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https://github.com/Noratrieb/elven-forest.git
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This commit is contained in:
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fb0b512991
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03a4287bee
4 changed files with 228 additions and 31 deletions
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@ -5,7 +5,13 @@
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pub mod consts;
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use consts as c;
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use std::{ffi::CStr, fmt::Debug, mem, ops, slice::SliceIndex};
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use std::{
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ffi::CStr,
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fmt::Debug,
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mem,
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ops::{self},
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slice::SliceIndex,
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};
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use bytemuck::{Pod, PodCastError, Zeroable};
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@ -50,6 +56,8 @@ pub enum ElfParseError {
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IndexOutOfBounds(&'static str, usize),
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#[error("String in string table does not end with a nul terminator: String offset: {0}")]
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NoStringNulTerm(usize),
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#[error("The SHT_SYMTAB section was not found")]
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SymtabNotFound,
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}
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type Result<T> = std::result::Result<T, ElfParseError>;
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@ -82,13 +90,13 @@ pub struct ElfHeader {
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#[derive(Debug, Clone, Copy, Zeroable, Pod)]
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#[repr(C)]
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pub struct ElfIdent {
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magic: [u8; c::SELFMAG],
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class: u8,
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data: u8,
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version: u8,
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osabi: u8,
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abiversion: u8,
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_pad: [u8; 7],
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pub magic: [u8; c::SELFMAG],
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pub class: c::Class,
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pub data: c::Data,
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pub version: u8,
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pub osabi: c::OsAbi,
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pub abiversion: u8,
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pub _pad: [u8; 7],
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}
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const _: [u8; c::EI_NIDENT] = [0; mem::size_of::<ElfIdent>()];
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@ -121,6 +129,52 @@ pub struct Shdr {
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pub entsize: u64,
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}
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#[derive(Debug, Clone, Copy, Zeroable, Pod)]
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#[repr(C)]
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pub struct Sym {
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pub name: u32,
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pub info: u8,
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pub other: u8,
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pub shndx: u16,
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pub value: Addr,
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pub size: u64,
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}
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#[derive(Debug, Clone, Copy, Zeroable, Pod)]
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#[repr(C)]
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pub struct Rel {
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pub offset: Addr,
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pub info: RelInfo,
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}
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#[derive(Debug, Clone, Copy, Zeroable, Pod)]
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#[repr(C)]
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pub struct Rela {
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pub offset: Addr,
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pub info: RelInfo,
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pub addend: u64,
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}
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#[derive(Clone, Copy, Zeroable, Pod)]
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#[repr(transparent)]
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pub struct RelInfo(u64);
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impl RelInfo {
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pub fn sym(&self) -> u32 {
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(self.0 >> 32) as u32
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}
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pub fn r#type(&self) -> u32 {
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(self.0 & 0xffffffff) as u32
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}
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}
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impl Debug for RelInfo {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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write!(f, "{:?} @ {}", c::RX86_64(self.r#type()), self.sym())
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}
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}
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impl<'a> Elf<'a> {
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pub fn new(data: &'a [u8]) -> Result<Self> {
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let magic = data[..c::SELFMAG].try_into().unwrap();
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@ -141,6 +195,10 @@ impl<'a> Elf<'a> {
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pub fn program_headers(&self) -> Result<&[Phdr]> {
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let header = self.header()?;
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if header.phnum == 0 {
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return Ok(&[]);
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}
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let expected_ent_size = mem::size_of::<Phdr>();
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let actual_ent_size = usize::from(header.phentsize);
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if actual_ent_size != expected_ent_size {
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@ -160,6 +218,10 @@ impl<'a> Elf<'a> {
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pub fn section_headers(&self) -> Result<&[Shdr]> {
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let header = self.header()?;
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if header.shnum == 0 {
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return Ok(&[]);
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}
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let expected_ent_size = mem::size_of::<Shdr>();
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let actual_ent_size = usize::from(header.shentsize);
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if actual_ent_size != expected_ent_size {
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@ -222,6 +284,33 @@ impl<'a> Elf<'a> {
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.ok_or(ElfParseError::NoStringNulTerm(idx))?;
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Ok(CStr::from_bytes_with_nul(&indexed[..=end]).unwrap())
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}
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pub fn relas(&self) -> Result<impl Iterator<Item = (&Shdr, &Rela)>> {
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Ok(self
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.section_headers()?
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.iter()
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.filter(|sh| sh.r#type == c::SHT_RELA)
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.map(|sh| {
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let content = self.section_content(sh)?;
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let relas = load_slice::<Rela>(content, content.len() / mem::size_of::<Rela>())?;
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Ok((sh, relas))
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})
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.collect::<Result<Vec<_>>>()?
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.into_iter()
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.flat_map(|(sh, relas)| relas.iter().map(move |rela| (sh, rela))))
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}
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pub fn symbols(&self) -> Result<&[Sym]> {
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let sh = self
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.section_headers()?
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.iter()
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.find(|sh| sh.r#type == c::SHT_SYMTAB)
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.ok_or(ElfParseError::SymtabNotFound)?;
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let data = self.section_content(sh)?;
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load_slice(data, data.len() / mem::size_of::<Sym>())
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}
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}
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fn load_ref<T: Pod>(data: &[u8]) -> Result<&T> {
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@ -334,4 +423,34 @@ mod tests {
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Ok(())
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}
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#[test]
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fn c_hello_world_object() -> super::Result<()> {
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let file = load_test_file("hello_world_obj");
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let elf = Elf::new(&file)?;
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let header = elf.header()?;
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assert_eq!(header.ident.class, c::ELFCLASS64);
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assert_eq!(header.ident.data, c::ELFDATA2LSB);
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assert_eq!(header.ident.osabi, c::ELFOSABI_SYSV);
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assert_eq!(header.r#type, c::ET_REL);
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assert_eq!(header.entry, Addr(0));
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elf.program_headers()?;
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elf.section_headers()?;
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for sh in elf.section_headers()? {
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let name = elf.string(sh.name as usize)?.to_str().unwrap();
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println!("{name:20} {:5} {:?}", sh.size, sh.r#type);
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}
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println!("Relocations:");
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for (sh, rela) in elf.relas()? {
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let section_name = elf.string(sh.name as usize)?.to_str().unwrap();
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println!("{section_name:20} {:?}", rela);
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}
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Ok(())
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}
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}
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@ -22,10 +22,16 @@ macro_rules! const_group_with_fmt {
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$(
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$value => f.write_str(stringify!($name)),
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)*
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a => write!(f, "Invalid {}: {a}", $group_name,)
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a => write!(f, "Other {}: {a}", $group_name,)
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}
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}
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}
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impl PartialEq<$ty> for $struct_name {
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fn eq(&self, other: &$ty) -> bool {
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self.0 == *other
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}
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}
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};
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}
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@ -38,36 +44,48 @@ pub const ELFMAG: &[u8; SELFMAG] = b"\x7fELF";
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pub const SELFMAG: usize = 4;
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pub const EI_CLASS: usize = 4; /* File class byte index */
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pub const ELFCLASSNONE: u8 = 0; /* Invalid class */
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pub const ELFCLASS32: u8 = 1; /* 32-bit objects */
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pub const ELFCLASS64: u8 = 2; /* 64-bit objects */
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const_group_with_fmt! {
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pub struct Class(u8): "Class"
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pub const ELFCLASSNONE = 0; /* Invalid class */
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pub const ELFCLASS32 = 1; /* 32-bit objects */
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pub const ELFCLASS64 = 2; /* 64-bit objects */
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}
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pub const ELFCLASSNUM: u8 = 3;
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pub const EI_DATA: usize = 5; /* Data encoding byte index */
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pub const ELFDATANONE: u8 = 0; /* Invalid data encoding */
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pub const ELFDATA2LSB: u8 = 1; /* 2's complement, little endian */
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pub const ELFDATA2MSB: u8 = 2; /* 2's complement, big endian */
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const_group_with_fmt! {
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pub struct Data(u8): "Data"
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pub const ELFDATANONE = 0; /* Invalid data encoding */
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pub const ELFDATA2LSB = 1; /* 2's complement, little endian */
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pub const ELFDATA2MSB = 2; /* 2's complement, big endian */
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}
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pub const ELFDATANUM: u8 = 3;
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pub const EI_VERSION: usize = 6; /* File version byte index */
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pub const EI_OSABI: usize = 7; /* OS ABI identification */
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const_group_with_fmt! {
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pub struct OsAbi(u8): "OS ABI"
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pub const ELFOSABI_SYSV = 0; /* Alias. */
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pub const ELFOSABI_HPUX = 1; /* HP-UX */
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pub const ELFOSABI_NETBSD = 2; /* NetBSD. */
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pub const ELFOSABI_GNU = 3; /* Object uses GNU ELF extensions. */
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pub const ELFOSABI_SOLARIS = 6; /* Sun Solaris. */
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pub const ELFOSABI_AIX = 7; /* IBM AIX. */
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pub const ELFOSABI_IRIX = 8; /* SGI Irix. */
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pub const ELFOSABI_FREEBSD = 9; /* FreeBSD. */
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pub const ELFOSABI_TRU64 = 10; /* Compaq TRU64 UNIX. */
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pub const ELFOSABI_MODESTO = 11; /* Novell Modesto. */
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pub const ELFOSABI_OPENBSD = 12; /* OpenBSD. */
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pub const ELFOSABI_ARM_AEABI = 64; /* ARM EABI */
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pub const ELFOSABI_ARM = 97; /* ARM */
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pub const ELFOSABI_STANDALONE = 255; /* Standalone (embedded) application */
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}
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pub const ELFOSABI_NONE: u8 = 0; /* UNIX System V ABI */
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pub const ELFOSABI_SYSV: u8 = 0; /* Alias. */
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pub const ELFOSABI_HPUX: u8 = 1; /* HP-UX */
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pub const ELFOSABI_NETBSD: u8 = 2; /* NetBSD. */
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pub const ELFOSABI_GNU: u8 = 3; /* Object uses GNU ELF extensions. */
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pub const ELFOSABI_LINUX: u8 = ELFOSABI_GNU; /* Compatibility alias. */
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pub const ELFOSABI_SOLARIS: u8 = 6; /* Sun Solaris. */
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pub const ELFOSABI_AIX: u8 = 7; /* IBM AIX. */
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pub const ELFOSABI_IRIX: u8 = 8; /* SGI Irix. */
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pub const ELFOSABI_FREEBSD: u8 = 9; /* FreeBSD. */
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pub const ELFOSABI_TRU64: u8 = 10; /* Compaq TRU64 UNIX. */
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pub const ELFOSABI_MODESTO: u8 = 11; /* Novell Modesto. */
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pub const ELFOSABI_OPENBSD: u8 = 12; /* OpenBSD. */
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pub const ELFOSABI_ARM_AEABI: u8 = 64; /* ARM EABI */
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pub const ELFOSABI_ARM: u8 = 97; /* ARM */
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pub const ELFOSABI_STANDALONE: u8 = 255; /* Standalone (embedded) application */
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pub const ELFOSABI_LINUX: u8 = 3; /* Compatibility alias. */
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pub const EI_ABIVERSION: usize = 8; /* ABI version */
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@ -144,3 +162,52 @@ pub const SHT_LOOS: u32 = 0x60000000; /* Start OS-specific. */
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pub const SHT_LOSUNW: u32 = 0x6ffffffa; /* Sun-specific low bound. */
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pub const SHT_HISUNW: u32 = 0x6fffffff; /* Sun-specific high bound. */
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pub const SHT_HIOS: u32 = 0x6fffffff; /* End OS-specific type */
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const_group_with_fmt! {
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pub struct RX86_64(u32): "x86_64 Relocation type"
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pub const R_X86_64_NONE = 0; /* No reloc */
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pub const R_X86_64_64 = 1; /* Direct 64 bit */
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pub const R_X86_64_PC32 = 2; /* PC relative 32 bit signed */
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pub const R_X86_64_GOT32 = 3; /* 32 bit GOT entry */
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pub const R_X86_64_PLT32 = 4; /* 32 bit PLT address */
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pub const R_X86_64_COPY = 5; /* Copy symbol at runtime */
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pub const R_X86_64_GLOB_DAT = 6; /* Create GOT entry */
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pub const R_X86_64_JUMP_SLOT = 7; /* Create PLT entry */
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pub const R_X86_64_RELATIVE = 8; /* Adjust by program base */
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pub const R_X86_64_GOTPCREL = 9; /* 32 bit signed PC relative offset to GOT */
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pub const R_X86_64_32 = 10; /* Direct 32 bit zero extended */
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pub const R_X86_64_32S = 11; /* Direct 32 bit sign extended */
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pub const R_X86_64_16 = 12; /* Direct 16 bit zero extended */
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pub const R_X86_64_PC16 = 13; /* 16 bit sign extended pc relative */
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pub const R_X86_64_8 = 14; /* Direct 8 bit sign extended */
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pub const R_X86_64_PC8 = 15; /* 8 bit sign extended pc relative */
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pub const R_X86_64_DTPMOD64 = 16; /* ID of module containing symbol */
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pub const R_X86_64_DTPOFF64 = 17; /* Offset in module's TLS block */
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pub const R_X86_64_TPOFF64 = 18; /* Offset in initial TLS block */
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pub const R_X86_64_TLSGD = 19; /* 32 bit signed PC relative offset to two GOT entries for GD symbol */
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pub const R_X86_64_TLSLD = 20; /* 32 bit signed PC relative offset to two GOT entries for LD symbol */
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pub const R_X86_64_DTPOFF32 = 21; /* Offset in TLS block */
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pub const R_X86_64_GOTTPOFF = 22; /* 32 bit signed PC relative offset to GOT entry for IE symbol */
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pub const R_X86_64_TPOFF32 = 23; /* Offset in initial TLS block */
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pub const R_X86_64_PC64 = 24; /* PC relative 64 bit */
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pub const R_X86_64_GOTOFF64 = 25; /* 64 bit offset to GOT */
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pub const R_X86_64_GOTPC32 = 26; /* 32 bit signed pc relative offset to GOT */
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pub const R_X86_64_GOT64 = 27; /* 64-bit GOT entry offset */
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pub const R_X86_64_GOTPCREL64 = 28; /* 64-bit PC relative offset to GOT entry */
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pub const R_X86_64_GOTPC64 = 29; /* 64-bit PC relative offset to GOT */
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pub const R_X86_64_GOTPLT64 = 30; /* like GOT64, says PLT entry needed */
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pub const R_X86_64_PLTOFF64 = 31; /* 64-bit GOT relative offset to PLT entry */
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pub const R_X86_64_SIZE32 = 32; /* Size of symbol plus 32-bit addend */
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pub const R_X86_64_SIZE64 = 33; /* Size of symbol plus 64-bit addend */
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pub const R_X86_64_GOTPC32_TLSDESC = 34; /* GOT offset for TLS descriptor. */
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pub const R_X86_64_TLSDESC_CALL = 35; /* Marker for call through TLS descriptor. */
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pub const R_X86_64_TLSDESC = 36; /* TLS descriptor. */
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pub const R_X86_64_IRELATIVE = 37; /* Adjust indirectly by program base */
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pub const R_X86_64_RELATIVE64 = 38; /* 64-bit adjust by program base */
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/* 39 Reserved was R_X86_64_PC32_BND */
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/* 40 Reserved was R_X86_64_PLT32_BND */
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pub const R_X86_64_GOTPCRELX = 41; /* Load from 32 bit signed pc relative offset to GOT entry without REX prefix, relaxable. */
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pub const R_X86_64_REX_GOTPCRELX = 42; /* Load from 32 bit signed pc relative offset to GOT entry with REX prefix, relaxable. */
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pub const R_X86_64_NUM = 43;
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}
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@ -5,4 +5,9 @@ SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
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for rust_file in $SCRIPT_DIR/*.rs; do
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# Use -Cprefer-dynamic to keep the binary small
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rustc --edition 2021 "$rust_file" -Cprefer-dynamic -Copt-level=3 --out-dir="$SCRIPT_DIR/out"
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done
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done
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for c_obj_file in $SCRIPT_DIR/*_obj.c; do
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echo $c_obj_file
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cc "$c_obj_file" -c -o "$SCRIPT_DIR/out/$(basename $c_obj_file .c)"
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done
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6
test_data/hello_world_obj.c
Normal file
6
test_data/hello_world_obj.c
Normal file
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@ -0,0 +1,6 @@
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#include<stdio.h>
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int main(int argc, char **argv) {
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puts("Hello, World!");
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return 0;
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}
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