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 * @(#)findfp.c 8.2 (Berkeley) 1/4/94 37 * $FreeBSD: src/lib/libc/stdio/findfp.c,v 1.7.2.3 2001/08/17 02:56:31 peter Exp $ 38 * $DragonFly: src/lib/libc/stdio/findfp.c,v 1.8 2005/07/23 20:23:06 joerg Exp $ 39 */ 40 41 #include <sys/param.h> 42 #include <machine/atomic.h> 43 #include <unistd.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 48 #include <spinlock.h> 49 50 #include <libc_private.h> 51 #include "local.h" 52 #include "priv_stdio.h" 53 54 int __sdidinit; 55 56 #define NDYNAMIC 10 /* add ten more whenever necessary */ 57 58 #define std(flags, file) \ 59 {{0,flags,file,0,0,0},{NULL, 0},__sF+file,__sclose,__sread,__sseek,__swrite, \ 60 {NULL,0}, __sFX + file, 0, {0,0,0}, {0}, {NULL,0}, 0,0 } 61 /* p flags file r w _bf cookie close read seek write */ 62 /* _ub _extra */ 63 64 /* the usual - (stdin + stdout + stderr) */ 65 static FILE usual[FOPEN_MAX - 3]; 66 static struct __sFILEX usual_extra[FOPEN_MAX - 3]; 67 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 68 69 static struct __sFILEX __sFX[3]; 70 71 FILE __sF[3] = { 72 std(__SRD, STDIN_FILENO), /* stdin */ 73 std(__SWR, STDOUT_FILENO), /* stdout */ 74 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ 75 }; 76 77 /* 78 * note: __sglue starts the walk chain for exit flushing and other things. 79 */ 80 struct glue __sglue = { &uglue, 3, __sF }; /* GLOBAL, START OF LIST */ 81 static struct glue *lastglue = &uglue; 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 */ 90 FILE *__stdinp = &__sF[0]; 91 FILE *__stdoutp = &__sF[1]; 92 FILE *__stderrp = &__sF[2]; 93 94 static struct glue * moreglue (int); 95 96 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 97 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 98 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 99 100 #if NOT_YET 101 #define SET_GLUE_PTR(ptr, val) atomic_set_ptr(&(ptr), (uintptr_t)(val)) 102 #else 103 #define SET_GLUE_PTR(ptr, val) ptr = val 104 #endif 105 106 static 107 struct glue * 108 moreglue(int n) 109 { 110 struct glue *g; 111 static FILE empty; 112 static struct __sFILEX emptyx; 113 FILE *p; 114 struct __sFILEX *fx; 115 116 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) + 117 n * sizeof(struct __sFILEX)); 118 if (g == NULL) 119 return (NULL); 120 p = (FILE *)ALIGN(g + 1); 121 fx = (struct __sFILEX *)&p[n]; 122 g->next = NULL; 123 g->niobs = n; 124 g->iobs = p; 125 while (--n >= 0) { 126 *p = empty; 127 p->_extra = fx; 128 *p->_extra = emptyx; 129 p++, fx++; 130 } 131 return (g); 132 } 133 134 /* 135 * Find a free FILE for fopen et al. 136 */ 137 FILE * 138 __sfp(void) 139 { 140 FILE *fp; 141 int n; 142 struct glue *g; 143 144 if (!__sdidinit) 145 __sinit(); 146 /* 147 * The list must be locked because a FILE may be updated. 148 */ 149 THREAD_LOCK(); 150 for (g = &__sglue; g != NULL; g = g->next) { 151 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 152 if (fp->pub._flags == 0) 153 goto found; 154 } 155 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 156 if ((g = moreglue(NDYNAMIC)) == NULL) 157 return (NULL); 158 THREAD_LOCK(); /* reacquire the lock */ 159 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 160 lastglue = g; /* not atomic; only accessed when locked */ 161 fp = g->iobs; 162 found: 163 fp->pub._flags = 1; /* reserve this slot; caller sets real flags */ 164 THREAD_UNLOCK(); 165 fp->pub._p = NULL; /* no current pointer */ 166 fp->pub._w = 0; /* nothing to read or write */ 167 fp->pub._r = 0; 168 fp->_bf._base = NULL; /* no buffer */ 169 fp->_bf._size = 0; 170 fp->pub._lbfsize = 0; /* not line buffered */ 171 fp->pub._fileno = -1; /* no file */ 172 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 173 fp->_ub._base = NULL; /* no ungetc buffer */ 174 fp->_ub._size = 0; 175 fp->_lb._base = NULL; /* no line buffer */ 176 fp->_lb._size = 0; 177 /* fp->_lock = NULL; */ 178 return (fp); 179 } 180 181 /* 182 * XXX. Force immediate allocation of internal memory. Not used by stdio, 183 * but documented historically for certain applications. Bad applications. 184 */ 185 void f_prealloc(void); 186 187 __warn_references(f_prealloc, 188 "warning: this program uses f_prealloc(), which is not recommended."); 189 190 void 191 f_prealloc(void) 192 { 193 struct glue *g; 194 int n; 195 196 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 197 /* 198 * It should be safe to walk the list without locking it; 199 * new nodes are only added to the end and none are ever 200 * removed. 201 */ 202 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 203 /* void */; 204 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 205 THREAD_LOCK(); 206 SET_GLUE_PTR(lastglue->next, g); 207 lastglue = g; 208 THREAD_UNLOCK(); 209 } 210 } 211 212 /* 213 * exit() calls _cleanup() through *__cleanup, set whenever we 214 * open or buffer a file. This chicanery is done so that programs 215 * that do not use stdio need not link it all in. 216 * 217 * The name `_cleanup' is, alas, fairly well known outside stdio. 218 */ 219 void 220 _cleanup(void) 221 { 222 /* (void) _fwalk(fclose); */ 223 (void) _fwalk(__sflush); /* `cheating' */ 224 } 225 226 /* 227 * __sinit() is called whenever stdio's internal variables must be set up. 228 */ 229 void 230 __sinit(void) 231 { 232 int i; 233 234 THREAD_LOCK(); 235 if (__sdidinit == 0) { 236 /* Set _extra for the usual suspects. */ 237 for (i = 0; i < FOPEN_MAX - 3; i++) 238 usual[i]._extra = &usual_extra[i]; 239 240 /* Make sure we clean up on exit. */ 241 __cleanup = _cleanup; /* conservative */ 242 __sdidinit = 1; 243 } 244 THREAD_UNLOCK(); 245 } 246