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 * 4. 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 #include "priv_stdio.h" 48 49 int __sdidinit; 50 51 #define NDYNAMIC 10 /* add ten more whenever necessary */ 52 53 #define std(flags, file) { \ 54 .pub = { \ 55 ._flags = (flags), \ 56 ._fileno = (file), \ 57 }, \ 58 ._cookie = __sF + (file), \ 59 ._close = __sclose, \ 60 ._read = __sread, \ 61 ._seek = __sseek, \ 62 ._write = __swrite, \ 63 } 64 /* the usual - (stdin + stdout + stderr) */ 65 static FILE usual[FOPEN_MAX - 3]; 66 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 67 68 static FILE __sF[3] = { 69 std(__SRD, STDIN_FILENO), 70 std(__SWR, STDOUT_FILENO), 71 std(__SWR|__SNBF, STDERR_FILENO) 72 }; 73 74 FILE *__stdinp = &__sF[0]; 75 FILE *__stdoutp = &__sF[1]; 76 FILE *__stderrp = &__sF[2]; 77 78 struct glue __sglue = { &uglue, 3, __sF }; 79 static struct glue *lastglue = &uglue; 80 81 static struct glue * moreglue(int); 82 83 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER; 84 #define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock) 85 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock) 86 87 #if NOT_YET 88 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 89 #else 90 #define SET_GLUE_PTR(ptr, val) ptr = val 91 #endif 92 93 static struct glue * 94 moreglue(int n) 95 { 96 struct glue *g; 97 static FILE empty; 98 FILE *p; 99 100 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)); 101 if (g == NULL) 102 return (NULL); 103 p = (FILE *)ALIGN(g + 1); 104 g->next = NULL; 105 g->niobs = n; 106 g->iobs = p; 107 while (--n >= 0) 108 *p++ = empty; 109 return (g); 110 } 111 112 /* 113 * Find a free FILE for fopen et al. 114 */ 115 FILE * 116 __sfp(void) 117 { 118 FILE *fp; 119 int n; 120 struct glue *g; 121 122 if (!__sdidinit) 123 __sinit(); 124 /* 125 * The list must be locked because a FILE may be updated. 126 */ 127 THREAD_LOCK(); 128 for (g = &__sglue; g != NULL; g = g->next) { 129 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 130 if (fp->pub._flags == 0) 131 goto found; 132 } 133 THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 134 if ((g = moreglue(NDYNAMIC)) == NULL) 135 return (NULL); 136 THREAD_LOCK(); /* reacquire the lock */ 137 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 138 lastglue = g; /* not atomic; only accessed when locked */ 139 fp = g->iobs; 140 found: 141 fp->pub._flags = 1; /* reserve this slot; caller sets real flags */ 142 THREAD_UNLOCK(); 143 fp->pub._p = NULL; /* no current pointer */ 144 fp->pub._w = 0; /* nothing to read or write */ 145 fp->pub._r = 0; 146 fp->_bf._base = NULL; /* no buffer */ 147 fp->_bf._size = 0; 148 fp->pub._lbfsize = 0; /* not line buffered */ 149 fp->pub._fileno = -1; /* no file */ 150 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 151 fp->_ub._base = NULL; /* no ungetc buffer */ 152 fp->_ub._size = 0; 153 fp->_lb._base = NULL; /* no line buffer */ 154 fp->_lb._size = 0; 155 /* fp->_lock = NULL; */ /* once set always set (reused) */ 156 memset(WCIO_GET(fp), 0, sizeof(struct wchar_io_data)); 157 return (fp); 158 } 159 160 /* 161 * XXX. Force immediate allocation of internal memory. Not used by stdio, 162 * but documented historically for certain applications. Bad applications. 163 */ 164 __warn_references(f_prealloc, 165 "warning: this program uses f_prealloc(), which is not recommended."); 166 167 void 168 f_prealloc(void) 169 { 170 struct glue *g; 171 int n; 172 173 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 174 /* 175 * It should be safe to walk the list without locking it; 176 * new nodes are only added to the end and none are ever 177 * removed. 178 */ 179 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 180 /* void */; 181 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 182 THREAD_LOCK(); 183 SET_GLUE_PTR(lastglue->next, g); 184 lastglue = g; 185 THREAD_UNLOCK(); 186 } 187 } 188 189 /* 190 * exit() calls _cleanup() through *__cleanup, set whenever we 191 * open or buffer a file. This chicanery is done so that programs 192 * that do not use stdio need not link it all in. 193 * 194 * The name `_cleanup' is, alas, fairly well known outside stdio. 195 */ 196 void 197 _cleanup(void) 198 { 199 /* _fwalk(fclose); */ 200 _fwalk(__sflush); /* `cheating' */ 201 } 202 203 /* 204 * __sinit() is called whenever stdio's internal variables must be set up. 205 */ 206 void 207 __sinit(void) 208 { 209 210 /* Make sure we clean up on exit. */ 211 __cleanup = _cleanup; /* conservative */ 212 __sdidinit = 1; 213 } 214