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_inode_data_blocks(fs,&ei)) {
54 retval = ext2fs_bmap2(fs, inode, &ei, NULL, 0, 0, NULL, &blk);
55 if (retval)
56 return retval;
57
58 retval = ext2fs_get_mem(fs->blocksize, &buffer);
59 if (retval)
60 return retval;
61
62 retval = io_channel_read_blk64(fs->io, blk, 1, buffer);
63 if (retval) {
64 ext2fs_free_mem(&buffer);
65 return retval;
66 }
67 pathname = buffer;
68 } else
69 pathname = (char *)&(ei.i_block[0]);
70 retval = open_namei(fs, root, dir, pathname, ei.i_size, 1,
71 link_count, buf, res_inode);
72 if (buffer)
73 ext2fs_free_mem(&buffer);
74 return retval;
75 }
76
77 /*
78 * This routine interprets a pathname in the context of the current
79 * directory and the root directory, and returns the inode of the
80 * containing directory, and a pointer to the filename of the file
81 * (pointing into the pathname) and the length of the filename.
82 */
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)83 static errcode_t dir_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t dir,
84 const char *pathname, int pathlen,
85 int link_count, char *buf,
86 const char **name, int *namelen,
87 ext2_ino_t *res_inode)
88 {
89 char c;
90 const char *thisname;
91 int len;
92 ext2_ino_t inode;
93 errcode_t retval;
94
95 if ((c = *pathname) == '/') {
96 dir = root;
97 pathname++;
98 pathlen--;
99 }
100 while (1) {
101 thisname = pathname;
102 for (len=0; --pathlen >= 0;len++) {
103 c = *(pathname++);
104 if (c == '/')
105 break;
106 }
107 if (pathlen < 0)
108 break;
109 retval = ext2fs_lookup (fs, dir, thisname, len, buf, &inode);
110 if (retval) return retval;
111 retval = follow_link (fs, root, dir, inode,
112 link_count, buf, &dir);
113 if (retval) return retval;
114 }
115 *name = thisname;
116 *namelen = len;
117 *res_inode = dir;
118 return 0;
119 }
120
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)121 static errcode_t open_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t base,
122 const char *pathname, size_t pathlen, int follow,
123 int link_count, char *buf, ext2_ino_t *res_inode)
124 {
125 const char *base_name;
126 int namelen;
127 ext2_ino_t dir, inode;
128 errcode_t retval;
129
130 #ifdef NAMEI_DEBUG
131 printf("open_namei: root=%lu, dir=%lu, path=%*s, lc=%d\n",
132 root, base, pathlen, pathname, link_count);
133 #endif
134 retval = dir_namei(fs, root, base, pathname, pathlen,
135 link_count, buf, &base_name, &namelen, &dir);
136 if (retval) return retval;
137 if (!namelen) { /* special case: '/usr/' etc */
138 *res_inode=dir;
139 return 0;
140 }
141 retval = ext2fs_lookup (fs, dir, base_name, namelen, buf, &inode);
142 if (retval)
143 return retval;
144 if (follow) {
145 retval = follow_link(fs, root, dir, inode, link_count,
146 buf, &inode);
147 if (retval)
148 return retval;
149 }
150 #ifdef NAMEI_DEBUG
151 printf("open_namei: (link_count=%d) returns %lu\n",
152 link_count, inode);
153 #endif
154 *res_inode = inode;
155 return 0;
156 }
157
ext2fs_namei(ext2_filsys fs,ext2_ino_t root,ext2_ino_t cwd,const char * name,ext2_ino_t * inode)158 errcode_t ext2fs_namei(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
159 const char *name, ext2_ino_t *inode)
160 {
161 char *buf;
162 errcode_t retval;
163
164 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
165
166 retval = ext2fs_get_mem(fs->blocksize, &buf);
167 if (retval)
168 return retval;
169
170 retval = open_namei(fs, root, cwd, name, strlen(name), 0, 0,
171 buf, inode);
172
173 ext2fs_free_mem(&buf);
174 return retval;
175 }
176
ext2fs_namei_follow(ext2_filsys fs,ext2_ino_t root,ext2_ino_t cwd,const char * name,ext2_ino_t * inode)177 errcode_t ext2fs_namei_follow(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
178 const char *name, ext2_ino_t *inode)
179 {
180 char *buf;
181 errcode_t retval;
182
183 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
184
185 retval = ext2fs_get_mem(fs->blocksize, &buf);
186 if (retval)
187 return retval;
188
189 retval = open_namei(fs, root, cwd, name, strlen(name), 1, 0,
190 buf, inode);
191
192 ext2fs_free_mem(&buf);
193 return retval;
194 }
195
ext2fs_follow_link(ext2_filsys fs,ext2_ino_t root,ext2_ino_t cwd,ext2_ino_t inode,ext2_ino_t * res_inode)196 errcode_t ext2fs_follow_link(ext2_filsys fs, ext2_ino_t root, ext2_ino_t cwd,
197 ext2_ino_t inode, ext2_ino_t *res_inode)
198 {
199 char *buf;
200 errcode_t retval;
201
202 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
203
204 retval = ext2fs_get_mem(fs->blocksize, &buf);
205 if (retval)
206 return retval;
207
208 retval = follow_link(fs, root, cwd, inode, 0, buf, res_inode);
209
210 ext2fs_free_mem(&buf);
211 return retval;
212 }
213
214