4 * Code to read and set symbolic links in WIM files.
8 * Copyright (C) 2012 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
36 * Except the first 8 bytes aren't included in the resource (presumably because
37 * we already know the reparse tag from the dentry, and we already know the
38 * reparse tag len from the lookup table entry resource length).
40 static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
41 char *buf, size_t buf_len,
44 const u8 *p = resource;
45 u16 substitute_name_offset;
46 u16 substitute_name_len;
47 u16 print_name_offset;
50 size_t link_target_len;
53 char *translated_target;
57 if (resource_len < 12)
59 p = get_u16(p, &substitute_name_offset);
60 p = get_u16(p, &substitute_name_len);
61 p = get_u16(p, &print_name_offset);
62 p = get_u16(p, &print_name_len);
65 wimlib_assert(reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
66 reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
68 /* I think that some junction points incorrectly get marked as symbolic
69 * links. So, parse the link buffer as a symlink if the flags seem
72 reparse_tag = WIM_IO_REPARSE_TAG_SYMLINK;
74 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT) {
77 is_absolute = (flags & 1) ? false : true;
81 if (header_size + substitute_name_offset + substitute_name_len > resource_len)
84 ret = utf16_to_utf8((const char *)p + substitute_name_offset,
86 &link_target, &link_target_len);
87 if (ret == WIMLIB_ERR_INVALID_UTF16_STRING)
89 else if (ret == WIMLIB_ERR_NOMEM)
92 wimlib_assert(ret == 0);
97 if (link_target_len + 1 > buf_len) {
102 translated_target = link_target;
103 if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT || is_absolute) {
104 if (link_target_len < 7
105 || memcmp(translated_target, "\\??\\", 4) != 0
106 || translated_target[4] == '\0'
107 || translated_target[5] != ':'
108 || translated_target[6] != '\\') {
112 translated_target += 4;
113 link_target_len -= 4;
114 /* There's a drive letter, so just leave the backslashes since
115 * it won't go anyhwere on UNIX anyway...
118 * NTFS-3g tries to re-map these links to actually point to
119 * something, so maybe we could do something like that here
122 for (size_t i = 0; i < link_target_len; i++)
123 if (translated_target[i] == '\\')
124 translated_target[i] = '/';
127 memcpy(buf, translated_target, link_target_len + 1);
128 ret = link_target_len;
134 static int make_symlink_reparse_data_buf(const char *symlink_target,
135 size_t *len_ret, void **buf_ret)
137 size_t utf8_len = strlen(symlink_target);
142 ret = utf8_to_utf16(symlink_target, utf8_len,
143 &name_utf16, &utf16_len);
147 for (size_t i = 0; i < utf16_len / 2; i++)
148 if (((u16*)name_utf16)[i] == cpu_to_le16('/'))
149 ((u16*)name_utf16)[i] = cpu_to_le16('\\');
150 size_t len = 12 + utf16_len * 2;
151 void *buf = MALLOC(len);
154 return WIMLIB_ERR_NOMEM;
158 p = put_u16(p, utf16_len); /* Substitute name offset */
159 p = put_u16(p, utf16_len); /* Substitute name length */
160 p = put_u16(p, 0); /* Print name offset */
161 p = put_u16(p, utf16_len); /* Print name length */
162 p = put_u32(p, 1); /* flags: 0 iff *full* target, including drive letter??? */
163 p = put_bytes(p, utf16_len, (const u8*)name_utf16);
164 p = put_bytes(p, utf16_len, (const u8*)name_utf16);
172 /* Get the symlink target from a dentry.
174 * The dentry may be either "real" symlink or a junction point.
176 ssize_t inode_readlink(const struct inode *inode, char *buf, size_t buf_len,
177 const WIMStruct *w, int read_resource_flags)
179 const struct lookup_table_entry *lte;
182 wimlib_assert(inode_is_symlink(inode));
184 lte = inode_unnamed_lte(inode, w->lookup_table);
188 if (wim_resource_size(lte) > 10000)
191 u8 res_buf[wim_resource_size(lte)];
192 ret = read_full_wim_resource(lte, res_buf, read_resource_flags);
195 return get_symlink_name(res_buf, wim_resource_size(lte), buf,
196 buf_len, inode->reparse_tag);
200 * Sets @inode to be a symbolic link pointing to @target.
202 * A lookup table entry for the symbolic link data buffer is created and
203 * inserted into @lookup_table, unless there is an existing lookup table entry
204 * for the exact same data, in which its reference count is incremented.
206 * The lookup table entry is returned in @lte_ret.
208 * On failure @dentry and @lookup_table are not modified.
210 int inode_set_symlink(struct inode *inode, const char *target,
211 struct lookup_table *lookup_table,
212 struct lookup_table_entry **lte_ret)
216 size_t symlink_buf_len;
217 struct lookup_table_entry *lte = NULL, *existing_lte;
218 u8 symlink_buf_hash[SHA1_HASH_SIZE];
221 ret = make_symlink_reparse_data_buf(target, &symlink_buf_len,
226 DEBUG("Made symlink reparse data buf (len = %zu, name len = %zu)",
227 symlink_buf_len, symlink_buf_len);
229 sha1_buffer(symlink_buf, symlink_buf_len, symlink_buf_hash);
231 existing_lte = __lookup_resource(lookup_table, symlink_buf_hash);
238 DEBUG("Creating new lookup table entry for symlink buf");
239 lte = new_lookup_table_entry();
241 ret = WIMLIB_ERR_NOMEM;
242 goto out_free_symlink_buf;
244 lte->resource_location = RESOURCE_IN_ATTACHED_BUFFER;
245 lte->attached_buffer = symlink_buf;
246 lte->resource_entry.original_size = symlink_buf_len;
247 lte->resource_entry.size = symlink_buf_len;
248 copy_hash(lte->hash, symlink_buf_hash);
252 inode->resolved = true;
254 DEBUG("Loaded symlink buf");
259 lookup_table_insert(lookup_table, lte);
263 out_free_symlink_buf: