summaryrefslogtreecommitdiff
path: root/fs/erofs/namei.c
blob: bde995f1bf2f2953a58c7c15211883ca93a43d5c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
// SPDX-License-Identifier: GPL-2.0+
#include "internal.h"

#define makedev(major, minor) ((dev_t)((((major) & 0xfff) << 8) | ((minor) & 0xff)))
static dev_t erofs_new_decode_dev(u32 dev)
{
	const unsigned int major = (dev & 0xfff00) >> 8;
	const unsigned int minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);

	return makedev(major, minor);
}

int erofs_read_inode_from_disk(struct erofs_inode *vi)
{
	int ret, ifmt;
	char buf[sizeof(struct erofs_inode_extended)];
	struct erofs_inode_compact *dic;
	struct erofs_inode_extended *die;
	const erofs_off_t inode_loc = iloc(vi->nid);

	ret = erofs_dev_read(0, buf, inode_loc, sizeof(*dic));
	if (ret < 0)
		return -EIO;

	dic = (struct erofs_inode_compact *)buf;
	ifmt = le16_to_cpu(dic->i_format);

	vi->datalayout = erofs_inode_datalayout(ifmt);
	if (vi->datalayout >= EROFS_INODE_DATALAYOUT_MAX) {
		erofs_err("unsupported datalayout %u of nid %llu",
			  vi->datalayout, vi->nid | 0ULL);
		return -EOPNOTSUPP;
	}
	switch (erofs_inode_version(ifmt)) {
	case EROFS_INODE_LAYOUT_EXTENDED:
		vi->inode_isize = sizeof(struct erofs_inode_extended);

		ret = erofs_dev_read(0, buf + sizeof(*dic),
				     inode_loc + sizeof(*dic),
				     sizeof(*die) - sizeof(*dic));
		if (ret < 0)
			return -EIO;

		die = (struct erofs_inode_extended *)buf;
		vi->xattr_isize = erofs_xattr_ibody_size(die->i_xattr_icount);
		vi->i_mode = le16_to_cpu(die->i_mode);

		switch (vi->i_mode & S_IFMT) {
		case S_IFREG:
		case S_IFDIR:
		case S_IFLNK:
			vi->u.i_blkaddr = le32_to_cpu(die->i_u.raw_blkaddr);
			break;
		case S_IFCHR:
		case S_IFBLK:
			vi->u.i_rdev =
				erofs_new_decode_dev(le32_to_cpu(die->i_u.rdev));
			break;
		case S_IFIFO:
		case S_IFSOCK:
			vi->u.i_rdev = 0;
			break;
		default:
			goto bogusimode;
		}

		vi->i_uid = le32_to_cpu(die->i_uid);
		vi->i_gid = le32_to_cpu(die->i_gid);
		vi->i_nlink = le32_to_cpu(die->i_nlink);

		vi->i_mtime = le64_to_cpu(die->i_mtime);
		vi->i_mtime_nsec = le64_to_cpu(die->i_mtime_nsec);
		vi->i_size = le64_to_cpu(die->i_size);
		if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
			/* fill chunked inode summary info */
			vi->u.chunkformat = le16_to_cpu(die->i_u.c.format);
		break;
	case EROFS_INODE_LAYOUT_COMPACT:
		vi->inode_isize = sizeof(struct erofs_inode_compact);
		vi->xattr_isize = erofs_xattr_ibody_size(dic->i_xattr_icount);
		vi->i_mode = le16_to_cpu(dic->i_mode);

		switch (vi->i_mode & S_IFMT) {
		case S_IFREG:
		case S_IFDIR:
		case S_IFLNK:
			vi->u.i_blkaddr = le32_to_cpu(dic->i_u.raw_blkaddr);
			break;
		case S_IFCHR:
		case S_IFBLK:
			vi->u.i_rdev =
				erofs_new_decode_dev(le32_to_cpu(dic->i_u.rdev));
			break;
		case S_IFIFO:
		case S_IFSOCK:
			vi->u.i_rdev = 0;
			break;
		default:
			goto bogusimode;
		}

		vi->i_uid = le16_to_cpu(dic->i_uid);
		vi->i_gid = le16_to_cpu(dic->i_gid);
		vi->i_nlink = le16_to_cpu(dic->i_nlink);

		vi->i_mtime = sbi.build_time;
		vi->i_mtime_nsec = sbi.build_time_nsec;

		vi->i_size = le32_to_cpu(dic->i_size);
		if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
			vi->u.chunkformat = le16_to_cpu(dic->i_u.c.format);
		break;
	default:
		erofs_err("unsupported on-disk inode version %u of nid %llu",
			  erofs_inode_version(ifmt), vi->nid | 0ULL);
		return -EOPNOTSUPP;
	}

	vi->flags = 0;
	if (vi->datalayout == EROFS_INODE_CHUNK_BASED) {
		if (vi->u.chunkformat & ~EROFS_CHUNK_FORMAT_ALL) {
			erofs_err("unsupported chunk format %x of nid %llu",
				  vi->u.chunkformat, vi->nid | 0ULL);
			return -EOPNOTSUPP;
		}
		vi->u.chunkbits = sbi.blkszbits +
			(vi->u.chunkformat & EROFS_CHUNK_FORMAT_BLKBITS_MASK);
	} else if (erofs_inode_is_data_compressed(vi->datalayout)) {
		if (erofs_blksiz() != EROFS_MAX_BLOCK_SIZE)
			return -EOPNOTSUPP;
		return z_erofs_fill_inode(vi);
	}
	return 0;
bogusimode:
	erofs_err("bogus i_mode (%o) @ nid %llu", vi->i_mode, vi->nid | 0ULL);
	return -EFSCORRUPTED;
}

struct erofs_dirent *find_target_dirent(erofs_nid_t pnid,
					void *dentry_blk,
					const char *name, unsigned int len,
					unsigned int nameoff,
					unsigned int maxsize)
{
	struct erofs_dirent *de = dentry_blk;
	const struct erofs_dirent *end = dentry_blk + nameoff;

	while (de < end) {
		const char *de_name;
		unsigned int de_namelen;

		nameoff = le16_to_cpu(de->nameoff);
		de_name = (char *)dentry_blk + nameoff;

		/* the last dirent in the block? */
		if (de + 1 >= end)
			de_namelen = strnlen(de_name, maxsize - nameoff);
		else
			de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;

		/* a corrupted entry is found */
		if (nameoff + de_namelen > maxsize ||
		    de_namelen > EROFS_NAME_LEN) {
			erofs_err("bogus dirent @ nid %llu", pnid | 0ULL);
			DBG_BUGON(1);
			return ERR_PTR(-EFSCORRUPTED);
		}

		if (len == de_namelen && !memcmp(de_name, name, de_namelen))
			return de;
		++de;
	}
	return NULL;
}

struct nameidata {
	erofs_nid_t	nid;
	unsigned int	ftype;
};

int erofs_namei(struct nameidata *nd, const char *name, unsigned int len)
{
	erofs_nid_t nid = nd->nid;
	int ret;
	char buf[EROFS_MAX_BLOCK_SIZE];
	struct erofs_inode vi = { .nid = nid };
	erofs_off_t offset;

	ret = erofs_read_inode_from_disk(&vi);
	if (ret)
		return ret;

	offset = 0;
	while (offset < vi.i_size) {
		erofs_off_t maxsize = min_t(erofs_off_t,
					    vi.i_size - offset, erofs_blksiz());
		struct erofs_dirent *de = (void *)buf;
		unsigned int nameoff;

		ret = erofs_pread(&vi, buf, maxsize, offset);
		if (ret)
			return ret;

		nameoff = le16_to_cpu(de->nameoff);
		if (nameoff < sizeof(struct erofs_dirent) ||
		    nameoff >= erofs_blksiz()) {
			erofs_err("invalid de[0].nameoff %u @ nid %llu",
				  nameoff, nid | 0ULL);
			return -EFSCORRUPTED;
		}

		de = find_target_dirent(nid, buf, name, len,
					nameoff, maxsize);
		if (IS_ERR(de))
			return PTR_ERR(de);

		if (de) {
			nd->nid = le64_to_cpu(de->nid);
			return 0;
		}
		offset += maxsize;
	}
	return -ENOENT;
}

static int link_path_walk(const char *name, struct nameidata *nd)
{
	nd->nid = sbi.root_nid;

	while (*name == '/')
		name++;

	/* At this point we know we have a real path component. */
	while (*name != '\0') {
		const char *p = name;
		int ret;

		do {
			++p;
		} while (*p != '\0' && *p != '/');

		DBG_BUGON(p <= name);
		ret = erofs_namei(nd, name, p - name);
		if (ret)
			return ret;

		name = p;
		/* Skip until no more slashes. */
		for (name = p; *name == '/'; ++name)
			;
	}
	return 0;
}

int erofs_ilookup(const char *path, struct erofs_inode *vi)
{
	int ret;
	struct nameidata nd;

	ret = link_path_walk(path, &nd);
	if (ret)
		return ret;

	vi->nid = nd.nid;
	return erofs_read_inode_from_disk(vi);
}