[RFC PATCH 03/11] fs: fat: Use strlower() to normalise case

[Simon Glass <sjg@chromium.org>]

Drop the local downcase() helper. The two get_name() call sites
operate on buffers that are NUL-terminated before the lowercase
pass, and the trailing FAT-name padding is spaces which tolower()
leaves untouched, so strlower() gives the same result without
needing an explicit length.

Move the 'ptr[3] = '\0'' assignment in get_name() to before the
extension is lowercased so strlower() sees a terminated string.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

 fs/fat/fat.c       | 20 ++++----------------
 fs/fat/fat_write.c |  2 +-
 2 files changed, 5 insertions(+), 17 deletions(-)

diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index c1ccf30771a..dd328f948fb 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -26,23 +26,11 @@
 #include <linux/compiler.h>
 #include <linux/ctype.h>
 #include <linux/log2.h>
+#include <linux/string.h>
 
 /* maximum number of clusters for FAT12 */
 #define MAX_FAT12	0xFF4
 
-/*
- * Convert a string to lowercase.  Converts at most 'len' characters,
- * 'len' may be larger than the length of 'str' if 'str' is NULL
- * terminated.
- */
-static void downcase(char *str, size_t len)
-{
-	while (*str != '\0' && len--) {
-		*str = tolower(*str);
-		str++;
-	}
-}
-
 static struct blk_desc *cur_dev;
 static struct disk_partition cur_part_info;
 static int fat_sect_size;
@@ -270,13 +258,13 @@ static void get_name(dir_entry *dirent, char *s_name)
 	while (*ptr && *ptr != ' ')
 		ptr++;
 	if (dirent->lcase & CASE_LOWER_BASE)
-		downcase(s_name, (unsigned)(ptr - s_name));
+		strlower(s_name);
 	if (dirent->nameext.ext[0] && dirent->nameext.ext[0] != ' ') {
 		*ptr++ = '.';
 		memcpy(ptr, dirent->nameext.ext, 3);
-		if (dirent->lcase & CASE_LOWER_EXT)
-			downcase(ptr, 3);
 		ptr[3] = '\0';
+		if (dirent->lcase & CASE_LOWER_EXT)
+			strlower(ptr);
 		while (*ptr && *ptr != ' ')
 			ptr++;
 	}
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index c98b530f747..ea8d301514c 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -1464,7 +1464,7 @@ static int normalize_longname(char *l_filename, const char *filename)
 	}
 
 	strcpy(l_filename, filename);
-	downcase(l_filename, VFAT_MAXLEN_BYTES);
+	strlower(l_filename);
 
 	return 0;
 }
-- 
2.43.0