linux-ext4 - [PATCH 16/20] nls: ascii: Support casefold and normalization operations

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Date:   Tue,  3 Jul 2018 13:06:56 -0400
From:   Gabriel Krisman Bertazi <krisman@...labora.co.uk>
To:     tytso@....edu
Cc:     linux-ext4@...r.kernel.org, darrick.wong@...cle.com,
        kernel@...labora.com,
        Gabriel Krisman Bertazi <krisman@...labora.co.uk>
Subject: [PATCH 16/20] nls: ascii: Support casefold and normalization operations

Normalization is identity, but casefold can be implemented with toupper
or tolower, and we have no specification on that. We should be safe, as
long as it is constant.

Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.co.uk>
---
 fs/nls/nls_ascii.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/fs/nls/nls_ascii.c b/fs/nls/nls_ascii.c
index 2f4826478d3d..40b8e7acfe1e 100644
--- a/fs/nls/nls_ascii.c
+++ b/fs/nls/nls_ascii.c
@@ -12,6 +12,7 @@
 #include <linux/string.h>
 #include <linux/nls.h>
 #include <linux/errno.h>
+#include <linux/slab.h>
 
 static const wchar_t charset2uni[256] = {
 	/* 0x00*/
@@ -152,11 +153,43 @@ static unsigned char charset_toupper(const struct nls_table *table,
 	return charset2upper[c];
 }
 
+/* Ascii casefold can be defined as either to lower or to upper. As long
+ * as it is stable. */
+static int ascii_casefold(const struct nls_table *charset,
+			  const unsigned char *str, size_t len,
+			  unsigned char *dest, size_t dlen)
+{
+	unsigned int i;
+
+	if (dlen < len)
+		return -EINVAL;
+
+	for (i = 0; i < len; i++)
+		dest[i] = charset_tolower(charset, str[i]);
+
+	return 0;
+}
+
+/* Ascii normalization is identity. */
+static int ascii_normalize(const struct nls_table *charset,
+			   const unsigned char *str, size_t len,
+			   unsigned char *dest, size_t dlen)
+{
+	if (dlen < len)
+		return -EINVAL;
+
+	memcpy(dest, str, len);
+
+	return 0;
+}
+
 static const struct nls_ops charset_ops = {
 	.lowercase = charset_toupper,
 	.uppercase = charset_tolower,
 	.uni2char = uni2char,
 	.char2uni = char2uni,
+	.casefold = ascii_casefold,
+	.normalize = ascii_normalize,
 };
 
 static struct nls_charset nls_charset;
-- 
2.18.0