findfp.c revision 1.6
1 /* $NetBSD: findfp.c,v 1.6 1995/02/02 02:09:17 jtc 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 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)findfp.c 8.2 (Berkeley) 1/4/94"; 42 #endif 43 static char rcsid[] = "$NetBSD: findfp.c,v 1.6 1995/02/02 02:09:17 jtc Exp $"; 44 #endif /* LIBC_SCCS and not lint */ 45 46 #include <sys/param.h> 47 #include <unistd.h> 48 #include <stdio.h> 49 #include <errno.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include "local.h" 53 #include "glue.h" 54 55 int __sdidinit; 56 57 #define NDYNAMIC 10 /* add ten more whenever necessary */ 58 59 #define std(flags, file) \ 60 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite} 61 /* p r w flags file _bf z cookie close read seek write */ 62 63 /* the usual - (stdin + stdout + stderr) */ 64 static FILE usual[FOPEN_MAX - 3]; 65 static struct glue uglue = { 0, FOPEN_MAX - 3, usual }; 66 67 FILE __sF[3] = { 68 std(__SRD, STDIN_FILENO), /* stdin */ 69 std(__SWR, STDOUT_FILENO), /* stdout */ 70 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ 71 }; 72 struct glue __sglue = { &uglue, 3, __sF }; 73 74 static struct glue * 75 moreglue(n) 76 register int n; 77 { 78 register struct glue *g; 79 register FILE *p; 80 static FILE empty; 81 82 g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)); 83 if (g == NULL) 84 return (NULL); 85 p = (FILE *)ALIGN(g + 1); 86 g->next = NULL; 87 g->niobs = n; 88 g->iobs = p; 89 while (--n >= 0) 90 *p++ = empty; 91 return (g); 92 } 93 94 /* 95 * Find a free FILE for fopen et al. 96 */ 97 FILE * 98 __sfp() 99 { 100 register FILE *fp; 101 register int n; 102 register struct glue *g; 103 104 if (!__sdidinit) 105 __sinit(); 106 for (g = &__sglue;; g = g->next) { 107 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 108 if (fp->_flags == 0) 109 goto found; 110 if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL) 111 break; 112 } 113 return (NULL); 114 found: 115 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 116 fp->_p = NULL; /* no current pointer */ 117 fp->_w = 0; /* nothing to read or write */ 118 fp->_r = 0; 119 fp->_bf._base = NULL; /* no buffer */ 120 fp->_bf._size = 0; 121 fp->_lbfsize = 0; /* not line buffered */ 122 fp->_file = -1; /* no file */ 123 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 124 fp->_ub._base = NULL; /* no ungetc buffer */ 125 fp->_ub._size = 0; 126 fp->_lb._base = NULL; /* no line buffer */ 127 fp->_lb._size = 0; 128 return (fp); 129 } 130 131 /* 132 * XXX. Force immediate allocation of internal memory. Not used by stdio, 133 * but documented historically for certain applications. Bad applications. 134 */ 135 void 136 f_prealloc() 137 { 138 register struct glue *g; 139 int n; 140 141 n = getdtablesize() - FOPEN_MAX + 20; /* 20 for slop. */ 142 for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next) 143 /* void */; 144 if (n > 0) 145 g->next = moreglue(n); 146 } 147 148 /* 149 * exit() calls _cleanup() through *__cleanup, set whenever we 150 * open or buffer a file. This chicanery is done so that programs 151 * that do not use stdio need not link it all in. 152 * 153 * The name `_cleanup' is, alas, fairly well known outside stdio. 154 */ 155 void 156 _cleanup() 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() 167 { 168 /* make sure we clean up on exit */ 169 __cleanup = _cleanup; /* conservative */ 170 __sdidinit = 1; 171 } 172
Indexes created Mon Sep 22 05:09:51 GMT 2025