1 /*
2 * namei.c --- ext2fs directory lookup operations
3 *
4 * Copyright (C) 1993, 1994, 1994, 1995 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12 #include "config.h"
13 #include <stdio.h>
14 #include <string.h>
15 #if HAVE_UNISTD_H
16 #include <unistd.h>
17 #endif
18
19 /* #define NAMEI_DEBUG */
20
21 #include "ext2_fs.h"
22 #include "ext2fs.h"
23 #include "ext2fsP.h"
24
25 static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
26 const char *pathname, size_t pathlen, int follow,
27 int link_count, char *buf, ext2_ino_t *res_inode);
28
follow_link(ext2_filsys fs,ext2_ino_t root,ext2_ino_t dir,ext2_ino_t inode,int link_count,char * buf,ext2_ino_t * res_inode)29 static errcode_t follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
30 ext2_ino_t inode, int link_count,
31 char *buf, ext2_ino_t *res_inode)
32 {
33 char *pathname;
34 char *buffer = 0;
35 errcode_t retval;
36 struct ext2_inode ei;
37 blk64_t blk;
38
39 #ifdef NAMEI_DEBUG
40 printf("follow_link: root=%lu, dir=%lu, inode=%lu, lc=%d\n",
41 root, dir, inode, link_count);
42
43 #endif
44 retval = ext2fs_read_inode (fs, inode, &ei);
45 if (retval) return retval;
46 if (!LINUX_S_ISLNK (ei.i_mode)) {
47 *res_inode = inode;
48 return 0;
49 }
50 if (link_count++ >= EXT2FS_MAX_NESTED_LINKS)
51 return EXT2_ET_SYMLINK_LOOP;
52
53 if (ext2fs_is_fast_symlink(&ei))
54 pathname = (char *)&(ei.i_block[0]);
55 else if (ei.i_flags & EXT4_INLINE_DATA_FL) {
56 retval = ext2fs_get_memzero(ei.i_size, &buffer);
57 if (retval)
58 return retval;
59
60 retval = ext2fs_inline_data_get(fs, inode,
61 &ei, buffer, NULL);
62 if (retval) {
63 ext2fs_free_mem(&buffer);
64 return retval;
65 }
66 pathname = buffer;
67 } else {
68 retval = ext2fs_bmap2(fs, inode, &ei, NULL, 0, 0, NULL, &blk);
69 if (retval)
70 return retval;
71
72 retval = ext2fs_get_mem(fs->blocksize, &buffer);
73 if (retval)
74 return retval;
75
76 retval = io_channel_read_blk64(fs->io, blk, 1, buffer);
77 if (retval) {
78 ext2fs_free_mem(&buffer);
79 return retval;
80 }
81 pathname = buffer;
82 }
83
84 retval = open_namei(fs, root, dir, pathname, ei.i_size, 1,
85 link_count, buf, res_inode);
86 if (buffer)
87 ext2fs_free_mem(&buffer);
88 return retval;
89 }
90
91 /*
92 * This routine interprets a pathname in the context of the current
93 * directory and the root directory, and returns the inode of the
94 * containing directory, and a pointer to the filename of the file
95 * (pointing into the pathname) and the length of the filename.
96 */
dir_namei(ext2_filsys fs,ext2_ino_t root,ext2_ino_t dir,const char * pathname,int pathlen,int link_count,char * buf,const char ** name,int * namelen,ext2_ino_t * res_inode)97 static errcode_t dir_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
98 const char *pathname, int pathlen,
99 int link_count, char *buf,
100 const char **name, int *namelen,
101 ext2_ino_t *res_inode)
102 {
103 char c;
104 const char *thisname;
105 int len;
106 ext2_ino_t inode;
107 errcode_t retval;
108
109 if ((c = *pathname) == '/') {
110 dir = root;
111 pathname++;
112 pathlen--;
113 }
114 while (1) {
115 thisname = pathname;
116 for (len=0; --pathlen >= 0;len++) {
117 c = *(pathname++);
118 if (c == '/')
119 break;
120 }
121 if (pathlen < 0)
122 break;
123 retval = ext2fs_lookup (fs, dir, thisname, len, buf, &inode);
124 if (retval) return retval;
125 retval = follow_link (fs, root, dir, inode,
126 link_count, buf, &dir);
127 if (retval) return retval;
128 }
129 *name = thisname;
130 *namelen = len;
131 *res_inode = dir;
132 return 0;
133 }
134
open_namei(ext2_filsys fs,ext2_ino_t root,ext2_ino_t base,const char * pathname,size_t pathlen,int follow,int link_count,char * buf,ext2_ino_t * res_inode)135 static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
136 const char *pathname, size_t pathlen, int follow,
137 int link_count, char *buf, ext2_ino_t *res_inode)
138 {
139 const char *base_name;
140 int namelen;
141 ext2_ino_t dir, inode;
142 errcode_t retval;
143
144 #ifdef NAMEI_DEBUG
145 printf("open_namei: root=%lu, dir=%lu, path=%.*s, lc=%d\n",
146 root, base, pathlen, pathname, link_count);
147 #endif
148 retval = dir_namei(fs, root, base, pathname, pathlen,
149 link_count, buf, &base_name, &namelen, &dir);
150 if (retval) return retval;
151 if (!namelen) { /* special case: '/usr/' etc */
152 *res_inode=dir;
153 return 0;
154 }
155 retval = ext2fs_lookup (fs, dir, base_name, namelen, buf, &inode);
156 if (retval)
157 return retval;
158 if (follow) {
159 retval = follow_link(fs, root, dir, inode, link_count,
160 buf, &inode);
161 if (retval)
162 return retval;
163 }
164 #ifdef NAMEI_DEBUG
165 printf("open_namei: (link_count=%d) returns %lu\n",
166 link_count, inode);
167 #endif
168 *res_inode = inode;
169 return 0;
170 }
171
ext2fs_namei(ext2_filsys fs,ext2_ino_t root,ext2_ino_t cwd,const char * name,ext2_ino_t * inode)172 errcode_t ext2fs_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
173 const char *name, ext2_ino_t *inode)
174 {
175 char *buf;
176 errcode_t retval;
177
178 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
179
180 retval = ext2fs_get_mem(fs->blocksize, &buf);
181 if (retval)
182 return retval;
183
184 retval = open_namei(fs, root, cwd, name, strlen(name), 0, 0,
185 buf, inode);
186
187 ext2fs_free_mem(&buf);
188 return retval;
189 }
190
ext2fs_namei_follow(ext2_filsys fs,ext2_ino_t root,ext2_ino_t cwd,const char * name,ext2_ino_t * inode)191 errcode_t ext2fs_namei_follow(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
192 const char *name, ext2_ino_t *inode)
193 {
194 char *buf;
195 errcode_t retval;
196
197 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
198
199 retval = ext2fs_get_mem(fs->blocksize, &buf);
200 if (retval)
201 return retval;
202
203 retval = open_namei(fs, root, cwd, name, strlen(name), 1, 0,
204 buf, inode);
205
206 ext2fs_free_mem(&buf);
207 return retval;
208 }
209
ext2fs_follow_link(ext2_filsys fs,ext2_ino_t root,ext2_ino_t cwd,ext2_ino_t inode,ext2_ino_t * res_inode)210 errcode_t ext2fs_follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
211 ext2_ino_t inode, ext2_ino_t *res_inode)
212 {
213 char *buf;
214 errcode_t retval;
215
216 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
217
218 retval = ext2fs_get_mem(fs->blocksize, &buf);
219 if (retval)
220 return retval;
221
222 retval = follow_link(fs, root, cwd, inode, 0, buf, res_inode);
223
224 ext2fs_free_mem(&buf);
225 return retval;
226 }
227
228