fs/namei.c: Add hashlen_string() function

[cascardo/linux.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index 42f8ca0..dd98d43 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1822,19 +1822,20 @@ static inline unsigned long mix_hash(unsigned long hash)
 
 #endif
 
-unsigned int full_name_hash(const unsigned char *name, unsigned int len)
+/* Return the hash of a string of known length */
+unsigned int full_name_hash(const char *name, unsigned int len)
 {
        unsigned long a, hash = 0;
 
        for (;;) {
+               if (!len)
+                       goto done;
                a = load_unaligned_zeropad(name);
                if (len < sizeof(unsigned long))
                        break;
                hash = mix_hash(hash + a);
                name += sizeof(unsigned long);
                len -= sizeof(unsigned long);
-               if (!len)
-                       goto done;
        }
        hash += a & bytemask_from_count(len);
 done:
@@ -1842,6 +1843,29 @@ done:
 }
 EXPORT_SYMBOL(full_name_hash);
 
+/* Return the "hash_len" (hash and length) of a null-terminated string */
+u64 hashlen_string(const char *name)
+{
+       unsigned long a, adata, mask, hash, len;
+       const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
+
+       hash = a = 0;
+       len = -sizeof(unsigned long);
+       do {
+               hash = mix_hash(hash + a);
+               len += sizeof(unsigned long);
+               a = load_unaligned_zeropad(name+len);
+       } while (!has_zero(a, &adata, &constants));
+
+       adata = prep_zero_mask(a, adata, &constants);
+       mask = create_zero_mask(adata);
+       hash += a & zero_bytemask(mask);
+       len += find_zero(mask);
+
+       return hashlen_create(fold_hash(hash), len);
+}
+EXPORT_SYMBOL(hashlen_string);
+
 /*
  * Calculate the length and hash of the path component, and
  * return the "hash_len" as the result.
@@ -1872,15 +1896,32 @@ static inline u64 hash_name(const char *name)
 
 #else
 
-unsigned int full_name_hash(const unsigned char *name, unsigned int len)
+/* Return the hash of a string of known length */
+unsigned int full_name_hash(const char *name, unsigned int len)
 {
        unsigned long hash = init_name_hash();
        while (len--)
-               hash = partial_name_hash(*name++, hash);
+               hash = partial_name_hash((unsigned char)*name++, hash);
        return end_name_hash(hash);
 }
 EXPORT_SYMBOL(full_name_hash);
 
+/* Return the "hash_len" (hash and length) of a null-terminated string */
+u64 hash_string(const char *name)
+{
+       unsigned long hash = init_name_hash();
+       unsigned long len = 0, c;
+
+       c = (unsigned char)*name;
+       do {
+               len++;
+               hash = partial_name_hash(c, hash);
+               c = (unsigned char)name[len];
+       } while (c);
+       return hashlen_create(end_name_hash(hash), len);
+}
+EXPORT_SYMBOL(hash_string);
+
 /*
  * We know there's a real path component here of at least
  * one character.