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