New helper macro: ALIGN()

[wimlib] / src / tagged_items.c

diff --git a/src/tagged_items.c b/src/tagged_items.c
index e3ba53f496612c7d95e8dabaa12d3512865edca6..1ed3b4a914454b6938dd193bb31b2d400dd8eba3 100644 (file)
--- a/src/tagged_items.c
+++ b/src/tagged_items.c
@@ -44,12 +44,7 @@ struct tagged_item_header {
        le32 tag;
 
        /* Size of the data of this tagged item, in bytes.  This excludes 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.)  */
+        * header and should be a multiple of 8.  */
        le32 length;
 
        /* Variable length data  */
@@ -90,14 +85,16 @@ 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_remaining <= sizeof(struct tagged_item_header) + len)
-                       return NULL;
                len_remaining -= sizeof(struct tagged_item_header) + len;
                p += sizeof(struct tagged_item_header) + len;
        }
@@ -116,7 +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 + 7) & ~7);
+       itemsize = sizeof(struct tagged_item_header) + ALIGN(len, 8);
        newsize = itemsize + inode->i_extra_size;
 
        buf = MALLOC(newsize);
@@ -133,7 +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 memset(hdr->data, 0, (len + 7) & ~7);
+       return memset(hdr->data, 0, ALIGN(len, 8));
 }
 
 static inline struct wimlib_unix_data_disk *