unicode: Add utf8_casefold_hash

This adds a case insensitive hash function to allow taking the hash
without needing to allocate a casefolded copy of the string.

The existing d_hash implementations for casefolding allocate memory
within rcu-walk, by avoiding it we can be more efficient and avoid
worrying about a failed allocation.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Daniel Rosenberg 2020-07-08 02:12:34 -07:00 committed by Jaegeuk Kim
parent e6c3948de2
commit 3d7bfea8b8
2 changed files with 25 additions and 1 deletions

View File

@ -6,6 +6,7 @@
#include <linux/parser.h>
#include <linux/errno.h>
#include <linux/unicode.h>
#include <linux/stringhash.h>
#include "utf8n.h"
@ -122,9 +123,29 @@ int utf8_casefold(const struct unicode_map *um, const struct qstr *str,
}
return -EINVAL;
}
EXPORT_SYMBOL(utf8_casefold);
int utf8_casefold_hash(const struct unicode_map *um, const void *salt,
struct qstr *str)
{
const struct utf8data *data = utf8nfdicf(um->version);
struct utf8cursor cur;
int c;
unsigned long hash = init_name_hash(salt);
if (utf8ncursor(&cur, data, str->name, str->len) < 0)
return -EINVAL;
while ((c = utf8byte(&cur))) {
if (c < 0)
return -EINVAL;
hash = partial_name_hash((unsigned char)c, hash);
}
str->hash = end_name_hash(hash);
return 0;
}
EXPORT_SYMBOL(utf8_casefold_hash);
int utf8_normalize(const struct unicode_map *um, const struct qstr *str,
unsigned char *dest, size_t dlen)
{

View File

@ -27,6 +27,9 @@ int utf8_normalize(const struct unicode_map *um, const struct qstr *str,
int utf8_casefold(const struct unicode_map *um, const struct qstr *str,
unsigned char *dest, size_t dlen);
int utf8_casefold_hash(const struct unicode_map *um, const void *salt,
struct qstr *str);
struct unicode_map *utf8_load(const char *version);
void utf8_unload(struct unicode_map *um);