[PATCH v2 08/11] fs: exfat: Fix conversion overflow errors

[Marek Vasut]

Fix the following conversion overflow errors. The UTF8-to-UTF16
conversion is done through 32bit wchar_t, but U-Boot codebase is
built with -fshort-wchar which limits wchar_t to 16bit. Replace
the built-in wchar_t with u32 to assure the intermediate type is
32bit.

"
fs/exfat/utf.c: In function ‘utf8_to_wchar’:
fs/exfat/utf.c:165:23: warning: overflow in conversion from ‘int’ to ‘wchar_t’ {aka ‘short unsigned int’} changes value from ‘(int)(short unsigned int)*input << 18 & 1835008’ to ‘0’ [-Woverflow]
  165 |                 *wc = ((wchar_t) input[0] & 0x07) << 18;
      |                       ^
fs/exfat/utf.c:170:23: warning: overflow in conversion from ‘int’ to ‘wchar_t’ {aka ‘short unsigned int’} changes value from ‘(int)(short unsigned int)*input << 24 & 50331648’ to ‘0’ [-Woverflow]
  170 |                 *wc = ((wchar_t) input[0] & 0x03) << 24;
      |                       ^
fs/exfat/utf.c:175:23: warning: overflow in conversion from ‘int’ to ‘wchar_t’ {aka ‘short unsigned int’} changes value from ‘(int)(short unsigned int)*input << 30 & 1073741824’ to ‘0’ [-Woverflow]
  175 |                 *wc = ((wchar_t) input[0] & 0x01) << 30;
      |                       ^
"

Signed-off-by: Marek Vasut <marex at denx.de>
---
Cc: Baruch Siach <baruch at tkos.co.il>
Cc: Francesco Dolcini <francesco.dolcini at toradex.com>
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
Cc: Hiago De Franco <hiago.franco at toradex.com>
Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Cc: Nam Cao <namcao at linutronix.de>
Cc: Simon Glass <sjg at chromium.org>
Cc: Sughosh Ganu <sughosh.ganu at linaro.org>
Cc: Tom Rini <trini at konsulko.com>
Cc: u-boot at lists.denx.de
---
V2: Rework the patch, replace wchar_t with u32
---
 fs/exfat/utf.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/fs/exfat/utf.c b/fs/exfat/utf.c
index b1d09e76478..8a28e7621ca 100644
--- a/fs/exfat/utf.c
+++ b/fs/exfat/utf.c
@@ -23,7 +23,7 @@
 #include "exfat.h"
 #include <errno.h>
 
-static char* wchar_to_utf8(char* output, wchar_t wc, size_t outsize)
+static char* wchar_to_utf8(char* output, u32 wc, size_t outsize)
 {
 	if (wc <= 0x7f)
 	{
@@ -82,14 +82,14 @@ static char* wchar_to_utf8(char* output, wchar_t wc, size_t outsize)
 	return output;
 }
 
-static const le16_t* utf16_to_wchar(const le16_t* input, wchar_t* wc,
+static const le16_t* utf16_to_wchar(const le16_t* input, u32* wc,
 		size_t insize)
 {
 	if ((le16_to_cpu(input[0]) & 0xfc00) == 0xd800)
 	{
 		if (insize < 2 || (le16_to_cpu(input[1]) & 0xfc00) != 0xdc00)
 			return NULL;
-		*wc = ((wchar_t) (le16_to_cpu(input[0]) & 0x3ff) << 10);
+		*wc = ((u32) (le16_to_cpu(input[0]) & 0x3ff) << 10);
 		*wc |= (le16_to_cpu(input[1]) & 0x3ff);
 		*wc += 0x10000;
 		return input + 2;
@@ -108,7 +108,7 @@ int exfat_utf16_to_utf8(char* output, const le16_t* input, size_t outsize,
 	const le16_t* iend = input + insize;
 	char* optr = output;
 	const char* oend = output + outsize;
-	wchar_t wc;
+	u32 wc;
 
 	while (iptr < iend)
 	{
@@ -136,7 +136,7 @@ int exfat_utf16_to_utf8(char* output, const le16_t* input, size_t outsize,
 	return 0;
 }
 
-static const char* utf8_to_wchar(const char* input, wchar_t* wc,
+static const char* utf8_to_wchar(const char* input, u32* wc,
 		size_t insize)
 {
 	size_t size;
@@ -147,32 +147,32 @@ static const char* utf8_to_wchar(const char* input, wchar_t* wc,
 
 	if ((input[0] & 0x80) == 0)
 	{
-		*wc = (wchar_t) input[0];
+		*wc = (u32) input[0];
 		return input + 1;
 	}
 	else if ((input[0] & 0xe0) == 0xc0)
 	{
-		*wc = ((wchar_t) input[0] & 0x1f) << 6;
+		*wc = ((u32) input[0] & 0x1f) << 6;
 		size = 2;
 	}
 	else if ((input[0] & 0xf0) == 0xe0)
 	{
-		*wc = ((wchar_t) input[0] & 0x0f) << 12;
+		*wc = ((u32) input[0] & 0x0f) << 12;
 		size = 3;
 	}
 	else if ((input[0] & 0xf8) == 0xf0)
 	{
-		*wc = ((wchar_t) input[0] & 0x07) << 18;
+		*wc = ((u32) input[0] & 0x07) << 18;
 		size = 4;
 	}
 	else if ((input[0] & 0xfc) == 0xf8)
 	{
-		*wc = ((wchar_t) input[0] & 0x03) << 24;
+		*wc = ((u32) input[0] & 0x03) << 24;
 		size = 5;
 	}
 	else if ((input[0] & 0xfe) == 0xfc)
 	{
-		*wc = ((wchar_t) input[0] & 0x01) << 30;
+		*wc = ((u32) input[0] & 0x01) << 30;
 		size = 6;
 	}
 	else
@@ -192,7 +192,7 @@ static const char* utf8_to_wchar(const char* input, wchar_t* wc,
 	return input + size;
 }
 
-static le16_t* wchar_to_utf16(le16_t* output, wchar_t wc, size_t outsize)
+static le16_t* wchar_to_utf16(le16_t* output, u32 wc, size_t outsize)
 {
 	if (wc <= 0xffff) /* if character is from BMP */
 	{
@@ -216,7 +216,7 @@ int exfat_utf8_to_utf16(le16_t* output, const char* input, size_t outsize,
 	const char* iend = input + insize;
 	le16_t* optr = output;
 	const le16_t* oend = output + outsize;
-	wchar_t wc;
+	u32 wc;
 
 	while (iptr < iend)
 	{
-- 
2.47.2