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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)findfp.c 8.2 (Berkeley) 1/4/94 33 * $FreeBSD: src/lib/libc/stdio/findfp.c,v 1.33 2009/03/01 19:25:40 das Exp $ 34 */ 35 36 #include <sys/param.h> 37 #include <machine/atomic.h> 38 #include <unistd.h> 39 #include <stdio.h> 40 #include <stdlib.h> 41 #include <string.h> 42 43 #include <spinlock.h> 44 45 #include "libc_private.h" 46 #include "local.h" 47 48 int __sdidinit; 49 50 #define NDYNAMIC 10 /* add ten more whenever necessary */ 51 52 #define std(flags, file) { \ 53 .pub = { \ 54 ._flags = (flags), \ 55 ._fileno = (file), \ 56 }, \ 57 ._cookie = __sF + (file), \ 58 ._close = __sclose, \ 59 ._read = __sread, \ 60 ._seek = __sseek, \ 61 ._write = __swrite, \ 62 } 63 /* the usual - (stdin + stdout + stderr) */ 64 static FILE usual[FOPEN_MAX - 3]; 65 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 66 67 static FILE __sF[3] = { 68 std(__SRD, STDIN_FILENO), 69 std(__SWR, STDOUT_FILENO), 70 std(__SWR|__SNBF, STDERR_FILENO) 71 }; 72 73 FILE *__stdinp = &__sF[0]; 74 FILE *__stdoutp = &__sF[1]; 75 FILE *__stderrp = &__sF[2]; 76 77 struct glue __sglue = { &uglue, 3, __sF }; 78 static struct glue *lastglue = &uglue; 79 80 static struct glue * moreglue(int); 81 82 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 83 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 84 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 85 86 #if NOT_YET 87 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 88 #else 89 #define SET_GLUE_PTR(ptr, val) ptr = val 90 #endif 91 92 static struct glue * 93 moreglue(int n) 94 { 95 struct glue *g; 96 static FILE empty; 97 FILE *p; 98 99 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)); 100 if (g == NULL) 101 return (NULL); 102 p = (FILE *)ALIGN(g + 1); 103 g->next = NULL; 104 g->niobs = n; 105 g->iobs = p; 106 while (--n >= 0) 107 *p++ = empty; 108 return (g); 109 } 110 111 /* 112 * Find a free FILE for fopen et al. 113 */ 114 FILE * 115 __sfp(void) 116 { 117 FILE *fp; 118 int n; 119 struct glue *g; 120 121 if (!__sdidinit) 122 __sinit(); 123 /* 124 * The list must be locked because a FILE may be updated. 125 */ 126 THREAD_LOCK(); 127 for (g = &__sglue; g != NULL; g = g->next) { 128 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 129 if (fp->pub._flags == 0) 130 goto found; 131 } 132 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 133 if ((g = moreglue(NDYNAMIC)) == NULL) 134 return (NULL); 135 THREAD_LOCK(); /* reacquire the lock */ 136 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 137 lastglue = g; /* not atomic; only accessed when locked */ 138 fp = g->iobs; 139 found: 140 fp->pub._flags = 1; /* reserve this slot; caller sets real flags */ 141 THREAD_UNLOCK(); 142 fp->pub._p = NULL; /* no current pointer */ 143 fp->pub._w = 0; /* nothing to read or write */ 144 fp->pub._r = 0; 145 fp->_bf._base = NULL; /* no buffer */ 146 fp->_bf._size = 0; 147 fp->pub._lbfsize = 0; /* not line buffered */ 148 fp->pub._fileno = -1; /* no file */ 149 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 150 fp->_ub._base = NULL; /* no ungetc buffer */ 151 fp->_ub._size = 0; 152 fp->_lb._base = NULL; /* no line buffer */ 153 fp->_lb._size = 0; 154 /* fp->_lock = NULL; */ /* once set always set (reused) */ 155 memset(WCIO_GET(fp), 0, sizeof(struct wchar_io_data)); 156 return (fp); 157 } 158 159 /* 160 * XXX. Force immediate allocation of internal memory. Not used by stdio, 161 * but documented historically for certain applications. Bad applications. 162 */ 163 __warn_references(f_prealloc, 164 "warning: this program uses f_prealloc(), which is not recommended."); 165 166 void 167 f_prealloc(void) 168 { 169 struct glue *g; 170 int n; 171 172 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 173 /* 174 * It should be safe to walk the list without locking it; 175 * new nodes are only added to the end and none are ever 176 * removed. 177 */ 178 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 179 /* void */; 180 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 181 THREAD_LOCK(); 182 SET_GLUE_PTR(lastglue->next, g); 183 lastglue = g; 184 THREAD_UNLOCK(); 185 } 186 } 187 188 /* 189 * exit() calls _cleanup() through *__cleanup, set whenever we 190 * open or buffer a file. This chicanery is done so that programs 191 * that do not use stdio need not link it all in. 192 * 193 * The name `_cleanup' is, alas, fairly well known outside stdio. 194 */ 195 void 196 _cleanup(void) 197 { 198 /* _fwalk(fclose); */ 199 _fwalk(__sflush); /* `cheating' */ 200 } 201 202 /* 203 * __sinit() is called whenever stdio's internal variables must be set up. 204 */ 205 void 206 __sinit(void) 207 { 208 209 /* Make sure we clean up on exit. */ 210 __cleanup = _cleanup; /* conservative */ 211 __sdidinit = 1; 212 } 213