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#include <map>
#include <memory>
#include <optional>
#include <set>
#include <stdexcept>
#include <string>
#include <vector>
#include "elf.h"
using FileContents = std::shared_ptr<std::vector<unsigned char>>;
#define ElfFileParams class Elf_Ehdr, class Elf_Phdr, class Elf_Shdr, class Elf_Addr, class Elf_Off, class Elf_Dyn, class Elf_Sym, class Elf_Verneed, class Elf_Versym
#define ElfFileParamNames Elf_Ehdr, Elf_Phdr, Elf_Shdr, Elf_Addr, Elf_Off, Elf_Dyn, Elf_Sym, Elf_Verneed, Elf_Versym
template<ElfFileParams>
class ElfFile
{
public:
const FileContents fileContents;
private:
std::vector<Elf_Phdr> phdrs;
std::vector<Elf_Shdr> shdrs;
bool littleEndian;
bool changed = false;
bool isExecutable = false;
using SectionName = std::string;
using ReplacedSections = std::map<SectionName, std::string>;
ReplacedSections replacedSections;
std::string sectionNames; /* content of the .shstrtab section */
/* Align on 4 or 8 bytes boundaries on 32- or 64-bit platforms
respectively. */
static constexpr size_t sectionAlignment = sizeof(Elf_Off);
std::vector<SectionName> sectionsByOldIndex;
public:
explicit ElfFile(FileContents fileContents);
[[nodiscard]] bool isChanged() const noexcept
{
return changed;
}
private:
struct CompPhdr
{
const ElfFile * elfFile;
bool operator ()(const Elf_Phdr & x, const Elf_Phdr & y) const noexcept
{
// A PHDR comes before everything else.
if (elfFile->rdi(y.p_type) == PT_PHDR) return false;
if (elfFile->rdi(x.p_type) == PT_PHDR) return true;
// Sort non-PHDRs by address.
return elfFile->rdi(x.p_paddr) < elfFile->rdi(y.p_paddr);
}
};
void sortPhdrs();
struct CompShdr
{
const ElfFile * elfFile;
bool operator ()(const Elf_Shdr & x, const Elf_Shdr & y) const noexcept
{
return elfFile->rdi(x.sh_offset) < elfFile->rdi(y.sh_offset);
}
};
[[nodiscard]] unsigned int getPageSize() const noexcept;
void sortShdrs();
void shiftFile(unsigned int extraPages, size_t sizeOffset, size_t extraBytes);
[[nodiscard]] std::string getSectionName(const Elf_Shdr & shdr) const;
Elf_Shdr & findSectionHeader(const SectionName & sectionName);
[[nodiscard]] std::optional<std::reference_wrapper<Elf_Shdr>> tryFindSectionHeader(const SectionName & sectionName);
[[nodiscard]] unsigned int getSectionIndex(const SectionName & sectionName) const;
std::string & replaceSection(const SectionName & sectionName,
unsigned int size);
[[nodiscard]] bool haveReplacedSection(const SectionName & sectionName) const;
void writeReplacedSections(Elf_Off & curOff,
Elf_Addr startAddr, Elf_Off startOffset);
void rewriteHeaders(Elf_Addr phdrAddress);
void rewriteSectionsLibrary();
void rewriteSectionsExecutable();
void normalizeNoteSegments();
public:
void rewriteSections(bool force = false);
[[nodiscard]] std::string getInterpreter();
typedef enum { printOsAbi, replaceOsAbi } osAbiMode;
void modifyOsAbi(osAbiMode op, const std::string & newOsAbi);
typedef enum { printSoname, replaceSoname } sonameMode;
void modifySoname(sonameMode op, const std::string & newSoname);
void setInterpreter(const std::string & newInterpreter);
typedef enum { rpPrint, rpShrink, rpSet, rpAdd, rpRemove } RPathOp;
void modifyRPath(RPathOp op, const std::vector<std::string> & allowedRpathPrefixes, std::string newRPath);
std::string shrinkRPath(char* rpath, std::vector<std::string> &neededLibs, const std::vector<std::string> & allowedRpathPrefixes);
void removeRPath(Elf_Shdr & shdrDynamic);
void addNeeded(const std::set<std::string> & libs);
void removeNeeded(const std::set<std::string> & libs);
void replaceNeeded(const std::map<std::string, std::string> & libs);
void printNeededLibs() /* should be const */;
void noDefaultLib();
void addDebugTag();
void clearSymbolVersions(const std::set<std::string> & syms);
enum class ExecstackMode { print, set, clear };
void modifyExecstack(ExecstackMode op);
private:
/* Convert an integer in big or little endian representation (as
specified by the ELF header) to this platform's integer
representation. */
template<class I>
constexpr I rdi(I i) const noexcept;
/* Convert back to the ELF representation. */
template<class I, class U>
constexpr inline I wri(I & t, U i) const
{
I val = static_cast<I>(i);
if (static_cast<U>(val) != i)
throw std::runtime_error { "value truncation" };
t = rdi(val);
return val;
}
[[nodiscard]] Elf_Ehdr *hdr() noexcept {
return reinterpret_cast<Elf_Ehdr *>(fileContents->data());
}
[[nodiscard]] const Elf_Ehdr *hdr() const noexcept {
return reinterpret_cast<const Elf_Ehdr *>(fileContents->data());
}
};
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