1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 #include <sys/param.h> 40 #include <machine/atomic.h> 41 #include <unistd.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <stdint.h> 45 #include <string.h> 46 47 #include <spinlock.h> 48 49 #include "libc_private.h" 50 #include "local.h" 51 #include "glue.h" 52 53 int __sdidinit; 54 55 #define NDYNAMIC 10 /* add ten more whenever necessary */ 56 57 #define std(flags, file) { \ 58 ._flags = (flags), \ 59 ._file = (file), \ 60 ._cookie = __sF + (file), \ 61 ._close = __sclose, \ 62 ._read = __sread, \ 63 ._seek = __sseek, \ 64 ._write = __swrite, \ 65 ._fl_mutex = PTHREAD_MUTEX_INITIALIZER, \ 66 } 67 /* the usual - (stdin + stdout + stderr) */ 68 static FILE usual[FOPEN_MAX - 3]; 69 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual }; 70 71 static FILE __sF[3] = { 72 std(__SRD, STDIN_FILENO), 73 std(__SWR, STDOUT_FILENO), 74 std(__SWR|__SNBF, STDERR_FILENO) 75 }; 76 77 FILE *__stdinp = &__sF[0]; 78 FILE *__stdoutp = &__sF[1]; 79 FILE *__stderrp = &__sF[2]; 80 81 struct glue __sglue = { &uglue, 3, __sF }; 82 static struct glue *lastglue = &uglue; 83 84 static struct glue * moreglue(int); 85 86 spinlock_t __stdio_thread_lock = _SPINLOCK_INITIALIZER; 87 88 #if NOT_YET 89 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 90 #else 91 #define SET_GLUE_PTR(ptr, val) ptr = val 92 #endif 93 94 static struct glue * 95 moreglue(int n) 96 { 97 struct glue *g; 98 static FILE empty = { ._fl_mutex = PTHREAD_MUTEX_INITIALIZER }; 99 FILE *p; 100 size_t align; 101 102 align = __alignof__(FILE); 103 g = (struct glue *)malloc(sizeof(*g) + align + n * sizeof(FILE)); 104 if (g == NULL) 105 return (NULL); 106 p = (FILE *)roundup((uintptr_t)(g + 1), align); 107 g->next = NULL; 108 g->niobs = n; 109 g->iobs = p; 110 while (--n >= 0) 111 *p++ = empty; 112 return (g); 113 } 114 115 /* 116 * Find a free FILE for fopen et al. 117 */ 118 FILE * 119 __sfp(void) 120 { 121 FILE *fp; 122 int n; 123 struct glue *g; 124 125 if (!__sdidinit) 126 __sinit(); 127 /* 128 * The list must be locked because a FILE may be updated. 129 */ 130 STDIO_THREAD_LOCK(); 131 for (g = &__sglue; g != NULL; g = g->next) { 132 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 133 if (fp->_flags == 0) 134 goto found; 135 } 136 STDIO_THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 137 if ((g = moreglue(NDYNAMIC)) == NULL) 138 return (NULL); 139 STDIO_THREAD_LOCK(); /* reacquire the lock */ 140 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 141 lastglue = g; /* not atomic; only accessed when locked */ 142 fp = g->iobs; 143 found: 144 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 145 STDIO_THREAD_UNLOCK(); 146 fp->_p = NULL; /* no current pointer */ 147 fp->_w = 0; /* nothing to read or write */ 148 fp->_r = 0; 149 fp->_bf._base = NULL; /* no buffer */ 150 fp->_bf._size = 0; 151 fp->_lbfsize = 0; /* not line buffered */ 152 fp->_file = -1; /* no file */ 153 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 154 fp->_ub._base = NULL; /* no ungetc buffer */ 155 fp->_ub._size = 0; 156 fp->_lb._base = NULL; /* no line buffer */ 157 fp->_lb._size = 0; 158 /* fp->_fl_mutex = NULL; */ /* once set always set (reused) */ 159 fp->_orientation = 0; 160 memset(&fp->_mbstate, 0, sizeof(mbstate_t)); 161 fp->_flags2 = 0; 162 return (fp); 163 } 164 165 /* 166 * XXX. Force immediate allocation of internal memory. Not used by stdio, 167 * but documented historically for certain applications. Bad applications. 168 */ 169 __warn_references(f_prealloc, 170 "warning: this program uses f_prealloc(), which is not recommended."); 171 void f_prealloc(void); 172 173 void 174 f_prealloc(void) 175 { 176 struct glue *g; 177 int n; 178 179 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 180 /* 181 * It should be safe to walk the list without locking it; 182 * new nodes are only added to the end and none are ever 183 * removed. 184 */ 185 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 186 /* void */; 187 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 188 STDIO_THREAD_LOCK(); 189 SET_GLUE_PTR(lastglue->next, g); 190 lastglue = g; 191 STDIO_THREAD_UNLOCK(); 192 } 193 } 194 195 /* 196 * exit() calls _cleanup() through *__cleanup, set whenever we 197 * open or buffer a file. This chicanery is done so that programs 198 * that do not use stdio need not link it all in. 199 * 200 * The name `_cleanup' is, alas, fairly well known outside stdio. 201 */ 202 void 203 _cleanup(void) 204 { 205 /* (void) _fwalk(fclose); */ 206 (void) _fwalk(__sflush); /* `cheating' */ 207 } 208 209 /* 210 * __sinit() is called whenever stdio's internal variables must be set up. 211 */ 212 void 213 __sinit(void) 214 { 215 216 /* Make sure we clean up on exit. */ 217 __cleanup = _cleanup; /* conservative */ 218 __sdidinit = 1; 219 } 220