Separated code and data

build/Build.go

@@ -2,6 +2,7 @@ package build
 
 import (
 	"bufio"
+	"bytes"
 	"os"
 	"path/filepath"
 
@@ -11,61 +12,62 @@ import (
 
 // Build describes a compiler build.
 type Build struct {
-	ExecutableName  string
-	ExecutablePath  string
+	Name            string
+	Directory       string
+	Code            bytes.Buffer
+	Data            bytes.Buffer
 	WriteExecutable bool
 }
 
 // New creates a new build.
-func New(directory string) (*Build, error) {
-	directory, err := filepath.Abs(directory)
+func New(directory string) *Build {
+	return &Build{
+		Name:            filepath.Base(directory),
+		Directory:       directory,
+		WriteExecutable: true,
+	}
+}
+
+// Run parses the input files and generates an executable file.
+func (build *Build) Run() error {
+	err := build.Compile()
 
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	file, err := os.Open(directory)
+	if build.WriteExecutable {
+		return writeToDisk(build.Executable(), build.Code.Bytes(), build.Data.Bytes())
+	}
+
+	return nil
+}
+
+// Executable returns the path to the executable.
+func (build *Build) Executable() string {
+	return filepath.Join(build.Directory, build.Name)
+}
+
+// Compile compiles all the functions.
+func (build *Build) Compile() error {
+	file, err := os.Open(build.Directory)
 
 	if err != nil {
-		return nil, err
+		return err
 	}
 
 	defer file.Close()
 	files, err := file.Readdirnames(0)
 
 	if err != nil {
-		return nil, err
+		return err
 	}
 
 	for _, name := range files {
 		log.Info.Println(name)
 	}
 
-	executableName := filepath.Base(directory)
-
-	build := &Build{
-		ExecutableName:  executableName,
-		ExecutablePath:  filepath.Join(directory, executableName),
-		WriteExecutable: true,
-	}
-
-	return build, nil
-}
-
-// Run parses the input files and generates an executable file.
-func (build *Build) Run() error {
-	code := build.Compile()
-
-	if build.WriteExecutable {
-		return writeToDisk(build.ExecutablePath, code)
-	}
-
-	return nil
-}
-
-// Compile compiles all the functions.
-func (build *Build) Compile() []byte {
-	return []byte{
+	build.Code.Write([]byte{
 		0xb8, 0x01, 0x00, 0x00, 0x00, // mov eax, 1
 		0xbf, 0x01, 0x00, 0x00, 0x00, // mov edi, 1
 		0xbe, 0xa2, 0x00, 0x40, 0x00, // mov esi, 0x4000a2
@@ -75,13 +77,14 @@ func (build *Build) Compile() []byte {
 		0xb8, 0x3c, 0x00, 0x00, 0x00, // mov eax, 60
 		0xbf, 0x00, 0x00, 0x00, 0x00, // mov edi, 0
 		0x0f, 0x05, // syscall
+	})
 
-		'H', 'e', 'l', 'l', 'o', '\n',
-	}
+	build.Data.Write([]byte{'H', 'e', 'l', 'l', 'o', '\n'})
+	return nil
 }
 
 // writeToDisk writes the executable file to disk.
-func writeToDisk(filePath string, code []byte) error {
+func writeToDisk(filePath string, code []byte, data []byte) error {
 	file, err := os.Create(filePath)
 
 	if err != nil {
@@ -89,7 +92,7 @@ func writeToDisk(filePath string, code []byte) error {
 	}
 
 	buffer := bufio.NewWriter(file)
-	executable := elf.New(code)
+	executable := elf.New(code, data)
 	executable.Write(buffer)
 	buffer.Flush()
 

build/elf/ELF64.go

@@ -10,16 +10,17 @@ const (
 	baseAddress = 0x40 * minAddress
 )
 
-// ELF64 represents an ELF 64-bit file.
-type ELF64 struct {
+// ELF represents an ELF file.
+type ELF struct {
 	Header
 	ProgramHeader
 	Code []byte
+	Data []byte
 }
 
-// New creates a new 64-bit ELF binary.
-func New(code []byte) *ELF64 {
-	elf := &ELF64{
+// New creates a new ELF binary.
+func New(code []byte, data []byte) *ELF {
+	elf := &ELF{
 		Header: Header{
 			Magic:                       [4]byte{0x7F, 'E', 'L', 'F'},
 			Class:                       2,
@@ -43,7 +44,7 @@ func New(code []byte) *ELF64 {
 		},
 		ProgramHeader: ProgramHeader{
 			Type:            ProgramTypeLOAD,
-			Flags:           ProgramFlagsExecutable | ProgramFlagsReadable,
+			Flags:           ProgramFlagsExecutable,
 			Offset:          0x80,
 			VirtualAddress:  baseAddress + 0x80,
 			PhysicalAddress: baseAddress + 0x80,
@@ -52,15 +53,17 @@ func New(code []byte) *ELF64 {
 			Align:           Align,
 		},
 		Code: code,
+		Data: data,
 	}
 
 	return elf
 }
 
 // Write writes the ELF64 format to the given writer.
-func (elf *ELF64) Write(writer io.Writer) {
+func (elf *ELF) Write(writer io.Writer) {
 	binary.Write(writer, binary.LittleEndian, &elf.Header)
 	binary.Write(writer, binary.LittleEndian, &elf.ProgramHeader)
 	writer.Write([]byte{0, 0, 0, 0, 0, 0, 0, 0})
 	writer.Write(elf.Code)
+	writer.Write(elf.Data)
 }