Function emitElf

src/e9patch/e9elf.cpp:448–820

* Emit the (modified) ELF binary. */

 * Emit the (modified) ELF binary.
 */
size_t emitElf(Binary *B, const MappingSet &mappings, size_t mapping_size)
{
    uint8_t *data = B->patched.bytes;
    size_t size = B->patched.size;

    // Step (0): Round-up to nearest page boundary (zero-fill)
    stat_input_file_size = size;
    size = (size % PAGE_SIZE == 0? size:
        size + PAGE_SIZE - (size % PAGE_SIZE));

    // Step (1): Refactor the patching (if necessary):
    RefactorSet refactors;
    size += emitRefactoredPatch(B->original.bytes, data, size, mapping_size,
        B->Is, refactors);
    
    // Step (2): Disable incompatible ELF features:
    ElfInfo &info = B->elf;
    if (info.features != nullptr)
    {
        if ((*info.features & GNU_PROPERTY_X86_FEATURE_1_IBT) != 0)
            *info.features &= ~GNU_PROPERTY_X86_FEATURE_1_IBT;
        if ((*info.features & GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0)
            *info.features &= ~GNU_PROPERTY_X86_FEATURE_1_SHSTK;
    }
 
    // Step (3): Emit all mappings:
    for (auto *mapping: mappings)
    {
        uint8_t *base = data + size;
        mapping->offset = (off_t)size;
        flattenMapping(B, base, mapping, /*int3=*/0xcc);
        size += mapping->size;
    }

    // Step (4): Emit the loader:
    size = (size % PAGE_SIZE == 0? size:
        size + PAGE_SIZE - (size % PAGE_SIZE));
    struct e9_config_s *config = (struct e9_config_s *)(data + size);
    size_t config_offset = size;
    size += sizeof(struct e9_config_s);
    struct e9_config_elf_s *config_elf =
        (struct e9_config_elf_s *)(data + size);
    size += sizeof(struct e9_config_elf_s);
    const char magic[] = "E9PATCH";
    memcpy(config->magic, magic, sizeof(magic));
    const char version[] = STRING(VERSION);
    static_assert(sizeof(version) <= sizeof(config->version),
        "VERSION string is too long");
    memcpy(config->version, version, sizeof(version));
    config->base = option_loader_base;
    if (B->mmap != INTPTR_MIN)
    {
        config->mmap  = BASE_ADDRESS(B->mmap);
        config->mmap |= (IS_ABSOLUTE(config->mmap)? E9_ABS_ADDR: 0);
    }
    std::vector<uint32_t> preinits, postinits;
    for (auto preinit: B->preinits)
    {