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-rw-r--r--src/elf.rs120
1 files changed, 57 insertions, 63 deletions
diff --git a/src/elf.rs b/src/elf.rs
index 033910a..4fe2759 100644
--- a/src/elf.rs
+++ b/src/elf.rs
@@ -1,7 +1,7 @@
// basic ELF types and constants
-use std::{io, mem, fmt};
use io::{BufRead, Seek};
+use std::{fmt, io, mem};
pub trait ToBytes<const N: usize> {
fn to_bytes(self) -> [u8; N];
@@ -11,8 +11,6 @@ pub trait FromBytes<const N: usize> {
fn from_bytes(bytes: [u8; N]) -> Self;
}
-// @TODO: make all of these constants private
-
// executable type
pub const ET_REL: u16 = 1;
pub const ET_EXEC: u16 = 2;
@@ -40,9 +38,7 @@ pub const PT_INTERP: u32 = 3;
pub const SHT_PROGBITS: u32 = 1; // Program data
pub const SHT_SYMTAB: u32 = 2; // Symbol table
-//pub const SHT_STRTAB: u32 = 3; // String table
pub const SHT_RELA: u32 = 4; // Relocation entries with addends
-//pub const SHT_DYNAMIC: u32 = 6; // Dynamic linking information
pub const SHT_NOBITS: u32 = 8; // Program space with no data (bss)
pub const SHT_REL: u32 = 9; // Relocation entries, no addends
@@ -227,7 +223,6 @@ pub enum Error {
NoStrtab,
}
-
impl From<io::Error> for Error {
fn from(e: io::Error) -> Error {
Error::IO(e)
@@ -278,7 +273,7 @@ fn bytes_to_string(bytes: Vec<u8>) -> Result<String> {
String::from_utf8(bytes).map_err(|_| Error::BadUtf8)
}
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum Machine {
X86,
Amd64,
@@ -296,14 +291,14 @@ impl From<u16> for Machine {
}
}
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum SectionType {
ProgBits,
NoBits,
Rel,
Rela,
Symtab,
- Other(u32)
+ Other(u32),
}
impl From<u32> for SectionType {
@@ -320,11 +315,11 @@ impl From<u32> for SectionType {
}
}
-#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum Type {
Rel,
Exec,
- Other(u16)
+ Other(u16),
}
impl From<u16> for Type {
@@ -338,12 +333,12 @@ impl From<u16> for Type {
}
}
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum SymbolBind {
Global,
Weak,
Local,
- Other(u8)
+ Other(u8),
}
impl From<u8> for SymbolBind {
@@ -358,12 +353,12 @@ impl From<u8> for SymbolBind {
}
}
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum SymbolType {
Function,
Object,
Section,
- Other(u8)
+ Other(u8),
}
impl From<u8> for SymbolType {
@@ -403,8 +398,8 @@ pub enum RelType {
impl RelType {
fn from_u8(id: u8, machine: Machine) -> Self {
- use RelType::*;
use Machine::*;
+ use RelType::*;
match (machine, id) {
(X86, 1) => Direct32,
(X86, 2) => Pc32,
@@ -422,7 +417,6 @@ impl RelType {
}
}
-
pub struct Relocation {
pub r#type: RelType,
pub entry_offset: u64, // file offset of relocation metadata (for debugging)
@@ -431,7 +425,10 @@ pub struct Relocation {
pub addend: i64,
}
-pub trait Reader where Self: Sized {
+pub trait Reader
+where
+ Self: Sized,
+{
fn new<T: BufRead + Seek>(reader: T) -> Result<Self>;
fn r#type(&self) -> Type;
fn machine(&self) -> Machine;
@@ -466,11 +463,11 @@ impl Reader32LE {
impl Reader for Reader32LE {
fn new<T: BufRead + Seek>(mut reader: T) -> Result<Self> {
use Error::*;
-
+
let mut hdr_buf = [0; 0x34];
reader.read_exact(&mut hdr_buf)?;
let ehdr = Ehdr32::from_bytes(hdr_buf);
-
+
if ehdr.ident != [0x7f, b'E', b'L', b'F'] {
return Err(NotAnElf);
}
@@ -480,29 +477,27 @@ impl Reader for Reader32LE {
if ehdr.version != 1 || ehdr.version2 != 1 {
return Err(BadVersion);
}
-
+
let mut shdrs = Vec::with_capacity(ehdr.shnum.into());
for i in 0..ehdr.shnum {
let offset = u64::from(ehdr.shoff) + u64::from(ehdr.shentsize) * u64::from(i);
reader.seek(io::SeekFrom::Start(offset))?;
let mut shdr_buf = [0; 0x28];
reader.read_exact(&mut shdr_buf)?;
- shdrs.push(Shdr32::from_bytes(shdr_buf));
+ shdrs.push(Shdr32::from_bytes(shdr_buf));
}
-
+
let mut symtabs = Vec::with_capacity(ehdr.shnum.into());
let mut symbols = vec![];
let mut section_data = Vec::with_capacity(ehdr.shnum.into());
let mut strtab_idx = None;
-
-
-
+
for (s_idx, shdr) in shdrs.iter().enumerate() {
let mut data = vec![0; shdr.size as usize];
reader.seek(io::SeekFrom::Start(shdr.offset.into()))?;
reader.read_exact(&mut data)?;
section_data.push(data);
-
+
if let Some(shstrhdr) = shdrs.get(ehdr.shstrndx as usize) {
// get name
reader.seek(io::SeekFrom::Start(
@@ -512,14 +507,12 @@ impl Reader for Reader32LE {
reader.read_until(0, &mut bytes)?;
bytes.pop(); // remove terminating \0
let name = bytes_to_string(bytes)?;
-
+
if name == ".strtab" {
strtab_idx = Some(s_idx as u16);
}
}
-
-
-
+
let mut symtab = vec![];
if shdr.r#type == SHT_SYMTAB && shdr.entsize as usize >= mem::size_of::<Sym32>() {
// read symbol table
@@ -532,7 +525,7 @@ impl Reader for Reader32LE {
let r#type = (sym.info & 0xf).into();
let bind = (sym.info >> 4).into();
let mut size = sym.size.into();
-
+
let value = match sym.shndx {
SHN_UNDEF => SymbolValue::Undefined,
SHN_ABS => SymbolValue::Absolute(sym.value.into()),
@@ -544,11 +537,10 @@ impl Reader for Reader32LE {
size = shdrs[idx as usize].size.into();
}
SymbolValue::SectionOffset(idx, sym.value.into())
- },
+ }
x => return Err(BadSymShNdx(x)),
};
-
-
+
let symbol = Symbol {
name: sym.name.into(),
value,
@@ -558,11 +550,11 @@ impl Reader for Reader32LE {
};
symtab.push(symbols.len());
symbols.push(symbol);
- }
+ }
}
symtabs.push(symtab);
}
-
+
// read relocations
let mut relocations = vec![];
for shdr in shdrs.iter() {
@@ -571,21 +563,20 @@ impl Reader for Reader32LE {
continue;
}
let is_rela = r#type == SHT_RELA;
-
+
if shdr.entsize < 8 {
continue;
}
let count = shdr.size / shdr.entsize;
-
+
reader.seek(io::SeekFrom::Start(shdr.offset.into()))?;
-
+
let my_symbols = symtabs.get(shdr.link as usize).ok_or(BadLink(shdr.link))?;
for r_idx in 0..count {
-
let info;
let mut offset;
let addend;
-
+
if is_rela {
let mut rela_buf = [0; 12];
reader.read_exact(&mut rela_buf)?;
@@ -601,20 +592,20 @@ impl Reader for Reader32LE {
offset = rel.offset;
addend = 0;
};
-
-
+
if ehdr.r#type == ET_REL {
// rel.offset is relative to section
if let Some(info_hdr) = shdrs.get(shdr.info as usize) {
offset += info_hdr.offset;
}
}
-
-
+
let sym_idx = info >> 8;
- let symbols_idx = my_symbols.get(sym_idx as usize).ok_or(BadSymIndex(sym_idx.into()))?;
+ let symbols_idx = my_symbols
+ .get(sym_idx as usize)
+ .ok_or_else(|| BadSymIndex(sym_idx.into()))?;
let symbol = &symbols[*symbols_idx];
-
+
relocations.push(Relocation {
r#type: RelType::from_u8(info as u8, ehdr.machine.into()),
entry_offset: shdr.offset as u64 + r_idx as u64 * shdr.entsize as u64,
@@ -624,37 +615,37 @@ impl Reader for Reader32LE {
});
}
}
-
+
Ok(Self {
ehdr,
shdrs,
symbols,
strtab_idx,
relocations,
- section_data
+ section_data,
})
}
-
+
fn r#type(&self) -> Type {
self.ehdr.r#type.into()
}
-
+
fn machine(&self) -> Machine {
self.ehdr.machine.into()
}
-
+
fn entry(&self) -> u64 {
self.ehdr.entry.into()
}
-
+
fn relocations(&self) -> &[Relocation] {
&self.relocations
}
-
+
fn symbols(&self) -> &[Symbol] {
&self.symbols
}
-
+
fn symbol_name(&self, sym: &Symbol) -> Result<String> {
let strtab = &self.section_data[self.strtab_idx.ok_or(Error::NoStrtab)? as usize];
let i = sym.name as usize;
@@ -662,23 +653,26 @@ impl Reader for Reader32LE {
while end < strtab.len() && strtab[end] != b'\0' {
end += 1;
}
- bytes_to_string((&strtab[i..end]).to_vec())
+ bytes_to_string(strtab[i..end].to_vec())
}
-
+
fn section_type(&self, idx: u16) -> Option<SectionType> {
self.shdrs.get(idx as usize).map(|shdr| shdr.r#type.into())
}
-
+
fn read_section_data_exact(&self, idx: u16, offset: u64, data: &mut [u8]) -> Result<()> {
- let section = self.section_data.get(usize::from(idx)).ok_or(Error::BadSectionIndex(idx))?;
+ let section = self
+ .section_data
+ .get(usize::from(idx))
+ .ok_or(Error::BadSectionIndex(idx))?;
if offset + data.len() as u64 > section.len() as u64 {
return Err(Error::IO(io::Error::from(io::ErrorKind::UnexpectedEof)));
}
-
+
let offset = offset as usize;
-
+
data.copy_from_slice(&section[offset..offset + data.len()]);
-
+
Ok(())
}
}
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-01 12:45:09 +0000