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use alloc::fmt;
use core::convert::TryInto;
use core::str;
use crate::endian::{LittleEndian as LE, U32Bytes};
use crate::pe;
use crate::pod::{Bytes, Pod};
use crate::read::util::StringTable;
use crate::read::{
ReadError, Result, SectionIndex, Symbol, SymbolFlags, SymbolIndex, SymbolKind, SymbolScope,
SymbolSection,
};
#[derive(Debug)]
pub struct SymbolTable<'data> {
symbols: &'data [pe::ImageSymbolBytes],
strings: StringTable<'data>,
}
impl<'data> SymbolTable<'data> {
pub fn parse(header: &pe::ImageFileHeader, mut data: Bytes<'data>) -> Result<Self> {
let symbol_offset = header.pointer_to_symbol_table.get(LE) as usize;
let (symbols, strings) = if symbol_offset != 0 {
data.skip(symbol_offset)
.read_error("Invalid COFF symbol table offset")?;
let symbols = data
.read_slice(header.number_of_symbols.get(LE) as usize)
.read_error("Invalid COFF symbol table size")?;
let length = data
.read_at::<U32Bytes<_>>(0)
.read_error("Missing COFF string table")?
.get(LE);
let strings = data
.read_bytes(length as usize)
.read_error("Invalid COFF string table length")?;
(symbols, strings)
} else {
(&[][..], Bytes(&[]))
};
Ok(SymbolTable {
symbols,
strings: StringTable::new(strings),
})
}
#[inline]
pub fn strings(&self) -> StringTable<'data> {
self.strings
}
#[inline]
pub fn is_empty(&self) -> bool {
self.symbols.is_empty()
}
#[inline]
pub fn len(&self) -> usize {
self.symbols.len()
}
#[inline]
pub fn symbol(&self, index: usize) -> Option<&'data pe::ImageSymbol> {
self.get::<pe::ImageSymbol>(index)
}
pub fn get<T: Pod>(&self, index: usize) -> Option<&'data T> {
let bytes = self.symbols.get(index)?;
Bytes(&bytes.0[..]).read().ok()
}
}
impl pe::ImageSymbol {
pub fn name<'data>(&'data self, strings: StringTable<'data>) -> Result<&'data [u8]> {
if self.name[0] == 0 {
let offset = u32::from_le_bytes(self.name[4..8].try_into().unwrap());
strings
.get(offset)
.read_error("Invalid COFF symbol name offset")
} else {
Ok(match self.name.iter().position(|&x| x == 0) {
Some(end) => &self.name[..end],
None => &self.name[..],
})
}
}
}
pub struct CoffSymbolIterator<'data, 'file>
where
'data: 'file,
{
pub(crate) symbols: &'file SymbolTable<'data>,
pub(crate) index: usize,
}
impl<'data, 'file> fmt::Debug for CoffSymbolIterator<'data, 'file> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("CoffSymbolIterator").finish()
}
}
impl<'data, 'file> Iterator for CoffSymbolIterator<'data, 'file> {
type Item = (SymbolIndex, Symbol<'data>);
fn next(&mut self) -> Option<Self::Item> {
let index = self.index;
let symbol = self.symbols.get::<pe::ImageSymbol>(index)?;
self.index += 1 + symbol.number_of_aux_symbols as usize;
Some((
SymbolIndex(index),
parse_symbol(self.symbols, index, symbol),
))
}
}
pub(crate) fn parse_symbol<'data>(
symbols: &SymbolTable<'data>,
index: usize,
symbol: &'data pe::ImageSymbol,
) -> Symbol<'data> {
let value = symbol.value.get(LE);
let section_number = symbol.section_number.get(LE);
let name = if symbol.storage_class == pe::IMAGE_SYM_CLASS_FILE {
if symbol.number_of_aux_symbols > 0 {
symbols.symbols.get(index + 1).map(|s| {
match s.0.iter().position(|&x| x == 0) {
Some(end) => &s.0[..end],
None => &s.0[..],
}
})
} else {
None
}
} else {
symbol.name(symbols.strings()).ok()
};
let name = name.and_then(|s| str::from_utf8(s).ok());
let derived_kind = if symbol.derived_type() == pe::IMAGE_SYM_DTYPE_FUNCTION {
SymbolKind::Text
} else {
SymbolKind::Data
};
let mut flags = SymbolFlags::None;
let (kind, address, size) = match symbol.storage_class {
pe::IMAGE_SYM_CLASS_STATIC => {
if value == 0 && symbol.number_of_aux_symbols > 0 {
let mut size = 0;
if let Some(aux) = symbols.get::<pe::ImageAuxSymbolSection>(index + 1) {
size = u64::from(aux.length.get(LE));
let number = aux.number.get(LE) as usize;
flags = SymbolFlags::CoffSection {
selection: aux.selection,
associative_section: SectionIndex(number),
};
}
(SymbolKind::Section, 0, size)
} else {
(derived_kind, u64::from(value), 0)
}
}
pe::IMAGE_SYM_CLASS_EXTERNAL => {
if section_number == pe::IMAGE_SYM_UNDEFINED {
(derived_kind, 0, u64::from(value))
} else if symbol.derived_type() == pe::IMAGE_SYM_DTYPE_FUNCTION
&& symbol.number_of_aux_symbols > 0
{
let mut size = 0;
if let Some(aux) = symbols.get::<pe::ImageAuxSymbolFunction>(index + 1) {
size = u64::from(aux.total_size.get(LE));
}
(derived_kind, u64::from(value), size)
} else {
(derived_kind, u64::from(value), 0)
}
}
pe::IMAGE_SYM_CLASS_WEAK_EXTERNAL => (derived_kind, u64::from(value), 0),
pe::IMAGE_SYM_CLASS_SECTION => (SymbolKind::Section, 0, 0),
pe::IMAGE_SYM_CLASS_FILE => (SymbolKind::File, 0, 0),
pe::IMAGE_SYM_CLASS_LABEL => (SymbolKind::Label, u64::from(value), 0),
_ => {
(SymbolKind::Unknown, 0, 0)
}
};
let section = match section_number {
pe::IMAGE_SYM_UNDEFINED => {
if symbol.storage_class == pe::IMAGE_SYM_CLASS_EXTERNAL && value != 0 {
SymbolSection::Common
} else {
SymbolSection::Undefined
}
}
pe::IMAGE_SYM_ABSOLUTE => SymbolSection::Absolute,
pe::IMAGE_SYM_DEBUG => {
if symbol.storage_class == pe::IMAGE_SYM_CLASS_FILE {
SymbolSection::None
} else {
SymbolSection::Unknown
}
}
index if index > 0 => SymbolSection::Section(SectionIndex(index as usize - 1)),
_ => SymbolSection::Unknown,
};
let weak = symbol.storage_class == pe::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
let scope = match symbol.storage_class {
_ if section == SymbolSection::Undefined => SymbolScope::Unknown,
pe::IMAGE_SYM_CLASS_EXTERNAL | pe::IMAGE_SYM_CLASS_WEAK_EXTERNAL => {
SymbolScope::Linkage
}
_ => SymbolScope::Compilation,
};
Symbol {
name,
address,
size,
kind,
section,
weak,
scope,
flags,
}
}