Reorganized elf sections

src/elf/AddSections.go

@@ -1,19 +1,15 @@
 package elf
 
-import "bytes"
+import "strings"
 
 // 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:      int32(bytes.Index(elf.StringTable, []byte(".text\000"))),
+			NameIndex:      int32(strings.Index(StringTable, ".text\000")),
 			Type:           SectionTypePROGBITS,
 			Flags:          SectionFlagsAllocate | SectionFlagsExecutable,
 			VirtualAddress: elf.CodeHeader.VirtualAddress,
@@ -22,16 +18,25 @@ func (elf *ELF) AddSections() {
 			Align:          elf.CodeHeader.Align,
 		},
 		{
-			NameIndex:  int32(bytes.Index(elf.StringTable, []byte(".shstrtab\000"))),
+			NameIndex:      int32(strings.Index(StringTable, ".rodata\000")),
+			Type:           SectionTypePROGBITS,
+			Flags:          SectionFlagsAllocate,
+			VirtualAddress: elf.DataHeader.VirtualAddress,
+			Offset:         elf.DataHeader.Offset,
+			SizeInFile:     elf.DataHeader.SizeInFile,
+			Align:          elf.DataHeader.Align,
+		},
+		{
+			NameIndex:  int32(strings.Index(StringTable, ".shstrtab\000")),
 			Type:       SectionTypeSTRTAB,
-			Offset:     int64(stringTableStart),
+			Offset:     int64(StringTableStart),
-			SizeInFile: int64(len(elf.StringTable)),
+			SizeInFile: int64(len(StringTable)),
 			Align:      1,
 		},
 	}
 
 	elf.SectionHeaderEntrySize = SectionHeaderSize
 	elf.SectionHeaderEntryCount = int16(len(elf.SectionHeaders))
-	elf.SectionHeaderOffset = int64(sectionHeaderStart)
+	elf.SectionHeaderOffset = int64(SectionHeaderStart)
-	elf.SectionNameStringTableIndex = 2
+	elf.SectionNameStringTableIndex = int16(len(elf.SectionHeaders) - 1)
 }

src/elf/Constants.go

@@ -1,11 +1,15 @@
 package elf
 
 const (
-	LittleEndian      = 1
+	LittleEndian       = 1
-	TypeExecutable    = 2
+	TypeExecutable     = 2
-	TypeDynamic       = 3
+	TypeDynamic        = 3
-	ArchitectureAMD64 = 0x3E
+	ArchitectureAMD64  = 0x3E
-	ArchitectureARM64 = 0xB7
+	ArchitectureARM64  = 0xB7
-	ArchitectureRISCV = 0xF3
+	ArchitectureRISCV  = 0xF3
-	HeaderEnd         = HeaderSize + ProgramHeaderSize*2
+	StringTable        = "\000.text\000.rodata\000.shstrtab\000"
+	StringTableStart   = ProgramHeaderEnd
+	SectionHeaderStart = StringTableStart + len(StringTable)
+	ProgramHeaderEnd   = HeaderSize + ProgramHeaderSize*2
+	HeaderEnd          = ProgramHeaderEnd + len(StringTable) + 4*SectionHeaderSize
 )

src/elf/ELF.go

@@ -14,7 +14,6 @@ type ELF struct {
 	CodeHeader     ProgramHeader
 	DataHeader     ProgramHeader
 	SectionHeaders []SectionHeader
-	StringTable    []byte
 }
 
 // Write writes the ELF64 format to the given writer.
@@ -70,10 +69,10 @@ func Write(writer io.WriteSeeker, b *build.Build, codeBytes []byte, dataBytes []
 	binary.Write(writer, binary.LittleEndian, &elf.Header)
 	binary.Write(writer, binary.LittleEndian, &elf.CodeHeader)
 	binary.Write(writer, binary.LittleEndian, &elf.DataHeader)
+	writer.Write([]byte(StringTable))
+	binary.Write(writer, binary.LittleEndian, &elf.SectionHeaders)
 	writer.Seek(int64(code.Padding), io.SeekCurrent)
 	writer.Write(code.Bytes)
 	writer.Seek(int64(data.Padding), io.SeekCurrent)
 	writer.Write(data.Bytes)
-	writer.Write(elf.StringTable)
-	binary.Write(writer, binary.LittleEndian, &elf.SectionHeaders)
 }