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 * 35 * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University 36 * All Rights Reserved. 37 * 38 * Author: Alessandro Forin 39 * 40 * Permission to use, copy, modify and distribute this software and its 41 * documentation is hereby granted, provided that both the copyright 42 * notice and this permission notice appear in all copies of the 43 * software, derivative works or modified versions, and any portions 44 * thereof, and that both notices appear in supporting documentation. 45 * 46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 48 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 49 * 50 * Carnegie Mellon requests users of this software to return to 51 * 52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 53 * School of Computer Science 54 * Carnegie Mellon University 55 * Pittsburgh PA 15213-3890 56 * 57 * any improvements or extensions that they make and grant Carnegie the 58 * rights to redistribute these changes. 59 */ 60 61 #include "stand.h" 62 63 struct fs_ops *exclusive_file_system; 64 65 /* 66 * Open file list. The current implementation and assumption is, 67 * we only remove entries from tail and we only add new entries to tail. 68 * This decision is to keep file id management simple - we get list 69 * entries ordered by continiously growing f_id field. 70 * If we do have multiple files open and we do close file not from tail, 71 * this entry will be marked unused. open() will reuse unused entry, or 72 * close will free all unused tail entries. 73 * 74 * Only case we expect open file list to grow long, is with zfs pools with 75 * many disks. 76 */ 77 file_list_t files = TAILQ_HEAD_INITIALIZER(files); 78 79 /* 80 * Walk file list and return pointer to open_file structure. 81 * if fd is < 0, return first unused open_file. 82 */ 83 struct open_file * 84 fd2open_file(int fd) 85 { 86 struct open_file *f; 87 88 TAILQ_FOREACH(f, &files, f_link) { 89 if (fd >= 0) { 90 if (f->f_id == fd) 91 break; 92 continue; 93 } 94 95 if (f->f_flags == 0) 96 break; 97 } 98 return (f); 99 } 100 101 static int 102 o_gethandle(struct open_file **ptr) 103 { 104 struct open_file *f, *last; 105 106 /* Pick up unused entry */ 107 f = fd2open_file(-1); 108 if (f != NULL) { 109 *ptr = f; 110 return (f->f_id); 111 } 112 113 /* Add new entry */ 114 f = calloc(1, sizeof (*f)); 115 if (f == NULL) 116 return (-1); 117 118 last = TAILQ_LAST(&files, file_list); 119 if (last != NULL) 120 f->f_id = last->f_id + 1; 121 TAILQ_INSERT_TAIL(&files, f, f_link); 122 123 *ptr = f; 124 return (f->f_id); 125 } 126 127 static void 128 o_rainit(struct open_file *f) 129 { 130 f->f_rabuf = malloc(SOPEN_RASIZE); 131 f->f_ralen = 0; 132 f->f_raoffset = 0; 133 } 134 135 int 136 open(const char *fname, int mode) 137 { 138 struct fs_ops *fs; 139 struct open_file *f; 140 int fd, i, error, besterror; 141 const char *file; 142 143 TSENTER(); 144 145 if ((fd = o_gethandle(&f)) == -1) { 146 errno = EMFILE; 147 return (-1); 148 } 149 150 f->f_flags = mode + 1; 151 f->f_dev = NULL; 152 f->f_ops = NULL; 153 f->f_offset = 0; 154 f->f_devdata = NULL; 155 file = NULL; 156 157 if (exclusive_file_system != NULL) { 158 fs = exclusive_file_system; 159 error = (fs->fo_open)(fname, f); 160 if (error == 0) 161 goto ok; 162 goto err; 163 } 164 165 error = devopen(f, fname, &file); 166 if (error || 167 (((f->f_flags & F_NODEV) == 0) && f->f_dev == NULL)) 168 goto err; 169 170 /* see if we opened a raw device; otherwise, 'file' is the file name. */ 171 if (file == NULL || *file == '\0') { 172 f->f_flags |= F_RAW; 173 f->f_rabuf = NULL; 174 TSEXIT(); 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 TSEXIT(); 199 return (-1); 200 201 ok: 202 f->f_ops = fs; 203 o_rainit(f); 204 TSEXIT(); 205 return (fd); 206 } 207