From 8b66c9588c5cac219f3785f0e7865f8a351672a8 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <admin@akyoto.dev>
Date: Tue, 17 Oct 2023 22:08:40 +0200
Subject: [PATCH] Added ELF program header

---
 build/Build.go      |  2 +-
 build/elf/Header.go |  1 +
 build/elf/elf.go    | 30 +++++++++++++++++++++++-------
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/build/Build.go b/build/Build.go
index 338c5be..0d0b156 100644
--- a/build/Build.go
+++ b/build/Build.go
@@ -58,7 +58,7 @@ func writeToDisk(filePath string, code []byte, data []byte) error {
 	}
 
 	buffer := bufio.NewWriter(file)
-	executable := elf.New()
+	executable := elf.New(code)
 	executable.Write(buffer)
 	buffer.Flush()
 
diff --git a/build/elf/Header.go b/build/elf/Header.go
index 672f065..bdb7e24 100644
--- a/build/elf/Header.go
+++ b/build/elf/Header.go
@@ -4,6 +4,7 @@ const (
 	LittleEndian      = 1
 	TypeExecutable    = 2
 	ArchitectureAMD64 = 0x3E
+	Align             = 16
 	HeaderSize        = 64
 )
 
diff --git a/build/elf/elf.go b/build/elf/elf.go
index 68f7bab..740ab77 100644
--- a/build/elf/elf.go
+++ b/build/elf/elf.go
@@ -6,18 +6,19 @@ import (
 )
 
 const (
-	baseAddress  = 0x400000
-	programAlign = 16
-	sectionAlign = 16
+	baseAddress = 0x10000
 )
 
 // ELF64 represents an ELF 64-bit file.
 type ELF64 struct {
 	Header
+	ProgramHeader
+	Padding []byte
+	Code    []byte
 }
 
 // New creates a new 64-bit ELF binary.
-func New() *ELF64 {
+func New(code []byte) *ELF64 {
 	elf := &ELF64{
 		Header: Header{
 			Magic:                       [4]byte{0x7F, 'E', 'L', 'F'},
@@ -29,17 +30,29 @@ func New() *ELF64 {
 			Type:                        TypeExecutable,
 			Architecture:                ArchitectureAMD64,
 			FileVersion:                 1,
-			EntryPointInMemory:          0,
+			EntryPointInMemory:          baseAddress + 0x80,
 			ProgramHeaderOffset:         HeaderSize,
-			SectionHeaderOffset:         0, // TODO
+			SectionHeaderOffset:         0,
 			Flags:                       0,
 			Size:                        HeaderSize,
 			ProgramHeaderEntrySize:      ProgramHeaderSize,
-			ProgramHeaderEntryCount:     0,
+			ProgramHeaderEntryCount:     1,
 			SectionHeaderEntrySize:      SectionHeaderSize,
 			SectionHeaderEntryCount:     0,
 			SectionNameStringTableIndex: 0,
 		},
+		ProgramHeader: ProgramHeader{
+			Type:            ProgramTypeLOAD,
+			Flags:           ProgramFlagsExecutable,
+			Offset:          0x80,
+			VirtualAddress:  baseAddress + 0x80,
+			PhysicalAddress: baseAddress + 0x80,
+			SizeInFile:      int64(len(code)),
+			SizeInMemory:    int64(len(code)),
+			Align:           Align,
+		},
+		Padding: []byte{0, 0, 0, 0, 0, 0, 0, 0},
+		Code:    code,
 	}
 
 	return elf
@@ -48,4 +61,7 @@ func New() *ELF64 {
 // Write writes the ELF64 format to the given writer.
 func (elf *ELF64) Write(writer io.Writer) {
 	binary.Write(writer, binary.LittleEndian, &elf.Header)
+	binary.Write(writer, binary.LittleEndian, &elf.ProgramHeader)
+	writer.Write(elf.Padding)
+	writer.Write(elf.Code)
 }