Working on how to actually write the archive.

Made SuperblockFlags public so you can set options when writing

superblock.go

@@ -33,28 +33,38 @@ type superblock struct {
 	ExportTableStart uint64
 }
 
-//SuperblockFlags is the parsed version of Superblock.Flags
-type superblockFlags struct {
-	UncompressedInodes    bool
-	UncompressedData      bool
-	Check                 bool
+//SuperblockFlags is the series of flags describing how a squashfs archive is packed.
+type SuperblockFlags struct {
+	//If true, inodes are stored uncompressed
+	UncompressedInodes bool
+	//If true, data is stored uncompressed
+	UncompressedData bool
+	check            bool
+	//If true, fragments are stored uncompressed
 	UncompressedFragments bool
-	NoFragments           bool
-	AlwaysFragments       bool
-	Duplicates            bool
-	Exportable            bool
-	UncompressedXattr     bool
-	NoXattr               bool
-	CompressorOptions     bool
-	UncompressedIDs       bool
+	//If true, ALL data is stored in sequential data blocks instead of utilizing fragments
+	NoFragments bool
+	//If true, the last block of data will always be stored as a fragment if it's less then the block size.
+	AlwaysFragments bool
+	//If true, duplicate files are only stored once.
+	Duplicates bool
+	//If true, the export table is populated
+	Exportable bool
+	//If true, the xattr table is uncompressed
+	UncompressedXattr bool
+	//If true, the xattr table is not populated
+	NoXattr           bool
+	compressorOptions bool
+	//If true, the UID/GID table is stored uncompressed
+	UncompressedIDs bool
 }
 
 //GetFlags returns a SuperblockFlags for a given superblock.
-func (s *superblock) GetFlags() superblockFlags {
-	return superblockFlags{
+func (s *superblock) GetFlags() SuperblockFlags {
+	return SuperblockFlags{
 		UncompressedInodes:    s.Flags&0x1 == 0x1,
 		UncompressedData:      s.Flags&0x2 == 0x2,
-		Check:                 s.Flags&0x4 == 0x4,
+		check:                 s.Flags&0x4 == 0x4,
 		UncompressedFragments: s.Flags&0x8 == 0x8,
 		NoFragments:           s.Flags&0x10 == 0x10,
 		AlwaysFragments:       s.Flags&0x20 == 0x20,
@@ -62,7 +72,49 @@ func (s *superblock) GetFlags() superblockFlags {
 		Exportable:            s.Flags&0x80 == 0x80,
 		UncompressedXattr:     s.Flags&0x100 == 0x100,
 		NoXattr:               s.Flags&0x200 == 0x200,
-		CompressorOptions:     s.Flags&0x400 == 0x400,
+		compressorOptions:     s.Flags&0x400 == 0x400,
 		UncompressedIDs:       s.Flags&0x800 == 0x800,
 	}
 }
+
+//ToUint returns the uint16 representation of the given SuperblockFlags
+func (s *SuperblockFlags) ToUint() uint16 {
+	var out uint16
+	if s.UncompressedInodes {
+		out = out | 0x1
+	}
+	if s.UncompressedData {
+		out = out | 0x2
+	}
+	if s.check {
+		out = out | 0x4
+	}
+	if s.UncompressedFragments {
+		out = out | 0x8
+	}
+	if s.NoFragments {
+		out = out | 0x10
+	}
+	if s.AlwaysFragments {
+		out = out | 0x20
+	}
+	if s.Duplicates {
+		out = out | 0x40
+	}
+	if s.Exportable {
+		out = out | 0x80
+	}
+	if s.UncompressedXattr {
+		out = out | 0x100
+	}
+	if s.NoXattr {
+		out = out | 0x200
+	}
+	if s.compressorOptions {
+		out = out | 0x400
+	}
+	if s.UncompressedIDs {
+		out = out | 0x800
+	}
+	return out
+}