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-rw-r--r--fs/ntfs3/upcase.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/fs/ntfs3/upcase.c b/fs/ntfs3/upcase.c
new file mode 100644
index 000000000..b5e8256fd
--- /dev/null
+++ b/fs/ntfs3/upcase.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+
+#include "ntfs_fs.h"
+
+static inline u16 upcase_unicode_char(const u16 *upcase, u16 chr)
+{
+ if (chr < 'a')
+ return chr;
+
+ if (chr <= 'z')
+ return chr - ('a' - 'A');
+
+ return upcase[chr];
+}
+
+/*
+ * ntfs_cmp_names
+ *
+ * Thanks Kari Argillander <kari.argillander@gmail.com> for idea and implementation 'bothcase'
+ *
+ * Straight way to compare names:
+ * - Case insensitive
+ * - If name equals and 'bothcases' then
+ * - Case sensitive
+ * 'Straight way' code scans input names twice in worst case.
+ * Optimized code scans input names only once.
+ */
+int ntfs_cmp_names(const __le16 *s1, size_t l1, const __le16 *s2, size_t l2,
+ const u16 *upcase, bool bothcase)
+{
+ int diff1 = 0;
+ int diff2;
+ size_t len = min(l1, l2);
+
+ if (!bothcase && upcase)
+ goto case_insentive;
+
+ for (; len; s1++, s2++, len--) {
+ diff1 = le16_to_cpu(*s1) - le16_to_cpu(*s2);
+ if (diff1) {
+ if (bothcase && upcase)
+ goto case_insentive;
+
+ return diff1;
+ }
+ }
+ return l1 - l2;
+
+case_insentive:
+ for (; len; s1++, s2++, len--) {
+ diff2 = upcase_unicode_char(upcase, le16_to_cpu(*s1)) -
+ upcase_unicode_char(upcase, le16_to_cpu(*s2));
+ if (diff2)
+ return diff2;
+ }
+
+ diff2 = l1 - l2;
+ return diff2 ? diff2 : diff1;
+}
+
+int ntfs_cmp_names_cpu(const struct cpu_str *uni1, const struct le_str *uni2,
+ const u16 *upcase, bool bothcase)
+{
+ const u16 *s1 = uni1->name;
+ const __le16 *s2 = uni2->name;
+ size_t l1 = uni1->len;
+ size_t l2 = uni2->len;
+ size_t len = min(l1, l2);
+ int diff1 = 0;
+ int diff2;
+
+ if (!bothcase && upcase)
+ goto case_insentive;
+
+ for (; len; s1++, s2++, len--) {
+ diff1 = *s1 - le16_to_cpu(*s2);
+ if (diff1) {
+ if (bothcase && upcase)
+ goto case_insentive;
+
+ return diff1;
+ }
+ }
+ return l1 - l2;
+
+case_insentive:
+ for (; len; s1++, s2++, len--) {
+ diff2 = upcase_unicode_char(upcase, *s1) -
+ upcase_unicode_char(upcase, le16_to_cpu(*s2));
+ if (diff2)
+ return diff2;
+ }
+
+ diff2 = l1 - l2;
+ return diff2 ? diff2 : diff1;
+}