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 bool translate_slashes;
62 if (resource_len < 12)
64 p = get_u16(p, &substitute_name_offset);
65 p = get_u16(p, &substitute_name_len);
66 p = get_u16(p, &print_name_offset);
67 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)
78 if (header_size + substitute_name_offset + substitute_name_len > resource_len)
81 ret = utf16le_to_tstr((const utf16lechar*)(p + substitute_name_offset),
83 &link_target, &link_target_len);
87 if (link_target_len + 1 > buf_len) {
92 DEBUG("Interpeting substitute name \"%s\" (ReparseTag=0x%x)",
93 link_target, reparse_tag);
94 translate_slashes = true;
95 if (link_target_len >= 7 &&
96 link_target[0] == '\\' &&
97 link_target[1] == '?' &&
98 link_target[2] == '?' &&
99 link_target[3] == '\\' &&
100 link_target[4] != '\0' &&
101 link_target[5] == ':' &&
102 link_target[6] == '\\')
104 /* "Full" symlink or junction (\??\x:\ prefixed path) */
106 link_target_len -= 6;
107 } else if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT &&
108 link_target_len >= 12 &&
109 memcmp(link_target, "\\\\?\\Volume{", 11) == 0 &&
110 link_target[link_target_len - 1] == '\\')
112 /* Volume junction. Can't really do anything with it. */
113 translate_slashes = false;
114 } else if (reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK &&
115 link_target_len >= 3 &&
116 link_target[0] != '\0' &&
117 link_target[1] == ':' &&
118 link_target[2] == '/')
120 /* "Absolute" symlink, with drive letter */
122 link_target_len -= 2;
123 } else if (reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK &&
124 link_target_len >= 1)
126 if (link_target[0] == '/')
127 /* "Absolute" symlink, without drive letter */
130 /* "Relative" symlink, without drive letter */
133 ERROR("Invalid reparse point: \"%s\"", link_target);
138 if (translate_slashes)
139 for (size_t i = 0; i < link_target_len; i++)
140 if (link_target[i] == '\\')
141 link_target[i] = '/';
142 memcpy(buf, link_target, link_target_len + 1);
143 ret = link_target_len;
150 make_symlink_reparse_data_buf(const char *symlink_target,
151 size_t *len_ret, void **buf_ret)
153 utf16lechar *name_utf16le;
154 size_t name_utf16le_nbytes;
157 ret = tstr_to_utf16le(symlink_target, strlen(symlink_target),
158 &name_utf16le, &name_utf16le_nbytes);
162 for (size_t i = 0; i < name_utf16le_nbytes / 2; i++)
163 if (name_utf16le[i] == cpu_to_le16('/'))
164 name_utf16le[i] = cpu_to_le16('\\');
166 size_t len = 12 + name_utf16le_nbytes * 2;
167 void *buf = MALLOC(len);
170 p = put_u16(p, name_utf16le_nbytes); /* Substitute name offset */
171 p = put_u16(p, name_utf16le_nbytes); /* Substitute name length */
172 p = put_u16(p, 0); /* Print name offset */
173 p = put_u16(p, name_utf16le_nbytes); /* Print name length */
174 p = put_u32(p, 1); /* flags: 0 iff *full* target, including drive letter??? */
175 p = put_bytes(p, name_utf16le_nbytes, name_utf16le);
176 p = put_bytes(p, name_utf16le_nbytes, name_utf16le);
181 ret = WIMLIB_ERR_NOMEM;
187 /* Get the symlink target from a WIM inode.
189 * The inode may be either a "real" symlink (reparse tag
190 * WIM_IO_REPARSE_TAG_SYMLINK), or it may be a junction point (reparse tag
191 * WIM_IO_REPARSE_TAG_MOUNT_POINT).
194 inode_readlink(const struct wim_inode *inode, char *buf, size_t buf_len,
195 const WIMStruct *w, bool threadsafe)
197 const struct wim_lookup_table_entry *lte;
200 wimlib_assert(inode_is_symlink(inode));
202 lte = inode_unnamed_lte(inode, w->lookup_table);
206 if (wim_resource_size(lte) > REPARSE_POINT_MAX_SIZE)
209 u8 res_buf[wim_resource_size(lte)];
210 ret = read_full_resource_into_buf(lte, res_buf, threadsafe);
213 return get_symlink_name(res_buf, wim_resource_size(lte), buf,
214 buf_len, inode->i_reparse_tag);
218 * Sets @inode to be a symbolic link pointing to @target.
220 * A lookup table entry for the symbolic link data buffer is created and
221 * inserted into @lookup_table, unless there is an existing lookup table entry
222 * for the exact same data, in which its reference count is incremented.
224 * The lookup table entry is returned in @lte_ret.
226 * On failure @dentry and @lookup_table are not modified.
229 inode_set_symlink(struct wim_inode *inode,
231 struct wim_lookup_table *lookup_table,
232 struct wim_lookup_table_entry **lte_ret)
236 size_t symlink_buf_len;
237 struct wim_lookup_table_entry *lte = NULL, *existing_lte;
238 u8 symlink_buf_hash[SHA1_HASH_SIZE];
241 ret = make_symlink_reparse_data_buf(target, &symlink_buf_len,
246 DEBUG("Made symlink reparse data buf (len = %zu, name len = %zu)",
247 symlink_buf_len, symlink_buf_len);
249 sha1_buffer(symlink_buf, symlink_buf_len, symlink_buf_hash);
251 existing_lte = __lookup_resource(lookup_table, symlink_buf_hash);
258 DEBUG("Creating new lookup table entry for symlink buf");
259 lte = new_lookup_table_entry();
261 ret = WIMLIB_ERR_NOMEM;
262 goto out_free_symlink_buf;
264 lte->resource_location = RESOURCE_IN_ATTACHED_BUFFER;
265 lte->attached_buffer = symlink_buf;
266 lte->resource_entry.original_size = symlink_buf_len;
267 copy_hash(lte->hash, symlink_buf_hash);
271 inode->i_resolved = 1;
273 DEBUG("Loaded symlink buf");
278 lookup_table_insert(lookup_table, lte);
282 out_free_symlink_buf:
287 #endif /* !defined(__WIN32__) */