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bigbiff bigbiff9c754052013-01-09 09:09:08 -05001/*
2 lookup.c (02.09.09)
3 exFAT file system implementation library.
4
bigbiff bigbiff61cdc022013-08-08 08:35:06 -04005 Free exFAT implementation.
Matt Mower09ef1e42015-12-13 11:29:45 -06006 Copyright (C) 2010-2015 Andrew Nayenko
bigbiff bigbiff9c754052013-01-09 09:09:08 -05007
bigbiff bigbiff61cdc022013-08-08 08:35:06 -04008 This program is free software; you can redistribute it and/or modify
bigbiff bigbiff9c754052013-01-09 09:09:08 -05009 it under the terms of the GNU General Public License as published by
bigbiff bigbiff61cdc022013-08-08 08:35:06 -040010 the Free Software Foundation, either version 2 of the License, or
bigbiff bigbiff9c754052013-01-09 09:09:08 -050011 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
bigbiff bigbiff61cdc022013-08-08 08:35:06 -040018 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
bigbiff bigbiff9c754052013-01-09 09:09:08 -050021*/
22
23#include "exfat.h"
24#include <string.h>
25#include <errno.h>
26#include <inttypes.h>
27
28int exfat_opendir(struct exfat* ef, struct exfat_node* dir,
29 struct exfat_iterator* it)
30{
31 int rc;
32
33 exfat_get_node(dir);
34 it->parent = dir;
35 it->current = NULL;
36 rc = exfat_cache_directory(ef, dir);
37 if (rc != 0)
38 exfat_put_node(ef, dir);
39 return rc;
40}
41
42void exfat_closedir(struct exfat* ef, struct exfat_iterator* it)
43{
44 exfat_put_node(ef, it->parent);
45 it->parent = NULL;
46 it->current = NULL;
47}
48
Ethan Yonker58f21322018-08-24 11:17:36 -050049struct exfat_node* exfat_readdir(struct exfat* ef __unused, struct exfat_iterator* it)
bigbiff bigbiff9c754052013-01-09 09:09:08 -050050{
51 if (it->current == NULL)
52 it->current = it->parent->child;
53 else
54 it->current = it->current->next;
55
56 if (it->current != NULL)
57 return exfat_get_node(it->current);
58 else
59 return NULL;
60}
61
62static int compare_char(struct exfat* ef, uint16_t a, uint16_t b)
63{
64 if (a >= ef->upcase_chars || b >= ef->upcase_chars)
65 return (int) a - (int) b;
66
67 return (int) le16_to_cpu(ef->upcase[a]) - (int) le16_to_cpu(ef->upcase[b]);
68}
69
70static int compare_name(struct exfat* ef, const le16_t* a, const le16_t* b)
71{
72 while (le16_to_cpu(*a) && le16_to_cpu(*b))
73 {
74 int rc = compare_char(ef, le16_to_cpu(*a), le16_to_cpu(*b));
75 if (rc != 0)
76 return rc;
77 a++;
78 b++;
79 }
80 return compare_char(ef, le16_to_cpu(*a), le16_to_cpu(*b));
81}
82
83static int lookup_name(struct exfat* ef, struct exfat_node* parent,
84 struct exfat_node** node, const char* name, size_t n)
85{
86 struct exfat_iterator it;
87 le16_t buffer[EXFAT_NAME_MAX + 1];
88 int rc;
89
90 *node = NULL;
91
92 rc = utf8_to_utf16(buffer, name, EXFAT_NAME_MAX, n);
93 if (rc != 0)
94 return rc;
95
96 rc = exfat_opendir(ef, parent, &it);
97 if (rc != 0)
98 return rc;
99 while ((*node = exfat_readdir(ef, &it)))
100 {
101 if (compare_name(ef, buffer, (*node)->name) == 0)
102 {
103 exfat_closedir(ef, &it);
104 return 0;
105 }
106 exfat_put_node(ef, *node);
107 }
108 exfat_closedir(ef, &it);
109 return -ENOENT;
110}
111
112static size_t get_comp(const char* path, const char** comp)
113{
114 const char* end;
115
116 *comp = path + strspn(path, "/"); /* skip leading slashes */
117 end = strchr(*comp, '/');
118 if (end == NULL)
119 return strlen(*comp);
120 else
121 return end - *comp;
122}
123
124int exfat_lookup(struct exfat* ef, struct exfat_node** node,
125 const char* path)
126{
127 struct exfat_node* parent;
128 const char* p;
129 size_t n;
130 int rc;
131
132 /* start from the root directory */
133 parent = *node = exfat_get_node(ef->root);
134 for (p = path; (n = get_comp(p, &p)); p += n)
135 {
136 if (n == 1 && *p == '.') /* skip "." component */
137 continue;
138 rc = lookup_name(ef, parent, node, p, n);
139 if (rc != 0)
140 {
141 exfat_put_node(ef, parent);
142 return rc;
143 }
144 exfat_put_node(ef, parent);
145 parent = *node;
146 }
147 return 0;
148}
149
150static bool is_last_comp(const char* comp, size_t length)
151{
152 const char* p = comp + length;
153
154 return get_comp(p, &p) == 0;
155}
156
157static bool is_allowed(const char* comp, size_t length)
158{
159 size_t i;
160
161 for (i = 0; i < length; i++)
162 switch (comp[i])
163 {
164 case 0x01 ... 0x1f:
165 case '/':
166 case '\\':
167 case ':':
168 case '*':
169 case '?':
170 case '"':
171 case '<':
172 case '>':
173 case '|':
174 return false;
175 }
176 return true;
177}
178
179int exfat_split(struct exfat* ef, struct exfat_node** parent,
180 struct exfat_node** node, le16_t* name, const char* path)
181{
182 const char* p;
183 size_t n;
184 int rc;
185
186 memset(name, 0, (EXFAT_NAME_MAX + 1) * sizeof(le16_t));
187 *parent = *node = exfat_get_node(ef->root);
188 for (p = path; (n = get_comp(p, &p)); p += n)
189 {
190 if (n == 1 && *p == '.')
191 continue;
192 if (is_last_comp(p, n))
193 {
194 if (!is_allowed(p, n))
195 {
196 /* contains characters that are not allowed */
197 exfat_put_node(ef, *parent);
198 return -ENOENT;
199 }
200 rc = utf8_to_utf16(name, p, EXFAT_NAME_MAX, n);
201 if (rc != 0)
202 {
203 exfat_put_node(ef, *parent);
204 return rc;
205 }
206
207 rc = lookup_name(ef, *parent, node, p, n);
208 if (rc != 0 && rc != -ENOENT)
209 {
210 exfat_put_node(ef, *parent);
211 return rc;
212 }
213 return 0;
214 }
215 rc = lookup_name(ef, *parent, node, p, n);
216 if (rc != 0)
217 {
218 exfat_put_node(ef, *parent);
219 return rc;
220 }
221 exfat_put_node(ef, *parent);
222 *parent = *node;
223 }
224 exfat_bug("impossible");
225}