findfp.c (4610B)
1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char rcsid[] = "$OpenBSD: findfp.c,v 1.2 1996/08/19 08:32:36 tholo Exp $"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <unistd.h> 42 #include <stdio.h> 43 #include <errno.h> 44 #include <stdlib.h> 45 #include <string.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 {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite} 55 /* p r w flags file _bf z cookie close read seek write */ 56 57 /* the usual - (stdin + stdout + stderr) */ 58 static FILE usual[FOPEN_MAX - 3]; 59 static struct glue uglue = { 0, FOPEN_MAX - 3, usual }; 60 61 FILE __sF[3] = { 62 std(__SRD, STDIN_FILENO), /* stdin */ 63 std(__SWR, STDOUT_FILENO), /* stdout */ 64 std(__SWR|__SNBF, STDERR_FILENO) /* stderr */ 65 }; 66 struct glue __sglue = { &uglue, 3, __sF }; 67 68 static struct glue * 69 moreglue(n) 70 register int n; 71 { 72 register struct glue *g; 73 register FILE *p; 74 static FILE empty; 75 76 g = (struct glue *)malloc(sizeof(*g) + n * sizeof(FILE)); 77 if (g == NULL) 78 return (NULL); 79 p = (FILE *)(g+1); 80 g->next = NULL; 81 g->niobs = n; 82 g->iobs = p; 83 while (--n >= 0) 84 *p++ = empty; 85 return (g); 86 } 87 88 /* 89 * Find a free FILE for fopen et al. 90 */ 91 FILE * 92 __sfp() 93 { 94 register FILE *fp; 95 register int n; 96 register struct glue *g; 97 98 if (!__sdidinit) 99 __sinit(); 100 for (g = &__sglue;; g = g->next) { 101 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++) 102 if (fp->_flags == 0) 103 goto found; 104 if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL) 105 break; 106 } 107 return (NULL); 108 found: 109 fp->_flags = 1; /* reserve this slot; caller sets real flags */ 110 fp->_p = NULL; /* no current pointer */ 111 fp->_w = 0; /* nothing to read or write */ 112 fp->_r = 0; 113 fp->_bf._base = NULL; /* no buffer */ 114 fp->_bf._size = 0; 115 fp->_lbfsize = 0; /* not line buffered */ 116 fp->_file = -1; /* no file */ 117 /* fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */ 118 fp->_ub._base = NULL; /* no ungetc buffer */ 119 fp->_ub._size = 0; 120 fp->_lb._base = NULL; /* no line buffer */ 121 fp->_lb._size = 0; 122 return (fp); 123 } 124 125 /* 126 * exit() calls _cleanup() through *__cleanup, set whenever we 127 * open or buffer a file. This chicanery is done so that programs 128 * that do not use stdio need not link it all in. 129 * 130 * The name `_cleanup' is, alas, fairly well known outside stdio. 131 */ 132 void 133 _cleanup() 134 { 135 /* (void) _fwalk(fclose); */ 136 (void) _fwalk(__sflush); /* `cheating' */ 137 } 138 139 /* 140 * __sinit() is called whenever stdio's internal variables must be set up. 141 */ 142 void 143 __sinit() 144 { 145 extern void (*__exit_flush)(void); 146 147 /* make sure we clean up on exit */ 148 __exit_flush = _cleanup; /* conservative */ 149 __sdidinit = 1; 150 }