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 [email protected]
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 *
fd2open_file(int fd)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
o_gethandle(struct open_file ** ptr)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
o_rainit(struct open_file * f)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
open(const char * fname,int mode)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