xref: /linux/fs/isofs/dir.c (revision d2912cb15bdda8ba4a5dd73396ad62641af2f520)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/isofs/dir.c
4  *
5  *  (C) 1992, 1993, 1994  Eric Youngdale Modified for ISO 9660 filesystem.
6  *
7  *  (C) 1991  Linus Torvalds - minix filesystem
8  *
9  *  Steve Beynon		       : Missing last directory entries fixed
10  *  (stephen@askone.demon.co.uk)      : 21st June 1996
11  *
12  *  isofs directory handling functions
13  */
14 #include <linux/gfp.h>
15 #include "isofs.h"
16 
17 int isofs_name_translate(struct iso_directory_record *de, char *new, struct inode *inode)
18 {
19 	char * old = de->name;
20 	int len = de->name_len[0];
21 	int i;
22 
23 	for (i = 0; i < len; i++) {
24 		unsigned char c = old[i];
25 		if (!c)
26 			break;
27 
28 		if (c >= 'A' && c <= 'Z')
29 			c |= 0x20;	/* lower case */
30 
31 		/* Drop trailing '.;1' (ISO 9660:1988 7.5.1 requires period) */
32 		if (c == '.' && i == len - 3 && old[i + 1] == ';' && old[i + 2] == '1')
33 			break;
34 
35 		/* Drop trailing ';1' */
36 		if (c == ';' && i == len - 2 && old[i + 1] == '1')
37 			break;
38 
39 		/* Convert remaining ';' to '.' */
40 		/* Also '/' to '.' (broken Acorn-generated ISO9660 images) */
41 		if (c == ';' || c == '/')
42 			c = '.';
43 
44 		new[i] = c;
45 	}
46 	return i;
47 }
48 
49 /* Acorn extensions written by Matthew Wilcox <willy@infradead.org> 1998 */
50 int get_acorn_filename(struct iso_directory_record *de,
51 			    char *retname, struct inode *inode)
52 {
53 	int std;
54 	unsigned char *chr;
55 	int retnamlen = isofs_name_translate(de, retname, inode);
56 
57 	if (retnamlen == 0)
58 		return 0;
59 	std = sizeof(struct iso_directory_record) + de->name_len[0];
60 	if (std & 1)
61 		std++;
62 	if (de->length[0] - std != 32)
63 		return retnamlen;
64 	chr = ((unsigned char *) de) + std;
65 	if (strncmp(chr, "ARCHIMEDES", 10))
66 		return retnamlen;
67 	if ((*retname == '_') && ((chr[19] & 1) == 1))
68 		*retname = '!';
69 	if (((de->flags[0] & 2) == 0) && (chr[13] == 0xff)
70 		&& ((chr[12] & 0xf0) == 0xf0)) {
71 		retname[retnamlen] = ',';
72 		sprintf(retname+retnamlen+1, "%3.3x",
73 			((chr[12] & 0xf) << 8) | chr[11]);
74 		retnamlen += 4;
75 	}
76 	return retnamlen;
77 }
78 
79 /*
80  * This should _really_ be cleaned up some day..
81  */
82 static int do_isofs_readdir(struct inode *inode, struct file *file,
83 		struct dir_context *ctx,
84 		char *tmpname, struct iso_directory_record *tmpde)
85 {
86 	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
87 	unsigned char bufbits = ISOFS_BUFFER_BITS(inode);
88 	unsigned long block, offset, block_saved, offset_saved;
89 	unsigned long inode_number = 0;	/* Quiet GCC */
90 	struct buffer_head *bh = NULL;
91 	int len;
92 	int map;
93 	int first_de = 1;
94 	char *p = NULL;		/* Quiet GCC */
95 	struct iso_directory_record *de;
96 	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
97 
98 	offset = ctx->pos & (bufsize - 1);
99 	block = ctx->pos >> bufbits;
100 
101 	while (ctx->pos < inode->i_size) {
102 		int de_len;
103 
104 		if (!bh) {
105 			bh = isofs_bread(inode, block);
106 			if (!bh)
107 				return 0;
108 		}
109 
110 		de = (struct iso_directory_record *) (bh->b_data + offset);
111 
112 		de_len = *(unsigned char *)de;
113 
114 		/*
115 		 * If the length byte is zero, we should move on to the next
116 		 * CDROM sector.  If we are at the end of the directory, we
117 		 * kick out of the while loop.
118 		 */
119 
120 		if (de_len == 0) {
121 			brelse(bh);
122 			bh = NULL;
123 			ctx->pos = (ctx->pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
124 			block = ctx->pos >> bufbits;
125 			offset = 0;
126 			continue;
127 		}
128 
129 		block_saved = block;
130 		offset_saved = offset;
131 		offset += de_len;
132 
133 		/* Make sure we have a full directory entry */
134 		if (offset >= bufsize) {
135 			int slop = bufsize - offset + de_len;
136 			memcpy(tmpde, de, slop);
137 			offset &= bufsize - 1;
138 			block++;
139 			brelse(bh);
140 			bh = NULL;
141 			if (offset) {
142 				bh = isofs_bread(inode, block);
143 				if (!bh)
144 					return 0;
145 				memcpy((void *) tmpde + slop, bh->b_data, offset);
146 			}
147 			de = tmpde;
148 		}
149 		/* Basic sanity check, whether name doesn't exceed dir entry */
150 		if (de_len < de->name_len[0] +
151 					sizeof(struct iso_directory_record)) {
152 			printk(KERN_NOTICE "iso9660: Corrupted directory entry"
153 			       " in block %lu of inode %lu\n", block,
154 			       inode->i_ino);
155 			return -EIO;
156 		}
157 
158 		if (first_de) {
159 			isofs_normalize_block_and_offset(de,
160 							&block_saved,
161 							&offset_saved);
162 			inode_number = isofs_get_ino(block_saved,
163 							offset_saved, bufbits);
164 		}
165 
166 		if (de->flags[-sbi->s_high_sierra] & 0x80) {
167 			first_de = 0;
168 			ctx->pos += de_len;
169 			continue;
170 		}
171 		first_de = 1;
172 
173 		/* Handle the case of the '.' directory */
174 		if (de->name_len[0] == 1 && de->name[0] == 0) {
175 			if (!dir_emit_dot(file, ctx))
176 				break;
177 			ctx->pos += de_len;
178 			continue;
179 		}
180 
181 		len = 0;
182 
183 		/* Handle the case of the '..' directory */
184 		if (de->name_len[0] == 1 && de->name[0] == 1) {
185 			if (!dir_emit_dotdot(file, ctx))
186 				break;
187 			ctx->pos += de_len;
188 			continue;
189 		}
190 
191 		/* Handle everything else.  Do name translation if there
192 		   is no Rock Ridge NM field. */
193 
194 		/*
195 		 * Do not report hidden files if so instructed, or associated
196 		 * files unless instructed to do so
197 		 */
198 		if ((sbi->s_hide && (de->flags[-sbi->s_high_sierra] & 1)) ||
199 		    (!sbi->s_showassoc &&
200 				(de->flags[-sbi->s_high_sierra] & 4))) {
201 			ctx->pos += de_len;
202 			continue;
203 		}
204 
205 		map = 1;
206 		if (sbi->s_rock) {
207 			len = get_rock_ridge_filename(de, tmpname, inode);
208 			if (len != 0) {		/* may be -1 */
209 				p = tmpname;
210 				map = 0;
211 			}
212 		}
213 		if (map) {
214 #ifdef CONFIG_JOLIET
215 			if (sbi->s_joliet_level) {
216 				len = get_joliet_filename(de, tmpname, inode);
217 				p = tmpname;
218 			} else
219 #endif
220 			if (sbi->s_mapping == 'a') {
221 				len = get_acorn_filename(de, tmpname, inode);
222 				p = tmpname;
223 			} else
224 			if (sbi->s_mapping == 'n') {
225 				len = isofs_name_translate(de, tmpname, inode);
226 				p = tmpname;
227 			} else {
228 				p = de->name;
229 				len = de->name_len[0];
230 			}
231 		}
232 		if (len > 0) {
233 			if (!dir_emit(ctx, p, len, inode_number, DT_UNKNOWN))
234 				break;
235 		}
236 		ctx->pos += de_len;
237 
238 		continue;
239 	}
240 	if (bh)
241 		brelse(bh);
242 	return 0;
243 }
244 
245 /*
246  * Handle allocation of temporary space for name translation and
247  * handling split directory entries.. The real work is done by
248  * "do_isofs_readdir()".
249  */
250 static int isofs_readdir(struct file *file, struct dir_context *ctx)
251 {
252 	int result;
253 	char *tmpname;
254 	struct iso_directory_record *tmpde;
255 	struct inode *inode = file_inode(file);
256 
257 	tmpname = (char *)__get_free_page(GFP_KERNEL);
258 	if (tmpname == NULL)
259 		return -ENOMEM;
260 
261 	tmpde = (struct iso_directory_record *) (tmpname+1024);
262 
263 	result = do_isofs_readdir(inode, file, ctx, tmpname, tmpde);
264 
265 	free_page((unsigned long) tmpname);
266 	return result;
267 }
268 
269 const struct file_operations isofs_dir_operations =
270 {
271 	.llseek = generic_file_llseek,
272 	.read = generic_read_dir,
273 	.iterate_shared = isofs_readdir,
274 };
275 
276 /*
277  * directories can handle most operations...
278  */
279 const struct inode_operations isofs_dir_inode_operations =
280 {
281 	.lookup = isofs_lookup,
282 };
283 
284 
285