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#include "ELFImage.h"
#include <AK/kstdio.h>
ELFImage::ELFImage(const byte* buffer)
: m_buffer(buffer)
{
m_valid = parse();
}
ELFImage::~ELFImage()
{
}
static const char* object_file_type_to_string(Elf32_Half type)
{
switch (type) {
case ET_NONE: return "None";
case ET_REL: return "Relocatable";
case ET_EXEC: return "Executable";
case ET_DYN: return "Shared object";
case ET_CORE: return "Core";
default: return "(?)";
}
}
const char* ELFImage::section_index_to_string(unsigned index)
{
if (index == SHN_UNDEF)
return "Undefined";
if (index >= SHN_LORESERVE)
return "Reserved";
return section(index).name();
}
unsigned ELFImage::symbol_count() const
{
return section(m_symbol_table_section_index).entry_count();
}
void ELFImage::dump()
{
kprintf("ELFImage{%p} {\n", this);
kprintf(" is_valid: %u\n", is_valid());
if (!is_valid()) {
kprintf("}\n");
return;
}
kprintf(" type: %s\n", object_file_type_to_string(header().e_type));
kprintf(" machine: %u\n", header().e_machine);
kprintf(" entry: %x\n", header().e_entry);
kprintf(" shoff: %u\n", header().e_shoff);
kprintf(" shnum: %u\n", header().e_shnum);
kprintf(" shstrndx: %u\n", header().e_shstrndx);
for (unsigned i = 0; i < header().e_shnum; ++i) {
auto& section = this->section(i);
kprintf(" Section %u: {\n", i);
kprintf(" name: %s\n", section.name());
kprintf(" type: %x\n", section.type());
kprintf(" offset: %x\n", section.offset());
kprintf(" size: %u\n", section.size());
kprintf(" \n");
kprintf(" }\n");
}
kprintf("Symbol count: %u (table is %u)\n", symbol_count(), m_symbol_table_section_index);
for (unsigned i = 1; i < symbol_count(); ++i) {
auto& sym = symbol(i);
kprintf("Symbol @%u:\n", i);
kprintf(" Name: %s\n", sym.name());
kprintf(" In section: %s\n", section_index_to_string(sym.section_index()));
kprintf(" Value: %x\n", sym.value());
kprintf(" Size: %u\n", sym.size());
}
kprintf("}\n");
}
unsigned ELFImage::section_count() const
{
return header().e_shnum;
}
unsigned ELFImage::program_header_count() const
{
return header().e_phnum;
}
bool ELFImage::parse()
{
// We only support i386.
if (header().e_machine != 3)
return false;
// First locate the string tables.
for (unsigned i = 0; i < section_count(); ++i) {
auto& sh = section_header(i);
if (sh.sh_type == SHT_SYMTAB) {
ASSERT(!m_symbol_table_section_index);
m_symbol_table_section_index = i;
}
if (sh.sh_type == SHT_STRTAB && i != header().e_shstrndx) {
ASSERT(!m_string_table_section_index);
m_string_table_section_index = i;
}
}
#ifdef SUPPORT_RELOCATIONS
// Then create a name-to-index map.
for (unsigned i = 0; i < section_count(); ++i) {
auto& section = this->section(i);
m_sections.set(section.name(), move(i));
}
#endif
return true;
}
const char* ELFImage::section_header_table_string(unsigned offset) const
{
auto& sh = section_header(header().e_shstrndx);
if (sh.sh_type != SHT_STRTAB)
return nullptr;
return raw_data(sh.sh_offset + offset);
}
const char* ELFImage::table_string(unsigned offset) const
{
auto& sh = section_header(m_string_table_section_index);
if (sh.sh_type != SHT_STRTAB)
return nullptr;
return raw_data(sh.sh_offset + offset);
}
const char* ELFImage::raw_data(unsigned offset) const
{
return reinterpret_cast<const char*>(m_buffer) + offset;
}
const Elf32_Ehdr& ELFImage::header() const
{
return *reinterpret_cast<const Elf32_Ehdr*>(raw_data(0));
}
const Elf32_Phdr& ELFImage::program_header_internal(unsigned index) const
{
ASSERT(index < header().e_phnum);
return *reinterpret_cast<const Elf32_Phdr*>(raw_data(header().e_phoff + (index * sizeof(Elf32_Phdr))));
}
const Elf32_Shdr& ELFImage::section_header(unsigned index) const
{
ASSERT(index < header().e_shnum);
return *reinterpret_cast<const Elf32_Shdr*>(raw_data(header().e_shoff + (index * sizeof(Elf32_Shdr))));
}
const ELFImage::Symbol ELFImage::symbol(unsigned index) const
{
ASSERT(index < symbol_count());
auto* raw_syms = reinterpret_cast<const Elf32_Sym*>(raw_data(section(m_symbol_table_section_index).offset()));
return Symbol(*this, index, raw_syms[index]);
}
const ELFImage::Section ELFImage::section(unsigned index) const
{
ASSERT(index < section_count());
return Section(*this, index);
}
const ELFImage::ProgramHeader ELFImage::program_header(unsigned index) const
{
ASSERT(index < program_header_count());
return ProgramHeader(*this, index);
}
#ifdef SUPPORT_RELOCATIONS
const ELFImage::Relocation ELFImage::RelocationSection::relocation(unsigned index) const
{
ASSERT(index < relocation_count());
auto* rels = reinterpret_cast<const Elf32_Rel*>(m_image.raw_data(offset()));
return Relocation(m_image, rels[index]);
}
const ELFImage::RelocationSection ELFImage::Section::relocations() const
{
// FIXME: This is ugly.
char relocation_sectionName[128];
ksprintf(relocation_sectionName, ".rel%s", name());
#ifdef ELFIMAGE_DEBUG
kprintf("looking for '%s'\n", relocation_sectionName);
#endif
auto relocation_section = m_image.lookup_section(relocation_sectionName);
if (relocation_section.type() != SHT_REL)
return static_cast<const RelocationSection>(m_image.section(0));
#ifdef ELFIMAGE_DEBUG
kprintf("Found relocations for %s in %s\n", name(), relocation_section.name());
#endif
return static_cast<const RelocationSection>(relocation_section);
}
const ELFImage::Section ELFImage::lookup_section(const char* name) const
{
if (auto it = m_sections.find(name); it != m_sections.end())
return section((*it).value);
return section(0);
}
#endif
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