findfp.c revision 72529
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 72529 2001-02-16 06:11:22Z 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 glue uglue = { NULL, FOPEN_MAX - 3, usual }; 70 71static struct __sFILEX __sFX[3]; 72 73FILE __sF[3] = { 74 std(__SRD, STDIN_FILENO), 75 std(__SWR, STDOUT_FILENO), 76 std(__SWR|__SNBF, STDERR_FILENO) 77}; 78 79struct glue __sglue = { &uglue, 3, __sF }; 80static struct glue *lastglue = &uglue; 81 82static struct glue * moreglue __P((int)); 83 84static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 85#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 86#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 87 88#if NOT_YET 89#define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 90#else 91#define SET_GLUE_PTR(ptr, val) ptr = val 92#endif 93 94static struct glue * 95moreglue(n) 96 int n; 97{ 98 struct glue *g; 99 static FILE empty; 100 static struct __sFILEX emptyx; 101 FILE *p; 102 struct __sFILEX *fx; 103 104 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) + 105 n * sizeof(struct __sFILEX)); 106 if (g == NULL) 107 return (NULL); 108 p = (FILE *)ALIGN(g + 1); 109 fx = (struct __sFILEX *)&p[n]; 110 g->next = NULL; 111 g->niobs = n; 112 g->iobs = p; 113 while (--n >= 0) { 114 *p = empty; 115 p->_extra = fx; 116 *p->_extra = emptyx; 117 p++, fx++; 118 } 119 return (g); 120} 121 122/* 123 * Find a free FILE for fopen et al. 124 */ 125FILE * 126__sfp() 127{ 128 FILE *fp; 129 int n; 130 struct glue *g; 131 132 if (!__sdidinit) 133 __sinit(); 134 /* 135 * The list must be locked because a FILE may be updated. 136 */ 137 THREAD_LOCK(); 138 for (g = &__sglue; g != NULL; g = g->next) { 139 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 140 if (fp->_flags == 0) 141 goto found; 142 } 143 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 144 if ((g = moreglue(NDYNAMIC)) == NULL) 145 return (NULL); 146 THREAD_LOCK(); /* reacquire the lock */ 147 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 148 lastglue = g; /* not atomic; only accessed when locked */ 149 fp = g->iobs; 150found: 151 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 152 THREAD_UNLOCK(); 153 fp->_p = NULL; /* no current pointer */ 154 fp->_w = 0; /* nothing to read or write */ 155 fp->_r = 0; 156 fp->_bf._base = NULL; /* no buffer */ 157 fp->_bf._size = 0; 158 fp->_lbfsize = 0; /* not line buffered */ 159 fp->_file = -1; /* no file */ 160/* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 161 fp->_ub._base = NULL; /* no ungetc buffer */ 162 fp->_ub._size = 0; 163 fp->_lb._base = NULL; /* no line buffer */ 164 fp->_lb._size = 0; 165/* fp->_lock = NULL; */ /* once set always set (reused) */ 166 return (fp); 167} 168 169/* 170 * XXX. Force immediate allocation of internal memory. Not used by stdio, 171 * but documented historically for certain applications. Bad applications. 172 */ 173__warn_references(f_prealloc, 174 "warning: this program uses f_prealloc(), which is stupid."); 175 176void 177f_prealloc() 178{ 179 struct glue *g; 180 int n; 181 182 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 183 /* 184 * It should be safe to walk the list without locking it; 185 * new nodes are only added to the end and none are ever 186 * removed. 187 */ 188 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 189 /* void */; 190 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 191 THREAD_LOCK(); 192 SET_GLUE_PTR(lastglue->next, g); 193 lastglue = g; 194 THREAD_UNLOCK(); 195 } 196} 197 198/* 199 * exit() calls _cleanup() through *__cleanup, set whenever we 200 * open or buffer a file. This chicanery is done so that programs 201 * that do not use stdio need not link it all in. 202 * 203 * The name `_cleanup' is, alas, fairly well known outside stdio. 204 */ 205void 206_cleanup() 207{ 208 /* (void) _fwalk(fclose); */ 209 (void) _fwalk(__sflush); /* `cheating' */ 210} 211 212/* 213 * __sinit() is called whenever stdio's internal variables must be set up. 214 */ 215void 216__sinit() 217{ 218 /* Make sure we clean up on exit. */ 219 __cleanup = _cleanup; /* conservative */ 220 __sdidinit = 1; 221} 222