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use std::{collections::HashMap, fs::OpenOptions};
use object::{
write::{Relocation, SectionId, StandardSection, Symbol, SymbolId, SymbolSection},
RelocationEncoding, RelocationFlags, RelocationKind, SymbolFlags, SymbolKind, SymbolScope,
};
use crate::{Decl, Link, ObjectError, Scope};
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
/// Enum which specifies the binary format
///
/// E.g: Coff for Windows
pub enum BinFormat {
Elf,
Coff,
Macho,
}
impl BinFormat {
/// Function which returns the native binary format
///
/// For any unknown os it returns elf
pub fn host() -> BinFormat {
if cfg!(target_os = "windows") {
BinFormat::Coff
} else if cfg!(target_os = "macos") {
BinFormat::Macho
} else {
BinFormat::Elf
}
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
/// Enum which specifies the architecture
pub enum Arch {
X86_64,
Arm,
Riscv32,
Riscv64,
Wasm32,
Wasm64,
Unknown,
}
impl Arch {
/// Returns the native architecture
pub fn host() -> Arch {
if cfg!(target_arch = "x86_64") {
Arch::X86_64
} else if cfg!(target_arch = "arm") {
Arch::Arm
} else if cfg!(target_arch = "riscv32") {
Arch::Riscv32
} else if cfg!(target_arch = "riscv64") {
Arch::Riscv64
} else if cfg!(target_arch = "wasm32") {
Arch::Wasm32
} else if cfg!(target_arch = "wasm64") {
Arch::Wasm32
} else {
Arch::Unknown
}
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
/// Enum which specifies the endiannes
pub enum Endian {
Litte,
Big,
}
impl Endian {
/// Returns the native endian
pub fn host() -> Endian {
if cfg!(target_endian = "big") {
Endian::Big
} else {
Endian::Litte
}
}
}
#[derive(Debug, Clone)]
/// A struct for building object files
pub struct ObjectBuilder {
decls: Vec<(String, Decl)>,
sym: HashMap<String, Vec<u8>>,
links: Vec<Link>,
outpath: String,
}
impl ObjectBuilder {
//// Returns empty instance of self
pub fn new(path: &str) -> Self {
Self {
decls: vec![],
sym: HashMap::new(),
links: vec![],
outpath: path.into(),
}
}
/// Adds a list of decls
pub fn decls(&mut self, decls: Vec<(&str, Decl)>) {
for decl in decls {
let decl = (decl.0.into(), decl.1);
self.decls.push(decl);
}
}
/// Adds a decl
pub fn add_decl(&mut self, name: &str, decl: Decl) {
self.decls.push((name.into(), decl));
}
/// Defines a symbol
pub fn define(&mut self, sym: &str, data: Vec<u8>) {
self.sym.insert(sym.into(), data);
}
/// Adds an link to the object file
pub fn link(&mut self, link: Link) {
self.links.push(link);
}
/// Writes all internaly saved symbols etc. to a object file
///
/// Args:
/// * `format` - specifes the binary format of the object file
/// * `arch` - specifes the architecture of the object file
/// * `endian` - specifes the endian of the object file
pub fn write(
&mut self,
format: BinFormat,
arch: Arch,
endian: Endian,
) -> Result<(), Box<dyn std::error::Error>> {
let file = OpenOptions::new()
.create(true)
.write(true)
.open(self.outpath.clone().to_owned())?;
let obj_format = match format {
BinFormat::Elf => object::BinaryFormat::Elf,
BinFormat::Coff => object::BinaryFormat::Coff,
BinFormat::Macho => object::BinaryFormat::MachO,
};
let obj_arch = match arch {
Arch::X86_64 => object::Architecture::X86_64,
Arch::Arm => object::Architecture::Arm,
Arch::Riscv32 => object::Architecture::Riscv32,
Arch::Riscv64 => object::Architecture::Riscv64,
Arch::Wasm32 => object::Architecture::Wasm32,
Arch::Wasm64 => object::Architecture::Wasm64,
Arch::Unknown => object::Architecture::Unknown,
};
let obj_endian = match endian {
Endian::Litte => object::Endianness::Little,
Endian::Big => object::Endianness::Big,
};
let mut obj = object::write::Object::new(obj_format, obj_arch, obj_endian);
obj.add_file_symbol(self.outpath.to_owned().into_bytes());
let mut ids: HashMap<String, SymbolId> = HashMap::new();
let mut funcs: HashMap<String, ((SectionId, u64), SymbolId)> = HashMap::new();
for decl in self.decls.iter() {
let name = &decl.0;
let decl = &decl.1;
// get type
match decl {
Decl::Data(s) => match s {
Scope::Import => {
ids.insert(
name.to_string(),
obj.add_symbol(Symbol {
name: name.as_bytes().into(),
value: 0,
size: 0,
kind: SymbolKind::Data,
scope: SymbolScope::Dynamic,
weak: false,
section: SymbolSection::Undefined,
flags: SymbolFlags::None,
}),
);
}
_ => {
let dat_opt = self.sym.get(&name.clone());
if dat_opt.is_none() {
return Err(Box::from(ObjectError::DeclWithoutSymbol));
}
let data = dat_opt.unwrap();
let scope;
if s.to_owned() == Scope::Export {
scope = SymbolScope::Linkage
} else {
scope = SymbolScope::Compilation
}
let (section, offset) = obj.add_subsection(
StandardSection::Data,
name.as_bytes().into(),
data,
16,
);
let symbol = obj.add_symbol(Symbol {
name: name.as_bytes().into(),
value: offset,
size: data.len() as u64,
kind: SymbolKind::Data,
scope: scope,
weak: false,
section: SymbolSection::Section(section),
flags: SymbolFlags::None,
});
funcs.insert(name.into(), ((section, offset), symbol));
}
},
Decl::Function(s) => match s {
Scope::Import => {
ids.insert(
name.to_string(),
obj.add_symbol(Symbol {
name: name.as_bytes().into(),
value: 0,
size: 0,
kind: SymbolKind::Text,
scope: SymbolScope::Dynamic,
weak: false,
section: SymbolSection::Undefined,
flags: SymbolFlags::None,
}),
);
}
_ => {
let dat_opt = self.sym.get(&name.clone());
if dat_opt.is_none() {
return Err(Box::from(ObjectError::DeclWithoutSymbol));
}
let scope;
if s.to_owned() == Scope::Export {
scope = SymbolScope::Linkage
} else {
scope = SymbolScope::Compilation
}
let data = dat_opt.unwrap();
let (section, offset) = obj.add_subsection(
StandardSection::Text,
name.as_bytes().into(),
data,
16,
);
let symbol = obj.add_symbol(Symbol {
name: name.as_bytes().into(),
value: offset,
size: data.len() as u64,
kind: SymbolKind::Text,
scope: scope,
weak: false,
section: SymbolSection::Section(section),
flags: SymbolFlags::None,
});
funcs.insert(name.into(), ((section, offset), symbol));
}
},
}
}
for link in self.links.iter() {
let link = link.to_owned();
let func_opt = funcs.get(&link.from);
if func_opt.is_none() {
return Err(Box::from(ObjectError::UnknownFunction(
link.from.to_owned(),
)));
}
let func = func_opt.unwrap();
let id = func.0 .0;
let off = func.0 .1;
let sym;
if funcs.contains_key(&link.to) {
sym = Some(funcs.get(&link.to).unwrap().1);
} else if ids.contains_key(&link.to) {
sym = Some(ids.get(&link.to).unwrap().to_owned());
} else {
return Err(Box::from(ObjectError::UnknownTargetSymbol(
link.to.to_owned(),
)));
}
obj.add_relocation(
id,
Relocation {
offset: off + link.at as u64,
symbol: sym.unwrap(),
addend: -4,
flags: RelocationFlags::Generic {
kind: RelocationKind::PltRelative,
encoding: RelocationEncoding::X86Branch,
size: 32,
},
},
)?;
}
obj.write_stream(file)?;
Ok(())
}
}