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 1.6 2005/01/31 22:29:40 dillon 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 "glue.h" 53 54 int __sdidinit; 55 56 #define NDYNAMIC 10 /* add ten more whenever necessary */ 57 58 #define std(flags, file) \ 59 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite} 60 /* p r w flags file _bf z cookie close read seek write */ 61 62 /* the usual - (stdin + stdout + stderr) */ 63 static FILE usual[FOPEN_MAX - 3]; 64 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 65 66 FILE __sF[3] = { 67 std(__SRD, STDIN_FILENO), /* stdin */ 68 std(__SWR, STDOUT_FILENO), /* stdout */ 69 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ 70 }; 71 72 /* 73 * note: __sglue starts the walk chain for exit flushing and other things. 74 */ 75 struct glue __sglue = { &uglue, 3, __sF }; /* GLOBAL, START OF LIST */ 76 static struct glue *lastglue = &uglue; 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 */ 85 FILE *__stdinp = &__sF[0]; 86 FILE *__stdoutp = &__sF[1]; 87 FILE *__stderrp = &__sF[2]; 88 89 static struct glue * moreglue (int); 90 91 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 92 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 93 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 94 95 #if NOT_YET 96 #define SET_GLUE_PTR(ptr, val) atomic_set_ptr(&(ptr), (uintptr_t)(val)) 97 #else 98 #define SET_GLUE_PTR(ptr, val) ptr = val 99 #endif 100 101 static 102 struct glue * 103 moreglue(int n) 104 { 105 struct glue *g; 106 FILE *p; 107 static FILE empty; 108 109 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)); 110 if (g == NULL) 111 return (NULL); 112 p = (FILE *)ALIGN(g + 1); 113 g->next = NULL; 114 g->niobs = n; 115 g->iobs = p; 116 while (--n >= 0) 117 *p++ = empty; 118 return (g); 119 } 120 121 /* 122 * Find a free FILE for fopen et al. 123 */ 124 FILE * 125 __sfp(void) 126 { 127 FILE *fp; 128 int n; 129 struct glue *g; 130 131 if (!__sdidinit) 132 __sinit(); 133 /* 134 * The list must be locked because a FILE may be updated. 135 */ 136 THREAD_LOCK(); 137 for (g = &__sglue; g != NULL; g = g->next) { 138 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 139 if (fp->_flags == 0) 140 goto found; 141 } 142 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 143 if ((g = moreglue(NDYNAMIC)) == NULL) 144 return (NULL); 145 THREAD_LOCK(); /* reacquire the lock */ 146 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 147 lastglue = g; /* not atomic; only accessed when locked */ 148 fp = g->iobs; 149 found: 150 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 151 THREAD_UNLOCK(); 152 fp->_p = NULL; /* no current pointer */ 153 fp->_w = 0; /* nothing to read or write */ 154 fp->_r = 0; 155 fp->_bf._base = NULL; /* no buffer */ 156 fp->_bf._size = 0; 157 fp->_lbfsize = 0; /* not line buffered */ 158 fp->_file = -1; /* no file */ 159 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 160 fp->_ub._base = NULL; /* no ungetc buffer */ 161 fp->_ub._size = 0; 162 fp->_lb._base = NULL; /* no line buffer */ 163 fp->_lb._size = 0; 164 /* fp->_lock = NULL; */ 165 return (fp); 166 } 167 168 /* 169 * XXX. Force immediate allocation of internal memory. Not used by stdio, 170 * but documented historically for certain applications. Bad applications. 171 */ 172 __warn_references(f_prealloc, 173 "warning: this program uses f_prealloc(), which is not recommended."); 174 175 void 176 f_prealloc(void) 177 { 178 struct glue *g; 179 int n; 180 181 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 182 /* 183 * It should be safe to walk the list without locking it; 184 * new nodes are only added to the end and none are ever 185 * removed. 186 */ 187 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 188 /* void */; 189 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 190 THREAD_LOCK(); 191 SET_GLUE_PTR(lastglue->next, g); 192 lastglue = g; 193 THREAD_UNLOCK(); 194 } 195 } 196 197 /* 198 * exit() calls _cleanup() through *__cleanup, set whenever we 199 * open or buffer a file. This chicanery is done so that programs 200 * that do not use stdio need not link it all in. 201 * 202 * The name `_cleanup' is, alas, fairly well known outside stdio. 203 */ 204 void 205 _cleanup(void) 206 { 207 /* (void) _fwalk(fclose); */ 208 (void) _fwalk(__sflush); /* `cheating' */ 209 } 210 211 /* 212 * __sinit() is called whenever stdio's internal variables must be set up. 213 */ 214 void 215 __sinit(void) 216 { 217 /* make sure we clean up on exit */ 218 __cleanup = _cleanup; /* conservative */ 219 __sdidinit = 1; 220 } 221