// Emit the ELF header.
void ELFObjectWriter::writeHeader(const MCAssembler &Asm) {
// ELF Header
// ----------
//
// Note
// ----
// emitWord method behaves differently for ELF32 and ELF64, writing
// 4 bytes in the former and 8 in the latter.
writeBytes(ELF::ElfMagic); // e_ident[EI_MAG0] to e_ident[EI_MAG3]
write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
// e_ident[EI_DATA]
write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
// e_ident[EI_OSABI]
write8(TargetObjectWriter->getOSABI());
write8(0); // e_ident[EI_ABIVERSION]
WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
write16(ELF::ET_REL); // e_type
write16(TargetObjectWriter->getEMachine()); // e_machine = target
write32(ELF::EV_CURRENT); // e_version
WriteWord(0); // e_entry, no entry point in .o file
WriteWord(0); // e_phoff, no program header for .o
WriteWord(0); // e_shoff = sec hdr table off in bytes
// e_flags = whatever the target wants
write32(Asm.getELFHeaderEFlags());
// e_ehsize = ELF header size
write16(is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
write16(0); // e_phentsize = prog header entry size
write16(0); // e_phnum = # prog header entries = 0
// e_shentsize = Section header entry size
write16(is64Bit() ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
// e_shnum = # of section header ents
write16(0);
// e_shstrndx = Section # of '.shstrtab'
assert(StringTableIndex < ELF::SHN_LORESERVE);
write16(StringTableIndex);
}
