From 08021a3beb04e4d6ce44d4c47b8d4ce2e61e2351 Mon Sep 17 00:00:00 2001
From: Matej Horvat <matej.horvat@guest.arnes.si>
Date: Thu, 12 Jul 2018 17:14:15 +0200
Subject: [PATCH] fat: correctly read lowercase 8.3 filenames

Historically, FAT stored filenames as uppercase. Modern windows versions
will however be case-preserving. As a special case, all-uppercase files
from old FAT filesystems will be converted to all-lowercase. There are
two flags (one for filename and one for extension) indicating that this
should be done. We did not make the distinction between these two flags
when reading a filename.

We still don't set the flags properly when writing files, but we always
provide a long file name (even if the name would fit in the 8.3 pattern
for a short one, so when reading back our own entries, we should always
use the long filename and be safe.

Change-Id: I1618a5be22705de3a06534442b62074445069764
---
 .../kernel/file_systems/fat/encodings.cpp     | 31 ++++++++++++-------
 .../kernel/file_systems/fat/encodings.h       |  3 +-
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/add-ons/kernel/file_systems/fat/encodings.cpp b/src/add-ons/kernel/file_systems/fat/encodings.cpp
index 1076e0b99b..bfebd66e82 100644
--- a/src/add-ons/kernel/file_systems/fat/encodings.cpp
+++ b/src/add-ons/kernel/file_systems/fat/encodings.cpp
@@ -1507,7 +1507,7 @@ status_t generate_short_name(const uchar *name, const uchar *uni,
 /* called to convert a short ms-dos filename to utf8.
    XXX: encoding is assumed to be standard US code page, never shift-JIS
 */
-status_t msdos_to_utf8(uchar *msdos, uchar *utf8, uint32 utf8len, bool toLower)
+status_t msdos_to_utf8(uchar *msdos, uchar *utf8, uint32 utf8len, uint8 toLower)
 {
 	uchar normalized[8+1+3+1];
 	int32 i, pos;
@@ -1516,16 +1516,19 @@ status_t msdos_to_utf8(uchar *msdos, uchar *utf8, uint32 utf8len, bool toLower)
 
 	pos = 0;
 	for (i=0;i<8;i++) {
-		if (msdos[i] == ' ') break;
+		if (msdos[i] == ' ')
+			break;
 		normalized[pos++] = ((i == 0) && (msdos[i] == 5)) ? 0xe5 :
-			(toLower ? tolower(msdos[i]) : msdos[i]);
+			((toLower & 0x08) ? tolower(msdos[i]) : msdos[i]);
 	}
 
 	if (msdos[8] != ' ') {
 		normalized[pos++] = '.';
 		for (i=8;i<11;i++) {
-			if (msdos[i] == ' ') break;
-			normalized[pos++] = (toLower ? tolower(msdos[i]) : msdos[i]);
+			if (msdos[i] == ' ')
+				break;
+			normalized[pos++]
+				= ((toLower & 0x10) ? tolower(msdos[i]) : msdos[i]);
 		}
 	}
 
@@ -1535,20 +1538,26 @@ status_t msdos_to_utf8(uchar *msdos, uchar *utf8, uint32 utf8len, bool toLower)
 			(char *)utf8, (int32 *)&utf8len);
 }
 
-bool requires_munged_short_name(const uchar *utf8name, const uchar nshort[11], int encoding)
+bool requires_munged_short_name(const uchar *utf8name, const uchar nshort[11],
+	int encoding)
 {
 	int leading = 0;
 	int trailing = 0;
 	int i, len;
 
-	if (encoding != MS_DOS_CONVERSION) return true;
+	if (encoding != MS_DOS_CONVERSION)
+		return true;
 
 	for ( ; *utf8name != 0; utf8name++) {
-		if (!BEGINS_UTF8CHAR(*utf8name)) continue;
-		if (*utf8name == '.') break;
+		if (!BEGINS_UTF8CHAR(*utf8name))
+			continue;
+		if (*utf8name == '.')
+			break;
 		leading++;
-		if (leading > 8) return true;
-		if ((nshort[leading - 1] == '_') && (*utf8name != '_')) return true;
+		if (leading > 8)
+			return true;
+		if ((nshort[leading - 1] == '_') && (*utf8name != '_'))
+			return true;
 	}
 
 	if (*utf8name != 0) {
diff --git a/src/add-ons/kernel/file_systems/fat/encodings.h b/src/add-ons/kernel/file_systems/fat/encodings.h
index 782c4922ac..c902736cab 100644
--- a/src/add-ons/kernel/file_systems/fat/encodings.h
+++ b/src/add-ons/kernel/file_systems/fat/encodings.h
@@ -22,7 +22,8 @@ status_t munge_short_name1(uchar nshort[11], int iteration, int encoding);
 status_t generate_short_name(const uchar *name, const uchar *uni,
 		uint32 unilen, uchar nshort[11], int *encoding);
 
-status_t msdos_to_utf8(uchar *msdos, uchar *utf8, uint32 utf8len, bool toLower);
+status_t msdos_to_utf8(uchar *msdos, uchar *utf8, uint32 utf8len,
+		uint8 toLower);
 
 #ifdef __cplusplus
 }