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"
32 /* None of this file is ever needed in Win32 builds because the reparse point
33 * buffers are not parsed. */
34 #if !defined(__WIN32__)
37 * Find the symlink target of a symbolic link or junction point in the WIM.
39 * See http://msdn.microsoft.com/en-us/library/cc232006(v=prot.10).aspx for a
40 * description of the format of the so-called "reparse point data buffers".
42 * But, in the WIM format, the first 8 bytes of the reparse point data buffer
43 * are omitted, presumably because we already know the reparse tag from the
44 * dentry, and we already know the reparse tag length from the lookup table
45 * entry resource length.
48 get_symlink_name(const void *resource, size_t resource_len, char *buf,
49 size_t buf_len, u32 reparse_tag)
51 const void *p = resource;
52 u16 substitute_name_offset;
53 u16 substitute_name_len;
54 u16 print_name_offset;
57 size_t link_target_len;
60 char *translated_target;
64 if (resource_len < 12)
66 p = get_u16(p, &substitute_name_offset);
67 p = get_u16(p, &substitute_name_len);
68 p = get_u16(p, &print_name_offset);
69 p = get_u16(p, &print_name_len);
72 wimlib_assert(reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
73 reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
75 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT) {
78 is_absolute = (flags & 1) ? false : true;
82 if (header_size + substitute_name_offset + substitute_name_len > resource_len)
85 ret = utf16le_to_tstr((const utf16lechar*)(p + substitute_name_offset),
87 &link_target, &link_target_len);
91 if (link_target_len + 1 > buf_len) {
96 translated_target = link_target;
97 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT || is_absolute) {
98 if (link_target_len < 7
99 || memcmp(translated_target, "\\??\\", 4) != 0
100 || translated_target[4] == '\0'
101 || translated_target[5] != ':'
102 || translated_target[6] != '\\') {
106 translated_target += 4;
107 link_target_len -= 4;
108 /* There's a drive letter, so just leave the backslashes since
109 * it won't go anyhwere on UNIX anyway...
112 * NTFS-3g tries to re-map these links to actually point to
113 * something, so maybe we could do something like that here
116 for (size_t i = 0; i < link_target_len; i++)
117 if (translated_target[i] == '\\')
118 translated_target[i] = '/';
121 memcpy(buf, translated_target, link_target_len + 1);
122 ret = link_target_len;
129 make_symlink_reparse_data_buf(const char *symlink_target,
130 size_t *len_ret, void **buf_ret)
132 utf16lechar *name_utf16le;
133 size_t name_utf16le_nbytes;
136 ret = tstr_to_utf16le(symlink_target, strlen(symlink_target),
137 &name_utf16le, &name_utf16le_nbytes);
141 for (size_t i = 0; i < name_utf16le_nbytes / 2; i++)
142 if (name_utf16le[i] == cpu_to_le16('/'))
143 name_utf16le[i] = cpu_to_le16('\\');
145 size_t len = 12 + name_utf16le_nbytes * 2;
146 void *buf = MALLOC(len);
149 p = put_u16(p, name_utf16le_nbytes); /* Substitute name offset */
150 p = put_u16(p, name_utf16le_nbytes); /* Substitute name length */
151 p = put_u16(p, 0); /* Print name offset */
152 p = put_u16(p, name_utf16le_nbytes); /* Print name length */
153 p = put_u32(p, 1); /* flags: 0 iff *full* target, including drive letter??? */
154 p = put_bytes(p, name_utf16le_nbytes, name_utf16le);
155 p = put_bytes(p, name_utf16le_nbytes, name_utf16le);
160 ret = WIMLIB_ERR_NOMEM;
166 /* Get the symlink target from a WIM inode.
168 * The inode may be either a "real" symlink (reparse tag
169 * WIM_IO_REPARSE_TAG_SYMLINK), or it may be a junction point (reparse tag
170 * WIM_IO_REPARSE_TAG_MOUNT_POINT).
173 inode_readlink(const struct wim_inode *inode, char *buf, size_t buf_len,
174 const WIMStruct *w, int read_resource_flags)
176 const struct wim_lookup_table_entry *lte;
179 wimlib_assert(inode_is_symlink(inode));
181 lte = inode_unnamed_lte(inode, w->lookup_table);
185 if (wim_resource_size(lte) > 10000)
188 u8 res_buf[wim_resource_size(lte)];
189 ret = read_full_wim_resource(lte, res_buf, read_resource_flags);
192 return get_symlink_name(res_buf, wim_resource_size(lte), buf,
193 buf_len, inode->i_reparse_tag);
197 * Sets @inode to be a symbolic link pointing to @target.
199 * A lookup table entry for the symbolic link data buffer is created and
200 * inserted into @lookup_table, unless there is an existing lookup table entry
201 * for the exact same data, in which its reference count is incremented.
203 * The lookup table entry is returned in @lte_ret.
205 * On failure @dentry and @lookup_table are not modified.
208 inode_set_symlink(struct wim_inode *inode,
210 struct wim_lookup_table *lookup_table,
211 struct wim_lookup_table_entry **lte_ret)
215 size_t symlink_buf_len;
216 struct wim_lookup_table_entry *lte = NULL, *existing_lte;
217 u8 symlink_buf_hash[SHA1_HASH_SIZE];
220 ret = make_symlink_reparse_data_buf(target, &symlink_buf_len,
225 DEBUG("Made symlink reparse data buf (len = %zu, name len = %zu)",
226 symlink_buf_len, symlink_buf_len);
228 sha1_buffer(symlink_buf, symlink_buf_len, symlink_buf_hash);
230 existing_lte = __lookup_resource(lookup_table, symlink_buf_hash);
237 DEBUG("Creating new lookup table entry for symlink buf");
238 lte = new_lookup_table_entry();
240 ret = WIMLIB_ERR_NOMEM;
241 goto out_free_symlink_buf;
243 lte->resource_location = RESOURCE_IN_ATTACHED_BUFFER;
244 lte->attached_buffer = symlink_buf;
245 lte->resource_entry.original_size = symlink_buf_len;
246 lte->resource_entry.size = symlink_buf_len;
247 copy_hash(lte->hash, symlink_buf_hash);
251 inode->i_resolved = 1;
253 DEBUG("Loaded symlink buf");
258 lookup_table_insert(lookup_table, lte);
262 out_free_symlink_buf:
267 #endif /* !defined(__WIN32__) */