Flattened package hierarchy

src/elf/ELF.go

@@ -0,0 +1,82 @@
+package elf
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+
+	"git.akyoto.dev/cli/q/src/config"
+	"git.akyoto.dev/cli/q/src/exe"
+)
+
+// ELF represents an ELF file.
+type ELF struct {
+	Header
+	CodeHeader ProgramHeader
+	DataHeader ProgramHeader
+}
+
+// Write writes the ELF64 format to the given writer.
+func Write(writer io.Writer, code []byte, data []byte) {
+	const HeaderEnd = HeaderSize + ProgramHeaderSize*2
+
+	var (
+		codeStart, codePadding = exe.Align(HeaderEnd, config.Align)
+		dataStart, dataPadding = exe.Align(codeStart+len(code), config.Align)
+	)
+
+	elf := &ELF{
+		Header: Header{
+			Magic:                       [4]byte{0x7F, 'E', 'L', 'F'},
+			Class:                       2,
+			Endianness:                  LittleEndian,
+			Version:                     1,
+			OSABI:                       0,
+			ABIVersion:                  0,
+			Type:                        TypeExecutable,
+			Architecture:                ArchitectureAMD64,
+			FileVersion:                 1,
+			EntryPointInMemory:          config.BaseAddress + config.CodeOffset,
+			ProgramHeaderOffset:         HeaderSize,
+			SectionHeaderOffset:         0,
+			Flags:                       0,
+			Size:                        HeaderSize,
+			ProgramHeaderEntrySize:      ProgramHeaderSize,
+			ProgramHeaderEntryCount:     2,
+			SectionHeaderEntrySize:      0,
+			SectionHeaderEntryCount:     0,
+			SectionNameStringTableIndex: 0,
+		},
+		CodeHeader: ProgramHeader{
+			Type:            ProgramTypeLOAD,
+			Flags:           ProgramFlagsExecutable | ProgramFlagsReadable,
+			Offset:          config.CodeOffset,
+			VirtualAddress:  config.BaseAddress + config.CodeOffset,
+			PhysicalAddress: config.BaseAddress + config.CodeOffset,
+			SizeInFile:      int64(len(code)),
+			SizeInMemory:    int64(len(code)),
+			Align:           config.Align,
+		},
+		DataHeader: ProgramHeader{
+			Type:            ProgramTypeLOAD,
+			Flags:           ProgramFlagsReadable,
+			Offset:          int64(dataStart),
+			VirtualAddress:  int64(config.BaseAddress + dataStart),
+			PhysicalAddress: int64(config.BaseAddress + dataStart),
+			SizeInFile:      int64(len(data)),
+			SizeInMemory:    int64(len(data)),
+			Align:           config.Align,
+		},
+	}
+
+	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)
+
+	if len(data) > 0 {
+		writer.Write(bytes.Repeat([]byte{0x00}, dataPadding))
+		writer.Write(data)
+	}
+}