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 <sys/cdefs.h> 62 #include "stand.h" 63 64 struct fs_ops *exclusive_file_system; 65 66 /* 67 * Open file list. The current implementation and assumption is, 68 * we only remove entries from tail and we only add new entries to tail. 69 * This decision is to keep file id management simple - we get list 70 * entries ordered by continiously growing f_id field. 71 * If we do have multiple files open and we do close file not from tail, 72 * this entry will be marked unused. open() will reuse unused entry, or 73 * close will free all unused tail entries. 74 * 75 * Only case we expect open file list to grow long, is with zfs pools with 76 * many disks. 77 */ 78 file_list_t files = TAILQ_HEAD_INITIALIZER(files); 79 80 /* 81 * Walk file list and return pointer to open_file structure. 82 * if fd is < 0, return first unused open_file. 83 */ 84 struct open_file * 85 fd2open_file(int fd) 86 { 87 struct open_file *f; 88 89 TAILQ_FOREACH(f, &files, f_link) { 90 if (fd >= 0) { 91 if (f->f_id == fd) 92 break; 93 continue; 94 } 95 96 if (f->f_flags == 0) 97 break; 98 } 99 return (f); 100 } 101 102 static int 103 o_gethandle(struct open_file **ptr) 104 { 105 struct open_file *f, *last; 106 107 /* Pick up unused entry */ 108 f = fd2open_file(-1); 109 if (f != NULL) { 110 *ptr = f; 111 return (f->f_id); 112 } 113 114 /* Add new entry */ 115 f = calloc(1, sizeof (*f)); 116 if (f == NULL) 117 return (-1); 118 119 last = TAILQ_LAST(&files, file_list); 120 if (last != NULL) 121 f->f_id = last->f_id + 1; 122 TAILQ_INSERT_TAIL(&files, f, f_link); 123 124 *ptr = f; 125 return (f->f_id); 126 } 127 128 static void 129 o_rainit(struct open_file *f) 130 { 131 f->f_rabuf = malloc(SOPEN_RASIZE); 132 f->f_ralen = 0; 133 f->f_raoffset = 0; 134 } 135 136 int 137 open(const char *fname, int mode) 138 { 139 struct fs_ops *fs; 140 struct open_file *f; 141 int fd, i, error, besterror; 142 const char *file; 143 144 TSENTER(); 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 TSEXIT(); 176 return (fd); 177 } 178 179 /* pass file name to the different filesystem open routines */ 180 besterror = ENOENT; 181 for (i = 0; file_system[i] != NULL; i++) { 182 fs = file_system[i]; 183 error = (fs->fo_open)(file, f); 184 if (error == 0) 185 goto ok; 186 if (error != EINVAL) 187 besterror = error; 188 } 189 error = besterror; 190 191 if ((f->f_flags & F_NODEV) == 0 && f->f_dev != NULL) 192 f->f_dev->dv_close(f); 193 if (error) 194 devclose(f); 195 196 err: 197 f->f_flags = 0; 198 errno = error; 199 TSEXIT(); 200 return (-1); 201 202 ok: 203 f->f_ops = fs; 204 o_rainit(f); 205 TSEXIT(); 206 return (fd); 207 } 208