 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 173 THREAD_UNLOCK(); 174 fp->_p = NULL; /* no current pointer */ 175 fp->_w = 0; /* nothing to read or write */ 176 fp->_r = 0; 177 fp->_bf._base = NULL; /* no buffer */ 178 fp->_bf._size = 0; 179 fp->_lbfsize = 0; /* not line buffered */ 180 fp->_file = -1; /* no file */ 181/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 182 fp->_ub._base = NULL; /* no ungetc buffer */ 183 fp->_ub._size = 0; 184 fp->_lb._base = NULL; /* no line buffer */ 185 fp->_lb._size = 0; 186/* fp->_lock = NULL; */ /* once set always set (reused) */ 187 return (fp); 188} 189 190/* 191 * XXX. Force immediate allocation of internal memory. Not used by stdio, 192 * but documented historically for certain applications. Bad applications. 193 */ 194__warn_references(f_prealloc, 195 "warning: this program uses f_prealloc(), which is stupid."); 196 197void 198f_prealloc() 199{ 200 struct glue *g; 201 int n; 202 203 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 204 /* 205 * It should be safe to walk the list without locking it; 206 * new nodes are only added to the end and none are ever 207 * removed. 208 */ 209 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 210 /* void */; 211 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 212 THREAD_LOCK(); 213 SET_GLUE_PTR(lastglue->next, g); 214 lastglue = g; 215 THREAD_UNLOCK(); 216 } 217} 218 219/* 220 * exit() calls _cleanup() through *__cleanup, set whenever we 221 * open or buffer a file. This chicanery is done so that programs 222 * that do not use stdio need not link it all in. 223 * 224 * The name `_cleanup' is, alas, fairly well known outside stdio. 225 */ 226void 227_cleanup() 228{ 229 /* (void) _fwalk(fclose); */ 230 (void) _fwalk(__sflush); /* `cheating' */ 231} 232 233/* 234 * __sinit() is called whenever stdio's internal variables must be set up. 235 */ 236#define SIZEMSG "WARNING: FILE_SIZE != sizeof(FILE)\n" 237void 238__sinit() 239{ 240 int i; 241 242 if (FILE_SIZE != sizeof(FILE)) 243 write(2, SIZEMSG, sizeof(SIZEMSG) - 1); 244 THREAD_LOCK(); 245 if (__sdidinit == 0) { 246 /* Set _extra for the usual suspects. */ 247 for (i = 0; i < FOPEN_MAX - 3; i++) 248 usual[i]._extra = &usual_extra[i]; 249 250 /* Make sure we clean up on exit. */ 251 __cleanup = _cleanup; /* conservative */ 252 __sdidinit = 1; 253 } 254 THREAD_UNLOCK(); 255} 256