Move utf16 functions to kernel core and rename

We want to be able to use the utf16 functions that are currently present
in the EFI variables code in platform-specific code as well. Move them to
the kernel core, and in the process rename them to accurately describe what
they do - they don't handle UTF16, only UCS2.

Signed-off-by: Matthew Garrett <[e-mail]>
Signed-off-by: Matt Fleming <[e-mail]>

drivers/firmware/Kconfig

···
 config EFI_VARS
 	tristate "EFI Variable Support via sysfs"
 	depends on EFI
+	select UCS2_STRING
 	default n
 	help
 	  If you say Y here, you are able to get EFI (Extensible Firmware

drivers/firmware/efivars.c

···
 #include <linux/slab.h>
 #include <linux/pstore.h>
 #include <linux/ctype.h>
+#include <linux/ucs2_string.h>
 
 #include <linux/fs.h>
 #include <linux/ramfs.h>
···
 static DECLARE_WORK(efivar_work, efivar_update_sysfs_entries);
 static bool efivar_wq_enabled = true;
 
-/* Return the number of unicode characters in data */
-static unsigned long
-utf16_strnlen(efi_char16_t *s, size_t maxlength)
-{
-	unsigned long length = 0;
-
-	while (*s++ != 0 && length < maxlength)
-		length++;
-	return length;
-}
-
-static inline unsigned long
-utf16_strlen(efi_char16_t *s)
-{
-	return utf16_strnlen(s, ~0UL);
-}
-
-/*
- * Return the number of bytes is the length of this string
- * Note: this is NOT the same as the number of unicode characters
- */
-static inline unsigned long
-utf16_strsize(efi_char16_t *data, unsigned long maxlength)
-{
-	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 bool
 validate_device_path(struct efi_variable *var, int match, u8 *buffer,
 		     unsigned long len)
···
 	u16 filepathlength;
 	int i, desclength = 0, namelen;
 
-	namelen = utf16_strnlen(var->VariableName, sizeof(var->VariableName));
+	namelen = ucs2_strnlen(var->VariableName, sizeof(var->VariableName));
 
 	/* Either "Boot" or "Driver" followed by four digits of hex */
 	for (i = match; i < match+4; i++) {
···
 	 * There's no stored length for the description, so it has to be
 	 * found by hand
 	 */
-	desclength = utf16_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
+	desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
 
 	/* Each boot entry must have a descriptor */
 	if (!desclength)
···
 	spin_lock_irq(&efivars->lock);
 
 	status = check_var_size_locked(efivars, new_var->Attributes,
-	       new_var->DataSize + utf16_strsize(new_var->VariableName, 1024));
+	       new_var->DataSize + ucs2_strsize(new_var->VariableName, 1024));
 
 	if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED)
 		status = efivars->ops->set_variable(new_var->VariableName,
···
 	 * QueryVariableInfo() isn't supported by the firmware.
 	 */
 
-	varsize = datasize + utf16_strsize(var->var.VariableName, 1024);
+	varsize = datasize + ucs2_strsize(var->var.VariableName, 1024);
 	status = check_var_size(efivars, attributes, varsize);
 
 	if (status != EFI_SUCCESS) {
···
 
 		inode = NULL;
 
-		len = utf16_strlen(entry->var.VariableName);
+		len = ucs2_strlen(entry->var.VariableName);
 
 		/* name, plus '-', plus GUID, plus NUL*/
 		name = kmalloc(len + 1 + GUID_LEN + 1, GFP_ATOMIC);
···
 
 		if (efi_guidcmp(entry->var.VendorGuid, vendor))
 			continue;
-		if (utf16_strncmp(entry->var.VariableName, efi_name,
-				  utf16_strlen(efi_name))) {
+		if (ucs2_strncmp(entry->var.VariableName, efi_name,
+				  ucs2_strlen(efi_name))) {
 			/*
 			 * Check if an old format,
 			 * which doesn't support holding
···
 			for (i = 0; i < DUMP_NAME_LEN; i++)
 				efi_name_old[i] = name_old[i];
 
-			if (utf16_strncmp(entry->var.VariableName, efi_name_old,
-					  utf16_strlen(efi_name_old)))
+			if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
+					  ucs2_strlen(efi_name_old)))
 				continue;
 		}
 
···
 	 * Does this variable already exist?
 	 */
 	list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
-		strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
-		strsize2 = utf16_strsize(new_var->VariableName, 1024);
+		strsize1 = ucs2_strsize(search_efivar->var.VariableName, 1024);
+		strsize2 = ucs2_strsize(new_var->VariableName, 1024);
 		if (strsize1 == strsize2 &&
 			!memcmp(&(search_efivar->var.VariableName),
 				new_var->VariableName, strsize1) &&
···
 	}
 
 	status = check_var_size_locked(efivars, new_var->Attributes,
-	       new_var->DataSize + utf16_strsize(new_var->VariableName, 1024));
+	       new_var->DataSize + ucs2_strsize(new_var->VariableName, 1024));
 
 	if (status && status != EFI_UNSUPPORTED) {
 		spin_unlock_irq(&efivars->lock);
···
 
 	/* Create the entry in sysfs.  Locking is not required here */
 	status = efivar_create_sysfs_entry(efivars,
-					   utf16_strsize(new_var->VariableName,
+					   ucs2_strsize(new_var->VariableName,
 							 1024),
 					   new_var->VariableName,
 					   &new_var->VendorGuid);
···
 	 * Does this variable already exist?
 	 */
 	list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
-		strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
-		strsize2 = utf16_strsize(del_var->VariableName, 1024);
+		strsize1 = ucs2_strsize(search_efivar->var.VariableName, 1024);
+		strsize2 = ucs2_strsize(del_var->VariableName, 1024);
 		if (strsize1 == strsize2 &&
 			!memcmp(&(search_efivar->var.VariableName),
 				del_var->VariableName, strsize1) &&
···
 	unsigned long strsize1, strsize2;
 	bool found = false;
 
-	strsize1 = utf16_strsize(variable_name, 1024);
+	strsize1 = ucs2_strsize(variable_name, 1024);
 	list_for_each_entry_safe(entry, n, &efivars->list, list) {
-		strsize2 = utf16_strsize(entry->var.VariableName, 1024);
+		strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
 		if (strsize1 == strsize2 &&
 			!memcmp(variable_name, &(entry->var.VariableName),
 				strsize2) &&

include/linux/ucs2_string.h

···
+#ifndef _LINUX_UCS2_STRING_H_
+#define _LINUX_UCS2_STRING_H_
+
+#include <linux/types.h>	/* for size_t */
+#include <linux/stddef.h>	/* for NULL */
+
+typedef u16 ucs2_char_t;
+
+unsigned long ucs2_strnlen(const ucs2_char_t *s, size_t maxlength);
+unsigned long ucs2_strlen(const ucs2_char_t *s);
+unsigned long ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength);
+int ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len);
+
+#endif /* _LINUX_UCS2_STRING_H_ */

lib/Kconfig

···
 	help
 	  Enable fast lookup object identifier registry.
 
+config UCS2_STRING
+        tristate
+
 endmenu

lib/Makefile

···
       cmd_build_OID_registry = perl $(srctree)/$(src)/build_OID_registry $< $@
 
 clean-files	+= oid_registry_data.c
+
+obj-$(CONFIG_UCS2_STRING) += ucs2_string.o

lib/ucs2_string.c

···
+#include <linux/ucs2_string.h>
+#include <linux/module.h>
+
+/* Return the number of unicode characters in data */
+unsigned long
+ucs2_strnlen(const ucs2_char_t *s, size_t maxlength)
+{
+        unsigned long length = 0;
+
+        while (*s++ != 0 && length < maxlength)
+                length++;
+        return length;
+}
+EXPORT_SYMBOL(ucs2_strnlen);
+
+unsigned long
+ucs2_strlen(const ucs2_char_t *s)
+{
+        return ucs2_strnlen(s, ~0UL);
+}
+EXPORT_SYMBOL(ucs2_strlen);
+
+/*
+ * Return the number of bytes is the length of this string
+ * Note: this is NOT the same as the number of unicode characters
+ */
+unsigned long
+ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength)
+{
+        return ucs2_strnlen(data, maxlength/sizeof(ucs2_char_t)) * sizeof(ucs2_char_t);
+}
+EXPORT_SYMBOL(ucs2_strsize);
+
+int
+ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_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--;
+        }
+}
+EXPORT_SYMBOL(ucs2_strncmp);