Method plan

src/os/linux/elf_core_stream.cpp:43–104

}

void ElfCoreStream::plan() {
    // Filter to readable, non-empty VMAs. No size cap any more — streaming
    // means a 5 GiB process produces a 5 GiB virtual file at zero RAM cost.
    std::vector<const Vma*> use;
    use.reserve(vmas_.size());
    for (auto& v : vmas_) {
        if (!v.readable()) continue;
        if (v.size() == 0) continue;
        use.push_back(&v);
    }

    // Layout: [Ehdr][N × Phdr][padding to kHdrAlign][segment 0 data][seg 1]…
    const std::size_t hdr_struct_size =
        sizeof(Elf64_Ehdr) + use.size() * sizeof(Elf64_Phdr);
    const std::size_t hdr_padded =
        (hdr_struct_size + (kHdrAlign - 1)) & ~(kHdrAlign - 1);

    header_blob_.assign(hdr_padded, 0);

    Elf64_Ehdr eh{};
    std::memcpy(eh.e_ident, "\x7f""ELF", 4);
    eh.e_ident[4]  = 2;   // ELFCLASS64
    eh.e_ident[5]  = 1;   // ELFDATA2LSB
    eh.e_ident[6]  = 1;   // EV_CURRENT
    eh.e_type      = ET_CORE;
    eh.e_machine   = EM_X86_64;
    eh.e_version   = 1;
    eh.e_phoff     = sizeof(Elf64_Ehdr);
    eh.e_ehsize    = sizeof(Elf64_Ehdr);
    eh.e_phentsize = sizeof(Elf64_Phdr);
    eh.e_phnum     = static_cast<u16>(use.size());
    std::memcpy(header_blob_.data(), &eh, sizeof(eh));

    Elf64_Phdr* phdrs = reinterpret_cast<Elf64_Phdr*>(
        header_blob_.data() + sizeof(Elf64_Ehdr));

    u64 file_off = hdr_padded;
    segs_.reserve(use.size());
    for (std::size_t i = 0; i < use.size(); ++i) {
        const Vma& v = *use[i];
        const u64 sz = v.size();

        Elf64_Phdr& ph = phdrs[i];
        std::memset(&ph, 0, sizeof(ph));
        ph.p_type   = PT_LOAD;
        ph.p_flags  = (v.executable() ? PF_X : 0) |
                      (v.writable()   ? PF_W : 0) |
                      (v.readable()   ? PF_R : 0);
        ph.p_offset = file_off;
        ph.p_vaddr  = v.vm_start;
        ph.p_paddr  = 0;
        ph.p_filesz = sz;
        ph.p_memsz  = sz;
        ph.p_align  = 0x1000;

        segs_.push_back({ file_off, sz, v.vm_start });
        file_off += sz;
    }