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#![no_std]
pub mod header;
pub mod note;
pub mod program;
pub mod section;
pub mod symbol;
use crate::{
header::Header,
program::ProgramHeader,
section::{SectionHeader, SectionType},
symbol::Symbol,
};
use core::{marker::PhantomData, mem, str};
use scroll::{ctx::TryFromCtx, Pread};
#[derive(Debug)]
pub struct Elf<'a> {
bytes: &'a [u8],
header: Header,
symbol_table: Option<SectionHeader>,
}
impl Elf<'_> {
pub fn new<'a>(bytes: &'a [u8]) -> Result<Elf<'a>, ElfError> {
if bytes.len() < mem::size_of::<Header>() {
return Err(ElfError::TooShort);
}
let header = bytes.pread::<Header>(0).map_err(|_| ElfError::MalformedHeader)?;
header.validate()?;
let mut elf = Elf { bytes, header, symbol_table: None };
elf.sections().map(|section| section.validate()).collect::<Result<_, ElfError>>()?;
elf.segments().map(|segment| segment.validate()).collect::<Result<_, ElfError>>()?;
elf.symbol_table = match elf.sections().find(|section| section.name(&elf) == Some(".symtab")) {
Some(symbol_table) => {
if symbol_table.section_type() != SectionType::SymTab {
return Err(ElfError::InvalidSymbolTable);
}
Some(symbol_table)
}
None => None,
};
Ok(elf)
}
pub fn sections(&self) -> EntryIter<SectionHeader> {
let start = self.header.section_header_offset as usize;
let end = start
+ self.header.section_header_entry_size as usize * self.header.number_of_section_headers as usize;
EntryIter::new(
&self.bytes[start..end],
self.header.number_of_section_headers as u64,
self.header.section_header_entry_size as u64,
)
}
pub fn segments(&self) -> EntryIter<ProgramHeader> {
let start = self.header.program_header_offset as usize;
let end = start
+ self.header.program_header_entry_size as usize * self.header.number_of_program_headers as usize;
EntryIter::new(
&self.bytes[start..end],
self.header.number_of_program_headers as u64,
self.header.program_header_entry_size as u64,
)
}
pub fn symbols(&self) -> EntryIter<Symbol> {
match &self.symbol_table {
None => EntryIter::new(&[], 0, 0),
Some(ref symbol_table) => match symbol_table.data(&self) {
Some(data) => {
EntryIter::new(data, symbol_table.size / symbol_table.entry_size, symbol_table.entry_size)
}
None => EntryIter::new(&[], 0, 0),
},
}
}
pub fn entry_point(&self) -> usize {
self.header.entry_point as usize
}
}
#[derive(PartialEq, Eq, Debug)]
pub enum ElfError {
TooShort,
MalformedHeader,
IncorrectMagic,
SectionInvalidType,
InvalidSymbolTable,
SegmentInvalidType,
}
pub struct EntryIter<'a, T: TryFromCtx<'a, scroll::Endian, Error = scroll::Error>> {
bytes: &'a [u8],
current_index: u64,
num_entries: u64,
entry_size: u64,
_phantom: PhantomData<T>,
}
impl<'a, T> EntryIter<'a, T>
where
T: TryFromCtx<'a, scroll::Endian, Error = scroll::Error>,
{
pub(crate) fn new(bytes: &'a [u8], num_entries: u64, entry_size: u64) -> EntryIter<'a, T> {
EntryIter { bytes, current_index: 0, num_entries, entry_size, _phantom: PhantomData }
}
}
impl<'a, T> Iterator for EntryIter<'a, T>
where
T: TryFromCtx<'a, scroll::Endian, Error = scroll::Error>,
{
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
if self.current_index == self.num_entries {
return None;
}
let entry = self
.bytes
.pread::<T>((self.current_index * self.entry_size) as usize)
.expect("Failed to read table / header");
self.current_index += 1;
Some(entry)
}
}
pub(crate) fn from_utf8_null_terminated(bytes: &[u8]) -> Result<&str, str::Utf8Error> {
let null_terminator_index = bytes.iter().position(|&c| c == b'\0').unwrap_or(bytes.len());
str::from_utf8(&bytes[0..null_terminator_index])
}