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