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 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include <sys/param.h> 40 #include <machine/atomic.h> 41 #include <unistd.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 46 #include <spinlock.h> 47 48 #include "libc_private.h" 49 #include "local.h" 50 #include "glue.h" 51 52 int __sdidinit; 53 54 #define NDYNAMIC 10 /* add ten more whenever necessary */ 55 56 #define std(flags, file) { \ 57 ._flags = (flags), \ 58 ._file = (file), \ 59 ._cookie = __sF + (file), \ 60 ._close = __sclose, \ 61 ._read = __sread, \ 62 ._seek = __sseek, \ 63 ._write = __swrite, \ 64 ._fl_mutex = PTHREAD_MUTEX_INITIALIZER, \ 65 } 66 /* the usual - (stdin + stdout + stderr) */ 67 static FILE usual[FOPEN_MAX - 3]; 68 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 69 70 static FILE __sF[3] = { 71 std(__SRD, STDIN_FILENO), 72 std(__SWR, STDOUT_FILENO), 73 std(__SWR|__SNBF, STDERR_FILENO) 74 }; 75 76 FILE *__stdinp = &__sF[0]; 77 FILE *__stdoutp = &__sF[1]; 78 FILE *__stderrp = &__sF[2]; 79 80 struct glue __sglue = { &uglue, 3, __sF }; 81 static struct glue *lastglue = &uglue; 82 83 static struct glue * moreglue(int); 84 85 spinlock_t __stdio_thread_lock = _SPINLOCK_INITIALIZER; 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 = { ._fl_mutex = PTHREAD_MUTEX_INITIALIZER }; 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() 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 STDIO_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->_flags == 0) 131 goto found; 132 } 133 STDIO_THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 134 if ((g = moreglue(NDYNAMIC)) == NULL) 135 return (NULL); 136 STDIO_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->_flags = 1; /* reserve this slot; caller sets real flags */ 142 STDIO_THREAD_UNLOCK(); 143 fp->_p = NULL; /* no current pointer */ 144 fp->_w = 0; /* nothing to read or write */ 145 fp->_r = 0; 146 fp->_bf._base = NULL; /* no buffer */ 147 fp->_bf._size = 0; 148 fp->_lbfsize = 0; /* not line buffered */ 149 fp->_file = -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->_fl_mutex = NULL; */ /* once set always set (reused) */ 156 fp->_orientation = 0; 157 memset(&fp->_mbstate, 0, sizeof(mbstate_t)); 158 return (fp); 159 } 160 161 /* 162 * XXX. Force immediate allocation of internal memory. Not used by stdio, 163 * but documented historically for certain applications. Bad applications. 164 */ 165 __warn_references(f_prealloc, 166 "warning: this program uses f_prealloc(), which is not recommended."); 167 168 void 169 f_prealloc(void) 170 { 171 struct glue *g; 172 int n; 173 174 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 175 /* 176 * It should be safe to walk the list without locking it; 177 * new nodes are only added to the end and none are ever 178 * removed. 179 */ 180 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 181 /* void */; 182 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 183 STDIO_THREAD_LOCK(); 184 SET_GLUE_PTR(lastglue->next, g); 185 lastglue = g; 186 STDIO_THREAD_UNLOCK(); 187 } 188 } 189 190 /* 191 * exit() calls _cleanup() through *__cleanup, set whenever we 192 * open or buffer a file. This chicanery is done so that programs 193 * that do not use stdio need not link it all in. 194 * 195 * The name `_cleanup' is, alas, fairly well known outside stdio. 196 */ 197 void 198 _cleanup() 199 { 200 /* (void) _fwalk(fclose); */ 201 (void) _fwalk(__sflush); /* `cheating' */ 202 } 203 204 /* 205 * __sinit() is called whenever stdio's internal variables must be set up. 206 */ 207 void 208 __sinit() 209 { 210 211 /* Make sure we clean up on exit. */ 212 __cleanup = _cleanup; /* conservative */ 213 __sdidinit = 1; 214 } 215