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