Fixed issue with Extended Symlinks

Removed some shadowed err's

file.go

@@ -28,14 +28,18 @@ var (
 //File can be either a file or folder. When reading from a squashfs, it reads from the datablocks.
 //When writing, this holds the information on WHERE the file will be placed inside the archive.
 //
-//Implements os.FileInfo and io.ReadCloser
+//If copying data from a squashfs, the returned reader from io.Sys() implements io.WriterTo which
+//will be significantly faster then calling Read directly.
+//Ex: use io.Sys().(io.Reader) for io.Copy instead of using the File directly.
+//
+//Implements os.FileInfo and io.Reader
 type File struct {
-	Reader  io.Reader
+	reader  io.Reader
 	Parent  *File
 	r       *Reader //Underlying reader. When writing, will probably be an os.File. When reading this is kept nil UNTIL reading to save memory.
 	in      *inode.Inode
 	name    string
-	path    string
+	dir     string
 	filType int //The file's type, using inode types.
 
 }
@@ -75,20 +79,20 @@ func (f *File) ModTime() time.Time {
 	return time.Unix(int64(f.in.Header.ModifiedTime), 0)
 }
 
-//Sys returns the underlying reader, file.Reader. If the reader isn't initialized, it will initialize it.
+//Sys returns the underlying reader. If the reader isn't initialized, it will initialize it.
 //If called on something other then a file, returns nil.
 func (f *File) Sys() interface{} {
-	if f.IsFile() {
+	if !f.IsFile() {
-		if f.Reader == nil && f.r != nil {
+		return nil
-			var err error
-			f.Reader, err = f.r.newFileReader(f.in)
-			if err != nil {
-				return nil
-			}
-		}
-		return f.Reader
 	}
-	return nil
+	if f.reader == nil && f.r != nil {
+		var err error
+		f.reader, err = f.r.newFileReader(f.in)
+		if err != nil {
+			return nil
+		}
+	}
+	return f.reader
 }
 
 //GetChildren returns a *squashfs.File slice of every direct child of the directory. If the File is not a directory, will return ErrNotDirectory
@@ -112,7 +116,7 @@ func (f *File) GetChildren() (children []*File, err error) {
 		}
 		fil.Parent = f
 		if f.name != "" {
-			fil.path = f.Path()
+			fil.dir = f.Path()
 		}
 		children = append(children, fil)
 	}
@@ -138,21 +142,14 @@ func (f *File) GetChildrenRecursively() (children []*File, err error) {
 			childFolders = append(childFolders, child)
 		}
 	}
-	foldChil := make(chan []*File)
-	errChan := make(chan error)
 	for _, folds := range childFolders {
-		go func(fil *File) {
+		var childs []*File
-			childs, err := fil.GetChildrenRecursively()
+		childs, err = folds.GetChildrenRecursively()
-			errChan <- err
-			foldChil <- childs
-		}(folds)
-	}
-	for range childFolders {
-		err = <-errChan
 		if err != nil {
+			fmt.Println(err)
 			return
 		}
-		children = append(children, <-foldChil...)
+		children = append(children, childs...)
 	}
 	return
 }
@@ -160,26 +157,23 @@ func (f *File) GetChildrenRecursively() (children []*File, err error) {
 //Path returns the path of the file within the archive.
 func (f *File) Path() string {
 	if f.name == "" {
-		return f.path
+		return f.dir
 	}
-	return f.path + "/" + f.name
+	return f.dir + "/" + f.name
 }
 
 //GetFileAtPath tries to return the File at the given path, relative to the file.
 //Returns nil if called on something other then a folder, OR if the path goes oustide the archive.
-//Allows wildcards supported by path.Match (namely * and ?).
+//Allows wildcards supported by path.Match (namely * and ?) and will return the FIRST file that matches.
 func (f *File) GetFileAtPath(dirPath string) *File {
-	if dirPath == "" {
+	dirPath = path.Clean(dirPath)
+	dirPath = strings.TrimPrefix(dirPath, "/")
+	if dirPath == "" || dirPath == "." {
 		return f
 	}
-	dirPath = strings.TrimSuffix(strings.TrimPrefix(dirPath, "/"), "/")
+	if dirPath != "." && !f.IsDir() {
-	if dirPath != "" && !f.IsDir() {
 		return nil
 	}
-	for strings.HasSuffix(dirPath, "./") {
-		//since you can TECHNICALLY have an infinite amount of ./ and it would still be valid.
-		dirPath = strings.TrimPrefix(dirPath, "./")
-	}
 	split := strings.Split(dirPath, "/")
 	if split[0] == ".." && f.name == "" {
 		return nil
@@ -209,7 +203,7 @@ func (f *File) IsDir() bool {
 
 //IsSymlink returns if the file is a symlink.
 func (f *File) IsSymlink() bool {
-	return f.filType == inode.SymType || f.filType == inode.ExtSymlinkType
+	return f.filType == inode.SymType || f.filType == inode.ExtSymType
 }
 
 //IsFile returns if the file is a file.
@@ -223,8 +217,8 @@ func (f *File) SymlinkPath() string {
 	switch f.filType {
 	case inode.SymType:
 		return f.in.Info.(inode.Sym).Path
-	case inode.ExtSymlinkType:
+	case inode.ExtSymType:
-		return f.in.Info.(inode.Sym).Path
+		return f.in.Info.(inode.ExtSym).Path
 	default:
 		return ""
 	}
@@ -319,7 +313,8 @@ func (f *File) ExtractWithOptions(path string, dereferenceSymlink, unbreakSymlin
 				errs = append(errs, err)
 				return
 			}
-			fil, err := os.Open(path + "/" + f.name)
+			var fil *os.File
+			fil, err = os.Open(path + "/" + f.name)
 			if err != nil {
 				if verbose {
 					fmt.Println("Error while opening:", path+"/"+f.name)
@@ -346,7 +341,8 @@ func (f *File) ExtractWithOptions(path string, dereferenceSymlink, unbreakSymlin
 				errs = append(errs, err)
 			}
 		}
-		children, err := f.GetChildren()
+		var children []*File
+		children, err = f.GetChildren()
 		if err != nil {
 			if verbose {
 				fmt.Println("Error getting children for:", f.Path())
@@ -370,7 +366,8 @@ func (f *File) ExtractWithOptions(path string, dereferenceSymlink, unbreakSymlin
 		}
 		return
 	case f.IsFile():
-		fil, err := os.Create(path + "/" + f.name)
+		var fil *os.File
+		fil, err = os.Create(path + "/" + f.name)
 		if os.IsExist(err) {
 			err = os.Remove(path + "/" + f.name)
 			if err != nil {
@@ -398,18 +395,7 @@ func (f *File) ExtractWithOptions(path string, dereferenceSymlink, unbreakSymlin
 			errs = append(errs, err)
 			return
 		} //Since we will be reading from the file
-		if f.Reader == nil && f.r != nil {
+		_, err = io.Copy(fil, f.Sys().(io.Reader))
-			f.Reader, err = f.r.newFileReader(f.in)
-			if err != nil {
-				if verbose {
-					fmt.Println("Error while Copying data to:", path+"/"+f.name)
-					fmt.Println(err)
-				}
-				errs = append(errs, err)
-				return
-			}
-		}
-		_, err = io.Copy(fil, f.Reader)
 		if err != nil {
 			if verbose {
 				fmt.Println("Error while Copying data to:", path+"/"+f.name)
@@ -495,13 +481,13 @@ func (f *File) Read(p []byte) (int, error) {
 		return 0, io.EOF
 	}
 	var err error
-	if f.Reader == nil && f.r != nil {
+	if f.reader == nil && f.r != nil {
-		f.Reader, err = f.r.newFileReader(f.in)
+		f.reader, err = f.r.newFileReader(f.in)
 		if err != nil {
 			return 0, err
 		}
 	}
-	return f.Reader.Read(p)
+	return f.reader.Read(p)
 }
 
 //ReadDirFromInode returns a fully populated Directory from a given Inode.

fragment.go

@@ -10,9 +10,9 @@ import (
 
 //FragmentEntry is an entry in the fragment table
 type fragmentEntry struct {
-	Start  uint64
+	Start uint64
-	Size   uint32
+	Size  uint32
-	Unused uint32
+	// Unused uint32
 }
 
 //GetFragmentDataFromInode returns the fragment data for a given inode.

go.mod

@@ -3,16 +3,17 @@ module github.com/CalebQ42/squashfs
 go 1.15
 
 require (
-	github.com/CalebQ42/GoAppImage v0.4.0
+	github.com/CalebQ42/GoAppImage v0.5.0
 	github.com/adrg/xdg v0.2.3 // indirect
 	github.com/google/go-cmp v0.5.4 // indirect
 	github.com/gopherjs/gopherjs v0.0.0-20200217142428-fce0ec30dd00 // indirect
-	github.com/klauspost/compress v1.11.4
+	github.com/klauspost/compress v1.11.6
 	github.com/kr/text v0.2.0 // indirect
-	github.com/pierrec/lz4/v4 v4.1.2
+	github.com/pierrec/lz4/v4 v4.1.3
 	github.com/smartystreets/assertions v1.2.0 // indirect
+	github.com/stretchr/testify v1.7.0 // indirect
 	github.com/ulikunitz/xz v0.5.9
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
-	gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -1,5 +1,5 @@
-github.com/CalebQ42/GoAppImage v0.4.0 h1:aF+Y/vyo/RGhoyZEW1CMY6WyRWrZZO4ydsRFAtIGnaY=
+github.com/CalebQ42/GoAppImage v0.5.0 h1:znoKNXtliH754tS9sYwyOIg/0wFDjFN5Twc7PAh1rSM=
-github.com/CalebQ42/GoAppImage v0.4.0/go.mod h1:qHudJKAn/dlkNWNnH4h1YKXp29EZ7Bppsn7sNP2HuvU=
+github.com/CalebQ42/GoAppImage v0.5.0/go.mod h1:qHudJKAn/dlkNWNnH4h1YKXp29EZ7Bppsn7sNP2HuvU=
 github.com/adrg/xdg v0.2.2 h1:A7ZHKRz5KGOLJX/bg7IPzStryhvCzAE1wX+KWawPiAo=
 github.com/adrg/xdg v0.2.2/go.mod h1:7I2hH/IT30IsupOpKZ5ue7/qNi3CoKzD6tL3HwpaRMQ=
 github.com/adrg/xdg v0.2.3 h1:GxXngdYxNDkoUvZXjNJGwqZxWXi43MKbOOlA/00qZi4=
@@ -18,8 +18,8 @@ github.com/gopherjs/gopherjs v0.0.0-20200217142428-fce0ec30dd00 h1:l5lAOZEym3oK3
 github.com/gopherjs/gopherjs v0.0.0-20200217142428-fce0ec30dd00/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
 github.com/jtolds/gls v4.20.0+incompatible h1:xdiiI2gbIgH/gLH7ADydsJ1uDOEzR8yvV7C0MuV77Wo=
 github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
-github.com/klauspost/compress v1.11.4 h1:kz40R/YWls3iqT9zX9AHN3WoVsrAWVyui5sxuLqiXqU=
+github.com/klauspost/compress v1.11.6 h1:EgWPCW6O3n1D5n99Zq3xXBt9uCwRGvpwGOusOLNBRSQ=
-github.com/klauspost/compress v1.11.4/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
+github.com/klauspost/compress v1.11.6/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
 github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -29,8 +29,8 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
-github.com/pierrec/lz4/v4 v4.1.2 h1:qvY3YFXRQE/XB8MlLzJH7mSzBs74eA2gg52YTk6jUPM=
+github.com/pierrec/lz4/v4 v4.1.3 h1:/dvQpkb0o1pVlSgKNQqfkavlnXaIK+hJ0LXsKRUN9D4=
-github.com/pierrec/lz4/v4 v4.1.2/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
+github.com/pierrec/lz4/v4 v4.1.3/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykElWQ6/NYmHa3jpm/yHnI4xSofP+UP6SpjHcSeM=
@@ -39,9 +39,12 @@ github.com/smartystreets/assertions v1.2.0 h1:42S6lae5dvLc7BrLu/0ugRtcFVjoJNMC/N
 github.com/smartystreets/assertions v1.2.0/go.mod h1:tcbTF8ujkAEcZ8TElKY+i30BzYlVhC/LOxJk7iOWnoo=
 github.com/smartystreets/goconvey v1.6.4 h1:fv0U8FUIMPNf1L9lnHLvLhgicrIVChEkdzIKYqbNC9s=
 github.com/smartystreets/goconvey v1.6.4/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9QV7WQ/tjFTllLA=
+github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/ulikunitz/xz v0.5.9 h1:RsKRIA2MO8x56wkkcd3LbtcE/uMszhb6DpRf+3uwa3I=
 github.com/ulikunitz/xz v0.5.9/go.mod h1:nbz6k7qbPmH4IRqmfOplQw/tblSgqTqBwxkY0oWt/14=
 go.lsp.dev/uri v0.3.0 h1:KcZJmh6nFIBeJzTugn5JTU6OOyG0lDOo3R9KwTxTYbo=
@@ -69,5 +72,5 @@ gopkg.in/ini.v1 v1.62.0 h1:duBzk771uxoUuOlyRLkHsygud9+5lrlGjdFBb4mSKDU=
 gopkg.in/ini.v1 v1.62.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776 h1:tQIYjPdBoyREyB9XMu+nnTclpTYkz2zFM+lzLJFO4gQ=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
-gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/inode/inodetypes.go

@@ -16,7 +16,7 @@ const (
 	SocketType
 	ExtDirType
 	ExtFileType
-	ExtSymlinkType
+	ExtSymType
 	ExtBlockDeviceType
 	ExtCharDeviceType
 	ExtFifoType
@@ -67,7 +67,8 @@ func NewExtendedDirectory(rdr io.Reader) (ExtDir, error) {
 		return inode, err
 	}
 	for i := uint16(0); i < inode.IndexCount; i++ {
-		tmp, err := NewDirectoryIndex(rdr)
+		var tmp DirIndex
+		tmp, err = NewDirectoryIndex(rdr)
 		if err != nil {
 			return inode, err
 		}

internal/inode/process.go

@@ -31,13 +31,15 @@ func ProcessInode(br io.Reader, blockSize uint32) (*Inode, error) {
 		}
 		info = inode
 	case FileType:
-		inode, err := NewFile(br, blockSize)
+		var inode File
+		inode, err = NewFile(br, blockSize)
 		if err != nil {
 			return nil, err
 		}
 		info = inode
 	case SymType:
-		inode, err := NewSymlink(br)
+		var inode Sym
+		inode, err = NewSymlink(br)
 		if err != nil {
 			return nil, err
 		}
@@ -71,19 +73,22 @@ func ProcessInode(br io.Reader, blockSize uint32) (*Inode, error) {
 		}
 		info = inode
 	case ExtDirType:
-		inode, err := NewExtendedDirectory(br)
+		var inode ExtDir
+		inode, err = NewExtendedDirectory(br)
 		if err != nil {
 			return nil, err
 		}
 		info = inode
 	case ExtFileType:
-		inode, err := NewExtendedFile(br, blockSize)
+		var inode ExtFile
+		inode, err = NewExtendedFile(br, blockSize)
 		if err != nil {
 			return nil, err
 		}
 		info = inode
-	case ExtSymlinkType:
+	case ExtSymType:
-		inode, err := NewExtendedSymlink(br)
+		var inode ExtSym
+		inode, err = NewExtendedSymlink(br)
 		if err != nil {
 			return nil, err
 		}

reader.go

@@ -30,6 +30,7 @@ var (
 type Reader struct {
 	r            io.ReaderAt
 	decompressor compression.Decompressor
+	root         *File
 	fragOffsets  []uint64
 	idTable      []uint32
 	super        superblock
@@ -55,7 +56,8 @@ func NewSquashfsReader(r io.ReaderAt) (*Reader, error) {
 	if rdr.flags.CompressorOptions {
 		switch rdr.super.CompressionType {
 		case GzipCompression:
-			gzip, err := compression.NewGzipCompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 8))
+			var gzip *compression.Gzip
+			gzip, err = compression.NewGzipCompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 8))
 			if err != nil {
 				return nil, err
 			}
@@ -64,7 +66,8 @@ func NewSquashfsReader(r io.ReaderAt) (*Reader, error) {
 			}
 			rdr.decompressor = gzip
 		case XzCompression:
-			xz, err := compression.NewXzCompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 8))
+			var xz *compression.Xz
+			xz, err = compression.NewXzCompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 8))
 			if err != nil {
 				return nil, err
 			}
@@ -73,13 +76,15 @@ func NewSquashfsReader(r io.ReaderAt) (*Reader, error) {
 			}
 			rdr.decompressor = xz
 		case Lz4Compression:
-			lz4, err := compression.NewLz4CompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 8))
+			var lz4 *compression.Lz4
+			lz4, err = compression.NewLz4CompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 8))
 			if err != nil {
 				return nil, err
 			}
 			rdr.decompressor = lz4
 		case ZstdCompression:
-			zstd, err := compression.NewZstdCompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 4))
+			var zstd *compression.Zstd
+			zstd, err = compression.NewZstdCompressorWithOptions(io.NewSectionReader(rdr.r, int64(binary.Size(rdr.super)), 4))
 			if err != nil {
 				return nil, err
 			}
@@ -153,46 +158,56 @@ func (r *Reader) ModTime() time.Time {
 
 //ExtractTo tries to extract ALL files to the given path. This is the same as getting the root folder and extracting that.
 func (r *Reader) ExtractTo(path string) []error {
-	root, err := r.GetRootFolder()
+	if r.root == nil {
-	if err != nil {
+		_, err := r.GetRootFolder()
-		return []error{err}
+		if err != nil {
+			return []error{err}
+		}
 	}
-	return root.ExtractTo(path)
+	return r.root.ExtractTo(path)
 }
 
 //GetRootFolder returns a squashfs.File that references the root directory of the squashfs archive.
-func (r *Reader) GetRootFolder() (root *File, err error) {
+func (r *Reader) GetRootFolder() (*File, error) {
-	root = new(File)
+	if r.root != nil {
+		return r.root, nil
+	}
 	mr, err := r.newMetadataReaderFromInodeRef(r.super.RootInodeRef)
 	if err != nil {
 		return nil, err
 	}
+	var root File
 	root.in, err = inode.ProcessInode(mr, r.super.BlockSize)
 	if err != nil {
 		return nil, err
 	}
-	root.path = "/"
+	root.dir = "/"
 	root.filType = root.in.Type
 	root.r = r
-	return root, nil
+	r.root = &root
+	return r.root, nil
 }
 
 //GetAllFiles returns a slice of ALL files and folders contained in the squashfs.
 func (r *Reader) GetAllFiles() (fils []*File, err error) {
-	root, err := r.GetRootFolder()
+	if r.root == nil {
-	if err != nil {
+		_, err := r.GetRootFolder()
-		return nil, err
+		if err != nil {
+			return nil, err
+		}
 	}
-	return root.GetChildrenRecursively()
+	return r.root.GetChildrenRecursively()
 }
 
 //FindFile returns the first file (in the same order as Reader.GetAllFiles) that the given function returns true for. Returns nil if nothing is found.
 func (r *Reader) FindFile(query func(*File) bool) *File {
-	root, err := r.GetRootFolder()
+	if r.root == nil {
-	if err != nil {
+		_, err := r.GetRootFolder()
-		return nil
+		if err != nil {
+			return nil
+		}
 	}
-	fils, err := root.GetChildren()
+	fils, err := r.root.GetChildren()
 	if err != nil {
 		return nil
 	}
@@ -228,11 +243,13 @@ func (r *Reader) FindFile(query func(*File) bool) *File {
 
 //FindAll returns all files where the given function returns true.
 func (r *Reader) FindAll(query func(*File) bool) (all []*File) {
-	root, err := r.GetRootFolder()
+	if r.root == nil {
-	if err != nil {
+		_, err := r.GetRootFolder()
-		return nil
+		if err != nil {
+			return nil
+		}
 	}
-	fils, err := root.GetChildrenRecursively()
+	fils, err := r.root.GetChildrenRecursively()
 	if err != nil {
 		return nil
 	}
@@ -245,10 +262,12 @@ func (r *Reader) FindAll(query func(*File) bool) (all []*File) {
 }
 
 //GetFileAtPath will return the file at the given path. If the file cannot be found, will return nil.
-func (r *Reader) GetFileAtPath(path string) *File {
+func (r *Reader) GetFileAtPath(filepath string) *File {
-	dir, err := r.GetRootFolder()
+	if r.root == nil {
-	if err != nil {
+		_, err := r.GetRootFolder()
-		return nil
+		if err != nil {
+			return nil
+		}
 	}
-	return dir.GetFileAtPath(path)
+	return r.root.GetFileAtPath(filepath)
 }

reader_test.go

@@ -16,7 +16,7 @@ import (
 const (
 	downloadURL  = "https://github.com/srevinsaju/Firefox-Appimage/releases/download/firefox-v84.0.r20201221152838/firefox-84.0.r20201221152838-x86_64.AppImage"
 	appImageName = "firefox-84.0.r20201221152838-x86_64.AppImage"
-	squashfsName = "balenaEtcher-1.5.113-x64.AppImage.sfs" //testing with a ArchLinux root fs from the live img
+	squashfsName = "balenaEtcher-1.5.113-x64.AppImage.sfs"
 )
 
 func TestSquashfs(t *testing.T) {
@@ -76,14 +76,14 @@ func TestAppImage(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	errs := rdr.ExtractTo(wd + "/testing/firefox")
+	rt := rdr.GetFileAtPath("/")
-	if len(errs) > 0 {
+	fils, err := rt.GetChildrenRecursively()
-		t.Fatal(errs)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, fil := range fils {
+		fmt.Println(fil.Path())
 	}
-	// os.RemoveAll(wd + "/testing/" + appImageName + ".d")
-	// root, _ := rdr.GetRootFolder()
-	// errs := root.ExtractWithOptions(wd+"/testing/"+appImageName+".d", true, os.ModePerm, true)
-	// t.Fatal(errs)
 	fmt.Println(time.Since(start))
 	t.Fatal("No problemo!")
 }

writer.go

@@ -33,6 +33,7 @@ type Writer struct {
 	symlinkTable    map[string]string //[oldpath]newpath
 	uidGUIDTable    []int
 	compressionType int
+	Flags           superblockFlags
 	allowErrors     bool
 }
 
@@ -81,6 +82,9 @@ func (w *Writer) AddFileTo(filepath string, file *os.File) error {
 	if !strings.HasPrefix(filepath, "/") {
 		filepath = "/" + filepath
 	}
+	if w.Contains(filepath) {
+		return errors.New("File already exists at " + filepath)
+	}
 	var holder fileHolder
 	holder.path, holder.name = path.Split(filepath)
 	holder.reader = file
@@ -150,6 +154,9 @@ func (w *Writer) AddReaderTo(filepath string, reader io.Reader) error {
 	if !strings.HasPrefix(filepath, "/") {
 		filepath = "/" + filepath
 	}
+	if w.Contains(filepath) {
+		return errors.New("File already exists at " + filepath)
+	}
 	var holder fileHolder
 	holder.path, holder.name = path.Split(filepath)
 	holder.reader = reader
@@ -171,10 +178,11 @@ func (w *Writer) Remove(filepath string) bool {
 			for i, fil := range files {
 				if match, _ = path.Match(name, fil.name); match {
 					matchFound = true
-					if i != len(files)-1 {
+					if len(w.structure[structDir]) > 1 {
-						w.structure[structDir] = append(w.structure[structDir][:i], w.structure[structDir][i+1:]...)
+						w.structure[structDir][i] = w.structure[structDir][len(w.structure[structDir])-1]
+						w.structure[structDir] = w.structure[structDir][:len(w.structure[structDir])-1]
 					} else {
-						w.structure[structDir] = w.structure[structDir][:i]
+						w.structure[structDir] = nil
 					}
 				}
 			}
@@ -185,11 +193,120 @@ func (w *Writer) Remove(filepath string) bool {
 
 //FixSymlinks will scan through the squashfs archive and try to find broken symlinks and fix them.
 //This done by replacing the symlink with the target file and then pointing other symlinks to that file.
-//
+//If all symlinks can be resolved, the error slice will be nil, and the bool false, otherwise all errors occured will be in the slice.
-//If this is not run before writing, you may end up with broken symlinks.
+func (w *Writer) FixSymlinks() (errs []error, problems bool) {
-func (w *Writer) FixSymlinks() error {
+	for dir, holderSlice := range w.structure {
-	//TODO
+		for i, holder := range holderSlice {
-	return errors.New("DON'T")
+			if !holder.symlink {
+				continue
+			}
+			sym := holder.symLocation
+			if !path.IsAbs(holder.symLocation) {
+				sym = path.Join(dir, holder.symLocation)
+			}
+			if path, ok := w.symlinkTable[sym]; ok {
+				w.structure[dir][i].symLocation = path
+				continue
+			}
+			if path.IsAbs(sym) || strings.HasPrefix(sym, "../") {
+				var symFil *os.File
+				var err error
+				if strings.HasPrefix(sym, "../") {
+					holderFil, ok := holder.reader.(*os.File)
+					if !ok {
+						problems = true
+						errs = append(errs, errors.New("Cannot resolve symlink at "+dir+holder.name))
+						continue
+					}
+					symFilPath := path.Dir(holderFil.Name())
+					symFilPath = path.Join(symFilPath, holder.symLocation)
+					symFil, err = os.Open(symFilPath)
+				} else {
+					symFil, err = os.Open(sym)
+				}
+				if err != nil {
+					problems = true
+					errs = append(errs, err)
+					continue
+				}
+				suc := w.Remove(dir + holder.name)
+				if !suc {
+					problems = true
+					errs = append(errs, errors.New("Cannot resolve symlink at "+dir+holder.name))
+					continue
+				}
+				err = w.AddFileTo(dir+holder.name, symFil)
+				if err != nil {
+					w.structure[dir] = append(w.structure[dir], holder)
+					problems = true
+					errs = append(errs, err)
+					continue
+				}
+				w.symlinkTable[sym] = dir + holder.name
+			} else {
+				symHolder := w.holderAt(sym)
+				if symHolder != nil {
+					w.symlinkTable[sym] = sym
+					continue
+				}
+				holderFil, ok := holder.reader.(*os.File)
+				if !ok {
+					problems = true
+					errs = append(errs, errors.New("Cannot resolve symlink at "+dir+holder.name))
+					continue
+				}
+				symFilPath := path.Dir(holderFil.Name())
+				symFilPath = path.Join(symFilPath, holder.symLocation)
+				symFil, err := os.Open(symFilPath)
+				if err != nil {
+					problems = true
+					errs = append(errs, err)
+					continue
+				}
+				err = w.AddFileTo(sym, symFil)
+				if err != nil {
+					problems = true
+					errs = append(errs, err)
+					continue
+				}
+				w.symlinkTable[sym] = sym
+			}
+		}
+	}
+	return
+}
+
+func (w *Writer) holderAt(filepath string) *fileHolder {
+	filepath = path.Clean(filepath)
+	if !strings.HasPrefix(filepath, "/") {
+		filepath = "/" + filepath
+	}
+	dir, name := path.Split(filepath)
+	if holderSlice, ok := w.structure[dir]; ok {
+		for _, holder := range holderSlice {
+			if holder.name == name {
+				return holder
+			}
+		}
+	}
+	return nil
+}
+
+//Contains returns whether a file is present at the given filepath
+func (w *Writer) Contains(filepath string) bool {
+	filepath = path.Clean(filepath)
+	if !strings.HasPrefix(filepath, "/") {
+		filepath = "/" + filepath
+	}
+	dir, name := path.Split(filepath)
+	if holderSlice, ok := w.structure[dir]; ok {
+		for _, holder := range holderSlice {
+			if holder.name == name {
+				return true
+			}
+		}
+	}
+	return false
 }
 
 //WriteToFilename creates the squashfs archive with the given filepath.