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.
43 static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
44 char *buf, size_t buf_len,
47 const u8 *p = resource;
48 u16 substitute_name_offset;
49 u16 substitute_name_len;
50 u16 print_name_offset;
53 size_t link_target_len;
56 char *translated_target;
60 if (resource_len < 12)
62 p = get_u16(p, &substitute_name_offset);
63 p = get_u16(p, &substitute_name_len);
64 p = get_u16(p, &print_name_offset);
65 p = get_u16(p, &print_name_len);
68 wimlib_assert(reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
69 reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
71 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT) {
74 is_absolute = (flags & 1) ? false : true;
78 if (header_size + substitute_name_offset + substitute_name_len > resource_len)
81 ret = utf16_to_utf8((const char *)p + substitute_name_offset,
83 &link_target, &link_target_len);
84 if (ret == WIMLIB_ERR_INVALID_UTF16_STRING)
86 else if (ret == WIMLIB_ERR_NOMEM)
89 wimlib_assert(ret == 0);
94 if (link_target_len + 1 > buf_len) {
99 translated_target = link_target;
100 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT || is_absolute) {
101 if (link_target_len < 7
102 || memcmp(translated_target, "\\??\\", 4) != 0
103 || translated_target[4] == '\0'
104 || translated_target[5] != ':'
105 || translated_target[6] != '\\') {
109 translated_target += 4;
110 link_target_len -= 4;
111 /* There's a drive letter, so just leave the backslashes since
112 * it won't go anyhwere on UNIX anyway...
115 * NTFS-3g tries to re-map these links to actually point to
116 * something, so maybe we could do something like that here
119 for (size_t i = 0; i < link_target_len; i++)
120 if (translated_target[i] == '\\')
121 translated_target[i] = '/';
124 memcpy(buf, translated_target, link_target_len + 1);
125 ret = link_target_len;
131 static int make_symlink_reparse_data_buf(const char *symlink_target,
132 size_t *len_ret, void **buf_ret)
134 size_t utf8_len = strlen(symlink_target);
139 ret = utf8_to_utf16(symlink_target, utf8_len,
140 &name_utf16, &utf16_len);
144 for (size_t i = 0; i < utf16_len / 2; i++)
145 if (((u16*)name_utf16)[i] == cpu_to_le16('/'))
146 ((u16*)name_utf16)[i] = cpu_to_le16('\\');
147 size_t len = 12 + utf16_len * 2;
148 void *buf = MALLOC(len);
151 p = put_u16(p, utf16_len); /* Substitute name offset */
152 p = put_u16(p, utf16_len); /* Substitute name length */
153 p = put_u16(p, 0); /* Print name offset */
154 p = put_u16(p, utf16_len); /* Print name length */
155 p = put_u32(p, 1); /* flags: 0 iff *full* target, including drive letter??? */
156 p = put_bytes(p, utf16_len, (const u8*)name_utf16);
157 p = put_bytes(p, utf16_len, (const u8*)name_utf16);
162 ret = WIMLIB_ERR_NOMEM;
168 /* Get the symlink target from a WIM inode.
170 * The inode may be either a "real" symlink (reparse tag
171 * WIM_IO_REPARSE_TAG_SYMLINK), or it may be a junction point (reparse tag
172 * WIM_IO_REPARSE_TAG_MOUNT_POINT).
174 ssize_t inode_readlink(const struct wim_inode *inode, char *buf, size_t buf_len,
175 const WIMStruct *w, int read_resource_flags)
177 const struct wim_lookup_table_entry *lte;
180 wimlib_assert(inode_is_symlink(inode));
182 lte = inode_unnamed_lte(inode, w->lookup_table);
186 if (wim_resource_size(lte) > 10000)
189 u8 res_buf[wim_resource_size(lte)];
190 ret = read_full_wim_resource(lte, res_buf, read_resource_flags);
193 return get_symlink_name(res_buf, wim_resource_size(lte), buf,
194 buf_len, inode->i_reparse_tag);
198 * Sets @inode to be a symbolic link pointing to @target.
200 * A lookup table entry for the symbolic link data buffer is created and
201 * inserted into @lookup_table, unless there is an existing lookup table entry
202 * for the exact same data, in which its reference count is incremented.
204 * The lookup table entry is returned in @lte_ret.
206 * On failure @dentry and @lookup_table are not modified.
208 int inode_set_symlink(struct wim_inode *inode, const char *target,
209 struct wim_lookup_table *lookup_table,
210 struct wim_lookup_table_entry **lte_ret)
214 size_t symlink_buf_len;
215 struct wim_lookup_table_entry *lte = NULL, *existing_lte;
216 u8 symlink_buf_hash[SHA1_HASH_SIZE];
219 ret = make_symlink_reparse_data_buf(target, &symlink_buf_len,
224 DEBUG("Made symlink reparse data buf (len = %zu, name len = %zu)",
225 symlink_buf_len, symlink_buf_len);
227 sha1_buffer(symlink_buf, symlink_buf_len, symlink_buf_hash);
229 existing_lte = __lookup_resource(lookup_table, symlink_buf_hash);
236 DEBUG("Creating new lookup table entry for symlink buf");
237 lte = new_lookup_table_entry();
239 ret = WIMLIB_ERR_NOMEM;
240 goto out_free_symlink_buf;
242 lte->resource_location = RESOURCE_IN_ATTACHED_BUFFER;
243 lte->attached_buffer = symlink_buf;
244 lte->resource_entry.original_size = symlink_buf_len;
245 lte->resource_entry.size = symlink_buf_len;
246 copy_hash(lte->hash, symlink_buf_hash);
250 inode->i_resolved = 1;
252 DEBUG("Loaded symlink buf");
257 lookup_table_insert(lookup_table, lte);
261 out_free_symlink_buf: