1 /*
2 * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
3 *
4 * Copyright (C) 2002-2011 Aleph One Ltd.
5 * for Toby Churchill Ltd and Brightstar Engineering
6 *
7 * Created by Charles Manning <charles@aleph1.co.uk>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
14 /*
15 * This simple implementation of a name-value store assumes a small number of
16 * values and fits into a small finite buffer.
17 *
18 * Each attribute is stored as a record:
19 * sizeof(int) bytes record size.
20 * yaffs_strnlen+1 bytes name null terminated.
21 * nbytes value.
22 * ----------
23 * total size stored in record size
24 *
25 * This code has not been tested with unicode yet.
26 */
27
28 #include "yaffs_nameval.h"
29
30 #include "yportenv.h"
31
nval_find(const char * xb,int xb_size,const YCHAR * name,int * exist_size)32 static int nval_find(const char *xb, int xb_size, const YCHAR *name,
33 int *exist_size)
34 {
35 int pos = 0;
36 int size;
37
38 memcpy(&size, xb, sizeof(int));
39 while (size > 0 && (size < xb_size) && (pos + size < xb_size)) {
40 if (!yaffs_strncmp((YCHAR *) (xb + pos + sizeof(int)),
41 name, size)) {
42 if (exist_size)
43 *exist_size = size;
44 return pos;
45 }
46 pos += size;
47 if (pos < xb_size - sizeof(int))
48 memcpy(&size, xb + pos, sizeof(int));
49 else
50 size = 0;
51 }
52 if (exist_size)
53 *exist_size = 0;
54 return -ENODATA;
55 }
56
nval_used(const char * xb,int xb_size)57 static int nval_used(const char *xb, int xb_size)
58 {
59 int pos = 0;
60 int size;
61
62 memcpy(&size, xb + pos, sizeof(int));
63 while (size > 0 && (size < xb_size) && (pos + size < xb_size)) {
64 pos += size;
65 if (pos < xb_size - sizeof(int))
66 memcpy(&size, xb + pos, sizeof(int));
67 else
68 size = 0;
69 }
70 return pos;
71 }
72
nval_del(char * xb,int xb_size,const YCHAR * name)73 int nval_del(char *xb, int xb_size, const YCHAR *name)
74 {
75 int pos = nval_find(xb, xb_size, name, NULL);
76 int size;
77
78 if (pos < 0 || pos >= xb_size)
79 return -ENODATA;
80
81 /* Find size, shift rest over this record,
82 * then zero out the rest of buffer */
83 memcpy(&size, xb + pos, sizeof(int));
84 memcpy(xb + pos, xb + pos + size, xb_size - (pos + size));
85 memset(xb + (xb_size - size), 0, size);
86 return 0;
87 }
88
nval_set(char * xb,int xb_size,const YCHAR * name,const char * buf,int bsize,int flags)89 int nval_set(char *xb, int xb_size, const YCHAR *name, const char *buf,
90 int bsize, int flags)
91 {
92 int pos;
93 int namelen = yaffs_strnlen(name, xb_size);
94 int reclen;
95 int size_exist = 0;
96 int space;
97 int start;
98
99 pos = nval_find(xb, xb_size, name, &size_exist);
100
101 if (flags & XATTR_CREATE && pos >= 0)
102 return -EEXIST;
103 if (flags & XATTR_REPLACE && pos < 0)
104 return -ENODATA;
105
106 start = nval_used(xb, xb_size);
107 space = xb_size - start + size_exist;
108
109 reclen = (sizeof(int) + namelen + 1 + bsize);
110
111 if (reclen > space)
112 return -ENOSPC;
113
114 if (pos >= 0) {
115 nval_del(xb, xb_size, name);
116 start = nval_used(xb, xb_size);
117 }
118
119 pos = start;
120
121 memcpy(xb + pos, &reclen, sizeof(int));
122 pos += sizeof(int);
123 yaffs_strncpy((YCHAR *) (xb + pos), name, reclen);
124 pos += (namelen + 1);
125 memcpy(xb + pos, buf, bsize);
126 return 0;
127 }
128
nval_get(const char * xb,int xb_size,const YCHAR * name,char * buf,int bsize)129 int nval_get(const char *xb, int xb_size, const YCHAR * name, char *buf,
130 int bsize)
131 {
132 int pos = nval_find(xb, xb_size, name, NULL);
133 int size;
134
135 if (pos >= 0 && pos < xb_size) {
136
137 memcpy(&size, xb + pos, sizeof(int));
138 pos += sizeof(int); /* advance past record length */
139 size -= sizeof(int);
140
141 /* Advance over name string */
142 while (xb[pos] && size > 0 && pos < xb_size) {
143 pos++;
144 size--;
145 }
146 /*Advance over NUL */
147 pos++;
148 size--;
149
150 /* If bsize is zero then this is a size query.
151 * Return the size, but don't copy.
152 */
153 if (!bsize)
154 return size;
155
156 if (size <= bsize) {
157 memcpy(buf, xb + pos, size);
158 return size;
159 }
160 }
161 if (pos >= 0)
162 return -ERANGE;
163
164 return -ENODATA;
165 }
166
nval_list(const char * xb,int xb_size,char * buf,int bsize)167 int nval_list(const char *xb, int xb_size, char *buf, int bsize)
168 {
169 int pos = 0;
170 int size;
171 int name_len;
172 int ncopied = 0;
173 int filled = 0;
174
175 memcpy(&size, xb + pos, sizeof(int));
176 while (size > sizeof(int) &&
177 size <= xb_size &&
178 (pos + size) < xb_size &&
179 !filled) {
180 pos += sizeof(int);
181 size -= sizeof(int);
182 name_len = yaffs_strnlen((YCHAR *) (xb + pos), size);
183 if (ncopied + name_len + 1 < bsize) {
184 memcpy(buf, xb + pos, name_len * sizeof(YCHAR));
185 buf += name_len;
186 *buf = '\0';
187 buf++;
188 if (sizeof(YCHAR) > 1) {
189 *buf = '\0';
190 buf++;
191 }
192 ncopied += (name_len + 1);
193 } else {
194 filled = 1;
195 }
196 pos += size;
197 if (pos < xb_size - sizeof(int))
198 memcpy(&size, xb + pos, sizeof(int));
199 else
200 size = 0;
201 }
202 return ncopied;
203 }
204
nval_hasvalues(const char * xb,int xb_size)205 int nval_hasvalues(const char *xb, int xb_size)
206 {
207 return nval_used(xb, xb_size) > 0;
208 }
209