RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-07-25 00:57:43 +00:00
Code Issues Activity Actions

LibELF+LibC: Split ELFDynamicObject into a Loader + Object

Browse source 
Separate some responsibilities:

ELFDynamicLoader is responsible for loading elf binaries from disk and
performing relocations, calling init functions, and eventually calling
finalizer functions.

ELFDynamicObject is a helper class to parse the .dynamic section of an
elf binary, or the table of Elf32_Dyn entries at the _DYNAMIC symbol.
ELFDynamicObject now owns the helper classes for Relocations, Symbols,
Sections and the like that ELFDynamicLoader will use to perform
relocations and symbol lookup.

Because these new helpers are constructed from offsets into the .dynamic
section within the loaded .data section of the binary, we don't need the
ELFImage for nearly as much of the loading processes as we did before.
Therefore we can remove most of the extra DynamicXXX classes and just
keep the one that lets us find the location of _DYNAMIC in the new ELF.

And finally, since we changed the name of the class that dlopen/dlsym
care about, we need to compile/link and use the new ELFDynamicLoader
class in LibC.
This commit is contained in:
Andrew Kaster 2020-01-03 23:31:51 -05:00 • committed by Andreas Kling
parent 85b95f472d
commit 767f4c7421
8 changed files with 788 additions and 634 deletions
Download patch file Download diff file Expand all files Collapse all files

46
Libraries/LibELF/ELFImage.cpp
View file

@ -43,11 +43,6 @@ unsigned ELFImage::symbol_count() const
return section(m_symbol_table_section_index).entry_count();
}
unsigned ELFImage::dynamic_symbol_count() const
{
return section(m_dynamic_symbol_table_section_index).entry_count();
}
void ELFImage::dump() const
{
dbgprintf("ELFImage{%p} {\n", this);
@ -117,24 +112,11 @@ bool ELFImage::parse()
if (sh.sh_type == SHT_STRTAB && i != header().e_shstrndx) {
if (StringView(".strtab") == section_header_table_string(sh.sh_name))
m_string_table_section_index = i;
else if (StringView(".dynstr") == section_header_table_string(sh.sh_name))
m_dynamic_string_table_section_index = i;
else
ASSERT_NOT_REACHED();
}
if (sh.sh_type == SHT_DYNAMIC) {
ASSERT(!m_dynamic_section_index || m_dynamic_section_index == i);
m_dynamic_section_index = i;
}
if (sh.sh_type == SHT_DYNSYM) {
ASSERT(!m_dynamic_symbol_table_section_index || m_dynamic_symbol_table_section_index == i);
m_dynamic_symbol_table_section_index = i;
}
if (sh.sh_type == SHT_REL) {
if (StringView(".rel.dyn") == section_header_table_string(sh.sh_name)) {
m_dynamic_relocation_section_index = i;
}
}
}
// Then create a name-to-index map.
@ -162,14 +144,6 @@ const char* ELFImage::table_string(unsigned offset) const
return raw_data(sh.sh_offset + offset);
}
const char* ELFImage::dynamic_table_string(unsigned offset) const
{
auto& sh = section_header(m_dynamic_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;
@ -199,13 +173,6 @@ const ELFImage::Symbol ELFImage::symbol(unsigned index) const
return Symbol(*this, index, raw_syms[index]);
}
const ELFImage::DynamicSymbol ELFImage::dynamic_symbol(unsigned index) const
{
ASSERT(index < symbol_count());
auto* raw_syms = reinterpret_cast<const Elf32_Sym*>(raw_data(section(m_dynamic_symbol_table_section_index).offset()));
return DynamicSymbol(*this, index, raw_syms[index]);
}
const ELFImage::Section ELFImage::section(unsigned index) const
{
ASSERT(index < section_count());
@ -225,13 +192,6 @@ const ELFImage::Relocation ELFImage::RelocationSection::relocation(unsigned inde
return Relocation(m_image, rels[index]);
}
const ELFImage::DynamicRelocation ELFImage::DynamicRelocationSection::relocation(unsigned index) const
{
ASSERT(index < relocation_count());
auto* rels = reinterpret_cast<const Elf32_Rel*>(m_image.raw_data(offset()));
return DynamicRelocation(m_image, rels[index]);
}
const ELFImage::RelocationSection ELFImage::Section::relocations() const
{
// FIXME: This is ugly.
@ -263,9 +223,3 @@ const ELFImage::DynamicSection ELFImage::dynamic_section() const
ASSERT(is_dynamic());
return section(m_dynamic_section_index);
}
const ELFImage::DynamicRelocationSection ELFImage::dynamic_relocation_section() const
{
ASSERT(is_dynamic());
return section(m_dynamic_relocation_section_index);
}