add gpt internal package and update mbr package

Author: soypat

Diff for: fat.go

@@ -1691,7 +1691,7 @@ func (dp *dir) create_name(path string) (string, fileResult) {
 		if isTermLFN(wc) || isSep(wc) {
 			break // Break on end of path or a separator.
 		}
-		if strings.IndexByte("*:<>|\"?\x7f", byte(wc)) >= 0 {
+		if strings.IndexByte(forbiddenChars, byte(wc)) >= 0 {
 			return "", frInvalidName
 		}
 		if di >= lfnBufSize {
@@ -2352,6 +2352,14 @@ func (fsys *FS) gen_numname(dst, src []byte, lfn []uint16, seq uint32) {
 	}
 }
 
+func clipname(s []byte) []byte {
+	i := 0
+	for i < len(s) && isfatchar(s[i]) {
+		i++
+	}
+	return s[:i]
+}
+
 func bstr(s []byte) []byte {
 	i := 0
 	for i < len(s) && s[i] != 0 {
@@ -2381,3 +2389,7 @@ func str16(s []uint16) string {
 	}
 	return string(buf)
 }
+
+func isfatchar(c byte) bool {
+	return c != ' ' && c != 0 && c < 0x7F
+}

Diff for: format.go

@@ -100,6 +100,11 @@ func (bs *bootsector) SectorSize() uint16 {
 	return binary.LittleEndian.Uint16(bs.data[bpbBytsPerSec:])
 }
 
+// SetSectorSize sets the size of a sector in bytes.
+func (bs *bootsector) SetSectorSize(size uint16) {
+	binary.LittleEndian.PutUint16(bs.data[bpbBytsPerSec:], size)
+}
+
 // SectorsPerFAT returns the number of sectors per File Allocation Table.
 func (bs *bootsector) SectorsPerFAT() uint32 {
 	fatsz := uint32(binary.LittleEndian.Uint16(bs.data[bpbFATSz16:]))
@@ -109,23 +114,44 @@ func (bs *bootsector) SectorsPerFAT() uint32 {
 	return fatsz
 }
 
+// SetSectorsPerFAT sets the number of sectors per File Allocation Table.
+func (bs *bootsector) SetSectorsPerFAT(fatsz uint32) {
+	binary.LittleEndian.PutUint16(bs.data[bpbFATSz16:], 0)
+	binary.LittleEndian.PutUint32(bs.data[bpbFATSz32:], fatsz)
+}
+
 // NumberOfFATs returns the number of File Allocation Tables. Should be 1 or 2.
 func (bs *bootsector) NumberOfFATs() uint8 {
 	return bs.data[bpbNumFATs]
 }
 
+// SetNumberOfFATs sets the number of FATs.
+func (bs *bootsector) SetNumberOfFATs(nfats uint8) {
+	bs.data[bpbNumFATs] = nfats
+}
+
 // SectorsPerCluster returns the number of sectors per cluster.
 // Should be a power of 2 and not larger than 128.
 func (bs *bootsector) SectorsPerCluster() uint16 {
 	return uint16(bs.data[bpbSecPerClus])
 }
 
+// SetSectorsPerCluster sets the number of sectors per cluster. Should be power of 2.
+func (bs *bootsector) SetSectorsPerCluster(spclus uint16) {
+	bs.data[bpbSecPerClus] = byte(spclus)
+}
+
 // ReservedSectors returns the number of reserved sectors at the beginning of the volume.
 // Should be at least 1.
 func (bs *bootsector) ReservedSectors() uint16 {
 	return binary.LittleEndian.Uint16(bs.data[bpbRsvdSecCnt:])
 }
 
+// SetReservedSectors sets the number of reserved sectors at the beginning of the volume.
+func (bs *bootsector) SetReservedSectors(rsvd uint16) {
+	binary.LittleEndian.PutUint16(bs.data[bpbRsvdSecCnt:], rsvd)
+}
+
 // TotalSectors returns the total number of sectors in the volume that
 // can be used by the filesystem.
 func (bs *bootsector) TotalSectors() uint32 {
@@ -136,22 +162,39 @@ func (bs *bootsector) TotalSectors() uint32 {
 	return totsec
 }
 
-// RootDirSectors returns the number of sectors occupied by the root directory.
+// SetTotalSectors sets the total number of sectors in the volume that
+// can be used by the filesystem.
+func (bs *bootsector) SetTotalSectors(totsec uint32) {
+	binary.LittleEndian.PutUint16(bs.data[bpbTotSec16:], 0)
+	binary.LittleEndian.PutUint32(bs.data[bpbTotSec32:], totsec)
+}
+
+// RootDirEntries returns the number of sectors occupied by the root directory.
 // Should be divisible by SectorSize/32.
 func (bs *bootsector) RootDirEntries() uint16 {
 	return binary.LittleEndian.Uint16(bs.data[bpbRootEntCnt:])
 }
 
-// Version returns the filesystem version, should be 0.0 for FAT32.
-func (bs *bootsector) Version() (major, minor uint8) {
-	return bs.data[bpbFSVer32], bs.data[bpbFSVer32+1]
+// SetRootDirEntries sets the number of sectors occupied by the root directory.
+func (bs *bootsector) SetRootDirEntries(entries uint16) {
+	binary.LittleEndian.PutUint16(bs.data[bpbRootEntCnt:], entries)
 }
 
 // RootCluster returns the first cluster of the root directory.
 func (bs *bootsector) RootCluster() uint32 {
 	return binary.LittleEndian.Uint32(bs.data[bpbRootClus32:])
 }
 
+// SetRootCluster sets the first cluster of the root directory.
+func (bs *bootsector) SetRootCluster(cluster uint32) {
+	binary.LittleEndian.PutUint32(bs.data[bpbRootClus32:], cluster)
+}
+
+// Version returns the filesystem version, should be 0.0 for FAT32.
+func (bs *bootsector) Version() (major, minor uint8) {
+	return bs.data[bpbFSVer32], bs.data[bpbFSVer32+1]
+}
+
 func (bs *bootsector) ExtendedBootSignature() uint8 {
 	return bs.data[bsBootSig32]
 }
@@ -178,12 +221,19 @@ func (bs *bootsector) VolumeSerialNumber() uint32 {
 }
 
 // VolumeLabel returns the volume label string.
-func (bs *bootsector) VolumeLabel() [8]byte {
-	var label [8]byte
+func (bs *bootsector) VolumeLabel() [11]byte {
+	var label [11]byte
 	copy(label[:], bs.data[bsVolLab32:])
 	return label
 }
 
+func (bs *bootsector) SetVolumeLabel(label string) {
+	n := copy(bs.data[bsVolLab32:bsVolLab32+11], label)
+	for i := n; i < 11; i++ {
+		bs.data[bsVolLab32+i] = ' '
+	}
+}
+
 // FilesystemType returns the filesystem type string, usually "FAT32   ".
 func (bs *bootsector) FilesystemType() [8]byte {
 	var label [8]byte
@@ -205,6 +255,15 @@ func (bs *bootsector) OEMName() [8]byte {
 	return oemname
 }
 
+// SetOEMName sets the Original Equipment Manufacturer name at the start of the bootsector.
+// Will clip off any characters beyond the 8th.
+func (bs *bootsector) SetOEMName(name string) {
+	n := copy(bs.data[bsOEMName:bsOEMName+8], name)
+	for i := n; i < 8; i++ {
+		bs.data[bsOEMName+i] = ' '
+	}
+}
+
 func (bs *bootsector) VolumeOffset() uint32 {
 	return binary.LittleEndian.Uint32(bs.data[bpbHiddSec:])
 }
@@ -230,11 +289,11 @@ func (bs *bootsector) Appendf(dst []byte, separator byte) []byte {
 		dst = append(dst, sep)
 	}
 	oem := bs.OEMName()
-	appendData("OEM", bstr(oem[:]), separator)
+	appendData("OEM", clipname(oem[:]), separator)
 	fstype := bs.FilesystemType()
-	appendData("FSType", bstr(fstype[:]), separator)
+	appendData("FSType", clipname(fstype[:]), separator)
 	volLabel := bs.VolumeLabel()
-	appendData("VolumeLabel", bstr(volLabel[:]), separator)
+	appendData("VolumeLabel", clipname(volLabel[:]), separator)
 	appendInt("VolumeSerialNumber", bs.VolumeSerialNumber(), separator)
 	appendInt("VolumeOffset", bs.VolumeOffset(), separator)
 	appendInt("SectorSize", uint32(bs.SectorSize()), separator)

Diff for: go.mod

@@ -1,3 +1,5 @@
 module github.com/soypat/fat
 
 go 1.21
+
+require golang.org/x/text v0.14.0

Diff for: go.sum

@@ -0,0 +1,2 @@
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=