xref: /linux/fs/qnx6/dir.c (revision 3932b9ca55b0be314a36d3e84faff3e823c081f5)
1 /*
2  * QNX6 file system, Linux implementation.
3  *
4  * Version : 1.0.0
5  *
6  * History :
7  *
8  * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
9  * 16-02-2012 pagemap extension by Al Viro
10  *
11  */
12 
13 #include "qnx6.h"
14 
15 static unsigned qnx6_lfile_checksum(char *name, unsigned size)
16 {
17 	unsigned crc = 0;
18 	char *end = name + size;
19 	while (name < end) {
20 		crc = ((crc >> 1) + *(name++)) ^
21 			((crc & 0x00000001) ? 0x80000000 : 0);
22 	}
23 	return crc;
24 }
25 
26 static struct page *qnx6_get_page(struct inode *dir, unsigned long n)
27 {
28 	struct address_space *mapping = dir->i_mapping;
29 	struct page *page = read_mapping_page(mapping, n, NULL);
30 	if (!IS_ERR(page))
31 		kmap(page);
32 	return page;
33 }
34 
35 static inline unsigned long dir_pages(struct inode *inode)
36 {
37 	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
38 }
39 
40 static unsigned last_entry(struct inode *inode, unsigned long page_nr)
41 {
42 	unsigned long last_byte = inode->i_size;
43 	last_byte -= page_nr << PAGE_CACHE_SHIFT;
44 	if (last_byte > PAGE_CACHE_SIZE)
45 		last_byte = PAGE_CACHE_SIZE;
46 	return last_byte / QNX6_DIR_ENTRY_SIZE;
47 }
48 
49 static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
50 					 struct qnx6_long_dir_entry *de,
51 					 struct page **p)
52 {
53 	struct qnx6_sb_info *sbi = QNX6_SB(sb);
54 	u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
55 	u32 n = s >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits); /* in pages */
56 	/* within page */
57 	u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_CACHE_MASK;
58 	struct address_space *mapping = sbi->longfile->i_mapping;
59 	struct page *page = read_mapping_page(mapping, n, NULL);
60 	if (IS_ERR(page))
61 		return ERR_CAST(page);
62 	kmap(*p = page);
63 	return (struct qnx6_long_filename *)(page_address(page) + offs);
64 }
65 
66 static int qnx6_dir_longfilename(struct inode *inode,
67 			struct qnx6_long_dir_entry *de,
68 			struct dir_context *ctx,
69 			unsigned de_inode)
70 {
71 	struct qnx6_long_filename *lf;
72 	struct super_block *s = inode->i_sb;
73 	struct qnx6_sb_info *sbi = QNX6_SB(s);
74 	struct page *page;
75 	int lf_size;
76 
77 	if (de->de_size != 0xff) {
78 		/* error - long filename entries always have size 0xff
79 		   in direntry */
80 		pr_err("invalid direntry size (%i).\n", de->de_size);
81 		return 0;
82 	}
83 	lf = qnx6_longname(s, de, &page);
84 	if (IS_ERR(lf)) {
85 		pr_err("Error reading longname\n");
86 		return 0;
87 	}
88 
89 	lf_size = fs16_to_cpu(sbi, lf->lf_size);
90 
91 	if (lf_size > QNX6_LONG_NAME_MAX) {
92 		pr_debug("file %s\n", lf->lf_fname);
93 		pr_err("Filename too long (%i)\n", lf_size);
94 		qnx6_put_page(page);
95 		return 0;
96 	}
97 
98 	/* calc & validate longfilename checksum
99 	   mmi 3g filesystem does not have that checksum */
100 	if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
101 			qnx6_lfile_checksum(lf->lf_fname, lf_size))
102 		pr_info("long filename checksum error.\n");
103 
104 	pr_debug("qnx6_readdir:%.*s inode:%u\n",
105 		 lf_size, lf->lf_fname, de_inode);
106 	if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
107 		qnx6_put_page(page);
108 		return 0;
109 	}
110 
111 	qnx6_put_page(page);
112 	/* success */
113 	return 1;
114 }
115 
116 static int qnx6_readdir(struct file *file, struct dir_context *ctx)
117 {
118 	struct inode *inode = file_inode(file);
119 	struct super_block *s = inode->i_sb;
120 	struct qnx6_sb_info *sbi = QNX6_SB(s);
121 	loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
122 	unsigned long npages = dir_pages(inode);
123 	unsigned long n = pos >> PAGE_CACHE_SHIFT;
124 	unsigned start = (pos & ~PAGE_CACHE_MASK) / QNX6_DIR_ENTRY_SIZE;
125 	bool done = false;
126 
127 	ctx->pos = pos;
128 	if (ctx->pos >= inode->i_size)
129 		return 0;
130 
131 	for ( ; !done && n < npages; n++, start = 0) {
132 		struct page *page = qnx6_get_page(inode, n);
133 		int limit = last_entry(inode, n);
134 		struct qnx6_dir_entry *de;
135 		int i = start;
136 
137 		if (IS_ERR(page)) {
138 			pr_err("%s(): read failed\n", __func__);
139 			ctx->pos = (n + 1) << PAGE_CACHE_SHIFT;
140 			return PTR_ERR(page);
141 		}
142 		de = ((struct qnx6_dir_entry *)page_address(page)) + start;
143 		for (; i < limit; i++, de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
144 			int size = de->de_size;
145 			u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
146 
147 			if (!no_inode || !size)
148 				continue;
149 
150 			if (size > QNX6_SHORT_NAME_MAX) {
151 				/* long filename detected
152 				   get the filename from long filename
153 				   structure / block */
154 				if (!qnx6_dir_longfilename(inode,
155 					(struct qnx6_long_dir_entry *)de,
156 					ctx, no_inode)) {
157 					done = true;
158 					break;
159 				}
160 			} else {
161 				pr_debug("%s():%.*s inode:%u\n",
162 					 __func__, size, de->de_fname,
163 					 no_inode);
164 				if (!dir_emit(ctx, de->de_fname, size,
165 				      no_inode, DT_UNKNOWN)) {
166 					done = true;
167 					break;
168 				}
169 			}
170 		}
171 		qnx6_put_page(page);
172 	}
173 	return 0;
174 }
175 
176 /*
177  * check if the long filename is correct.
178  */
179 static unsigned qnx6_long_match(int len, const char *name,
180 			struct qnx6_long_dir_entry *de, struct inode *dir)
181 {
182 	struct super_block *s = dir->i_sb;
183 	struct qnx6_sb_info *sbi = QNX6_SB(s);
184 	struct page *page;
185 	int thislen;
186 	struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
187 
188 	if (IS_ERR(lf))
189 		return 0;
190 
191 	thislen = fs16_to_cpu(sbi, lf->lf_size);
192 	if (len != thislen) {
193 		qnx6_put_page(page);
194 		return 0;
195 	}
196 	if (memcmp(name, lf->lf_fname, len) == 0) {
197 		qnx6_put_page(page);
198 		return fs32_to_cpu(sbi, de->de_inode);
199 	}
200 	qnx6_put_page(page);
201 	return 0;
202 }
203 
204 /*
205  * check if the filename is correct.
206  */
207 static unsigned qnx6_match(struct super_block *s, int len, const char *name,
208 			struct qnx6_dir_entry *de)
209 {
210 	struct qnx6_sb_info *sbi = QNX6_SB(s);
211 	if (memcmp(name, de->de_fname, len) == 0)
212 		return fs32_to_cpu(sbi, de->de_inode);
213 	return 0;
214 }
215 
216 
217 unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
218 			 struct page **res_page)
219 {
220 	struct super_block *s = dir->i_sb;
221 	struct qnx6_inode_info *ei = QNX6_I(dir);
222 	struct page *page = NULL;
223 	unsigned long start, n;
224 	unsigned long npages = dir_pages(dir);
225 	unsigned ino;
226 	struct qnx6_dir_entry *de;
227 	struct qnx6_long_dir_entry *lde;
228 
229 	*res_page = NULL;
230 
231 	if (npages == 0)
232 		return 0;
233 	start = ei->i_dir_start_lookup;
234 	if (start >= npages)
235 		start = 0;
236 	n = start;
237 
238 	do {
239 		page = qnx6_get_page(dir, n);
240 		if (!IS_ERR(page)) {
241 			int limit = last_entry(dir, n);
242 			int i;
243 
244 			de = (struct qnx6_dir_entry *)page_address(page);
245 			for (i = 0; i < limit; i++, de++) {
246 				if (len <= QNX6_SHORT_NAME_MAX) {
247 					/* short filename */
248 					if (len != de->de_size)
249 						continue;
250 					ino = qnx6_match(s, len, name, de);
251 					if (ino)
252 						goto found;
253 				} else if (de->de_size == 0xff) {
254 					/* deal with long filename */
255 					lde = (struct qnx6_long_dir_entry *)de;
256 					ino = qnx6_long_match(len,
257 								name, lde, dir);
258 					if (ino)
259 						goto found;
260 				} else
261 					pr_err("undefined filename size in inode.\n");
262 			}
263 			qnx6_put_page(page);
264 		}
265 
266 		if (++n >= npages)
267 			n = 0;
268 	} while (n != start);
269 	return 0;
270 
271 found:
272 	*res_page = page;
273 	ei->i_dir_start_lookup = n;
274 	return ino;
275 }
276 
277 const struct file_operations qnx6_dir_operations = {
278 	.llseek		= generic_file_llseek,
279 	.read		= generic_read_dir,
280 	.iterate	= qnx6_readdir,
281 	.fsync		= generic_file_fsync,
282 };
283 
284 const struct inode_operations qnx6_dir_inode_operations = {
285 	.lookup		= qnx6_lookup,
286 };
287