Change the xattr entry hash to use an unsighed char by default

[thirdparty/e2fsprogs.git] / lib / ext2fs / ext_attr.c

diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index efe4d29f2cff18a3db57ce854a0e2ac55c014166..5525045c2a3bcb3e74910fbd98a5575bf86728fa 100644 (file)
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -48,7 +48,8 @@ static errcode_t read_ea_inode_hash(ext2_filsys fs, ext2_ino_t ino, __u32 *hash)
 __u32 ext2fs_ext_attr_hash_entry(struct ext2_ext_attr_entry *entry, void *data)
 {
        __u32 hash = 0;
-       char *name = ((char *) entry) + sizeof(struct ext2_ext_attr_entry);
+       unsigned char *name = (((unsigned char *) entry) +
+                              sizeof(struct ext2_ext_attr_entry));
        int n;
 
        for (n = 0; n < entry->e_name_len; n++) {
@@ -71,18 +72,51 @@ __u32 ext2fs_ext_attr_hash_entry(struct ext2_ext_attr_entry *entry, void *data)
        return hash;
 }
 
+__u32 ext2fs_ext_attr_hash_entry_signed(struct ext2_ext_attr_entry *entry,
+                                       void *data)
+{
+       __u32 hash = 0;
+       signed char *name = (((signed char *) entry) +
+                            sizeof(struct ext2_ext_attr_entry));
+       int n;
+
+       for (n = 0; n < entry->e_name_len; n++) {
+               hash = (hash << NAME_HASH_SHIFT) ^
+                      (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
+                      *name++;
+       }
+
+       /* The hash needs to be calculated on the data in little-endian. */
+       if (entry->e_value_inum == 0 && entry->e_value_size != 0) {
+               __u32 *value = (__u32 *)data;
+               for (n = (entry->e_value_size + EXT2_EXT_ATTR_ROUND) >>
+                        EXT2_EXT_ATTR_PAD_BITS; n; n--) {
+                       hash = (hash << VALUE_HASH_SHIFT) ^
+                              (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
+                              ext2fs_le32_to_cpu(*value++);
+               }
+       }
+
+       return hash;
+}
+
+
 /*
- * ext2fs_ext_attr_hash_entry2()
+ * ext2fs_ext_attr_hash_entry3()
  *
- * Compute the hash of an extended attribute.
- * This version of the function supports hashing entries that reference
- * external inodes (ea_inode feature).
+ * Compute the hash of an extended attribute.  This version of the
+ * function supports hashing entries that reference external inodes
+ * (ea_inode feature) as well as calculating the old legacy signed
+ * hash variant.
  */
-errcode_t ext2fs_ext_attr_hash_entry2(ext2_filsys fs,
+errcode_t ext2fs_ext_attr_hash_entry3(ext2_filsys fs,
                                      struct ext2_ext_attr_entry *entry,
-                                     void *data, __u32 *hash)
+                                     void *data, __u32 *hash,
+                                     __u32 *signed_hash)
 {
        *hash = ext2fs_ext_attr_hash_entry(entry, data);
+       if (signed_hash)
+               *signed_hash = ext2fs_ext_attr_hash_entry_signed(entry, data);
 
        if (entry->e_value_inum) {
                __u32 ea_inode_hash;
@@ -96,10 +130,29 @@ errcode_t ext2fs_ext_attr_hash_entry2(ext2_filsys fs,
                *hash = (*hash << VALUE_HASH_SHIFT) ^
                        (*hash >> (8*sizeof(*hash) - VALUE_HASH_SHIFT)) ^
                        ea_inode_hash;
+               if (signed_hash)
+                       *signed_hash = (*signed_hash << VALUE_HASH_SHIFT) ^
+                               (*signed_hash >> (8*sizeof(*hash) -
+                                                 VALUE_HASH_SHIFT)) ^
+                               ea_inode_hash;
        }
        return 0;
 }
 
+/*
+ * ext2fs_ext_attr_hash_entry2()
+ *
+ * Compute the hash of an extended attribute.
+ * This version of the function supports hashing entries that reference
+ * external inodes (ea_inode feature).
+ */
+errcode_t ext2fs_ext_attr_hash_entry2(ext2_filsys fs,
+                                     struct ext2_ext_attr_entry *entry,
+                                     void *data, __u32 *hash)
+{
+       return ext2fs_ext_attr_hash_entry3(fs, entry, data, hash, NULL);
+}
+
 #undef NAME_HASH_SHIFT
 #undef VALUE_HASH_SHIFT
 
@@ -940,15 +993,18 @@ static errcode_t read_xattrs_from_buffer(struct ext2_xattr_handle *handle,
 
                /* e_hash may be 0 in older inode's ea */
                if (entry->e_hash != 0) {
-                       __u32 hash;
+                       __u32 hash, signed_hash;
+
                        void *data = (entry->e_value_inum != 0) ?
                                        0 : value_start + entry->e_value_offs;
 
-                       err = ext2fs_ext_attr_hash_entry2(handle->fs, entry,
-                                                         data, &hash);
+                       err = ext2fs_ext_attr_hash_entry3(handle->fs, entry,
+                                                         data, &hash,
+                                                         &signed_hash);
                        if (err)
                                return err;
-                       if (entry->e_hash != hash) {
+                       if ((entry->e_hash != hash) &&
+                           (entry->e_hash != signed_hash)) {
                                struct ext2_inode child;
 
                                /* Check whether this is an old Lustre-style