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 #include <sys/param.h> 36 #include <machine/atomic.h> 37 #include <unistd.h> 38 #include <stdio.h> 39 #include <stdlib.h> 40 #include <stdint.h> 41 #include <string.h> 42 43 #include <spinlock.h> 44 45 #include "libc_private.h" 46 #include "local.h" 47 #include "glue.h" 48 49 int __sdidinit; 50 51 #define NDYNAMIC 10 /* add ten more whenever necessary */ 52 53 #define std(flags, file) { \ 54 ._flags = (flags), \ 55 ._file = (file), \ 56 ._cookie = __sF + (file), \ 57 ._close = __sclose, \ 58 ._read = __sread, \ 59 ._seek = __sseek, \ 60 ._write = __swrite, \ 61 ._fl_mutex = PTHREAD_MUTEX_INITIALIZER, \ 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 spinlock_t __stdio_thread_lock = _SPINLOCK_INITIALIZER; 83 84 #if NOT_YET 85 #define SET_GLUE_PTR(ptr, val) atomic_set_rel_ptr(&(ptr), (uintptr_t)(val)) 86 #else 87 #define SET_GLUE_PTR(ptr, val) ptr = val 88 #endif 89 90 static struct glue * 91 moreglue(int n) 92 { 93 struct glue *g; 94 static FILE empty = { ._fl_mutex = PTHREAD_MUTEX_INITIALIZER }; 95 FILE *p; 96 size_t align; 97 98 align = __alignof__(FILE); 99 g = (struct glue *)malloc(sizeof(*g) + align + n * sizeof(FILE)); 100 if (g == NULL) 101 return (NULL); 102 p = (FILE *)roundup((uintptr_t)(g + 1), align); 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 STDIO_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->_flags == 0) 130 goto found; 131 } 132 STDIO_THREAD_UNLOCK(); /* don't hold lock while malloc()ing. */ 133 if ((g = moreglue(NDYNAMIC)) == NULL) 134 return (NULL); 135 STDIO_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->_flags = 1; /* reserve this slot; caller sets real flags */ 141 STDIO_THREAD_UNLOCK(); 142 fp->_p = NULL; /* no current pointer */ 143 fp->_w = 0; /* nothing to read or write */ 144 fp->_r = 0; 145 fp->_bf._base = NULL; /* no buffer */ 146 fp->_bf._size = 0; 147 fp->_lbfsize = 0; /* not line buffered */ 148 fp->_file = -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->_fl_mutex = NULL; */ /* once set always set (reused) */ 155 fp->_orientation = 0; 156 memset(&fp->_mbstate, 0, sizeof(mbstate_t)); 157 fp->_flags2 = 0; 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 void f_prealloc(void); 168 169 void 170 f_prealloc(void) 171 { 172 struct glue *g; 173 int n; 174 175 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 176 /* 177 * It should be safe to walk the list without locking it; 178 * new nodes are only added to the end and none are ever 179 * removed. 180 */ 181 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 182 /* void */; 183 if ((n > 0) && ((g = moreglue(n)) != NULL)) { 184 STDIO_THREAD_LOCK(); 185 SET_GLUE_PTR(lastglue->next, g); 186 lastglue = g; 187 STDIO_THREAD_UNLOCK(); 188 } 189 } 190 191 /* 192 * exit() calls _cleanup() through *__cleanup, set whenever we 193 * open or buffer a file. This chicanery is done so that programs 194 * that do not use stdio need not link it all in. 195 * 196 * The name `_cleanup' is, alas, fairly well known outside stdio. 197 */ 198 void 199 _cleanup(void) 200 { 201 /* (void) _fwalk(fclose); */ 202 (void) _fwalk(__sflush); /* `cheating' */ 203 } 204 205 /* 206 * __sinit() is called whenever stdio's internal variables must be set up. 207 */ 208 void 209 __sinit(void) 210 { 211 212 /* Make sure we clean up on exit. */ 213 __cleanup = _cleanup; /* conservative */ 214 __sdidinit = 1; 215 } 216