Added optional section headers

src/elf/AddSections.go

@@ -0,0 +1,35 @@
+package elf
+
+// AddSections adds section headers to the ELF file.
+func (elf *ELF) AddSections() {
+	elf.StringTable = []byte("\000.text\000.shstrtab\000")
+	stringTableStart := elf.DataHeader.Offset + elf.DataHeader.SizeInFile
+	sectionHeaderStart := stringTableStart + int64(len(elf.StringTable))
+
+	elf.SectionHeaders = []SectionHeader{
+		{
+			Type: SectionTypeNULL,
+		},
+		{
+			NameIndex:      1,
+			Type:           SectionTypePROGBITS,
+			Flags:          SectionFlagsAllocate | SectionFlagsExecutable,
+			VirtualAddress: elf.CodeHeader.VirtualAddress,
+			Offset:         elf.CodeHeader.Offset,
+			SizeInFile:     elf.CodeHeader.SizeInFile,
+			Align:          elf.CodeHeader.Align,
+		},
+		{
+			NameIndex:  7,
+			Type:       SectionTypeSTRTAB,
+			Offset:     int64(stringTableStart),
+			SizeInFile: int64(len(elf.StringTable)),
+			Align:      1,
+		},
+	}
+
+	elf.SectionHeaderEntrySize = SectionHeaderSize
+	elf.SectionHeaderEntryCount = int16(len(elf.SectionHeaders))
+	elf.SectionHeaderOffset = int64(sectionHeaderStart)
+	elf.SectionNameStringTableIndex = 2
+}

src/elf/ELF.go

@@ -14,8 +14,10 @@ const HeaderEnd = HeaderSize + ProgramHeaderSize*2
 // ELF represents an ELF file.
 type ELF struct {
 	Header
-	CodeHeader ProgramHeader
-	DataHeader ProgramHeader
+	CodeHeader     ProgramHeader
+	DataHeader     ProgramHeader
+	SectionHeaders []SectionHeader
+	StringTable    []byte
 }
 
 // Write writes the ELF64 format to the given writer.
@@ -77,14 +79,20 @@ func Write(writer io.Writer, code []byte, data []byte) {
 		},
 	}
 
+	if config.Sections {
+		elf.AddSections()
+	}
+
 	binary.Write(writer, binary.LittleEndian, &elf.Header)
 	binary.Write(writer, binary.LittleEndian, &elf.CodeHeader)
 	binary.Write(writer, binary.LittleEndian, &elf.DataHeader)
 	writer.Write(bytes.Repeat([]byte{0x00}, codePadding))
 	writer.Write(code)
+	writer.Write(bytes.Repeat([]byte{0x00}, dataPadding))
+	writer.Write(data)
 
-	if len(data) > 0 {
-		writer.Write(bytes.Repeat([]byte{0x00}, dataPadding))
-		writer.Write(data)
+	if config.Sections {
+		writer.Write(elf.StringTable)
+		binary.Write(writer, binary.LittleEndian, &elf.SectionHeaders)
 	}
 }