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 65 #include "stand.h" 66 67 struct fs_ops *exclusive_file_system; 68 69 /* 70 * Open file list. The current implementation and assumption is, 71 * we only remove entries from tail and we only add new entries to tail. 72 * This decision is to keep file id management simple - we get list 73 * entries ordered by continiously growing f_id field. 74 * If we do have multiple files open and we do close file not from tail, 75 * this entry will be marked unused. open() will reuse unused entry, or 76 * close will free all unused tail entries. 77 * 78 * Only case we expect open file list to grow long, is with zfs pools with 79 * many disks. 80 */ 81 file_list_t files = TAILQ_HEAD_INITIALIZER(files); 82 83 /* 84 * Walk file list and return pointer to open_file structure. 85 * if fd is < 0, return first unused open_file. 86 */ 87 struct open_file * 88 fd2open_file(int fd) 89 { 90 struct open_file *f; 91 92 TAILQ_FOREACH(f, &files, f_link) { 93 if (fd >= 0) { 94 if (f->f_id == fd) 95 break; 96 continue; 97 } 98 if (f->f_flags == 0) 99 break; 100 } 101 return (f); 102 } 103 104 static int 105 o_gethandle(struct open_file **ptr) 106 { 107 struct open_file *f, *last; 108 109 /* Pick up unused entry */ 110 f = fd2open_file(-1); 111 if (f != NULL) { 112 *ptr = f; 113 return (f->f_id); 114 } 115 116 /* Add new entry */ 117 f = calloc(1, sizeof (*f)); 118 if (f == NULL) 119 return (-1); 120 121 last = TAILQ_LAST(&files, file_list); 122 if (last != NULL) 123 f->f_id = last->f_id + 1; 124 TAILQ_INSERT_TAIL(&files, f, f_link); 125 126 *ptr = f; 127 return (f->f_id); 128 } 129 130 static void 131 o_rainit(struct open_file *f) 132 { 133 f->f_rabuf = malloc(SOPEN_RASIZE); 134 f->f_ralen = 0; 135 f->f_raoffset = 0; 136 } 137 138 int 139 open(const char *fname, int mode) 140 { 141 struct fs_ops *fs; 142 struct open_file *f; 143 int fd, i, error, besterror; 144 const char *file; 145 146 if ((fd = o_gethandle(&f)) == -1) { 147 errno = EMFILE; 148 return (-1); 149 } 150 151 f->f_flags = mode + 1; 152 f->f_dev = NULL; 153 f->f_ops = NULL; 154 f->f_offset = 0; 155 f->f_devdata = NULL; 156 file = NULL; 157 158 if (exclusive_file_system != NULL) { 159 fs = exclusive_file_system; 160 error = (fs->fo_open)(fname, f); 161 if (error == 0) 162 goto ok; 163 goto err; 164 } 165 166 error = devopen(f, fname, &file); 167 if (error || 168 (((f->f_flags & F_NODEV) == 0) && f->f_dev == NULL)) 169 goto err; 170 171 /* see if we opened a raw device; otherwise, 'file' is the file name. */ 172 if (file == NULL || *file == '\0') { 173 f->f_flags |= F_RAW; 174 f->f_rabuf = NULL; 175 return (fd); 176 } 177 178 /* pass file name to the different filesystem open routines */ 179 besterror = ENOENT; 180 for (i = 0; file_system[i] != NULL; i++) { 181 fs = file_system[i]; 182 error = (fs->fo_open)(file, f); 183 if (error == 0) 184 goto ok; 185 if (error != EINVAL) 186 besterror = error; 187 } 188 error = besterror; 189 190 if ((f->f_flags & F_NODEV) == 0 && f->f_dev != NULL) 191 f->f_dev->dv_close(f); 192 if (error) 193 devclose(f); 194 195 err: 196 f->f_flags = 0; 197 errno = error; 198 return (-1); 199 200 ok: 201 f->f_ops = fs; 202 o_rainit(f); 203 return (fd); 204 } 205