1 /* $NetBSD: open.c,v 1.16 1997/01/28 09:41:03 pk Exp $ */ 2 3 /*- 4 * Copyright (c) 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 * The Mach Operating System project at Carnegie-Mellon University. 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)open.c 8.1 (Berkeley) 6/11/93 35 * 36 * 37 * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University 38 * All Rights Reserved. 39 * 40 * Author: Alessandro Forin 41 * 42 * Permission to use, copy, modify and distribute this software and its 43 * documentation is hereby granted, provided that both the copyright 44 * notice and this permission notice appear in all copies of the 45 * software, derivative works or modified versions, and any portions 46 * thereof, and that both notices appear in supporting documentation. 47 * 48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 50 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 51 * 52 * Carnegie Mellon requests users of this software to return to 53 * 54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 55 * School of Computer Science 56 * Carnegie Mellon University 57 * Pittsburgh PA 15213-3890 58 * 59 * any improvements or extensions that they make and grant Carnegie the 60 * rights to redistribute these changes. 61 */ 62 63 #include <sys/cdefs.h> 64 __FBSDID("$FreeBSD$"); 65 66 #include "stand.h" 67 68 struct fs_ops *exclusive_file_system; 69 70 /* 71 * Open file list. The current implementation and assumption is, 72 * we only remove entries from tail and we only add new entries to tail. 73 * This decision is to keep file id management simple - we get list 74 * entries ordered by continiously growing f_id field. 75 * If we do have multiple files open and we do close file not from tail, 76 * this entry will be marked unused. open() will reuse unused entry, or 77 * close will free all unused tail entries. 78 * 79 * Only case we expect open file list to grow long, is with zfs pools with 80 * many disks. 81 */ 82 file_list_t files = TAILQ_HEAD_INITIALIZER(files); 83 84 /* 85 * Walk file list and return pointer to open_file structure. 86 * if fd is < 0, return first unused open_file. 87 */ 88 struct open_file * 89 fd2open_file(int fd) 90 { 91 struct open_file *f; 92 93 TAILQ_FOREACH(f, &files, f_link) { 94 if (fd >= 0) { 95 if (f->f_id == fd) 96 break; 97 continue; 98 } 99 100 if (f->f_flags == 0) 101 break; 102 } 103 return (f); 104 } 105 106 static int 107 o_gethandle(struct open_file **ptr) 108 { 109 struct open_file *f, *last; 110 111 /* Pick up unused entry */ 112 f = fd2open_file(-1); 113 if (f != NULL) { 114 *ptr = f; 115 return (f->f_id); 116 } 117 118 /* Add new entry */ 119 f = calloc(1, sizeof (*f)); 120 if (f == NULL) 121 return (-1); 122 123 last = TAILQ_LAST(&files, file_list); 124 if (last != NULL) 125 f->f_id = last->f_id + 1; 126 TAILQ_INSERT_TAIL(&files, f, f_link); 127 128 *ptr = f; 129 return (f->f_id); 130 } 131 132 static void 133 o_rainit(struct open_file *f) 134 { 135 f->f_rabuf = malloc(SOPEN_RASIZE); 136 f->f_ralen = 0; 137 f->f_raoffset = 0; 138 } 139 140 int 141 open(const char *fname, int mode) 142 { 143 struct fs_ops *fs; 144 struct open_file *f; 145 int fd, i, error, besterror; 146 const char *file; 147 148 TSENTER(); 149 150 if ((fd = o_gethandle(&f)) == -1) { 151 errno = EMFILE; 152 return (-1); 153 } 154 155 f->f_flags = mode + 1; 156 f->f_dev = NULL; 157 f->f_ops = NULL; 158 f->f_offset = 0; 159 f->f_devdata = NULL; 160 file = NULL; 161 162 if (exclusive_file_system != NULL) { 163 fs = exclusive_file_system; 164 error = (fs->fo_open)(fname, f); 165 if (error == 0) 166 goto ok; 167 goto err; 168 } 169 170 error = devopen(f, fname, &file); 171 if (error || 172 (((f->f_flags & F_NODEV) == 0) && f->f_dev == NULL)) 173 goto err; 174 175 /* see if we opened a raw device; otherwise, 'file' is the file name. */ 176 if (file == NULL || *file == '\0') { 177 f->f_flags |= F_RAW; 178 f->f_rabuf = NULL; 179 TSEXIT(); 180 return (fd); 181 } 182 183 /* pass file name to the different filesystem open routines */ 184 besterror = ENOENT; 185 for (i = 0; file_system[i] != NULL; i++) { 186 fs = file_system[i]; 187 error = (fs->fo_open)(file, f); 188 if (error == 0) 189 goto ok; 190 if (error != EINVAL) 191 besterror = error; 192 } 193 error = besterror; 194 195 if ((f->f_flags & F_NODEV) == 0 && f->f_dev != NULL) 196 f->f_dev->dv_close(f); 197 if (error) 198 devclose(f); 199 200 err: 201 f->f_flags = 0; 202 errno = error; 203 TSEXIT(); 204 return (-1); 205 206 ok: 207 f->f_ops = fs; 208 o_rainit(f); 209 TSEXIT(); 210 return (fd); 211 } 212