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