4 * Code to read and set symbolic links in WIM files.
8 * Copyright (C) 2012, 2013 Eric Biggers
10 * This file is part of wimlib, a library for working with WIM files.
12 * wimlib is free software; you can redistribute it and/or modify it under the
13 * terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 3 of the License, or (at your option)
17 * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
18 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
19 * A PARTICULAR PURPOSE. See the GNU General Public License for more
22 * You should have received a copy of the GNU General Public License
23 * along with wimlib; if not, see http://www.gnu.org/licenses/.
27 #include "buffer_io.h"
28 #include "lookup_table.h"
33 * Find the symlink target of a symbolic link or junction point in the WIM.
35 * See http://msdn.microsoft.com/en-us/library/cc232006(v=prot.10).aspx for a
36 * description of the format of the so-called "reparse point data buffers".
38 * But, in the WIM format, the first 8 bytes of the reparse point data buffer
39 * are omitted, presumably because we already know the reparse tag from the
40 * dentry, and we already know the reparse tag length from the lookup table
41 * entry resource length.
44 get_symlink_name(const void *resource, size_t resource_len,
45 void *buf, size_t buf_len,
48 const u8 *p = resource;
49 u16 substitute_name_offset;
50 u16 substitute_name_len;
51 u16 print_name_offset;
54 size_t link_target_len;
57 char *translated_target;
61 if (resource_len < 12)
63 p = get_u16(p, &substitute_name_offset);
64 p = get_u16(p, &substitute_name_len);
65 p = get_u16(p, &print_name_offset);
66 p = get_u16(p, &print_name_len);
69 wimlib_assert(reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
70 reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
72 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT) {
75 is_absolute = (flags & 1) ? false : true;
79 if (header_size + substitute_name_offset + substitute_name_len > resource_len)
82 ret = utf16_to_utf8((const char *)p + substitute_name_offset,
84 &link_target, &link_target_len);
85 if (ret == WIMLIB_ERR_INVALID_UTF16_STRING)
87 else if (ret == WIMLIB_ERR_NOMEM)
90 wimlib_assert(ret == 0);
95 if (link_target_len + 1 > buf_len) {
100 translated_target = link_target;
101 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT || is_absolute) {
102 if (link_target_len < 7
103 || memcmp(translated_target, "\\??\\", 4) != 0
104 || translated_target[4] == '\0'
105 || translated_target[5] != ':'
106 || translated_target[6] != '\\') {
110 translated_target += 4;
111 link_target_len -= 4;
112 /* There's a drive letter, so just leave the backslashes since
113 * it won't go anyhwere on UNIX anyway...
116 * NTFS-3g tries to re-map these links to actually point to
117 * something, so maybe we could do something like that here
120 for (size_t i = 0; i < link_target_len; i++)
121 if (translated_target[i] == '\\')
122 translated_target[i] = '/';
125 memcpy(buf, translated_target, link_target_len + 1);
126 ret = link_target_len;
133 make_symlink_reparse_data_buf(const mbchar *symlink_target,
134 size_t *len_ret, void **buf_ret)
136 size_t utf8_len = strlen(symlink_target);
141 ret = utf8_to_utf16(symlink_target, utf8_len,
142 &name_utf16, &utf16_len);
146 for (size_t i = 0; i < utf16_len / 2; i++)
147 if (((u16*)name_utf16)[i] == cpu_to_le16('/'))
148 ((u16*)name_utf16)[i] = cpu_to_le16('\\');
149 size_t len = 12 + utf16_len * 2;
150 void *buf = MALLOC(len);
153 p = put_u16(p, utf16_len); /* Substitute name offset */
154 p = put_u16(p, utf16_len); /* Substitute name length */
155 p = put_u16(p, 0); /* Print name offset */
156 p = put_u16(p, utf16_len); /* Print name length */
157 p = put_u32(p, 1); /* flags: 0 iff *full* target, including drive letter??? */
158 p = put_bytes(p, utf16_len, (const u8*)name_utf16);
159 p = put_bytes(p, utf16_len, (const u8*)name_utf16);
164 ret = WIMLIB_ERR_NOMEM;
170 /* Get the symlink target from a WIM inode.
172 * The inode may be either a "real" symlink (reparse tag
173 * WIM_IO_REPARSE_TAG_SYMLINK), or it may be a junction point (reparse tag
174 * WIM_IO_REPARSE_TAG_MOUNT_POINT).
177 inode_readlink(const struct wim_inode *inode, mbchar *buf, size_t buf_len,
178 const WIMStruct *w, int read_resource_flags)
180 const struct wim_lookup_table_entry *lte;
183 wimlib_assert(inode_is_symlink(inode));
185 lte = inode_unnamed_lte(inode, w->lookup_table);
189 if (wim_resource_size(lte) > 10000)
192 u8 res_buf[wim_resource_size(lte)];
193 ret = read_full_wim_resource(lte, res_buf, read_resource_flags);
196 return get_symlink_name(res_buf, wim_resource_size(lte), buf,
197 buf_len, inode->i_reparse_tag);
201 * Sets @inode to be a symbolic link pointing to @target.
203 * A lookup table entry for the symbolic link data buffer is created and
204 * inserted into @lookup_table, unless there is an existing lookup table entry
205 * for the exact same data, in which its reference count is incremented.
207 * The lookup table entry is returned in @lte_ret.
209 * On failure @dentry and @lookup_table are not modified.
212 inode_set_symlink(struct wim_inode *inode,
213 const mbchar *target,
214 struct wim_lookup_table *lookup_table,
215 struct wim_lookup_table_entry **lte_ret)
219 size_t symlink_buf_len;
220 struct wim_lookup_table_entry *lte = NULL, *existing_lte;
221 u8 symlink_buf_hash[SHA1_HASH_SIZE];
224 ret = make_symlink_reparse_data_buf(target, &symlink_buf_len,
229 DEBUG("Made symlink reparse data buf (len = %zu, name len = %zu)",
230 symlink_buf_len, symlink_buf_len);
232 sha1_buffer(symlink_buf, symlink_buf_len, symlink_buf_hash);
234 existing_lte = __lookup_resource(lookup_table, symlink_buf_hash);
241 DEBUG("Creating new lookup table entry for symlink buf");
242 lte = new_lookup_table_entry();
244 ret = WIMLIB_ERR_NOMEM;
245 goto out_free_symlink_buf;
247 lte->resource_location = RESOURCE_IN_ATTACHED_BUFFER;
248 lte->attached_buffer = symlink_buf;
249 lte->resource_entry.original_size = symlink_buf_len;
250 lte->resource_entry.size = symlink_buf_len;
251 copy_hash(lte->hash, symlink_buf_hash);
255 inode->i_resolved = 1;
257 DEBUG("Loaded symlink buf");
262 lookup_table_insert(lookup_table, lte);
266 out_free_symlink_buf: