efivars: introduce utf16_strncmp
Introduce utf16_strncmp which is used in the next patch. Semantics
should be the same as the strncmp C function.
Signed-off-by: Mike Waychison <mikew@google.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 4202a31..15b9a01 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -169,6 +169,24 @@
return utf16_strnlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
}
+static inline int
+utf16_strncmp(const efi_char16_t *a, const efi_char16_t *b, size_t len)
+{
+ while (1) {
+ if (len == 0)
+ return 0;
+ if (*a < *b)
+ return -1;
+ if (*a > *b)
+ return 1;
+ if (*a == 0) /* implies *b == 0 */
+ return 0;
+ a++;
+ b++;
+ len--;
+ }
+}
+
static efi_status_t
get_var_data_locked(struct efivars *efivars, struct efi_variable *var)
{