141 lines
3.4 KiB
C++
141 lines
3.4 KiB
C++
#include "ELF.h"
|
|
|
|
#include <cassert>
|
|
#include <cerrno>
|
|
#include <cstring>
|
|
#include <fcntl.h>
|
|
#include <iostream>
|
|
#include <sys/mman.h>
|
|
#include <unistd.h>
|
|
|
|
ELFFile::ELFFile(std::string_view path)
|
|
: m_path(path)
|
|
{
|
|
m_fd = open(m_path.c_str(), O_RDONLY);
|
|
if (m_fd == -1)
|
|
{
|
|
std::cerr << "Could not open '" << m_path << "': " << std::strerror(errno) << std::endl;
|
|
return;
|
|
}
|
|
|
|
if (fstat(m_fd, &m_stat) == -1)
|
|
{
|
|
std::cerr << "Could not stat '" << m_path << "': " << std::strerror(errno) << std::endl;
|
|
return;
|
|
}
|
|
|
|
void* mmap_addr = mmap(nullptr, m_stat.st_size, PROT_READ, MAP_PRIVATE, m_fd, 0);
|
|
if (mmap_addr == MAP_FAILED)
|
|
{
|
|
std::cerr << "Could not mmap '" << m_path << "': " << std::strerror(errno) << std::endl;
|
|
return;
|
|
}
|
|
m_mmap = reinterpret_cast<uint8_t*>(mmap_addr);
|
|
|
|
if (!validate_elf_header())
|
|
return;
|
|
|
|
m_success = true;
|
|
}
|
|
|
|
ELFFile::~ELFFile()
|
|
{
|
|
if (m_mmap)
|
|
munmap(m_mmap, m_stat.st_size);
|
|
m_mmap = nullptr;
|
|
|
|
if (m_fd != -1)
|
|
close(m_fd);
|
|
m_fd = -1;
|
|
}
|
|
|
|
const Elf64_Ehdr& ELFFile::elf_header() const
|
|
{
|
|
return *reinterpret_cast<Elf64_Ehdr*>(m_mmap);
|
|
}
|
|
|
|
bool ELFFile::validate_elf_header() const
|
|
{
|
|
if (m_stat.st_size < sizeof(Elf64_Ehdr))
|
|
{
|
|
std::cerr << m_path << " is too small to be a ELF executable" << std::endl;
|
|
return false;
|
|
}
|
|
|
|
const auto& elf_header = this->elf_header();
|
|
|
|
if (
|
|
elf_header.e_ident[EI_MAG0] != ELFMAG0 ||
|
|
elf_header.e_ident[EI_MAG1] != ELFMAG1 ||
|
|
elf_header.e_ident[EI_MAG2] != ELFMAG2 ||
|
|
elf_header.e_ident[EI_MAG3] != ELFMAG3
|
|
)
|
|
{
|
|
std::cerr << m_path << " doesn't have an ELF magic number" << std::endl;
|
|
return false;
|
|
}
|
|
|
|
if (elf_header.e_ident[EI_CLASS] != ELFCLASS64)
|
|
{
|
|
std::cerr << m_path << " is not 64 bit ELF" << std::endl;
|
|
return false;
|
|
}
|
|
|
|
if (elf_header.e_ident[EI_DATA] != ELFDATA2LSB)
|
|
{
|
|
std::cerr << m_path << " is not in little endian format" << std::endl;
|
|
return false;
|
|
}
|
|
|
|
if (elf_header.e_ident[EI_VERSION] != EV_CURRENT)
|
|
{
|
|
std::cerr << m_path << " has unsupported version" << std::endl;
|
|
return false;
|
|
}
|
|
|
|
if (elf_header.e_type != ET_EXEC)
|
|
{
|
|
std::cerr << m_path << " is not an executable ELF file" << std::endl;
|
|
return false;
|
|
}
|
|
|
|
if (elf_header.e_machine != EM_X86_64)
|
|
{
|
|
std::cerr << m_path << " is not an x86_64 ELF file" << std::endl;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
const Elf64_Shdr& ELFFile::section_header(std::size_t index) const
|
|
{
|
|
const auto& elf_header = this->elf_header();
|
|
assert(index < elf_header.e_shnum);
|
|
const uint8_t* section_array_start = m_mmap + elf_header.e_shoff;
|
|
return *reinterpret_cast<const Elf64_Shdr*>(section_array_start + index * elf_header.e_shentsize);
|
|
}
|
|
|
|
std::string_view ELFFile::section_name(const Elf64_Shdr& section_header) const
|
|
{
|
|
const auto& elf_header = this->elf_header();
|
|
assert(elf_header.e_shstrndx != SHN_UNDEF);
|
|
const auto& section_string_table = this->section_header(elf_header.e_shstrndx);
|
|
const char* string_table_start = reinterpret_cast<const char*>(m_mmap + section_string_table.sh_offset);
|
|
return string_table_start + section_header.sh_name;
|
|
}
|
|
|
|
std::optional<std::span<const uint8_t>> ELFFile::find_section(std::string_view name) const
|
|
{
|
|
const auto& elf_header = this->elf_header();
|
|
for (std::size_t i = 0; i < elf_header.e_shnum; i++)
|
|
{
|
|
const auto& section_header = this->section_header(i);
|
|
auto section_name = this->section_name(section_header);
|
|
if (section_name != name)
|
|
continue;
|
|
return std::span<const uint8_t>(m_mmap + section_header.sh_offset, section_header.sh_size);
|
|
}
|
|
return {};
|
|
}
|