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/param.h> 39 #include <machine/atomic.h> 40 #include <unistd.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <stdint.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 size_t align; 100 101 align = __alignof__(FILE); 102 g = (struct glue *)malloc(sizeof(*g) + align + n * sizeof(FILE)); 103 if (g == NULL) 104 return (NULL); 105 p = (FILE *)roundup((uintptr_t)(g + 1), align); 106 g->next = NULL; 107 g->niobs = n; 108 g->iobs = p; 109 while (--n >= 0) 110 *p++ = empty; 111 return (g); 112 } 113 114 /* 115 * Find a free FILE for fopen et al. 116 */ 117 FILE * 118 __sfp(void) 119 { 120 FILE *fp; 121 int n; 122 struct glue *g; 123 124 if (!__sdidinit) 125 __sinit(); 126 /* 127 * The list must be locked because a FILE may be updated. 128 */ 129 STDIO_THREAD_LOCK(); 130 for (g = &__sglue; g != NULL; g = g->next) { 131 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 132 if (fp->_flags == 0) 133 goto found; 134 } 135 STDIO_THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 136 if ((g = moreglue(NDYNAMIC)) == NULL) 137 return (NULL); 138 STDIO_THREAD_LOCK(); /* reacquire the lock */ 139 SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */ 140 lastglue = g; /* not atomic; only accessed when locked */ 141 fp = g->iobs; 142 found: 143 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 144 STDIO_THREAD_UNLOCK(); 145 fp->_p = NULL; /* no current pointer */ 146 fp->_w = 0; /* nothing to read or write */ 147 fp->_r = 0; 148 fp->_bf._base = NULL; /* no buffer */ 149 fp->_bf._size = 0; 150 fp->_lbfsize = 0; /* not line buffered */ 151 fp->_file = -1; /* no file */ 152 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 153 fp->_ub._base = NULL; /* no ungetc buffer */ 154 fp->_ub._size = 0; 155 fp->_lb._base = NULL; /* no line buffer */ 156 fp->_lb._size = 0; 157 /* fp->_fl_mutex = NULL; */ /* once set always set (reused) */ 158 fp->_orientation = 0; 159 memset(&fp->_mbstate, 0, sizeof(mbstate_t)); 160 fp->_flags2 = 0; 161 return (fp); 162 } 163 164 /* 165 * XXX. Force immediate allocation of internal memory. Not used by stdio, 166 * but documented historically for certain applications. Bad applications. 167 */ 168 __warn_references(f_prealloc, 169 "warning: this program uses f_prealloc(), which is not recommended."); 170 void f_prealloc(void); 171 172 void 173 f_prealloc(void) 174 { 175 struct glue *g; 176 int n; 177 178 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 179 /* 180 * It should be safe to walk the list without locking it; 181 * new nodes are only added to the end and none are ever 182 * removed. 183 */ 184 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 185 /* void */; 186 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 187 STDIO_THREAD_LOCK(); 188 SET_GLUE_PTR(lastglue->next, g); 189 lastglue = g; 190 STDIO_THREAD_UNLOCK(); 191 } 192 } 193 194 /* 195 * exit() calls _cleanup() through *__cleanup, set whenever we 196 * open or buffer a file. This chicanery is done so that programs 197 * that do not use stdio need not link it all in. 198 * 199 * The name `_cleanup' is, alas, fairly well known outside stdio. 200 */ 201 void 202 _cleanup(void) 203 { 204 /* (void) _fwalk(fclose); */ 205 (void) _fwalk(__sflush); /* `cheating' */ 206 } 207 208 /* 209 * __sinit() is called whenever stdio's internal variables must be set up. 210 */ 211 void 212 __sinit(void) 213 { 214 215 /* Make sure we clean up on exit. */ 216 __cleanup = _cleanup; /* conservative */ 217 __sdidinit = 1; 218 } 219