use alloc::fmt;
use alloc::vec::Vec;
use core::fmt::Debug;
use core::slice;
use crate::elf;
use crate::endian::{self, Endianness};
use crate::pod::Pod;
use crate::read::{
self, Error, Relocation, RelocationEncoding, RelocationKind, RelocationTarget, SymbolIndex,
};
use super::{ElfFile, FileHeader, SectionHeader, SectionTable};
#[derive(Debug)]
pub struct RelocationSections {
relocations: Vec<usize>,
}
impl RelocationSections {
pub fn parse<Elf: FileHeader>(
endian: Elf::Endian,
sections: &SectionTable<Elf>,
symbol_section: usize,
) -> read::Result<Self> {
let mut relocations = vec![0; sections.len()];
for (index, section) in sections.iter().enumerate().rev() {
let sh_type = section.sh_type(endian);
if sh_type == elf::SHT_REL || sh_type == elf::SHT_RELA {
let sh_link = section.sh_link(endian) as usize;
if sh_link != symbol_section {
continue;
}
let sh_info = section.sh_info(endian) as usize;
if sh_info == 0 {
continue;
}
if sh_info >= relocations.len() {
return Err(Error("Invalid ELF sh_info for relocation section"));
}
let next = relocations[sh_info];
relocations[sh_info] = index;
relocations[index] = next;
}
}
Ok(Self { relocations })
}
pub fn get(&self, index: usize) -> Option<usize> {
self.relocations.get(index).cloned().filter(|x| *x != 0)
}
}
pub(super) enum ElfRelaIterator<'data, Elf: FileHeader> {
Rel(slice::Iter<'data, Elf::Rel>),
Rela(slice::Iter<'data, Elf::Rela>),
}
impl<'data, Elf: FileHeader> ElfRelaIterator<'data, Elf> {
fn is_rel(&self) -> bool {
match self {
ElfRelaIterator::Rel(_) => true,
ElfRelaIterator::Rela(_) => false,
}
}
}
impl<'data, Elf: FileHeader> Iterator for ElfRelaIterator<'data, Elf> {
type Item = Elf::Rela;
fn next(&mut self) -> Option<Self::Item> {
match self {
ElfRelaIterator::Rel(ref mut i) => i.next().cloned().map(Self::Item::from),
ElfRelaIterator::Rela(ref mut i) => i.next().cloned(),
}
}
}
pub type ElfRelocationIterator32<'data, 'file, Endian = Endianness> =
ElfRelocationIterator<'data, 'file, elf::FileHeader32<Endian>>;
pub type ElfRelocationIterator64<'data, 'file, Endian = Endianness> =
ElfRelocationIterator<'data, 'file, elf::FileHeader64<Endian>>;
pub struct ElfRelocationIterator<'data, 'file, Elf>
where
'data: 'file,
Elf: FileHeader,
{
pub(super) section_index: usize,
pub(super) file: &'file ElfFile<'data, Elf>,
pub(super) relocations: Option<ElfRelaIterator<'data, Elf>>,
}
impl<'data, 'file, Elf: FileHeader> Iterator for ElfRelocationIterator<'data, 'file, Elf> {
type Item = (u64, Relocation);
fn next(&mut self) -> Option<Self::Item> {
let endian = self.file.endian;
loop {
if let Some(ref mut relocations) = self.relocations {
if let Some(reloc) = relocations.next() {
let mut encoding = RelocationEncoding::Generic;
let (kind, size) = match self.file.header.e_machine(endian) {
elf::EM_ARM => match reloc.r_type(endian) {
elf::R_ARM_ABS32 => (RelocationKind::Absolute, 32),
r_type => (RelocationKind::Elf(r_type), 0),
},
elf::EM_AARCH64 => match reloc.r_type(endian) {
elf::R_AARCH64_ABS64 => (RelocationKind::Absolute, 64),
elf::R_AARCH64_ABS32 => (RelocationKind::Absolute, 32),
elf::R_AARCH64_ABS16 => (RelocationKind::Absolute, 16),
elf::R_AARCH64_PREL64 => (RelocationKind::Relative, 64),
elf::R_AARCH64_PREL32 => (RelocationKind::Relative, 32),
elf::R_AARCH64_PREL16 => (RelocationKind::Relative, 16),
r_type => (RelocationKind::Elf(r_type), 0),
},
elf::EM_386 => match reloc.r_type(endian) {
elf::R_386_32 => (RelocationKind::Absolute, 32),
elf::R_386_PC32 => (RelocationKind::Relative, 32),
elf::R_386_GOT32 => (RelocationKind::Got, 32),
elf::R_386_PLT32 => (RelocationKind::PltRelative, 32),
elf::R_386_GOTOFF => (RelocationKind::GotBaseOffset, 32),
elf::R_386_GOTPC => (RelocationKind::GotBaseRelative, 32),
elf::R_386_16 => (RelocationKind::Absolute, 16),
elf::R_386_PC16 => (RelocationKind::Relative, 16),
elf::R_386_8 => (RelocationKind::Absolute, 8),
elf::R_386_PC8 => (RelocationKind::Relative, 8),
r_type => (RelocationKind::Elf(r_type), 0),
},
elf::EM_X86_64 => match reloc.r_type(endian) {
elf::R_X86_64_64 => (RelocationKind::Absolute, 64),
elf::R_X86_64_PC32 => (RelocationKind::Relative, 32),
elf::R_X86_64_GOT32 => (RelocationKind::Got, 32),
elf::R_X86_64_PLT32 => (RelocationKind::PltRelative, 32),
elf::R_X86_64_GOTPCREL => (RelocationKind::GotRelative, 32),
elf::R_X86_64_32 => (RelocationKind::Absolute, 32),
elf::R_X86_64_32S => {
encoding = RelocationEncoding::X86Signed;
(RelocationKind::Absolute, 32)
}
elf::R_X86_64_16 => (RelocationKind::Absolute, 16),
elf::R_X86_64_PC16 => (RelocationKind::Relative, 16),
elf::R_X86_64_8 => (RelocationKind::Absolute, 8),
elf::R_X86_64_PC8 => (RelocationKind::Relative, 8),
r_type => (RelocationKind::Elf(r_type), 0),
},
_ => (RelocationKind::Elf(reloc.r_type(endian)), 0),
};
let target =
RelocationTarget::Symbol(SymbolIndex(reloc.r_sym(endian) as usize));
return Some((
reloc.r_offset(endian).into(),
Relocation {
kind,
encoding,
size,
target,
addend: reloc.r_addend(endian).into(),
implicit_addend: relocations.is_rel(),
},
));
}
}
self.section_index = self.file.relocations.get(self.section_index)?;
let section = self.file.sections.section(self.section_index).unwrap();
match section.sh_type(endian) {
elf::SHT_REL => {
if let Ok(relocations) = section.data_as_array(endian, self.file.data) {
self.relocations = Some(ElfRelaIterator::Rel(relocations.iter()));
}
}
elf::SHT_RELA => {
if let Ok(relocations) = section.data_as_array(endian, self.file.data) {
self.relocations = Some(ElfRelaIterator::Rela(relocations.iter()));
}
}
_ => {}
}
}
}
}
impl<'data, 'file, Elf: FileHeader> fmt::Debug for ElfRelocationIterator<'data, 'file, Elf> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("ElfRelocationIterator").finish()
}
}
#[allow(missing_docs)]
pub trait Rela: Debug + Pod + Clone {
type Word: Into<u64>;
type Sword: Into<i64>;
type Endian: endian::Endian;
fn r_offset(&self, endian: Self::Endian) -> Self::Word;
fn r_info(&self, endian: Self::Endian) -> Self::Word;
fn r_addend(&self, endian: Self::Endian) -> Self::Sword;
fn r_sym(&self, endian: Self::Endian) -> u32;
fn r_type(&self, endian: Self::Endian) -> u32;
}
impl<Endian: endian::Endian> Rela for elf::Rela32<Endian> {
type Word = u32;
type Sword = i32;
type Endian = Endian;
#[inline]
fn r_offset(&self, endian: Self::Endian) -> Self::Word {
self.r_offset.get(endian)
}
#[inline]
fn r_info(&self, endian: Self::Endian) -> Self::Word {
self.r_info.get(endian)
}
#[inline]
fn r_addend(&self, endian: Self::Endian) -> Self::Sword {
self.r_addend.get(endian)
}
#[inline]
fn r_sym(&self, endian: Self::Endian) -> u32 {
self.r_sym(endian)
}
#[inline]
fn r_type(&self, endian: Self::Endian) -> u32 {
self.r_type(endian)
}
}
impl<Endian: endian::Endian> Rela for elf::Rela64<Endian> {
type Word = u64;
type Sword = i64;
type Endian = Endian;
#[inline]
fn r_offset(&self, endian: Self::Endian) -> Self::Word {
self.r_offset.get(endian)
}
#[inline]
fn r_info(&self, endian: Self::Endian) -> Self::Word {
self.r_info.get(endian)
}
#[inline]
fn r_addend(&self, endian: Self::Endian) -> Self::Sword {
self.r_addend.get(endian)
}
#[inline]
fn r_sym(&self, endian: Self::Endian) -> u32 {
self.r_sym(endian)
}
#[inline]
fn r_type(&self, endian: Self::Endian) -> u32 {
self.r_type(endian)
}
}