1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * QNX6 file system, Linux implementation.
  4 *
  5 * Version : 1.0.0
  6 *
  7 * History :
  8 *
  9 * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
 10 * 16-02-2012 pagemap extension by Al Viro
 11 *
 12 */
 13
 14#include "qnx6.h"
 15
 16static unsigned qnx6_lfile_checksum(char *name, unsigned size)
 17{
 18	unsigned crc = 0;
 19	char *end = name + size;
 20	while (name < end) {
 21		crc = ((crc >> 1) + *(name++)) ^
 22			((crc & 0x00000001) ? 0x80000000 : 0);
 23	}
 24	return crc;
 25}
 26
 27static struct page *qnx6_get_page(struct inode *dir, unsigned long n)
 28{
 29	struct address_space *mapping = dir->i_mapping;
 30	struct page *page = read_mapping_page(mapping, n, NULL);
 31	if (!IS_ERR(page))
 32		kmap(page);
 33	return page;
 34}
 35
 36static unsigned last_entry(struct inode *inode, unsigned long page_nr)
 37{
 38	unsigned long last_byte = inode->i_size;
 39	last_byte -= page_nr << PAGE_SHIFT;
 40	if (last_byte > PAGE_SIZE)
 41		last_byte = PAGE_SIZE;
 42	return last_byte / QNX6_DIR_ENTRY_SIZE;
 43}
 44
 45static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
 46					 struct qnx6_long_dir_entry *de,
 47					 struct page **p)
 48{
 49	struct qnx6_sb_info *sbi = QNX6_SB(sb);
 50	u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
 51	u32 n = s >> (PAGE_SHIFT - sb->s_blocksize_bits); /* in pages */
 52	/* within page */
 53	u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_MASK;
 54	struct address_space *mapping = sbi->longfile->i_mapping;
 55	struct page *page = read_mapping_page(mapping, n, NULL);
 56	if (IS_ERR(page))
 57		return ERR_CAST(page);
 58	kmap(*p = page);
 59	return (struct qnx6_long_filename *)(page_address(page) + offs);
 60}
 61
 62static int qnx6_dir_longfilename(struct inode *inode,
 63			struct qnx6_long_dir_entry *de,
 64			struct dir_context *ctx,
 65			unsigned de_inode)
 66{
 67	struct qnx6_long_filename *lf;
 68	struct super_block *s = inode->i_sb;
 69	struct qnx6_sb_info *sbi = QNX6_SB(s);
 70	struct page *page;
 71	int lf_size;
 72
 73	if (de->de_size != 0xff) {
 74		/* error - long filename entries always have size 0xff
 75		   in direntry */
 76		pr_err("invalid direntry size (%i).\n", de->de_size);
 77		return 0;
 78	}
 79	lf = qnx6_longname(s, de, &page);
 80	if (IS_ERR(lf)) {
 81		pr_err("Error reading longname\n");
 82		return 0;
 83	}
 84
 85	lf_size = fs16_to_cpu(sbi, lf->lf_size);
 86
 87	if (lf_size > QNX6_LONG_NAME_MAX) {
 88		pr_debug("file %s\n", lf->lf_fname);
 89		pr_err("Filename too long (%i)\n", lf_size);
 90		qnx6_put_page(page);
 91		return 0;
 92	}
 93
 94	/* calc & validate longfilename checksum
 95	   mmi 3g filesystem does not have that checksum */
 96	if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
 97			qnx6_lfile_checksum(lf->lf_fname, lf_size))
 98		pr_info("long filename checksum error.\n");
 99
100	pr_debug("qnx6_readdir:%.*s inode:%u\n",
101		 lf_size, lf->lf_fname, de_inode);
102	if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
103		qnx6_put_page(page);
104		return 0;
105	}
106
107	qnx6_put_page(page);
108	/* success */
109	return 1;
110}
111
112static int qnx6_readdir(struct file *file, struct dir_context *ctx)
113{
114	struct inode *inode = file_inode(file);
115	struct super_block *s = inode->i_sb;
116	struct qnx6_sb_info *sbi = QNX6_SB(s);
117	loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
118	unsigned long npages = dir_pages(inode);
119	unsigned long n = pos >> PAGE_SHIFT;
120	unsigned start = (pos & ~PAGE_MASK) / QNX6_DIR_ENTRY_SIZE;
121	bool done = false;
122
123	ctx->pos = pos;
124	if (ctx->pos >= inode->i_size)
125		return 0;
126
127	for ( ; !done && n < npages; n++, start = 0) {
128		struct page *page = qnx6_get_page(inode, n);
129		int limit = last_entry(inode, n);
130		struct qnx6_dir_entry *de;
131		int i = start;
132
133		if (IS_ERR(page)) {
134			pr_err("%s(): read failed\n", __func__);
135			ctx->pos = (n + 1) << PAGE_SHIFT;
136			return PTR_ERR(page);
137		}
138		de = ((struct qnx6_dir_entry *)page_address(page)) + start;
139		for (; i < limit; i++, de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
140			int size = de->de_size;
141			u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
142
143			if (!no_inode || !size)
144				continue;
145
146			if (size > QNX6_SHORT_NAME_MAX) {
147				/* long filename detected
148				   get the filename from long filename
149				   structure / block */
150				if (!qnx6_dir_longfilename(inode,
151					(struct qnx6_long_dir_entry *)de,
152					ctx, no_inode)) {
153					done = true;
154					break;
155				}
156			} else {
157				pr_debug("%s():%.*s inode:%u\n",
158					 __func__, size, de->de_fname,
159					 no_inode);
160				if (!dir_emit(ctx, de->de_fname, size,
161				      no_inode, DT_UNKNOWN)) {
162					done = true;
163					break;
164				}
165			}
166		}
167		qnx6_put_page(page);
168	}
169	return 0;
170}
171
172/*
173 * check if the long filename is correct.
174 */
175static unsigned qnx6_long_match(int len, const char *name,
176			struct qnx6_long_dir_entry *de, struct inode *dir)
177{
178	struct super_block *s = dir->i_sb;
179	struct qnx6_sb_info *sbi = QNX6_SB(s);
180	struct page *page;
181	int thislen;
182	struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
183
184	if (IS_ERR(lf))
185		return 0;
186
187	thislen = fs16_to_cpu(sbi, lf->lf_size);
188	if (len != thislen) {
189		qnx6_put_page(page);
190		return 0;
191	}
192	if (memcmp(name, lf->lf_fname, len) == 0) {
193		qnx6_put_page(page);
194		return fs32_to_cpu(sbi, de->de_inode);
195	}
196	qnx6_put_page(page);
197	return 0;
198}
199
200/*
201 * check if the filename is correct.
202 */
203static unsigned qnx6_match(struct super_block *s, int len, const char *name,
204			struct qnx6_dir_entry *de)
205{
206	struct qnx6_sb_info *sbi = QNX6_SB(s);
207	if (memcmp(name, de->de_fname, len) == 0)
208		return fs32_to_cpu(sbi, de->de_inode);
209	return 0;
210}
211
212
213unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
214			 struct page **res_page)
215{
216	struct super_block *s = dir->i_sb;
217	struct qnx6_inode_info *ei = QNX6_I(dir);
218	struct page *page = NULL;
219	unsigned long start, n;
220	unsigned long npages = dir_pages(dir);
221	unsigned ino;
222	struct qnx6_dir_entry *de;
223	struct qnx6_long_dir_entry *lde;
224
225	*res_page = NULL;
226
227	if (npages == 0)
228		return 0;
229	start = ei->i_dir_start_lookup;
230	if (start >= npages)
231		start = 0;
232	n = start;
233
234	do {
235		page = qnx6_get_page(dir, n);
236		if (!IS_ERR(page)) {
237			int limit = last_entry(dir, n);
238			int i;
239
240			de = (struct qnx6_dir_entry *)page_address(page);
241			for (i = 0; i < limit; i++, de++) {
242				if (len <= QNX6_SHORT_NAME_MAX) {
243					/* short filename */
244					if (len != de->de_size)
245						continue;
246					ino = qnx6_match(s, len, name, de);
247					if (ino)
248						goto found;
249				} else if (de->de_size == 0xff) {
250					/* deal with long filename */
251					lde = (struct qnx6_long_dir_entry *)de;
252					ino = qnx6_long_match(len,
253								name, lde, dir);
254					if (ino)
255						goto found;
256				} else
257					pr_err("undefined filename size in inode.\n");
258			}
259			qnx6_put_page(page);
260		}
261
262		if (++n >= npages)
263			n = 0;
264	} while (n != start);
265	return 0;
266
267found:
268	*res_page = page;
269	ei->i_dir_start_lookup = n;
270	return ino;
271}
272
273const struct file_operations qnx6_dir_operations = {
274	.llseek		= generic_file_llseek,
275	.read		= generic_read_dir,
276	.iterate_shared	= qnx6_readdir,
277	.fsync		= generic_file_fsync,
278};
279
280const struct inode_operations qnx6_dir_inode_operations = {
281	.lookup		= qnx6_lookup,
282};