Add Long File Name (VFAT) entry to the Mass Storage class bootloader, so that systems such as Linux that load a VFAT filesystem driver instead of the legacy MSDOS filesystem do not corrupt the volume by trying to write a LFN entry.

Bootloaders/MassStorage/Lib/VirtualFAT.c

@@ -72,33 +72,68 @@ static const FATBootBlock_t BootBlock =
 	};
 
 /** FAT 8.3 style directory entry, for the virtual FLASH contents file. */
-static FATDirectoryEntry_t FirmwareFileEntries[2] =
+static FATDirectoryEntry_t FirmwareFileEntries[] =
 	{
 		/* Root volume label entry; disk label is contained in the Filename and
 		 * Extension fields (concatenated) with a special attribute flag - other
 		 * fields are ignored. Should be the same as the label in the boot block.
 		 */
 		{
-			.Filename               = "LUFA BOO",
-			.Extension              = "T  ",
-			.Attributes             = (1 << 3),
-			.Reserved               = {0},
-			.CreationTime           = 0,
-			.CreationDate           = 0,
-			.StartingCluster        = 0,
-			.FileSizeBytes          = 0,
+			.MSDOS =
+				{
+					.Filename        = "LUFA BOO",
+					.Extension       = "T  ",
+					.Attributes      = FAT_FLAG_VOLUME_NAME,
+					.Reserved        = {0},
+					.CreationTime    = 0,
+					.CreationDate    = 0,
+					.StartingCluster = 0,
+					.FileSizeBytes   = 0,
+				}
 		},
 
-		/* File entry for the virtual Firmware image. */
+		/* VFAT Long File Name entry for the virtual firmware file; required to
+		 * prevent corruption of systems that are unable to detect the device
+		 * as being a legacy MSDOS style FAT12 volume to prevent corruption. */
 		{
-			.Filename               = "FIRMWARE",
-			.Extension              = "BIN",
-			.Attributes             = 0,
-			.Reserved               = {0},
-			.CreationTime           = FAT_TIME(1, 1, 0),
-			.CreationDate           = FAT_DATE(14, 2, 1989),
-			.StartingCluster        = 2,
-			.FileSizeBytes          = FIRMWARE_FILE_SIZE_BYTES,
+			.VFAT =
+				{
+					.Ordinal         = FAT_ORDINAL_LAST_ENTRY | 1,
+					.Attribute       = FAT_FLAG_LONG_FILE_NAME,
+					.Reserved1       = 0,
+					.Reserved2       = 0,
+
+					.Checksum        = 0x57,
+
+					.Unicode1        = 'F',
+					.Unicode2        = 'I',
+					.Unicode3        = 'R',
+					.Unicode4        = 'M',
+					.Unicode5        = 'W',
+					.Unicode6        = 'A',
+					.Unicode7        = 'R',
+					.Unicode8        = 'E',
+					.Unicode9        = '.',
+					.Unicode10       = 'B',
+					.Unicode11       = 'I',
+					.Unicode12       = 'N',
+					.Unicode13       = 0,
+				}
+		},
+
+		/* MSDOS file entry for the virtual Firmware image. */
+		{
+			.MSDOS =
+				{
+					.Filename        = "FIRMWARE",
+					.Extension       = "BIN",
+					.Attributes      = 0,
+					.Reserved        = {0},
+					.CreationTime    = FAT_TIME(1, 1, 0),
+					.CreationDate    = FAT_DATE(14, 2, 1989),
+					.StartingCluster = 2,
+					.FileSizeBytes   = FIRMWARE_FILE_SIZE_BYTES,
+				}
 		},
 	};
 

Bootloaders/MassStorage/Lib/VirtualFAT.h

@@ -94,6 +94,33 @@
 		 */
 		#define FAT_DATE(dd, mm, yyyy)    (((yyyy - 1980) << 9) | (mm << 5) | (dd << 0))
 
+		/** \name FAT Filesystem Flags */
+		//@{
+		/** FAT attribute flag to indicate a read-only file. */
+		#define FAT_FLAG_READONLY         (1 << 0)
+
+		/** FAT attribute flag to indicate a hidden file. */
+		#define FAT_FLAG_HIDDEN           (1 << 1)
+
+		/** FAT attribute flag to indicate a system file. */
+		#define FAT_FLAG_SYSTEM           (1 << 2)
+
+		/** FAT attribute flag to indicate a Volume name entry. */
+		#define FAT_FLAG_VOLUME_NAME      (1 << 3)
+
+		/** FAT attribute flag to indicate a directory entry. */
+		#define FAT_FLAG_DIRECTORY        (1 << 4)
+
+		/** FAT attribute flag to indicate a file ready for archiving. */
+		#define FAT_FLAG_ARCHIVE          (1 << 5)
+
+		/** FAT pseudo-attribute flag to indicate a Long File Name entry. */
+		#define FAT_FLAG_LONG_FILE_NAME   0x0F
+
+		/** Ordinal flag marker for FAT Long File Name entries to mark the last entry. */
+		#define FAT_ORDINAL_LAST_ENTRY    (1 << 6)
+		//@}
+
 	/* Type Definitions: */
 		/** FAT boot block structure definition, used to identify the core
 		 *  parameters of a FAT filesystem stored on a disk.
@@ -130,16 +157,41 @@
 		/** FAT legacy 8.3 style directory entry structure definition, used to
 		 *  identify the files and folders of FAT filesystem stored on a disk.
 		 */
-		typedef struct
+		typedef union
 		{
-			uint8_t  Filename[8];
-			uint8_t  Extension[3];
-			uint8_t  Attributes;
-			uint8_t  Reserved[10];
-			uint16_t CreationTime;
-			uint16_t CreationDate;
-			uint16_t StartingCluster;
-			uint32_t FileSizeBytes;
+			struct
+			{
+				uint8_t  Ordinal;
+				uint16_t Unicode1;
+				uint16_t Unicode2;
+				uint16_t Unicode3;
+				uint16_t Unicode4;
+				uint16_t Unicode5;
+				uint8_t  Attribute;
+				uint8_t  Reserved1;
+				uint8_t  Checksum;
+				uint16_t Unicode6;
+				uint16_t Unicode7;
+				uint16_t Unicode8;
+				uint16_t Unicode9;
+				uint16_t Unicode10;
+				uint16_t Unicode11;
+				uint16_t Reserved2;
+				uint16_t Unicode12;
+				uint16_t Unicode13;
+			} VFAT;
+
+			struct
+			{
+				uint8_t  Filename[8];
+				uint8_t  Extension[3];
+				uint8_t  Attributes;
+				uint8_t  Reserved[10];
+				uint16_t CreationTime;
+				uint16_t CreationDate;
+				uint16_t StartingCluster;
+				uint32_t FileSizeBytes;
+			} MSDOS;
 		} FATDirectoryEntry_t;
 
 	/* Function Prototypes: */