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   1 /*
   2  * Copyright (C) 2012 Eric Biggers
   3  *
   4  * This file is part of wimlib, a library for working with WIM files.
   5  *
   6  * wimlib is free software; you can redistribute it and/or modify it under the
   7  * terms of the GNU Lesser General Public License as published by the Free
   8  * Software Foundation; either version 2.1 of the License, or (at your option)
   9  * any later version.
  10  *
  11  * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
  12  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  13  * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  14  * details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  18  */
  19
  20 #include "dentry.h"
  21 #include "io.h"
  22 #include "lookup_table.h"
  23 #include "sha1.h"
  24 #include <errno.h>
  25
  26 /*
  27  * Find the symlink target of a symbolic link or junction point in the WIM.
  28  *
  29  * See http://msdn.microsoft.com/en-us/library/cc232006(v=prot.10).aspx
  30  * Except the first 8 bytes aren't included in the resource (presumably because
  31  * we already know the reparse tag from the dentry, and we already know the
  32  * reparse tag len from the lookup table entry resource length).
  33  */
  34 static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
  35                                 char *buf, size_t buf_len,
  36                                 u32 reparse_tag)
  37 {
  38         const u8 *p = resource;
  39         u16 substitute_name_offset;
  40         u16 substitute_name_len;
  41         u16 print_name_offset;
  42         u16 print_name_len;
  43         char *link_target;
  44         size_t link_target_len;
  45         ssize_t ret;
  46         unsigned header_size;
  47         char *translated_target;
  48         bool is_absolute;
  49         u32 flags;
  50
  51         if (resource_len < 12)
  52                 return -EIO;
  53         p = get_u16(p, &substitute_name_offset);
  54         p = get_u16(p, &substitute_name_len);
  55         p = get_u16(p, &print_name_offset);
  56         p = get_u16(p, &print_name_len);
  57         get_u32(p, &flags);
  58
  59         wimlib_assert(reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
  60                       reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
  61
  62         /* I think that some junction points incorrectly get marked as symbolic
  63          * links.  So, parse the link buffer as a symlink if the flags seem
  64          * plausible. */
  65         if (flags <= 1)
  66                 reparse_tag = WIM_IO_REPARSE_TAG_SYMLINK;
  67
  68         if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT) {
  69                 header_size = 8;
  70         } else {
  71                 is_absolute = (flags & 1) ? false : true;
  72                 header_size = 12;
  73                 p += 4;
  74         }
  75         if (header_size + substitute_name_offset + substitute_name_len > resource_len)
  76                 return -EIO;
  77         link_target = utf16_to_utf8(p + substitute_name_offset,
  78                                     substitute_name_len,
  79                                     &link_target_len);
  80
  81         if (!link_target)
  82                 return -EIO;
  83
  84         if (link_target_len + 1 > buf_len) {
  85                 ret = -ENAMETOOLONG;
  86                 goto out;
  87         }
  88
  89         translated_target = link_target;
  90         if (reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT || is_absolute) {
  91                 if (link_target_len < 7
  92                       || memcmp(translated_target, "\\??\\", 4) != 0
  93                       || translated_target[4] == '\0'
  94                       || translated_target[5] != ':'
  95                       || translated_target[6] != '\\') {
  96                         ret = -EIO;
  97                         goto out;
  98                 }
  99                 translated_target += 4;
 100                 link_target_len -= 4;
 101                 /* There's a drive letter, so just leave the backslashes since
 102                  * it won't go anyhwere on UNIX anyway... */
 103         } else {
 104                 for (size_t i = 0; i < link_target_len; i++)
 105                         if (translated_target[i] == '\\')
 106                                 translated_target[i] = '/';
 107         }
 108
 109         memcpy(buf, translated_target, link_target_len + 1);
 110         ret = link_target_len;
 111 out:
 112         FREE(link_target);
 113         return ret;
 114 }
 115
 116 void *make_symlink_reparse_data_buf(const char *symlink_target, size_t *len_ret)
 117 {
 118         size_t utf8_len = strlen(symlink_target);
 119         size_t utf16_len;
 120         char *name_utf16 = utf8_to_utf16(symlink_target, utf8_len, &utf16_len);
 121         if (!name_utf16)
 122                 return NULL;
 123         /*DEBUG("utf16_len = %zu", utf16_len);*/
 124         for (size_t i = 0; i < utf16_len / 2; i++)
 125                 if (((u16*)name_utf16)[i] == to_le16('/'))
 126                         ((u16*)name_utf16)[i] = to_le16('\\');
 127         size_t len = 12 + utf16_len * 2;
 128         void *buf = MALLOC(len);
 129         if (!buf)
 130                 goto out;
 131         /* XXX Fix absolute paths */
 132
 133         u8 *p = buf;
 134         p = put_u16(p, 0); /* Substitute name offset */
 135         p = put_u16(p, utf16_len); /* Substitute name length */
 136         p = put_u16(p, utf16_len); /* Print name offset */
 137         p = put_u16(p, utf16_len); /* Print name length */
 138         p = put_u32(p, 1);
 139         p = put_bytes(p, utf16_len, name_utf16);
 140         p = put_bytes(p, utf16_len, name_utf16);
 141         /*DEBUG("utf16_len = %zu, len = %zu", utf16_len, len);*/
 142         *len_ret = len;
 143 out:
 144         FREE(name_utf16);
 145         return buf;
 146 }
 147
 148 static const struct lookup_table_entry *
 149 dentry_first_lte(const struct dentry *dentry, const struct lookup_table *table)
 150 {
 151         const struct lookup_table_entry *lte;
 152         if (dentry->resolved) {
 153                 if (dentry->lte)
 154                         return dentry->lte;
 155                 for (u16 i = 0; i < dentry->num_ads; i++)
 156                         if (dentry->ads_entries[i].lte)
 157                                 return dentry->ads_entries[i].lte;
 158         } else {
 159                 const u8 *hash = dentry->hash;
 160                 u16 i = 0;
 161                 while (1) {
 162                         if ((lte = __lookup_resource(table, hash)))
 163                                 break;
 164                         if (i == dentry->num_ads)
 165                                 return NULL;
 166                         hash = dentry->ads_entries[i].hash;
 167                         i++;
 168                 }
 169         }
 170         return NULL;
 171 }
 172
 173 /* Get the symlink target from a dentry that's already checked to be either a
 174  * "real" symlink or a junction point. */
 175 ssize_t dentry_readlink(const struct dentry *dentry, char *buf, size_t buf_len,
 176                         const WIMStruct *w)
 177 {
 178         const struct resource_entry *res_entry;
 179         const struct lookup_table_entry *lte;
 180
 181         wimlib_assert(dentry_is_symlink(dentry));
 182
 183         lte = dentry_first_lte(dentry, w->lookup_table);
 184         if (!lte)
 185                 return -EIO;
 186
 187         res_entry = &lte->resource_entry;
 188         if (res_entry->original_size > 10000)
 189                 return -EIO;
 190
 191         char __res_buf[res_entry->original_size];
 192         const char *res_buf;
 193         if (lte->is_symlink && lte->symlink_buf) {
 194                 res_buf = lte->symlink_buf;
 195         } else {
 196                 res_buf = __res_buf;
 197                 if (read_full_resource(w->fp, res_entry->size,
 198                                        res_entry->original_size,
 199                                        res_entry->offset,
 200                                        wim_resource_compression_type(w, res_entry),
 201                                        __res_buf) != 0)
 202                         return -EIO;
 203                 res_buf = __res_buf;
 204         }
 205         return get_symlink_name(res_buf, res_entry->original_size, buf,
 206                                 buf_len, dentry->reparse_tag);
 207 }
 208
 209 static int dentry_set_symlink_buf(struct dentry *dentry,
 210                                   const u8 symlink_buf_hash[])
 211 {
 212         struct ads_entry *ads_entries;
 213
 214         ads_entries = CALLOC(2, sizeof(struct ads_entry));
 215         if (!ads_entries)
 216                 return WIMLIB_ERR_NOMEM;
 217         memcpy(ads_entries[1].hash, symlink_buf_hash, WIM_HASH_SIZE);
 218         wimlib_assert(dentry->num_ads == 0);
 219         wimlib_assert(!dentry->ads_entries);
 220         /*dentry_free_ads_entries(dentry);*/
 221         dentry->num_ads = 2;
 222         dentry->ads_entries = ads_entries;
 223         return 0;
 224 }
 225
 226 int dentry_set_symlink(struct dentry *dentry, const char *target,
 227                        struct lookup_table *lookup_table,
 228                        struct lookup_table_entry **lte_ret)
 229
 230 {
 231         int ret;
 232         size_t symlink_buf_len;
 233         struct lookup_table_entry *lte = NULL, *existing_lte;
 234         u8 symlink_buf_hash[WIM_HASH_SIZE];
 235         void *symlink_buf;
 236
 237         symlink_buf = make_symlink_reparse_data_buf(target, &symlink_buf_len);
 238         if (!symlink_buf)
 239                 return WIMLIB_ERR_NOMEM;
 240
 241         DEBUG("Made symlink reparse data buf (len = %zu, name len = %zu)",
 242                         symlink_buf_len, ret);
 243
 244         sha1_buffer(symlink_buf, symlink_buf_len, symlink_buf_hash);
 245
 246         existing_lte = __lookup_resource(lookup_table, symlink_buf_hash);
 247
 248         if (existing_lte) {
 249                 existing_lte->refcnt++;
 250                 lte = existing_lte;
 251         } else {
 252                 DEBUG("Creating new lookup table entry for symlink buf");
 253                 lte = new_lookup_table_entry();
 254                 if (!lte) {
 255                         ret = WIMLIB_ERR_NOMEM;
 256                         goto out_free_symlink_buf;
 257                 }
 258                 lte->is_symlink = true;
 259                 lte->symlink_buf = symlink_buf;
 260                 lte->resource_entry.original_size = symlink_buf_len;
 261                 lte->resource_entry.size = symlink_buf_len;
 262                 memcpy(lte->hash, symlink_buf_hash, WIM_HASH_SIZE);
 263         }
 264
 265         ret = dentry_set_symlink_buf(dentry, symlink_buf_hash);
 266
 267         if (ret != 0)
 268                 goto out_free_lte;
 269
 270         DEBUG("Loaded symlink buf");
 271
 272         if (!existing_lte)
 273                 lookup_table_insert(lookup_table, lte);
 274         if (lte_ret)
 275                 *lte_ret = lte;
 276         return 0;
 277 out_free_lte:
 278         if (lte != existing_lte)
 279                 FREE(lte);
 280 out_free_symlink_buf:
 281         FREE(symlink_buf);
 282         return ret;
 283 }