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 bool is_dir;
142 size_t n;
143 const char *file;
144
145 TSENTER();
146
147 if ((fd = o_gethandle(&f)) == -1) {
148 errno = EMFILE;
149 return (-1);
150 }
151
152 f->f_flags = mode + 1;
153 f->f_dev = NULL;
154 f->f_ops = NULL;
155 f->f_offset = 0;
156 f->f_devdata = NULL;
157 file = NULL;
158
159 if (exclusive_file_system == NULL ||
160 (exclusive_file_system->fs_flags & FS_OPS_NO_DEVOPEN) == 0) {
161 error = devopen(f, fname, &file);
162 if (error ||
163 (((f->f_flags & F_NODEV) == 0) && f->f_dev == NULL))
164 goto err;
165
166 /* see if we opened a raw device; otherwise, 'file' is the file name. */
167 if (file == NULL || *file == '\0') {
168 f->f_flags |= F_RAW;
169 f->f_rabuf = NULL;
170 TSEXIT();
171 return (fd);
172 }
173 } else
174 file = fname;
175
176 if (exclusive_file_system != NULL) {
177 /* loader is forcing the filesystem to be used */
178 fs = exclusive_file_system;
179 error = (fs->fo_open)(file, f);
180 if (error == 0)
181 goto ok;
182 goto err;
183 }
184
185 /* pass file name to the different filesystem open routines */
186 besterror = ENOENT;
187 n = strlen(file);
188 is_dir = (n > 0 && file[n - 1] == '/');
189 for (i = 0; file_system[i] != NULL; i++) {
190 fs = file_system[i];
191 if (is_dir && is_tftp()) {
192 error = EOPNOTSUPP;
193 goto err;
194 }
195 error = (fs->fo_open)(file, f);
196 if (error == 0)
197 goto ok;
198 if (error != EINVAL)
199 besterror = error;
200 }
201 error = besterror;
202
203 if ((f->f_flags & F_NODEV) == 0 && f->f_dev != NULL)
204 f->f_dev->dv_close(f);
205 if (error)
206 devclose(f);
207
208 err:
209 f->f_flags = 0;
210 errno = error;
211 TSEXIT();
212 return (-1);
213
214 ok:
215 f->f_ops = fs;
216 o_rainit(f);
217 TSEXIT();
218 return (fd);
219 }
220