Function readLLVMCoverageMapping

src/Common/LLVMCoverageMapping.cpp:197–569

std::vector<CoverageRegion> readLLVMCoverageMapping(const char * binary_path)
{
    std::vector<CoverageRegion> result;

    const int fd = ::open(binary_path, O_RDONLY | O_CLOEXEC);
    if (fd < 0)
        return result;

    struct stat st;
    if (::fstat(fd, &st) < 0)
    {
        [[maybe_unused]] int err = ::close(fd);
        return result;
    }

    const size_t size = static_cast<size_t>(st.st_size);
    void * mapped = ::mmap(nullptr, size, PROT_READ, MAP_PRIVATE, fd, 0);
    [[maybe_unused]] int err = ::close(fd); /// mmap keeps the mapping valid after close
    if (mapped == MAP_FAILED)
        return result;

    const uint8_t * const base = static_cast<const uint8_t *>(mapped);

    auto cleanup = [&]
    {
        ::munmap(mapped, size);
    };

    /// Validate ELF magic and class (64-bit only).
    if (size < sizeof(Elf64_Ehdr)
        || memcmp(base, ELFMAG, SELFMAG) != 0
        || base[EI_CLASS] != ELFCLASS64)
    {
        cleanup();
        return result;
    }

    const Elf64_Ehdr * const elf = reinterpret_cast<const Elf64_Ehdr *>(base);

    if (elf->e_shoff == 0
        || elf->e_shstrndx == SHN_UNDEF
        || elf->e_shstrndx >= elf->e_shnum)
    {
        cleanup();
        return result;
    }

    /// Bounds check: verify section header table fits in the file.
    if (elf->e_shoff + static_cast<size_t>(elf->e_shnum) * sizeof(Elf64_Shdr) > size)
    {
        cleanup();
        return result;
    }

    const Elf64_Shdr * const shdrs =
        reinterpret_cast<const Elf64_Shdr *>(base + elf->e_shoff);

    /// Bounds check: verify the string table section offset is within the file.