1 /* $OpenBSD: findfp.c,v 1.9 2005/08/08 08:05:36 espie 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 43 int __sdidinit; 44 45 #define NDYNAMIC 10 /* add ten more whenever necessary */ 46 47 #define std(flags, file) \ 48 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \ 49 {(unsigned char *)(__sFext+file), 0}} 50 /* p r w flags file _bf z cookie close read seek write 51 ext */ 52 53 /* the usual - (stdin + stdout + stderr) */ 54 static FILE usual[FOPEN_MAX - 3]; 55 static struct __sfileext usualext[FOPEN_MAX - 3]; 56 static struct glue uglue = { 0, FOPEN_MAX - 3, usual }; 57 58 struct __sfileext __sFext[3]; 59 FILE __sF[3] = { 60 std(__SRD, STDIN_FILENO), /* stdin */ 61 std(__SWR, STDOUT_FILENO), /* stdout */ 62 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ 63 }; 64 struct glue __sglue = { &uglue, 3, __sF }; 65 66 static struct glue * 67 moreglue(int n) 68 { 69 struct glue *g; 70 FILE *p; 71 struct __sfileext *pext; 72 static FILE empty; 73 char *data; 74 75 data = malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) 76 + n * sizeof(struct __sfileext)); 77 if (data == NULL) 78 return (NULL); 79 g = (struct glue *)data; 80 p = (FILE *)ALIGN(data + sizeof(*g)); 81 pext = (struct __sfileext *) 82 (ALIGN(data + sizeof(*g)) + n * sizeof(FILE)); 83 g->next = NULL; 84 g->niobs = n; 85 g->iobs = p; 86 while (--n >= 0) { 87 *p = empty; 88 _FILEEXT_SETUP(p, pext); 89 p++; 90 pext++; 91 } 92 return (g); 93 } 94 95 /* 96 * Find a free FILE for fopen et al. 97 */ 98 FILE * 99 __sfp(void) 100 { 101 FILE *fp; 102 int n; 103 struct glue *g; 104 105 if (!__sdidinit) 106 __sinit(); 107 for (g = &__sglue;; g = g->next) { 108 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 109 if (fp->_flags == 0) 110 goto found; 111 if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL) 112 break; 113 } 114 return (NULL); 115 found: 116 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 117 fp->_p = NULL; /* no current pointer */ 118 fp->_w = 0; /* nothing to read or write */ 119 fp->_r = 0; 120 fp->_bf._base = NULL; /* no buffer */ 121 fp->_bf._size = 0; 122 fp->_lbfsize = 0; /* not line buffered */ 123 fp->_file = -1; /* no file */ 124 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 125 fp->_lb._base = NULL; /* no line buffer */ 126 fp->_lb._size = 0; 127 _FILEEXT_INIT(fp); 128 return (fp); 129 } 130 131 #define getdtablesize() sysconf(_SC_OPEN_MAX) 132 133 /* 134 * XXX. Force immediate allocation of internal memory. Not used by stdio, 135 * but documented historically for certain applications. Bad applications. 136 */ 137 void 138 f_prealloc(void) 139 { 140 struct glue *g; 141 int n; 142 143 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 144 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 145 /* void */; 146 if (n > 0) 147 g->next = moreglue(n); 148 } 149 150 /* 151 * exit() and abort() call _cleanup() through the callback registered 152 * with __atexit_register_cleanup(), set whenever we open or buffer a 153 * file. This chicanery is done so that programs that do not use stdio 154 * need not link it all in. 155 * 156 * The name `_cleanup' is, alas, fairly well known outside stdio. 157 */ 158 void 159 _cleanup(void) 160 { 161 /* (void) _fwalk(fclose); */ 162 (void) _fwalk(__sflush); /* `cheating' */ 163 } 164 165 /* 166 * __sinit() is called whenever stdio's internal variables must be set up. 167 */ 168 void 169 __sinit(void) 170 { 171 int i; 172 173 for (i = 0; i < FOPEN_MAX - 3; i++) { 174 _FILEEXT_SETUP(usual+i, usualext+i); 175 } 176 /* make sure we clean up on exit */ 177 __atexit_register_cleanup(_cleanup); /* conservative */ 178 __sdidinit = 1; 179 } 180