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 inline unsigned long dir_pages(struct inode *inode)
36{
37	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
38}
39
40static 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
49static 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
66static 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
116static 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 */
179static 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 */
207static 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
217unsigned 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
271found:
272	*res_page = page;
273	ei->i_dir_start_lookup = n;
274	return ino;
275}
276
277const 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
284const struct inode_operations qnx6_dir_inode_operations = {
285	.lookup		= qnx6_lookup,
286};
287