findfp.c revision 1.9
1 /* $NetBSD: findfp.c,v 1.9 1998/02/03 18:41:10 perry Exp $ */ 2 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94"; 43 #else 44 __RCSID("$NetBSD: findfp.c,v 1.9 1998/02/03 18:41:10 perry Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <sys/param.h> 49 #include <unistd.h> 50 #include <stdio.h> 51 #include <errno.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include "local.h" 55 #include "glue.h" 56 #include "reentrant.h" 57 58 int __sdidinit; 59 60 #define NDYNAMIC 10 /* add ten more whenever necessary */ 61 62 #define std(flags, file) \ 63 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite} 64 /* p r w flags file _bf z cookie close read seek write */ 65 66 /* the usual - (stdin + stdout + stderr) */ 67 static FILE usual[FOPEN_MAX - 3]; 68 static struct glue uglue = { 0, FOPEN_MAX - 3, usual }; 69 70 FILE __sF[3] = { 71 std(__SRD, STDIN_FILENO), /* stdin */ 72 std(__SWR, STDOUT_FILENO), /* stdout */ 73 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ 74 }; 75 struct glue __sglue = { &uglue, 3, __sF }; 76 77 static struct glue *moreglue __P((int)); 78 void f_prealloc __P((void)); 79 80 #ifdef _REENT 81 rwlock_t __sfp_lock = RWLOCK_INITIALIZER; 82 #endif 83 84 static struct glue * 85 moreglue(n) 86 int n; 87 { 88 struct glue *g; 89 FILE *p; 90 static FILE empty; 91 92 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)); 93 if (g == NULL) 94 return (NULL); 95 p = (FILE *)ALIGN(g + 1); 96 g->next = NULL; 97 g->niobs = n; 98 g->iobs = p; 99 while (--n >= 0) 100 *p++ = empty; 101 return (g); 102 } 103 104 /* 105 * Find a free FILE for fopen et al. 106 */ 107 FILE * 108 __sfp() 109 { 110 FILE *fp; 111 int n; 112 struct glue *g; 113 114 if (!__sdidinit) 115 __sinit(); 116 117 rwlock_wrlock(&__sfp_lock); 118 for (g = &__sglue;; g = g->next) { 119 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 120 if (fp->_flags == 0) 121 goto found; 122 if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL) 123 break; 124 } 125 rwlock_unlock(&__sfp_lock); 126 return (NULL); 127 found: 128 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 129 fp->_p = NULL; /* no current pointer */ 130 fp->_w = 0; /* nothing to read or write */ 131 fp->_r = 0; 132 fp->_bf._base = NULL; /* no buffer */ 133 fp->_bf._size = 0; 134 fp->_lbfsize = 0; /* not line buffered */ 135 fp->_file = -1; /* no file */ 136 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 137 fp->_ub._base = NULL; /* no ungetc buffer */ 138 fp->_ub._size = 0; 139 fp->_lb._base = NULL; /* no line buffer */ 140 fp->_lb._size = 0; 141 rwlock_unlock(&__sfp_lock); 142 return (fp); 143 } 144 145 /* 146 * XXX. Force immediate allocation of internal memory. Not used by stdio, 147 * but documented historically for certain applications. Bad applications. 148 */ 149 void 150 f_prealloc() 151 { 152 struct glue *g; 153 int n; 154 155 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 156 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 157 /* void */; 158 if (n > 0) 159 g->next = moreglue(n); 160 } 161 162 /* 163 * exit() calls _cleanup() through *__cleanup, set whenever we 164 * open or buffer a file. This chicanery is done so that programs 165 * that do not use stdio need not link it all in. 166 * 167 * The name `_cleanup' is, alas, fairly well known outside stdio. 168 */ 169 void 170 _cleanup() 171 { 172 /* (void) _fwalk(fclose); */ 173 (void) _fwalk(__sflush); /* `cheating' */ 174 } 175 176 /* 177 * __sinit() is called whenever stdio's internal variables must be set up. 178 */ 179 void 180 __sinit() 181 { 182 /* make sure we clean up on exit */ 183 __cleanup = _cleanup; /* conservative */ 184 __sdidinit = 1; 185 } 186
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