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 void *qnx6_get_folio(struct inode *dir, unsigned long n,
 28		struct folio **foliop)
 29{
 30	struct folio *folio = read_mapping_folio(dir->i_mapping, n, NULL);
 31
 32	if (IS_ERR(folio))
 33		return folio;
 34	*foliop = folio;
 35	return kmap_local_folio(folio, 0);
 36}
 37
 38static unsigned last_entry(struct inode *inode, unsigned long page_nr)
 39{
 40	unsigned long last_byte = inode->i_size;
 41	last_byte -= page_nr << PAGE_SHIFT;
 42	if (last_byte > PAGE_SIZE)
 43		last_byte = PAGE_SIZE;
 44	return last_byte / QNX6_DIR_ENTRY_SIZE;
 45}
 46
 47static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
 48					 struct qnx6_long_dir_entry *de,
 49					 struct folio **foliop)
 50{
 51	struct qnx6_sb_info *sbi = QNX6_SB(sb);
 52	u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
 53	u32 n = s >> (PAGE_SHIFT - sb->s_blocksize_bits); /* in pages */
 54	u32 offs;
 55	struct address_space *mapping = sbi->longfile->i_mapping;
 56	struct folio *folio = read_mapping_folio(mapping, n, NULL);
 57
 58	if (IS_ERR(folio))
 59		return ERR_CAST(folio);
 60	offs = offset_in_folio(folio, s << sb->s_blocksize_bits);
 61	*foliop = folio;
 62	return kmap_local_folio(folio, offs);
 63}
 64
 65static int qnx6_dir_longfilename(struct inode *inode,
 66			struct qnx6_long_dir_entry *de,
 67			struct dir_context *ctx,
 68			unsigned de_inode)
 69{
 70	struct qnx6_long_filename *lf;
 71	struct super_block *s = inode->i_sb;
 72	struct qnx6_sb_info *sbi = QNX6_SB(s);
 73	struct folio *folio;
 74	int lf_size;
 75
 76	if (de->de_size != 0xff) {
 77		/* error - long filename entries always have size 0xff
 78		   in direntry */
 79		pr_err("invalid direntry size (%i).\n", de->de_size);
 80		return 0;
 81	}
 82	lf = qnx6_longname(s, de, &folio);
 83	if (IS_ERR(lf)) {
 84		pr_err("Error reading longname\n");
 85		return 0;
 86	}
 87
 88	lf_size = fs16_to_cpu(sbi, lf->lf_size);
 89
 90	if (lf_size > QNX6_LONG_NAME_MAX) {
 91		pr_debug("file %s\n", lf->lf_fname);
 92		pr_err("Filename too long (%i)\n", lf_size);
 93		folio_release_kmap(folio, lf);
 94		return 0;
 95	}
 96
 97	/* calc & validate longfilename checksum
 98	   mmi 3g filesystem does not have that checksum */
 99	if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
100			qnx6_lfile_checksum(lf->lf_fname, lf_size))
101		pr_info("long filename checksum error.\n");
102
103	pr_debug("qnx6_readdir:%.*s inode:%u\n",
104		 lf_size, lf->lf_fname, de_inode);
105	if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
106		folio_release_kmap(folio, lf);
107		return 0;
108	}
109
110	folio_release_kmap(folio, lf);
111	/* success */
112	return 1;
113}
114
115static int qnx6_readdir(struct file *file, struct dir_context *ctx)
116{
117	struct inode *inode = file_inode(file);
118	struct super_block *s = inode->i_sb;
119	struct qnx6_sb_info *sbi = QNX6_SB(s);
120	loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
121	unsigned long npages = dir_pages(inode);
122	unsigned long n = pos >> PAGE_SHIFT;
123	unsigned offset = (pos & ~PAGE_MASK) / QNX6_DIR_ENTRY_SIZE;
124	bool done = false;
125
126	ctx->pos = pos;
127	if (ctx->pos >= inode->i_size)
128		return 0;
129
130	for ( ; !done && n < npages; n++, offset = 0) {
131		struct qnx6_dir_entry *de;
132		struct folio *folio;
133		char *kaddr = qnx6_get_folio(inode, n, &folio);
134		char *limit;
135
136		if (IS_ERR(kaddr)) {
137			pr_err("%s(): read failed\n", __func__);
138			ctx->pos = (n + 1) << PAGE_SHIFT;
139			return PTR_ERR(kaddr);
140		}
141		de = (struct qnx6_dir_entry *)(kaddr + offset);
142		limit = kaddr + last_entry(inode, n);
143		for (; (char *)de < limit; 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		folio_release_kmap(folio, kaddr);
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 folio *folio;
185	int thislen;
186	struct qnx6_long_filename *lf = qnx6_longname(s, de, &folio);
187
188	if (IS_ERR(lf))
189		return 0;
190
191	thislen = fs16_to_cpu(sbi, lf->lf_size);
192	if (len != thislen) {
193		folio_release_kmap(folio, lf);
194		return 0;
195	}
196	if (memcmp(name, lf->lf_fname, len) == 0) {
197		folio_release_kmap(folio, lf);
198		return fs32_to_cpu(sbi, de->de_inode);
199	}
200	folio_release_kmap(folio, lf);
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_ino(int len, struct inode *dir, const char *name)
218{
219	struct super_block *s = dir->i_sb;
220	struct qnx6_inode_info *ei = QNX6_I(dir);
221	struct folio *folio;
222	unsigned long start, n;
223	unsigned long npages = dir_pages(dir);
224	unsigned ino;
225	struct qnx6_dir_entry *de;
226	struct qnx6_long_dir_entry *lde;
227
228	if (npages == 0)
229		return 0;
230	start = ei->i_dir_start_lookup;
231	if (start >= npages)
232		start = 0;
233	n = start;
234
235	do {
236		de = qnx6_get_folio(dir, n, &folio);
237		if (!IS_ERR(de)) {
238			int limit = last_entry(dir, n);
239			int i;
240
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			folio_release_kmap(folio, de - i);
260		}
261
262		if (++n >= npages)
263			n = 0;
264	} while (n != start);
265	return 0;
266
267found:
268	ei->i_dir_start_lookup = n;
269	folio_release_kmap(folio, de);
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};