+#include "dentry.h"
+#include "io.h"
+#include "lookup_table.h"
+
+/*
+ * Find the symlink target of a symbolic link or junction point in the WIM.
+ *
+ * See http://msdn.microsoft.com/en-us/library/cc232006(v=prot.10).aspx
+ * Except the first 8 bytes aren't included in the resource (presumably because
+ * we already know the reparse tag from the dentry, and we already know the
+ * reparse tag len from the lookup table entry resource length).
+ */
+static ssize_t get_symlink_name(const u8 *resource, size_t resource_len,
+ char *buf, size_t buf_len,
+ bool is_junction_point)
+{
+ const u8 *p = resource;
+ u16 substitute_name_offset;
+ u16 substitute_name_len;
+ u16 print_name_offset;
+ u16 print_name_len;
+ char *link_target;
+ size_t link_target_len;
+ ssize_t ret;
+ unsigned header_size;
+ char *translated_target;
+ bool is_absolute;
+
+ if (resource_len < 12)
+ return -EIO;
+ p = get_u16(p, &substitute_name_offset);
+ p = get_u16(p, &substitute_name_len);
+ p = get_u16(p, &print_name_offset);
+ p = get_u16(p, &print_name_len);
+ if (is_junction_point) {
+ header_size = 8;
+ } else {
+ u32 flags;
+ p = get_u32(p, &flags);
+ is_absolute = (flags & 1) ? false : true;
+ header_size = 12;
+ }
+ if (header_size + substitute_name_offset + substitute_name_len > resource_len)
+ return -EIO;
+ link_target = utf16_to_utf8(p + substitute_name_offset,
+ substitute_name_len,
+ &link_target_len);
+
+ if (!link_target)
+ return -EIO;
+
+ if (link_target_len + 1 > buf_len) {
+ ret = -ENAMETOOLONG;
+ goto out;
+ }
+
+ translated_target = link_target;
+ if (is_junction_point || is_absolute) {
+ if (link_target_len < 7
+ || memcmp(translated_target, "\\??\\", 4) != 0
+ || translated_target[4] == '\0'
+ || translated_target[5] != ':'
+ || translated_target[6] != '\\') {
+ ret = -EIO;
+ goto out;
+ }
+ translated_target += 4;
+ link_target_len -= 4;
+ }
+ for (size_t i = 0; i < link_target_len; i++)
+ if (translated_target[i] == '\\')
+ translated_target[i] = '/';
+
+ memcpy(buf, translated_target, link_target_len + 1);
+ ret = link_target_len;
+out:
+ FREE(link_target);
+ return ret;
+}
+
+void *make_symlink_reparse_data_buf(const char *symlink_target, size_t *len_ret)
+{
+ size_t utf8_len = strlen(symlink_target);
+ size_t utf16_len;
+ char *name_utf16 = utf8_to_utf16(symlink_target, utf8_len, &utf16_len);
+ if (!name_utf16)
+ return NULL;
+ /*DEBUG("utf16_len = %zu", utf16_len);*/
+ for (size_t i = 0; i < utf16_len / 2; i++)
+ if (((u16*)name_utf16)[i] == to_le16('/'))
+ ((u16*)name_utf16)[i] = to_le16('\\');
+ size_t len = 12 + utf16_len * 2;
+ void *buf = MALLOC(len);
+ if (!buf)
+ goto out;
+
+ u8 *p = buf;
+ p = put_u16(p, 0); /* Substitute name offset */
+ p = put_u16(p, utf16_len); /* Substitute name length */
+ p = put_u16(p, utf16_len); /* Print name offset */
+ p = put_u16(p, utf16_len); /* Print name length */
+ p = put_u32(p, (symlink_target[0] == '/') ? 0 : 1);
+ p = put_bytes(p, utf16_len, name_utf16);
+ p = put_bytes(p, utf16_len, name_utf16);
+ /*DEBUG("utf16_len = %zu, len = %zu", utf16_len, len);*/
+ *len_ret = len;
+out:
+ FREE(name_utf16);
+ return buf;
+}
+
+/* Get the symlink target from a dentry that's already checked to be either a
+ * "real" symlink or a junction point. */
+ssize_t dentry_readlink(const struct dentry *dentry, char *buf, size_t buf_len,
+ const WIMStruct *w)
+{
+ struct ads_entry *ads;
+ struct lookup_table_entry *entry;
+ struct resource_entry *res_entry;
+ bool is_junction_point;
+
+ wimlib_assert(dentry_is_symlink(dentry));
+
+ if (dentry->reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK) {
+ is_junction_point = false;
+ /*
+ * This is of course not actually documented, but what I think is going
+ * on here is that the symlink dentries have 2 alternate data streams;
+ * one is the default data stream, which is not used and is empty, and
+ * one is the symlink buffer data stream, which is confusingly also
+ * unnamed, but isn't empty as it contains the symlink target within the
+ * resource.
+ */
+ if (dentry->num_ads != 2)
+ return -EIO;
+ if ((entry = lookup_resource(w->lookup_table, dentry->ads_entries[0].hash)))
+ goto do_readlink;
+ if ((entry = lookup_resource(w->lookup_table, dentry->ads_entries[1].hash)))
+ goto do_readlink;
+ } else {
+ wimlib_assert(dentry->reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT);
+
+ is_junction_point = true;
+
+ if ((entry = lookup_resource(w->lookup_table, dentry->hash)))
+ goto do_readlink;
+ }
+ return -EIO;
+do_readlink:
+ res_entry = &entry->resource_entry;
+ if (res_entry->original_size > 10000)
+ return -EIO;
+ char res_buf[res_entry->original_size];
+ if (read_full_resource(w->fp, res_entry->size,
+ res_entry->original_size,
+ res_entry->offset,
+ wim_resource_compression_type(w, res_entry),
+ res_buf) != 0)
+ return -EIO;
+ return get_symlink_name(res_buf, res_entry->original_size, buf,
+ buf_len, is_junction_point);
+}
git://wimlib.net / wimlib / commitdiff