1 /* $OpenBSD: findfp.c,v 1.15 2013/12/17 16:33:27 deraadt Exp $ */ 2 /*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Chris Torek. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <sys/param.h> 35 #include <unistd.h> 36 #include <stdio.h> 37 #include <errno.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include "local.h" 41 #include "glue.h" 42 #include "private/thread_private.h" 43 44 #define ALIGNBYTES (sizeof(uintptr_t) - 1) 45 #define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) &~ ALIGNBYTES) 46 47 int __sdidinit; 48 49 #define NDYNAMIC 10 /* add ten more whenever necessary */ 50 51 #define std(flags, file) \ 52 {0,0,0,flags,file,{0,0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \ 53 {(unsigned char *)(__sFext+file), 0},NULL,0,{0},{0},{0,0},0,0} 54 55 /* the usual - (stdin + stdout + stderr) */ 56 static FILE usual[FOPEN_MAX - 3]; 57 static struct __sfileext usualext[FOPEN_MAX - 3]; 58 static struct glue uglue = { 0, FOPEN_MAX - 3, usual }; 59 static struct glue *lastglue = &uglue; 60 _THREAD_PRIVATE_MUTEX(__sfp_mutex); 61 62 static struct __sfileext __sFext[3]; 63 FILE __sF[3] = { 64 std(__SRD, STDIN_FILENO), /* stdin */ 65 std(__SWR, STDOUT_FILENO), /* stdout */ 66 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ 67 }; 68 FILE* stdin = &__sF[0]; 69 FILE* stdout = &__sF[1]; 70 FILE* stderr = &__sF[2]; 71 struct glue __sglue = { &uglue, 3, __sF }; 72 73 static struct glue * 74 moreglue(int n) 75 { 76 struct glue *g; 77 FILE *p; 78 struct __sfileext *pext; 79 static FILE empty; 80 char *data; 81 82 data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) 83 + n * sizeof(struct __sfileext)); 84 if (data == NULL) 85 return (NULL); 86 g = (struct glue *)data; 87 p = (FILE *)ALIGN(data + sizeof(*g)); 88 pext = (struct __sfileext *) 89 (ALIGN(data + sizeof(*g)) + n * sizeof(FILE)); 90 g->next = NULL; 91 g->niobs = n; 92 g->iobs = p; 93 while (--n >= 0) { 94 *p = empty; 95 _FILEEXT_SETUP(p, pext); 96 p++; 97 pext++; 98 } 99 return (g); 100 } 101 102 /* 103 * Find a free FILE for fopen et al. 104 */ 105 FILE * 106 __sfp(void) 107 { 108 FILE *fp; 109 int n; 110 struct glue *g; 111 112 if (!__sdidinit) 113 __sinit(); 114 115 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex); 116 for (g = &__sglue; g != NULL; g = g->next) { 117 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 118 if (fp->_flags == 0) 119 goto found; 120 } 121 122 /* release lock while mallocing */ 123 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex); 124 if ((g = moreglue(NDYNAMIC)) == NULL) 125 return (NULL); 126 _THREAD_PRIVATE_MUTEX_LOCK(__sfp_mutex); 127 lastglue->next = g; 128 lastglue = g; 129 fp = g->iobs; 130 found: 131 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 132 _THREAD_PRIVATE_MUTEX_UNLOCK(__sfp_mutex); 133 fp->_p = NULL; /* no current pointer */ 134 fp->_w = 0; /* nothing to read or write */ 135 fp->_r = 0; 136 fp->_bf._base = NULL; /* no buffer */ 137 fp->_bf._size = 0; 138 fp->_lbfsize = 0; /* not line buffered */ 139 fp->_file = -1; /* no file */ 140 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 141 fp->_lb._base = NULL; /* no line buffer */ 142 fp->_lb._size = 0; 143 _FILEEXT_INIT(fp); 144 return (fp); 145 } 146 147 /* 148 * exit() and abort() call _cleanup() through the callback registered 149 * with __atexit_register_cleanup(), set whenever we open or buffer a 150 * file. This chicanery is done so that programs that do not use stdio 151 * need not link it all in. 152 * 153 * The name `_cleanup' is, alas, fairly well known outside stdio. 154 */ 155 void 156 _cleanup(void) 157 { 158 /* (void) _fwalk(fclose); */ 159 (void) _fwalk(__sflush); /* `cheating' */ 160 } 161 162 /* 163 * __sinit() is called whenever stdio's internal variables must be set up. 164 */ 165 void 166 __sinit(void) 167 { 168 _THREAD_PRIVATE_MUTEX(__sinit_mutex); 169 170 _THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex); 171 if (__sdidinit) { 172 /* bail out if caller lost the race */ 173 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex); 174 return; 175 } 176 177 /* Initialize stdin/stdout/stderr (for the recursive mutex). http://b/18208568. */ 178 for (size_t i = 0; i < 3; ++i) { 179 _FILEEXT_SETUP(__sF+i, __sFext+i); 180 } 181 /* Initialize the pre-allocated (but initially unused) streams. */ 182 for (size_t i = 0; i < FOPEN_MAX - 3; ++i) { 183 _FILEEXT_SETUP(usual+i, usualext+i); 184 } 185 186 /* make sure we clean up on exit */ 187 __atexit_register_cleanup(_cleanup); /* conservative */ 188 __sdidinit = 1; 189 190 _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex); 191 } 192
