New helper macro: ALIGN()

[wimlib] / src / tagged_items.c

diff --git a/src/tagged_items.c b/src/tagged_items.c
index 6cd897fa7ae1bf167c7c4f6e21088b670d1a394c..1ed3b4a914454b6938dd193bb31b2d400dd8eba3 100644 (file)
--- a/src/tagged_items.c
+++ b/src/tagged_items.c
@@ -8,20 +8,18 @@
 /*
  * Copyright (C) 2014 Eric Biggers
  *
- * This file is part of wimlib, a library for working with WIM files.
+ * This file is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at your option) any
+ * later version.
  *
- * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free
- * Software Foundation; either version 3 of the License, or (at your option)
- * any later version.
- *
- * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- * A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * This file is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  * details.
  *
- * You should have received a copy of the GNU General Public License
- * along with wimlib; if not, see http://www.gnu.org/licenses/.
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this file; if not, see http://www.gnu.org/licenses/.
  */
 
 #ifdef HAVE_CONFIG_H
@@ -45,13 +43,8 @@ struct tagged_item_header {
        /* Unique identifier for this item.  */
        le32 tag;
 
-       /* Size of the data of this tagged item, in bytes.  This includes this
-        * header and should be a multiple of 8.
-        *
-        * (Actually, the MS implementation seems to round this up to an 8 byte
-        * boundary when calculating the offset to the next tagged item, but
-        * uses this length unmodified when validating the item.  We might as
-        * well do the same.)  */
+       /* Size of the data of this tagged item, in bytes.  This excludes this
+        * header and should be a multiple of 8.  */
        le32 length;
 
        /* Variable length data  */
@@ -92,16 +85,18 @@ inode_get_tagged_item(const struct wim_inode *inode,
 
                hdr = (struct tagged_item_header *)p;
                tag = le32_to_cpu(hdr->tag);
-               len = le32_to_cpu(hdr->length);
+               len = ALIGN(le32_to_cpu(hdr->length), 8);
+
+               /* Length overflow?  */
+               if (unlikely(len > len_remaining - sizeof(struct tagged_item_header)))
+                       return NULL;
 
+               /* Matches the item we wanted?  */
                if (tag == desired_tag && len >= min_data_len)
                        return hdr->data;
 
-               len = (len + 7) & ~7;
-               if (len >= len_remaining)
-                       return NULL;
-               len_remaining -= len;
-               p = hdr->data + len;
+               len_remaining -= sizeof(struct tagged_item_header) + len;
+               p += sizeof(struct tagged_item_header) + len;
        }
        return NULL;
 }
@@ -118,7 +113,7 @@ inode_add_tagged_item(struct wim_inode *inode, u32 tag, u32 len)
 
        /* We prepend the item instead of appending it because it's easier.  */
 
-       itemsize = sizeof(struct tagged_item_header) + len;
+       itemsize = sizeof(struct tagged_item_header) + ALIGN(len, 8);
        newsize = itemsize + inode->i_extra_size;
 
        buf = MALLOC(newsize);
@@ -135,7 +130,7 @@ inode_add_tagged_item(struct wim_inode *inode, u32 tag, u32 len)
        hdr = (struct tagged_item_header *)buf;
        hdr->tag = cpu_to_le32(tag);
        hdr->length = cpu_to_le32(len);
-       return hdr->data;
+       return memset(hdr->data, 0, ALIGN(len, 8));
 }
 
 static inline struct wimlib_unix_data_disk *